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Article

Acinetobacter Non-baumannii Species: Occurrence in Infections in Hospitalized Patients, Identification, and Antibiotic Resistance

by
Eugene Sheck
1,
Andrey Romanov
1,
Valeria Shapovalova
1,
Elvira Shaidullina
1,
Alexey Martinovich
1,
Natali Ivanchik
1,
Anna Mikotina
1,
Elena Skleenova
1,
Vladimir Oloviannikov
1,
Ilya Azizov
1,
Vera Vityazeva
2,
Alyona Lavrinenko
3,
Roman Kozlov
1 and
Mikhail Edelstein
1,*
1
Institute of Antimicrobial Chemotherapy, Smolensk State Medical University, 214019 Smolensk, Russia
2
Republican Children’s Hospital, 185000 Petrozavodsk, Republic of Karelia, Russia
3
Shared Resource Laboratory, Karaganda Medical University, 100008 Karaganda, Kazakhstan
*
Author to whom correspondence should be addressed.
Antibiotics 2023, 12(8), 1301; https://doi.org/10.3390/antibiotics12081301
Submission received: 17 July 2023 / Revised: 5 August 2023 / Accepted: 7 August 2023 / Published: 9 August 2023
(This article belongs to the Special Issue Molecular Detection, Characterization, Antimicrobial Resistance and Genomic Epidemiology of Pathogenic Bacteria)
Browse Figure
Review Reports Versions Notes

Abstract

:
Background: Acinetobacter species other than A. baumannii are becoming increasingly more important as opportunistic pathogens for humans. The primary aim of this study was to assess the prevalence, species distribution, antimicrobial resistance patterns, and carbapenemase gene content of clinical Acinetobacter non-baumannii (Anb) isolates that were collected as part of a sentinel surveillance program of bacterial infections in hospitalized patients. The secondary aim was to evaluate the performance of MALDI-TOF MS systems for the species-level identification of Anb isolates. Methods: Clinical bacterial isolates were collected from multiple sites across Russia and Kazakhstan in 2016–2022. Species identification was performed by means of MALDI-TOF MS, with the Autobio and Bruker systems used in parallel. The PCR detection of the species-specific blaOXA-51-like gene was used as a means of differentiating A. baumannii from Anb species, and the partial sequencing of the rpoB gene was used as a reference method for Anb species identification. The susceptibility of isolates to antibiotics (amikacin, cefepime, ciprofloxacin, colistin, gentamicin, imipenem, meropenem, sulbactam, tigecycline, tobramycin, and trimethoprim–sulfamethoxazole) was determined using the broth microdilution method. The presence of the most common in Acinetobacter-acquired carbapenemase genes (blaOXA-23-like, blaOXA-24/40-like, blaOXA-58-like, blaNDM, blaIMP, and blaVIM) was assessed using real-time PCR. Results: In total, 234 isolates were identified as belonging to 14 Anb species. These comprised 6.2% of Acinetobacter spp. and 0.7% of all bacterial isolates from the observations. Among the Anb species, the most abundant were A. pittii (42.7%), A. nosocomialis (13.7%), the A. calcoaceticus/oleivorans group (9.0%), A. bereziniae (7.7%), and A. geminorum (6.0%). Notably, two environmental species, A. oleivorans and A. courvalinii, were found for the first time in the clinical samples of patients with urinary tract infections. The prevalence of resistance to different antibiotics in Anb species varied from <4% (meropenem and colistin) to 11.2% (gentamicin). Most isolates were susceptible to all antibiotics; however, sporadic isolates of A. bereziniae, A. johnsonii, A. nosocomialis, A. oleivorans, A. pittii, and A. ursingii were resistant to carbapenems. A. bereziniae was more frequently resistant to sulbactam, aminoglycosides, trimethoprim–sulfamethoxazole, and tigecycline than the other species. Four (1.7%) isolates of A. bereziniae, A. johnsonii, A. pittii were found to carry carbapenemase genes (blaOXA-58-like and blaNDM, either alone or in combination). The overall accuracy rates of the species-level identification of Anb isolates with the Autobio and Bruker systems were 80.8% and 88.5%, with misidentifications occurring in 5 and 3 species, respectively. Conclusions: This study provides important new insights into the methods of identification, occurrence, species distribution, and antibiotic resistance traits of clinical Anb isolates.

1. Introduction

The genus Acinetobacter belongs to the family Moraxellaceae, class γ-proteobacteria, and comprises coccobacillary-shaped Gram-negative, aerobic, non-lactose fermenting, saprophytic bacteria. This genus has undergone substantial taxonomic modification and currently comprises 82 species with valid published names and 24 species with non-verified published or provisionally assigned names (https://lpsn.dsmz.de/genus/acinetobacter, accessed on 16 July 2023) [1]. Most Acinetobacter species are ubiquitous in the environment (soil, water, plants, and animals), and some have evolved as important opportunistic pathogens for humans and animals and have adapted to cause various infections, especially in compromised hosts [2]. A. baumannii is a primary human pathogen and is one of the main causes of nosocomial infections with the highest mortality rates [3,4]. Its intrinsic resistance to many antibiotics and its remarkable ability to acquire resistance to all available therapeutic agents, including carbapenems, have secured it a place in the group of ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) [5] and a top place in the WHO’s global priority list of antibiotic-resistant bacteria [6]. A. baumannii and seven other closely related species (A. calcoaceticus, A. geminorum (the most recently described species), A. lactucae (formerly also known as A. dijkshoorniae), A. nosocomialis, A. oleivorans (effectively but not validly published named species), A. pittii, and A. seifertii) together form the Acinetobacter calcoaceticus-baumannii (Acb) complex [7,8,9,10]. Species within the Acb complex are almost indistinguishable phenotypically but differ significantly in terms of their ecology, pathogenicity, epidemiology, and susceptibility to antibiotics [11]. As an example, while all Acb species are capable of causing infections in humans, A. calcoaceticus and A. oleivorans are primarily environmental species and are less frequently isolated from human clinical specimens [9,12]. In contrast, A. pittii and A. nosocomialis are more often associated with hospital-acquired infections [11]. As well as Acb, 20 more species of the genus Acinetobacter were included in the recently updated list of bacteria cultured from humans [13]; among them, A. bereziniae, A. johnsonii, A. junii, A. lwoffii, A. soli, and A. ursingii have commonly been reported in human infections. Although significantly less prevalent than A. baumannii and typically less resistant to antibiotics, Acinetobacter non-baumannii (Anb) species are becoming increasingly more important as nosocomial pathogens [14,15,16,17,18,19,20].
The accurate identification of Anb species is therefore crucial but remains challenging, especially within the Acb complex [21]. In the last two decades, molecular methods have been introduced to enable the more efficient differentiation of Acinetobacter species as compared to conventional phenotypic identification by manual biochemical tests or automated systems. The sequencing of certain protein-encoding genes (rpoB for RNA polymerase subunit B, which is used the most often, gyrB for DNA gyrase subunit B, or recA for DNA repair recombinase) and/or multilocus sequence analysis (MLSA) have proven the most accurate methods and thus constitute the current reference standard for the identification of Acinetobacter species [8,21,22,23]. The PCR detection of A. baumannii species-specific genes for class D β-lactamase (blaOXA-51-like) has also been used as a quick and effective means of differentiating A. baumannii from Anb species [24]. The use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the identification of bacterial species has been a major breakthrough in clinical microbiology. It has proven to be a rapid, cost-effective, and accurate method of differentiating even closely related bacterial species that are otherwise indistinguishable by conventional phenotypic methods [25]. Several studies have assessed the performance of MALDI-TOF MS systems for the identification of Acinetobacter species, and, notably, the results from these studies have demonstrated the crucial importance of the size and quality of reference spectra databases (libraries) for accurate species-level identification [21,26,27].
The epidemiology and mechanisms of antibiotic resistance have been most extensively studied for A. baumannii. In particular, numerous publications have addressed the problem of the global spread of carbapenem-resistant strains and acquired carbapenemase-producing strains of this species, which pose the most significant health threat [3,4,28]. Other Acinetobacter species have been less well studied, although there have been many reports from many parts of the world of isolates of different Anb species producing different carbapenemases [29,30,31,32,33,34,35,36,37,38,39,40,41,42]. A recent analysis of publicly available genome sequences showed that Anb species represent a reservoir of many transferrable resistance genes to different classes of antibiotics, other than carbapenems [43].
Therefore, this study specifically focused on clinical Anb isolates that were collected as part of a large sentinel surveillance program in 2016–2022. We aimed to assess: (i) the prevalence of Anb in infections in hospitalized patients; (ii) the performance of MALDI-TOF MS systems for the species-level identification of Anb in comparison with the reference rpoB sequencing method; and (iii) the prevalence of antibiotic resistance and acquired carbapenemases in Anb species.

2. Results

2.1. Species Distribution of Acinetobacter Isolates

A total of 3754 (10.9%) of the bacterial isolates collected in 2016–2022 within the frame of AMR sentinel surveillance program in Russia and Kazakhstan were identified as members of the Acinetobacter genus. A. baumannii was the most prevalent species, comprising 3520 (10.2%) isolates, while the other Acinetobacter species jointly comprised 234 (0.7%) bacterial isolates. The Anb isolates were collected from 41 hospitals in 27 cities across Russia and Kazakhstan. Using the phylogenetic clustering of rpoB gene sequence data, they were assigned to 14 different species (Figure 1). The clinical isolates clustered well with the corresponding reference strains and the clusters of different species were clearly separated on the tree. The only exception was A. geminorum, a species recently separated from A. pittii [7]. Fourteen isolates formed a monophyletic clade and had complete nucleotide sequence identity with the A. geminorum type strain J00019, which, however, was poorly discriminated from A. pittii (nucleotide distance 0.003; bootstrap value 67%). The two species A. oleivorans (https://lpsn.dsmz.de/species/acinetobacter-oleivorans, accessed on 16 July 2023) and A. septicus (https://lpsn.dsmz.de/species/acinetobacter-septicus, accessed on 16 July 2023), which have the nomenclatural status “not validly published”, were considered the same species, respectively, as A. calcoaceticus (A. calcoaceticus/oleivorans) and A. ursingii (A. ursingii/septicus). The latter two species/groups, as well as A. johnsonii and A. lwoffii, showed the highest intraspecies variability in rpoB gene sequences, with a maximum nucleotide divergence between strains of the same species of 0.049, 0.029, 0.027, and 0.033, respectively (Supplementary Table S1: Pairwise nucleotide distance matrix of partial rpoB sequences of the studied clinical isolates and reference strains).
A. pittii was the major Anb species, with 100 isolates that were geographically scattered. Three other species of the Acb complex (A. nosocomialis, A. calcoaceticus/oleivorans, and A. geminorum) and one species (A. bereziniae) that does not belong to the Acb complex each included more than 10 isolates from diverse geographic sites. The nine remaining Anb species (A. junii, A. soli, A. seifertii, A. johnsonii, A. lwoffii, A. ursingii/septicus, A. haemolyticus, A. radioresistens, and A. courvalinii) comprised one to nine isolates each. Curiously, one isolate, M19-2435, showed the highest nucleotide sequence identity (>99.4%) with the reference strains of A. courvalinii, a soil-dwelling species that had not previously been isolated from humans [13,44,45]. This isolate was recovered from a urine sample of an eight-year-old male patient with a neurogenic bladder after he was operated at the Children’s Hospital of Petrozavodsk, Russia, in April 2019.

2.2. Accuracy of Anb Species Identification Using MALDI-TOF MS Systems

Table 1 summarizes the results of the Anb species identification using two MALDI-TOF MS systems, the Autobio Autof and the Bruker Biotyper, compared to the reference method of rpoB gene sequencing. Figure 1 details the results for the individual isolates. Since A. oleivorans [9] has the nomenclatural status “not validly published”, it was considered the same species as A. calcoaceticus (A. calcoaceticus/oleivorans), and the identification of A. oleivorans as A. calcoaceticus was not considered incorrect. The overall rates of correct species identification were 189/234 (80.8%) for Autobio and 207/234 (88.5%) for Bruker. Both systems provided confident species-level identification of all isolates of A. haemolyticus, A. johnsonii, A. junii, A. lwoffii, A. radioresistens, A. soli, and A. ursingii. In addition, Autobio correctly identified all isolates of A. nosocomialis and A. pittii, two and eleven of which were misidentified by Bruker, respectively, as A. baumannii (log scores: 2.15–2.3) and A. lactucae (log scores: 1.99–2.26). On the other hand, Bruker correctly identified all isolates of A. bereziniae, A. calcoaceticus/oleivorans (as A. calcoaceticus), A. courvalinii, and A. seifertii, while Autobio misidentified all isolates of A. bereziniae as A. guillouiae (scores: 9.416–9.705), A. seifertii as A. pittii (scores: 8.990–9.348), a single isolate of A. courvalinii as A. haemolyticus (score 9.181); additionally, it provided no confident identification for four isolates of A. calcoaceticus/oleivorans (scores: 4.437–5.688). Finally, both the Autobio and Bruker systems misidentified all isolates of A. geminorum, respectively, as A. pittii (scores: 7.445–9.607) and A. lactucae (log scores: 2.1–2.23). In order to improve the accuracy of the identification, we generated reference mass spectra of representative Anb isolates and added them to the user libraries. Subsequently, all Anb isolates from our collection were correctly identified to the species level when tested against both the proprietary and our custom spectra libraries (data not shown).

2.3. Infections Caused by Anb Species

The Anb isolates were most often isolated from clinical samples of hospitalized patients with lower respiratory tract infections (75/234 (32.1%)) and urinary tract infections (UTIs) (65/234 (27.8%)). Other primary sites of infection included, in order of decreasing abundance: heart and blood vessels, 43/234 (18.4%), the abdominal cavity, 25/234 (10.7%), skin and soft tissues, 18/234 (7.7%), bones and joints, 4/234 (1.7%), the central nervous system, 3/284 (1.3%), and eye appendages, 1/234 (0.4%). Overall, we did not find any association between particular Anb species and the site of infection. All species represented by more than one isolate were isolated from diverse infections (Figure 1). Only two species were statistically significantly more abundant in specific loci: 14/16 (87.5%) A. oleivorans isolates were recovered from UTIs (the proportion of UTI isolates among other species was 51/218 (23.4%), p = 0.0001, Fisher’s exact test with the Holm correction), and 7/9 (77.8%) A. soli isolates were recovered from primary bloodstream infections (the proportion of bloodstream isolates among other species was 36/225 (16.0%), p = 0.0001). It should be noted, however, that all UTI isolates of A. oleivorans were isolated in the same pediatric hospital in Petrozavodsk city between October 2016 and February 2019. Likewise, all bloodstream isolates of A. soli were isolated in the same neonatal care unit in Kazan city between January 2019 and July 2019. Therefore, a common source of infection could not be excluded in the case of both A. oleivorans UTI and A. soli bloodstream isolates.
In addition to these two examples of potentially clonal expansions of A. oleivorans and A. soli, we observed a few more “in-hospital clusters” of isolates of the same species. These included five clusters of 7 to 15 isolates of A. pittii in different hospitals and one cluster of 11 isolates of A. nosocomialis. Records indicated that 171/234 (73.1%) infections due to Anb species were considered nosocomial as they occurred more than 48 h after patient admission to the hospital or were thought to be acquired during previous hospital admissions.

2.4. Susceptibility to Antibiotics and the Presence of Acquired Carbapenemase Genes

Table 2 provides a statistical summary of the susceptibility of Anb isolates to 11 antibiotics, and Figure 1 additionally shows the resistance profiles of the individual isolates to key agents representing major antibiotic classes. Most Anb isolates were susceptible to all antibiotics tested. The resistance rates to all β-lactam antibiotics and sulbactam were below 6%, and resistance to β-lactams was not confined to any particular species. Importantly, resistance to carbapenems (imipenem or meropenem) was detected in 11 sporadic isolates: 5 A. pittii, 2 A. bereziniae, and 1 isolate each of A. johnsonii, A. nosocomialis, A. oleivorans, and A. ursingii, all of which, except A. johnsonii, were additionally resistant to antibiotics of at least two other classes. Thirteen (5.6%) isolates, including five A. pittii, four A. bereziniae, and one isolate each of A. nosocomialis, A. oleivorans, A. seifertii, and A. ursingii, were resistant to sulbactam at an MIC breakpoint of ≥16 mg/L. The overall resistance rates to non-β-lactam agents were: 8.7% to tobramycin, 9.9% to amikacin, 11.2% to gentamicin, 7.4% to ciprofloxacin, 8.7% to trimethoprim–sulfamethoxazole, and 3.0% to colistin. The seven colistin-resistant isolates belonged to three species: four A. bereziniae, two A. pittii, and one A. seifertii. Notably, A. bereziniae displayed significantly higher resistance rates than other Anb species to colistin (22.2% vs. 1.4%, p = 0.0008, Fisher’s exact test with the Holm correction), sulbactam (22.2% vs. 4.21%, p = 0.0118), aminoglycosides (66.7% vs. 7.9%, p = 0.0001), and trimethoprim–sulfamethoxazole (66.7% vs. 3.8%, p = 0.0001); it also showed higher resistance levels to tigecycline (MIC90%: ≥16 mg/L vs. 1 mg/L).
Acquired carbapenemase genes were detected in 4/234 (1.7%) isolates collected at geographically distant sites. One isolate each of A. bereziniae and A. pittii carried the blaNDM gene, another isolate of A. pittii carried the blaOXA-58-like gene, and one isolate of A. johnsonii harbored the blaNDM and blaOXA-58-like genes simultaneously. The carbapenemase-positive isolates of A. bereziniae and A. pittii displayed high-level resistance to imipenem and meropenem, with MICs of ≥16 mg/L. Curiously, however, the double-carbapenemase-positive isolate of A. johnsonii showed borderline resistance to imipenem, with an MIC of 8 mg/L, and susceptibility to meropenem with an MIC of 1 mg/L. Finally, as expected, the isolates of A. radioresistens, which were susceptible to carbapenems, tested positive by PCR for the blaOXA-23-like gene, which is known to be intrinsic chromosomally-encoded and usually weakly expressed in this species [46].

3. Discussion

This study characterized 234 clinical Anb isolates collected from hospitalized patients in multiple centers across Russia and Kazakhstan over the last seven years. These isolates belonged to 14 different species, as was determined by rpoB gene sequencing, and jointly comprised 6.2% of Acinetobacter spp. (the remaining isolates were A. baumannii) and 0.7% of all bacterial isolates collected as part of the sentinel surveillance program [47]. Among the Anb species, the most abundant was A. pittii (42.7%), followed by A. nosocomialis (13.7%), A. calcoaceticus/oleivorans (9.0%), A. bereziniae (7.7%), and A. geminorum (6.0%). A. pittii and A. nosocomialis are both known to be the next most common Acinetobacter spp. after A. baumannii to cause nosocomial infections [20]. A. geminorum, which has recently been separated from A. pittii [7], has a highly similar rpoB gene sequence. On the contrary, A. oleivorans, which has not been assigned the nomenclatural status of a validly published named species, and which was therefore regarded in our analysis as one species with A. calcoaceticus, has a more divergent rpoB gene sequence. It is worth mentioning that the rpoB sequences of 16 isolates of the A. calcoaceticus/oleivorans group clustered closely with those of the reference strains of A. oleivorans, while only 5 isolates clustered with the reference strains of A. calcoaceticus. This is an unexpected finding given that A. oleivorans has commonly been described as a soil-dwelling carbohydrate-hydrolyzing bacterium and has not been associated with humans [9,48,49,50]. Another interesting finding was the isolation of A. courvalinii [44,45] from a urine clinical sample of an eight-year-old male patient with cystitis, which, to our knowledge, represents the first documented case of human infection with this species.
The studied Anb isolates were recovered from different primary sites of infection, mostly the lower respiratory tract, urinary system, and blood stream, with no particular association between the infection locus and the species. It is worth noting that A. oleivorans and A. soli were isolated significantly more often, respectively, from urine and blood. However, all the urine isolates of A. oleivorans were collected in the same hospital and could therefore have a common origin, as were all the blood isolates of A. soli. In addition to these two examples, we observed several in-hospital clusters of infections due to A. pittii and A. nosocomialis, indicating their likely nosocomial transmission.
One of the most important tasks of this study was to assess the performance of two MALDI-TOF MS systems for the identification of Anb species. The Autobio and Bruker systems demonstrated the overall rates of correct species-level identification, respectively, of 80.8% and 88.5% for our collection of Anb isolates. These rates are lower than those reported from the study of the routine collection of bacterial isolates of any species (>97%) [51]. However, our results correspond well with the findings of many studies that focus specifically on the MALDI-TOF MS identification of Acinetobacter spp. [21,26,27]. In line with these studies, we found that most cases of misidentification were likely due to the absence or insufficient number of mass spectra of new species in the reference libraries, as was the case for A. geminorum in the Autobio and Bruker libraries and A. courvalinii in the Autobio library; the misidentifications could also be due to the potentially inconsistent species identification of the reference strains present in the library, as was the case for A. bereziniae and A. seifertii being identified with high scores as A. guillouiae and A. pittii, respectively, by Autobio. The low-score identification results of single isolates of A. calcoaceticus/oleivorans, A. nosocomialis, and A. pittii were also likely due to the small number of mass spectra of these species in the reference libraries. Importantly, however, we found that all identification errors could be eliminated by adding the spectra of “difficult” strains, correctly identified using the reference method, to the custom user libraries. These findings once again highlight the importance of maintaining the reference spectra libraries in accordance with current taxonomy and nomenclature of Acinetobacter spp. and the need to include strains of newly described species in the libraries.
The studied Anb isolates were mostly susceptible to antibiotics. The resistance rates to all agents did not exceed 10% (except for gentamicin, at 11.2%). These rates are significantly lower than those reported for A. baumannii isolates from the same surveillance program [47,52,53]. For example, the prevalence of resistance to trimethoprim–sulfamethoxazole, aminoglycosides, ciprofloxacin, and carbapenems was 6 to 20 times lower in Anb than in A. baumannii (https://amrmap.net/?id=BWSMM21DC29DC11, accessed on 16 July 2023) [47]. The exception was resistance to colistin, which was more than three times higher in Anb than in A. baumannii (3.0% vs. 0.8%), with most colistin-resistant isolates being identified as A. bereziniae. The latter species was also more resistant to sulbactam, aminoglycosides, trimethoprim–sulfamethoxazole, and tigecycline than other Anb species. The acquired resistance to colistin in A. bereziniae has previously been found to be associated with mutations in the pmrB gene involved in lipopolysaccharide modification [54]. Resistance to most aminoglycosides, including amikacin, has been attributed to plasmid-carried genes for aminoglycoside-modifying enzymes (aphA6, aac(6′)-31 and aadA1) [36,55,56].
The primary mechanisms of resistance to carbapenems in Acinetobacter spp. include the overexpression of naturally occurring species-specific carbapenemases of molecular class D (OXA) [57] and the production of acquired carbapenemases of class D (mainly OXA-23-, OXA-24/40-, and OXA-58-like enzymes) and class B (mainly NDM and IMP) [4]. Our study revealed the low prevalence of acquired carbapenemases in Anb isolates (1.7%) as compared to A. baumannii (81.9%) (https://amrmap.net/?id=AN0Fl54mX14mX14, accessed on 16 July 2023). Moreover, only OXA-58-like and NDM carbapenemases were found alone or in combination in sporadic isolates of A. bereziniae, A. johnsonii, and A. pittii, whereas, in A. baumannii in Russia, these carbapenemases were rare, and the OXA-23- and OXA-24/40-types were the predominant carbapenemases detected [47,53]. Likewise, studies from many other countries have found the same differences in the frequency of various acquired carbapenemases in A. baumannii and Anb. OXA-58 has been detected in the early carbapenem-resistant isolates of A. baumannii in Europe, Asia, and South America [58,59] and, recently, mostly in Anb species, including A. bereziniae, A. colistiniresistens, A. johnsonii, A. junii, A. nosocomialis, A. pittii, A. radioresistens, A. seifertii, A. towneri, and A. ursingii, from all over the world [37,60,61,62,63,64,65,66,67,68,69]. Similarly, metallo-β-lactamases, mostly NDM-1 and IMP variants, have been found in global Anb isolates, often in combination with OXA-58 [62,63,64,70,71,72,73,74,75,76,77,78].
While our study covered a large geographic area and a long time period, it did not identify and include some of the Anb species that have been previously cultured from humans. This is an obvious limitation of the study, which demonstrates the importance of ongoing surveillance and research. Our further study will utilize whole-genome sequencing data to infer the phylogenetic relationships between closely related Acinetobacter spp., such as A. pittii and A. geminorum, and to explore in greater depth the mechanisms of antibiotic resistance in Anb isolates. Further studies will also be needed to continuously evaluate the performance of MALDI-TOF MS platforms with updated spectra libraries for identification of Acinetobacter spp.

4. Materials and Methods

4.1. Bacterial Isolates

All the studied isolates and accompanying metadata were collected as part of the national sentinel surveillance program of antimicrobial resistance (AMR) in bacterial pathogens isolated from hospitalized patients [47]. Between 1 January 2016 and 31 December 2022, 94 participating hospitals from 42 cities across Russia and 1 hospital in Karaganda, Kazakhstan, contributed a total of 34,524 non-duplicate (one per patient/case of infection) clinical bacterial isolates, of which 3754 (10.9%) were confirmed in the central surveillance laboratory as Acinetobacter species. The isolates were recovered from representative clinical specimens (blood, tissue biopsies, cerebrospinal fluid, bronchoalveolar lavage, sputum, urine, etc.) of patients with clinical symptoms of infections; isolates from surface swabs, screenings, and environmental samples were excluded. All isolates with accompanying clinical and epidemiological information were referred to the central surveillance laboratory of the Institute of Antimicrobial Chemotherapy (IAC), where species identification, antibiotic susceptibility testing, and molecular genetic characterizations of the isolates were performed.

4.2. Species Identification with MALDI-TOF MS

The bacterial isolates were identified with MALDI-TOF MS, using both the Microflex LT-MALDI Biotyper System with the Biotyper spectral database ver.11 (Bruker Daltonics, Bremen, Germany) and the Autof MS2000 System with the current online spectral library (Autobio Diagnostics, Zhengzhou, China). The standard methods of direct colony transfer and rapid (on-target) extraction with formic acid were used for sample preparation prior to the acquisition of mass spectra, as described previously [79,80]. The criteria for “confident species-level identification” were as follows: log scores ≥ 2.0 for the Bruker Biotyper System and scores ≥ 9.0 for the Autobio Autof System. Only the highest-match score values (1st of the 10 best hits) of the clinical isolates against the corresponding reference libraries were reported in the Results section. To generate the reference spectra of the selected Acinetobacter strains for the Autobio library, the full (in-tube) extraction method was used; the extracts from each culture were spotted four times onto a ground steel target and each spot was measured and processed three times according to the manufacturer’s instruction.

4.3. Additional Tests to Distinguish A. baumannii

A. baumannii isolates were additionally distinguished by the detection of species-specific blaOXA-51-like genes using real-time PCR [24] and by multilocus sequencing typing (MLST) using the University of Oxford and the Institute Pasteur typing schemes [81,82].

4.4. Sequencing of the rpoB Gene and Analysis of the Sequence Data

All isolates preliminarily identified as Anb species were subjected to rpoB gene sequencing, which was used a reference identification method [21]. Briefly, a 397 bp internal fragment of the rpoB gene was amplified by PCR using the primers Ac696F, 5′-TAYCGYAAAGAYTTGAAAGAAG-3′, and Ac1093R, 5′-CMACACCYTTGTTMCCRTGA-3′, as described elsewhere [83]. The PCR products were purified with exonuclease I and a shrimp alkaline phosphatase treatment and were sequenced on both strands using the same primers and a BigDye Terminator v3.1 Cycle Sequencing Kit (Thermo Fisher Scientific, Waltham, MA, USA). The sequencing products were analyzed using a Applied Biosystems 3500 Genetic Analyzer (Life Technologies, Carlsbad, CA, USA). Quality assessments and the assembly of sequences were performed using a QIAGEN CLC Genomics Workbench 21.0 (QIAGEN, Aarhus, Denmark).
The rpoB gene sequences of the reference and type strains (one to three per species) of 27 Acinetobacter spp. (A. baumannii, A. baylyi, A. beijerinckii, A. bereziniae, A. calcoaceticus, A. colistiniresistens, A. courvalinii, A. geminorum, A. guillouiae, A. haemolyticus, A. johnsonii, A. junii, A. lactucae, A. lwoffii, A. nosocomialis, A. oleivorans, A. parvus, A. pittii, A. radioresistens, A. schindleri, A. seifertii, A. septicus, A. soli, A. towneri, A. ursingii, A. variabilis, and A. venetianus) were obtained from the NCBI GenBank (https://www.ncbi.nlm.nih.gov/genbank/, accessed on 16 July 2023) and the ATCC Genome Portal (https://genomes.atcc.org/, accessed on 16 July 2023). The rpoB gene sequences of the studied clinical isolates and reference strains were aligned together (after trimming the primer sites) and the resulting alignment was used to produce a maximum-likelihood tree with the Tamura–Nei model and 1000 bootstraps using MEGA v.11.0.13 [84]. The visualization and annotation of the phylogenetic tree were performed using iTOL v.6.7.6 [85].

4.5. Antimicrobial Susceptibility Testing

Antimicrobial susceptibility testing (AST) was conducted for the following agents: amikacin, cefepime, ciprofloxacin, colistin, gentamicin, imipenem, meropenem, sulbactam, tigecycline, tobramycin, and trimethoprim–sulfamethoxazole (1:19). This was accomplished by using a reference broth microdilution method according to ISO 20776-2:2021 [86] and the methodology of the European committee on antimicrobial susceptibility testing (EUCAST) [87]. Escherichia coli ATCC 25922, E. coli NCTC 13846, and Pseudomonas aeruginosa ATCC 27853 were used as quality control strains for AST. The AST results were interpreted according to the EUCAST v.13.0 Clinical Breakpoints [88] for all agents except for cefepime and sulbactam, for which the results were interpreted using the CLSI M100 ED33 breakpoints [89], and for tigecycline, for which only the MIC50 and MIC90 values were reported due to lack of EUCAST and CLSI interpretive criteria.

4.6. Real-Time PCR Detection of Carbapenemase Genes

The detection of genes encoding the most common Acinetobacter-spp.-acquired carbapenemases of molecular class D (OXA-23-, OXA-24/40-, and OXA-58-like) and class B (metallo-β-lactamases: NDM, IMP and VIM) was performed using commercial real-time PCR assays: AmpliSens MDR Acinetobacter-OXA-FL and AmpliSens MDR MBL-FL (Central research institute of epidemiology, Moscow, Russia), according to manufacturer’s instructions. Amplification reactions were carried out using the DTPrime 5X1 Real-Time PCR System (DNA Technology, Moscow, Russia). Strains of A. baumannii, A. pittii, and P. aeruginosa carrying the genes of the known carbapenemases from the IAC collection [47] were used as positive controls.

4.7. Data Availability

The DNA sequences obtained in this study were deposited in the European Nucleotide Archive under the project accession number PRJEB61953. The clinical, epidemiological, geospatial, and temporal characteristics of the studied Anb isolates, the quantitative (MIC) and qualitative (categorical) AST data, the carbepenemase gene status, and the rpoB phylogenetic clustering data were made available as an open-access project at Microreact [90]: https://microreact.org/project/fKrejDn6vqcervyWwMAs8W-acinetobacter-non-baumannii-species (accessed on 16 July 2023).

5. Conclusions

This study represents one of the largest surveys of Anb isolates collected from infections in hospitalized patients. It provides new insights into the methods of identification, as well as the occurrence, species distribution, and antibiotic resistance traits of Anb isolates. It also reports for the first time the isolation of A. oleivorans and A. courvalinii from clinical samples of patients with urinary tract infections.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/antibiotics12081301/s1, Table S1: Pairwise nucleotide distance matrix of partial rpoB sequences of the studied clinical isolates and reference strains.

Author Contributions

Conceptualization, E.S. (Eugene Sheckand) and M.E.; methodology and experimental work, E.S. (Eugene Sheckand), A.R., E.S. (Elvira Shaidullinaand), A.M. (Alexey Martinovichand), N.I., A.M. (Anna Mikotina), E.S. (Elena Skleenova), V.O., I.A., V.V., and A.L.; data validation and analysis, V.S. and M.E.; writing—original draft preparation, E.S. (Eugene Sheckand); writing—review and editing, M.E.; supervision and project administration, R.K. and M.E. All authors have read and agreed to the published version of the manuscript.

Funding

The national sentinel surveillance program of antimicrobial resistance (AMR) in bacterial pathogens isolated from hospitalized patients is funded by the Ministry of Health of the Russian Federation (Grant no. 056-00050-21-03).

Institutional Review Board Statement

The studied bacterial isolates (ENA project accession no. PRJEB61953) from the national AMR surveillance program were recovered at local clinical hospitals in Russia as part of routine diagnostic sampling. The national AMR surveillance program was approved by the Review Board of the FSBEI HE “Smolensk State Medical University” of the Ministry of Health of the Russian Federation. Ethical approval was granted by the institutional Independent Ethics Committee, on 4 September 2015.

Informed Consent Statement

The informed consent was waived for this study because it did not involve any additional interventions; no personal patient data were collected and the data regarding the sources of the isolates were collected anonymously.

Data Availability Statement

The DNA sequences obtained in this study were deposited in the European Nucleotide Archive under the project accession number PRJEB61953. The clinical, epidemiological, geospatial, and temporal characteristics of studied Anb isolates, the quantitative (MIC) and qualitative (categorical) AST data, the carbepenemase gene status, and the rpoB phylogenetic clustering data were made available as an open-access project at Microreact (https://microreact.org/project/fKrejDn6vqcervyWwMAs8W-acinetobacter-non-baumannii-species, accessed on 16 July 2023).

Acknowledgments

We thank all the participants of the sentinel surveillance program for the collection of the clinical bacterial isolates used in this study. We also thank the entire IAC laboratory staff for maintaining the collection and undertaking susceptibility testing of isolates.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Meier-Kolthoff, J.P.; Carbasse, J.S.; Peinado-Olarte, R.L.; Göker, M. TYGS and LPSN: A Database Tandem for Fast and Reliable Genome-Based Classification and Nomenclature of Prokaryotes. Nucleic Acids Res. 2022, 50, D801–D807. [Google Scholar] [CrossRef]
  2. Wong, D.; Nielsen, T.B.; Bonomo, R.A.; Pantapalangkoor, P.; Luna, B.; Spellberg, B. Clinical and Pathophysiological Overview of Acinetobacter Infections: A Century of Challenges. Clin. Microbiol. Rev. 2017, 30, 409. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  3. Antunes, L.C.S.; Visca, P.; Towner, K.J. Acinetobacter baumannii: Evolution of a Global Pathogen. Pathog. Dis. 2014, 71, 292–301. [Google Scholar] [CrossRef] [Green Version]
  4. Ramirez, M.S.; Bonomo, R.A.; Tolmasky, M.E. Carbapenemases: Transforming Acinetobacter baumannii into a Yet More Dangerous Menace. Biomolecules 2020, 10, 720. [Google Scholar] [CrossRef] [PubMed]
  5. Boucher, H.W.; Talbot, G.H.; Bradley, J.S.; Edwards, J.E.; Gilbert, D.; Rice, L.B.; Scheld, M.; Spellberg, B.; Bartlett, J. Bad Bugs, No Drugs: No ESKAPE! An Update from the Infectious Diseases Society of America. Clin. Infect. Dis. 2009, 48, 1–12. [Google Scholar] [CrossRef] [Green Version]
  6. World Health Organization. Prioritization of Pathogens to Guide Discovery, Research and Development of New Antibiotics for Drug-Resistant Bacterial Infections, Including Tuberculosis. 2017. Available online: https://www.who.int/publications/i/item/WHO-EMP-IAU-2017.12 (accessed on 17 July 2023).
  7. Wolf, S.; Barth-Jakschic, E.; Birkle, K.; Bader, B.; Marschal, M.; Liese, J.; Peter, S.; Oberhettinger, P. Acinetobacter geminorum sp. nov., Isolated from Human Throat Swabs. Int. J. Syst. Evol. Microbiol. 2021, 71, 005018. [Google Scholar] [CrossRef] [PubMed]
  8. Cosgaya, C.; Marí-Almirall, M.; Van Assche, A.; Fernández-Orth, D.; Mosqueda, N.; Telli, M.; Huys, G.; Higgins, P.G.; Seifert, H.; Lievens, B.; et al. Acinetobacter dijkshoorniae sp. nov., a Member of the Acinetobacter Calcoaceticus-Acinetobacter baumannii Complex Mainly Recovered from Clinical Samples in Different Countries. Int. J. Syst. Evol. Microbiol. 2016, 66, 4105–4111. [Google Scholar] [CrossRef] [PubMed]
  9. Kang, Y.S.; Jung, J.; Jeon, C.O.; Park, W. Acinetobacter oleivorans sp. nov. Is Capable of Adhering to and Growing on Diesel-Oil. J. Microbiol. 2011, 49, 29–34. [Google Scholar] [CrossRef]
  10. Dunlap, C.A.; Rooney, A.P. Acinetobacter dijkshoorniae Is a Later Heterotypic Synonym of Acinetobacter Lactucae. Int. J. Syst. Evol. Microbiol. 2018, 68, 131–132. [Google Scholar] [CrossRef]
  11. Nemec, A.; Krizova, L.; Maixnerova, M.; van der Reijden, T.J.K.; Deschaght, P.; Passet, V.; Vaneechoutte, M.; Brisse, S.; Dijkshoorn, L. Genotypic and Phenotypic Characterization of the Acinetobacter calcoaceticus–Acinetobacter baumannii Complex with the Proposal of Acinetobacter pittii sp. nov. (Formerly Acinetobacter Genomic Species 3) and Acinetobacter nosocomialis sp. nov. (Formerly Acinetobacter Genomic Species 13TU). Res. Microbiol. 2011, 162, 393–404. [Google Scholar] [CrossRef]
  12. Glover, J.S.; Ticer, T.D.; Engevik, M.A. Profiling Antibiotic Resistance in Acinetobacter calcoaceticus. Antibiotics 2022, 11, 978. [Google Scholar] [CrossRef] [PubMed]
  13. Diakite, A.; Dubourg, G.; Raoult, D. Updating the Repertoire of Cultured Bacteria from the Human Being. Microb. Pathog. 2021, 150, 104698. [Google Scholar] [CrossRef]
  14. Salzer, H.J.F.; Rolling, T.; Schmiede, S.; Klupp, E.M.; Lange, C.; Seifert, H. Severe Community-Acquired Bloodstream Infection with Acinetobacter ursingii in Person Who Injects Drugs. Emerg. Infect. Dis. 2016, 22, 134. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  15. Chusri, S.; Chongsuvivatwong, V.; Rivera, J.I.; Silpapojakul, K.; Singkhamanan, K.; McNeil, E.; Doi, Y. Clinical Outcomes of Hospital-Acquired Infection with Acinetobacter nosocomialis and Acinetobacter pittii. Antimicrob. Agents Chemother. 2014, 58, 4172–4179. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  16. Turton, J.F.; Shah, J.; Ozongwu, C.; Pike, R. Incidence of Acinetobacter Species Other than A. baumannii among Clinical Isolates of Acinetobacter: Evidence for Emerging Species. J. Clin. Microbiol. 2010, 48, 1445. [Google Scholar] [CrossRef] [Green Version]
  17. Mittal, S.; Sharma, M.; Yadav, A.; Bala, K.; Chaudhary, U. Acinetobacter lwoffii an Emerging Pathogen in Neonatal ICU. Infect. Disord. Drug Targets 2015, 15, 184–188. [Google Scholar] [CrossRef]
  18. Fitzpatrick, M.A.; Ozer, E.; Bolon, M.K.; Hauser, A.R. Influence of ACB Complex Genospecies on Clinical Outcomes in a U.S. Hospital with High Rates of Multidrug Resistance. J. Infect. 2015, 70, 144. [Google Scholar] [CrossRef] [Green Version]
  19. Matsui, M.; Suzuki, S.; Yamane, K.; Suzuki, M.; Konda, T.; Arakawa, Y.; Shibayama, K. Distribution of Carbapenem Resistance Determinants among Epidemic and Non-Epidemic Types of Acinetobacter Species in Japan. J. Med. Microbiol. 2014, 63, 870–877. [Google Scholar] [CrossRef]
  20. Al Atrouni, A.; Joly-Guillou, M.L.; Hamze, M.; Kempf, M. Reservoirs of Non-baumannii Acinetobacter Species. Front. Microbiol. 2016, 7, 49. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  21. Vijayakumar, S.; Biswas, I.; Veeraraghavan, B. Accurate Identification of Clinically Important Acinetobacter spp.: An Update. Future Sci. OA 2019, 5, FSO395. [Google Scholar] [CrossRef] [Green Version]
  22. La Scola, B.; Gundi, V.A.K.B.; Khamis, A.; Raoult, D. Sequencing of the RpoB Gene and Flanking Spacers for Molecular Identification of Acinetobacter Species. J. Clin. Microbiol. 2006, 44, 827–832. [Google Scholar] [CrossRef] [Green Version]
  23. Lee, M.J.; Jang, S.J.; Li, X.M.; Park, G.; Kook, J.K.; Kim, M.J.; Chang, Y.H.; Shin, J.H.; Kim, S.H.; Kim, D.M.; et al. Comparison of RpoB Gene Sequencing, 16S RRNA Gene Sequencing, GyrB Multiplex PCR, and the VITEK2 System for Identification of Acinetobacter Clinical Isolates. Diagn. Microbiol. Infect. Dis. 2014, 78, 29–34. [Google Scholar] [CrossRef]
  24. Turton, J.F.; Woodford, N.; Glover, J.; Yarde, S.; Kaufmann, M.E.; Pitt, T.L. Identification of Acinetobacter baumannii by Detection of the BlaOXA-51-like Carbapenemase Gene Intrinsic to This Species. J. Clin. Microbiol. 2006, 44, 2974. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  25. Cheng, K.; Chui, H.; Domish, L.; Hernandez, D.; Wang, G. Recent Development of Mass Spectrometry and Proteomics Applications in Identification and Typing of Bacteria. Proteomics Clin. Appl. 2016, 10, 346–357. [Google Scholar] [CrossRef]
  26. Marí-Almirall, M.; Cosgaya, C.; Higgins, P.G.; Van Assche, A.; Telli, M.; Huys, G.; Lievens, B.; Seifert, H.; Dijkshoorn, L.; Roca, I.; et al. MALDI-TOF/MS Identification of Species from the Acinetobacter baumannii (Ab) Group Revisited: Inclusion of the Novel A. seifertii and A. dijkshoorniae Species. Clin. Microbiol. Infect. 2017, 23, e1–e210. [Google Scholar] [CrossRef] [Green Version]
  27. Li, X.; Tang, Y.; Lu, X. Insight into Identification of Acinetobacter Species by Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS) in the Clinical Laboratory. J. Am. Soc. Mass. Spectrom. 2018, 29, 1546–1553. [Google Scholar] [CrossRef] [PubMed]
  28. Hamidian, M.; Nigro, S.J. Emergence, Molecular Mechanisms and Global Spread of Carbapenem-Resistant Acinetobacter baumannii. Microb. Genom. 2019, 5, e000306. [Google Scholar] [CrossRef]
  29. Li, P.; Yang, C.; Xie, J.; Liu, N.; Wang, H.; Zhang, L.; Wang, X.; Wang, Y.; Qiu, S.; Song, H. Acinetobacter calcoaceticus from a Fatal Case of Pneumonia Harboring BlaNDM-1 on a Widely Distributed Plasmid. BMC Infect. Dis. 2015, 15, 131. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  30. Rani, F.M.; Rahman, N.I.A.; Ismail, S.; Abdullah, F.H.; Othman, N.; Alattraqchi, A.G.; Cleary, D.W.; Clarke, S.C.; Yeo, C.C. Prevalence and Antimicrobial Susceptibilities of Acinetobacter baumannii and Non-baumannii Acinetobacters from Terengganu, Malaysia and Their Carriage of Carbapenemase Genes. J. Med. Microbiol. 2018, 67, 1538–1543. [Google Scholar] [CrossRef]
  31. Lee, K.; Kim, M.N.; Choi, T.Y.; Cho, S.E.; Lee, S.; Whang, D.H.; Yong, D.; Chong, Y.; Woodford, N.; Livermore, D.M. Wide Dissemination of OXA-Type Carbapenemases in Clinical Acinetobacter spp. Isolates from South Korea. Int. J. Antimicrob. Agents 2009, 33, 520–524. [Google Scholar] [CrossRef]
  32. Tietgen, M.; Kramer, J.S.; Brunst, S.; Djahanschiri, B.; Wohra, S.; Higgins, P.G.; Weidensdorfer, M.; Riedel-Christ, S.; Pos, K.M.; Gonzaga, A.; et al. Identification of the Novel Class D β-Lactamase OXA-679 Involved in Carbapenem Resistance in Acinetobacter calcoaceticus. J. Antimicrob. Chemother. 2019, 74, 1494–1502. [Google Scholar] [CrossRef]
  33. Lasarte-Monterrubio, C.; Guijarro-Sánchez, P.; Bellés, A.; Vázquez-Ucha, J.C.; Arca-Suárez, J.; Fernández-Lozano, C.; Bou, G.; Beceiro, A. Carbapenem Resistance in Acinetobacter nosocomialis and Acinetobacter junii Conferred by Acquisition of BlaOXA-24/40 and Genetic Characterization of the Transmission Mechanism between Acinetobacter Genomic Species. Microbiol. Spectr. 2022, 10, e02734-21. [Google Scholar] [CrossRef]
  34. Singkham-In, U.; Chatsuwan, T. Mechanisms of Carbapenem Resistance in Acinetobacter pittii and Acinetobacter nosocomialis Isolates from Thailand. J. Med. Microbiol. 2018, 67, 1667–1672. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  35. Mo, X.M.; Pan, Q.; Seifert, H.; Xing, X.W.; Yuan, J.; Zhou, Z.Y.; Luo, X.Y.; Liu, H.M.; Xie, Y.L.; Yang, L.Q.; et al. First Identification of Multidrug-Resistant Acinetobacter bereziniae Isolates Harboring BlaNDM-1 from Hospitals in South China. Heliyon 2023, 9, e12365. [Google Scholar] [CrossRef]
  36. Tavares, L.C.B.; Cunha, M.P.V.; De Vasconcellos, F.M.; Bertani, A.M.D.J.; De Barcellos, T.A.F.; Bueno, M.S.; Santos, C.A.; Sant’Ana, D.A.; Ferreira, A.M.; Mondelli, A.L.; et al. Genomic and Clinical Characterization of IMP-1-Producing Multidrug-Resistant Acinetobacter bereziniae Isolates from Bloodstream Infections in a Brazilian Tertiary Hospital. Microb. Drug Resist. 2020, 26, 1399–1404. [Google Scholar] [CrossRef]
  37. Cayô, R.; Rodrigues-Costa, F.; Matos, A.P.; Carvalhaes, C.G.; Dijkshoorn, L.; Gales, A.C. Old Clinical Isolates of Acinetobacter seifertii in Brazil Producing OXA-58. Antimicrob. Agents Chemother. 2016, 60, 2589. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  38. Montaña, S.; Palombarani, S.; Carulla, M.; Kunst, A.; Rodriguez, C.H.; Nastro, M.; Vay, C.; Ramirez, M.S.; Almuzara, M. First Case of Bacteraemia Due to Acinetobacter schindleri Harbouring BlaNDM-1 in an Immunocompromised Patient. New Microbes New Infect. 2018, 21, 28. [Google Scholar] [CrossRef]
  39. Cayô, R.; Streling, A.P.; Nodari, C.S.; Matos, A.P.; De Paula Luz, A.; Dijkshoorn, L.; Pignatari, A.C.C.; Gales, A.C. Occurrence of IMP-1 in Non-baumannii Acinetobacter Clinical Isolates from Brazil. J. Med. Microbiol. 2018, 67, 628–630. [Google Scholar] [CrossRef]
  40. Park, Y.K.; Jung, S.I.; Park, K.H.; Kim, S.H.; Ko, K.S. Characteristics of Carbapenem-Resistant Acinetobacter spp. Other than Acinetobacter baumannii in South Korea. Int. J. Antimicrob. Agents 2012, 39, 81–85. [Google Scholar] [CrossRef] [PubMed]
  41. Cui, C.Y.; Chen, C.; Liu, B.T.; He, Q.; Wu, X.T.; Sun, R.Y.; Zhang, Y.; Cui, Z.H.; Guo, W.Y.; Jia, Q.L.; et al. Co-Occurrence of Plasmid-Mediated Tigecycline and Carbapenem Resistance in Acinetobacter spp. from Waterfowls and Their Neighboring Environment. Antimicrob. Agents Chemother. 2020, 64, 02502-19. [Google Scholar] [CrossRef]
  42. Kimura, Y.; Harada, K.; Shimizu, T.; Sato, T.; Kajino, A.; Usui, M.; Tamura, Y.; Tsuyuki, Y.; Miyamoto, T.; Ohki, A.; et al. Species Distribution, Virulence Factors, and Antimicrobial Resistance of Acinetobacter spp. Isolates from Dogs and Cats: A Preliminary Study. Microbiol. Immunol. 2018, 62, 462–466. [Google Scholar] [CrossRef] [Green Version]
  43. Baraka, A.; Traglia, G.M.; Montaña, S.; Tolmasky, M.E.; Ramirez, M.S. An Acinetobacter Non-baumannii Population Study: Antimicrobial Resistance Genes (ARGs). Antibiotics 2021, 10, 16. [Google Scholar] [CrossRef] [PubMed]
  44. Nemec, A.; Radolfova-Krizova, L.; Maixnerova, M.; Vrestiakova, E.; Jezek, P.; Sedo, O. Taxonomy of Haemolytic and/or Proteolytic Strains of the Genus Acinetobacter with the Proposal of Acinetobacter courvalinii sp. nov. (Genomic Species 14 Sensu Bouvet & Jeanjean), Acinetobacter dispersus sp. nov. (Genomic Species 17), Acinetobacter modestus sp. nov., Acinetobacter proteolyticus sp. nov. and Acinetobacter vivianii sp. nov. Int. J. Syst. Evol. Microbiol. 2016, 66, 1673–1685. [Google Scholar] [CrossRef]
  45. Dey, D.K.; Park, J.; Kang, S.C. Genotypic, Phenotypic, and Pathogenic Characterization of the Soil Isolated Acinetobacter courvalinii. Microb. Pathog. 2020, 149, 104287. [Google Scholar] [CrossRef]
  46. Poirel, L.; Figueiredo, S.; Cattoir, V.; Carattoli, A.; Nordmann, P. Acinetobacter Radioresistens as a Silent Source of Carbapenem Resistance for Acinetobacter spp. Antimicrob. Agents Chemother. 2008, 52, 1252–1256. [Google Scholar] [CrossRef] [Green Version]
  47. Kuzmenkov, A.Y.; Trushin, I.V.; Vinogradova, A.G.; Avramenko, A.A.; Sukhorukova, M.V.; Malhotra-Kumar, S.; Dekhnich, A.V.; Edelstein, M.V.; Kozlov, R.S. AMRmap: An Interactive Web Platform for Analysis of Antimicrobial Resistance Surveillance Data in Russia. Front. Microbiol. 2021, 12, 620002. [Google Scholar] [CrossRef]
  48. Gkorezis, P.; Rineau, F.; Van Hamme, J.; Franzetti, A.; Daghio, M.; Thijs, S.; Weyens, N.; Vangronsveld, J. Draft Genome Sequence of Acinetobacter Oleivorans PF1, a Diesel-Degrading and Plant-Growth-Promoting Endophytic Strain Isolated from Poplar Trees Growing on a Diesel-Contaminated Plume. Genome Announc. 2015, 3, e01430-14. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  49. Deems, A.; Du Prey, M.; Dowd, S.E.; McLaughlin, R.W. Characterization of the Biodiesel Degrading Acinetobacter oleivorans Strain PT8 Isolated from the Fecal Material of a Painted Turtle (Chrysemys picta). Curr. Microbiol. 2021, 78, 522–527. [Google Scholar] [CrossRef] [PubMed]
  50. Wang, P.; Wei, H.; Ke, T.; Fu, Y.; Zeng, Y.; Chen, C.; Chen, L. Characterization and Genome Analysis of Acinetobacter oleivorans S4 as an Efficient Hydrocarbon-Degrading and Plant-Growth-Promoting rhizobacterium. Chemosphere 2023, 331, 138732. [Google Scholar] [CrossRef]
  51. Park, J.H.; Jang, Y.; Yoon, I.; Kim, T.S.; Park, H. Comparison of Autof Ms1000 and Bruker Biotyper MALDI-TOF MS Platforms for Routine Identification of Clinical Microorganisms. Biomed. Res. Int. 2021, 2021, 6667623. [Google Scholar] [CrossRef]
  52. Kozlov, R.S.; Azizov, I.S.; Dekhnich, V.; Ivanchik, N.V.; Kuzmenkov, Y.; Martinovich; Mikotina, V.; Sukhorukova, V.; Trushin, I.V.; Edelstein, V. In Vitro Activity of Biapenem and Other Carbapenems against Russian Clinical Isolates of Pseudomonas aeruginosa, Acinetobacter spp., and Enterobacterales. Klin. Mikrobiol. Antimikrobn. Himioter. 2021, 23, 280–291. [Google Scholar] [CrossRef]
  53. Shek, E.A.; Sukhorukova, M.V.; Edelstein, M.V.; Skleenova, E.Y.; Ivanchik, N.V.; Shajdullina, E.R.; Kuzmenkov, A.Y.; Dekhnich, A.V.; Kozlov, R.S.; Semyonova, N.V.; et al. Antimicrobial Resistance, Carbapenemase Production, and Genotypes of Nosocomial Acinetobacter spp. Isolates in Russia: Results of Multicenter Epidemiological Study “MARATHON 2015–2016”. Klin. Mikrobiol. Antimikrobn. Himioter. 2019, 21, 171–180. [Google Scholar] [CrossRef]
  54. Jayol, A.; Poirel, L.; Brink, A.; Villegas, M.V.; Yilmaz, M.; Nordmann, P. Resistance to Colistin Associated with a Single Amino Acid Change in Protein PmrB among Klebsiella pneumoniae Isolates of Worldwide Origin. Antimicrob. Agents Chemother. 2014, 58, 4762–4766. [Google Scholar] [CrossRef] [PubMed]
  55. Brovedan, M.; Repizo, G.D.; Marchiaro, P.; Viale, A.M.; Limansky, A. Characterization of the Diverse Plasmid Pool Harbored by the BlaNDM-1-Containing Acinetobacter bereziniae HPC229 Clinical Strain. PLoS ONE 2019, 14, e0220584. [Google Scholar] [CrossRef] [Green Version]
  56. Brovedan, M.; Marchiaro, P.M.; Morán-Barrio, J.; Revale, S.; Cameranesi, M.; Brambilla, L.; Viale, A.M.; Limansky, A.S. Draft Genome Sequence of Acinetobacter bereziniae HPC229, a Carbapenem-Resistant Clinical Strain from Argentina Harboring BlaNDM-1. Genome Announc. 2016, 4, 00117-16. [Google Scholar] [CrossRef] [Green Version]
  57. Kamolvit, W.; Higgins, P.G.; Paterson, D.L.; Seifert, H. Multiplex PCR to Detect the Genes Encoding Naturally Occurring Oxacillinases in Acinetobacter spp. J. Antimicrob. Chemother. 2014, 69, 959–963. [Google Scholar] [CrossRef] [Green Version]
  58. Marqué, S.; Poirel, L.; Héritier, C.; Brisse, S.; Blasco, M.D.; Filip, R.; Coman, G.; Naas, T.; Nordmann, P. Regional Occurrence of Plasmid-Mediated Carbapenem-Hydrolyzing Oxacillinase OXA-58 in Acinetobacter spp. in Europe. J. Clin. Microbiol. 2005, 43, 4885–4888. [Google Scholar] [CrossRef] [PubMed]
  59. Coelho, J.; Woodford, N.; Afzal-Shah, M.; Livermore, D. Occurrence of OXA-58-like Carbapenemases in Acinetobacter spp. Collected over 10 Years in Three Continents. Antimicrob. Agents Chemother. 2006, 50, 756–758. [Google Scholar] [CrossRef]
  60. Mendes, R.E.; Bell, J.M.; Turnidge, J.D.; Castanheira, M.; Deshpande, L.M.; Jones, R.N. Codetection of BlaOXA-23-like Gene (BlaOXA-133) and BlaOXA-58 in Acinetobacter Radioresistens: Report from the SENTRY Antimicrobial Surveillance Program. Antimicrob. Agents Chemother. 2009, 53, 843–844. [Google Scholar] [CrossRef] [Green Version]
  61. Peleg, A.Y.; Franklin, C.; Walters, L.J.; Bell, J.M.; Spelman, D.W. OXA-58 and IMP-4 Carbapenem-Hydrolyzing Beta-Lactamases in an Acinetobacter junii Blood Culture Isolate from Australia. Antimicrob. Agents Chemother. 2006, 50, 399–400. [Google Scholar] [CrossRef]
  62. Huang, L.Y.; Lu, P.L.; Chen, T.L.; Chang, F.Y.; Fung, C.P.; Siu, L.K. Molecular Characterization of Beta-Lactamase Genes and Their Genetic Structures in Acinetobacter Genospecies 3 Isolates in Taiwan. Antimicrob. Agents Chemother. 2010, 54, 2699–2703. [Google Scholar] [CrossRef] [Green Version]
  63. Feng, Y.; Yang, P.; Wang, X.; Zong, Z. Characterization of Acinetobacter johnsonii Isolate XBB1 Carrying Nine Plasmids and Encoding NDM-1, OXA-58 and PER-1 by Genome Sequencing. J. Antimicrob. Chemother. 2016, 71, 71–75. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  64. Jiang, N.; Zhang, X.; Zhou, Y.; Zhang, Z.; Zheng, X. Whole-Genome Sequencing of an NDM-1- and OXA-58-Producing Acinetobacter towneri Isolate from Hospital Sewage in Sichuan Province, China. J. Glob. Antimicrob. Resist. 2019, 16, 4–5. [Google Scholar] [CrossRef] [PubMed]
  65. Suzuki, Y.; Endo, S.; Nakano, R.; Nakano, A.; Saito, K.; Kakuta, R.; Kakuta, N.; Horiuchi, S.; Yano, H.; Kaku, M. Emergence of IMP-34- and OXA-58-Producing Carbapenem-Resistant Acinetobacter colistiniresistens. Antimicrob. Agents Chemother. 2019, 63, e02633-18. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  66. Hendrickx, A.P.A.; Schade, R.P.; Landman, F.; Bosch, T.; Schouls, L.M.; van Dijk, K. Comparative Analysis of IMP-4- and OXA-58-Containing Plasmids of Three Carbapenemase-Producing Acinetobacter ursingii Strains in the Netherlands. J. Glob. Antimicrob. Resist. 2022, 31, 207–211. [Google Scholar] [CrossRef] [PubMed]
  67. Fávaro, L.D.S.; de Paula-Petroli, S.B.; Romanin, P.; Tavares, E.D.R.; Ribeiro, R.A.; Hungria, M.; de Oliveira, A.G.; Yamauchi, L.M.; Yamada-Ogatta, S.F.; Carrara-Marroni, F.E. Detection of OXA-58-Producing Acinetobacter bereziniae in Brazil. J. Glob. Antimicrob. Resist. 2019, 19, 53–55. [Google Scholar] [CrossRef]
  68. Ang, G.Y.; Yu, C.Y.; Cheong, Y.M.; Yin, W.F.; Chan, K.G. Emergence of ST119 Acinetobacter pittii Co-Harbouring NDM-1 and OXA-58 in Malaysia. Int. J. Antimicrob. Agents 2016, 47, 168–169. [Google Scholar] [CrossRef]
  69. Strateva, T.; Sirakov, I.; Savov, E.; Mitov, I. First Detection of an OXA-58 Carbapenemase-Producing Acinetobacter nosocomialis Clinical Isolate in the Balkan States. J. Glob. Antimicrob. Resist. 2018, 13, 123–124. [Google Scholar] [CrossRef]
  70. Tognim, M.C.B.; Gales, A.C.; Penteado, A.P.; Silbert, S.; Sader, H.S. Dissemination of IMP-1 Metallo- Beta -Lactamase-Producing Acinetobacter Species in a Brazilian Teaching Hospital. Infect. Control Hosp. Epidemiol. 2006, 27, 742–747. [Google Scholar] [CrossRef]
  71. Lee, K.; Kim, C.K.; Hong, S.G.; Choi, J.; Song, S.; Koh, E.; Yong, D.; Jeong, S.H.; Yum, J.H.; Docquier, J.D.; et al. Characteristics of Clinical Isolates of Acinetobacter Genomospecies 10 Carrying Two Different Metallo-Beta-Lactamases. Int. J. Antimicrob. Agents 2010, 36, 259–263. [Google Scholar] [CrossRef]
  72. Hu, H.; Hu, Y.; Pan, Y.; Liang, H.; Wang, H.; Wang, X.; Hao, Q.; Yang, X.; Yang, X.; Xiao, X.; et al. Novel Plasmid and Its Variant Harboring Both a Bla(NDM-1) Gene and Type IV Secretion System in Clinical Isolates of Acinetobacter lwoffii. Antimicrob. Agents Chemother. 2012, 56, 1698–1702. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  73. Wang, Y.; Wu, C.; Zhang, Q.; Qi, J.; Liu, H.; Wang, Y.; He, T.; Ma, L.; Lai, J.; Shen, Z.; et al. Identification of New Delhi Metallo-β-Lactamase 1 in Acinetobacter lwoffii of Food Animal Origin. PLoS ONE 2012, 7, e37152. [Google Scholar] [CrossRef] [Green Version]
  74. Yamamoto, M.; Nagao, M.; Matsumura, Y.; Hotta, G.; Matsushima, A.; Ito, Y.; Takakura, S.; Ichiyama, S. Regional Dissemination of Acinetobacter Species Harbouring Metallo-β-Lactamase Genes in Japan. Clin. Microbiol. Infect. 2013, 19, 729–736. [Google Scholar] [CrossRef] [Green Version]
  75. Alattraqchi, A.G.; Mohd Rani, F.; Rahman, N.I.A.; Ismail, S.; Cleary, D.W.; Clarke, S.C.; Yeo, C.C. Complete Genome Sequencing of Acinetobacter baumannii AC1633 and Acinetobacter nosocomialis AC1530 Unveils a Large Multidrug-Resistant Plasmid Encoding the NDM-1 and OXA-58 Carbapenemases. mSphere 2021, 6, e01076-20. [Google Scholar] [CrossRef]
  76. Chen, Y.; Guo, P.; Huang, H.; Huang, Y.; Wu, Z.; Liao, K. Detection of Co-Harboring OXA-58 and NDM-1 Carbapenemase Producing Genes Resided on a Same Plasmid from an Acinetobacter pittii Clinical Isolate in China. Iran. J. Basic Med. Sci. 2019, 22, 106–111. [Google Scholar] [CrossRef]
  77. Cheikh, H.B.; Domingues, S.; Silveira, E.; Kadri, Y.; Rosário, N.; Mastouri, M.; Da Silva, G.J. Molecular Characterization of Carbapenemases of Clinical Acinetobacter baumannii-calcoaceticus Complex Isolates from a University Hospital in Tunisia. 3 Biotech. 2018, 8, 297. [Google Scholar] [CrossRef]
  78. Zhou, S.; Chen, X.; Meng, X.; Zhang, G.; Wang, J.; Zhou, D.; Guo, X. “Roar” of BlaNDM-1 and “Silence” of BlaOXA-58 Co-Exist in Acinetobacter pittii. Sci. Rep. 2015, 5, 8976. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  79. Wang, J.; Wang, H.; Cai, K.; Yu, P.; Liu, Y.; Zhao, G.; Chen, R.; Xu, R.; Yu, M. Evaluation of Three Sample Preparation Methods for the Identification of Clinical Strains by Using Two MALDI-TOF MS Systems. J. Mass Spectrom. 2021, 56, e4696. [Google Scholar] [CrossRef] [PubMed]
  80. Clinical and Laboratory Standards Institute (CLSI). Methods for the Identification of Cultured Microorganisms Using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry, 1st ed.; CLSI supplement M58; CLSI: Wayne, PA, USA, 2017. [Google Scholar]
  81. Diancourt, L.; Passet, V.; Nemec, A.; Dijkshoorn, L.; Brisse, S. The Population Structure of Acinetobacter baumannii: Expanding Multiresistant Clones from an Ancestral Susceptible Genetic Pool. PLoS ONE 2010, 5, e10034. [Google Scholar] [CrossRef] [Green Version]
  82. Bartual, S.G.; Seifert, H.; Hippler, C.; Luzon, M.A.D.; Wisplinghoff, H.; Rodríguez-Valera, F. Development of a Multilocus Sequence Typing Scheme for Characterization of Clinical Isolates of Acinetobacter baumannii. J. Clin. Microbiol. 2005, 43, 4382. [Google Scholar] [CrossRef] [Green Version]
  83. Gundi, V.A.K.B.; Dijkshoorn, L.; Burignat, S.; Raoult, D.; La Scola, B. Validation of Partial RpoB Gene Sequence Analysis for the Identification of Clinically Important and Emerging Acinetobacter Species. Microbiology 2009, 155, 2333–2341. [Google Scholar] [CrossRef] [Green Version]
  84. Tamura, K.; Stecher, G.; Kumar, S. MEGA11: Molecular Evolutionary Genetics Analysis Version 11. Mol. Biol. Evol. 2021, 38, 3022–3027. [Google Scholar] [CrossRef] [PubMed]
  85. Letunic, I.; Bork, P. Interactive Tree Of Life (ITOL) v5: An Online Tool for Phylogenetic Tree Display and Annotation. Nucleic Acids Res. 2021, 49, W293–W296. [Google Scholar] [CrossRef] [PubMed]
  86. ISO 20776-1:2019; Susceptibility Testing of Infectious Agents and Evaluation of Performance of Antimicrobial Susceptibility Test Devices—Part 1: Broth Micro-Dilution Reference Method for Testing the In Vitro Activity of Antimicrobial Agents against Rapidly Growing Aerobic Bacteria Involved in Infectious Diseases. ISO: Geneva, Switzerland, 2019.
  87. The European Committee on Antimicrobial Susceptibility Testing. EUCAST Reading Guide for Broth Microdilution v. 4.0. 2022. Available online: https://www.eucast.org/fileadmin/src/media/PDFs/EUCAST_files/Disk_test_documents/2022_manuals/Reading_guide_BMD_v_4.0_2022.pdf (accessed on 17 July 2023).
  88. The European Committee on Antimicrobial Susceptibility Testing. Breakpoint Tables for Interpretation of MICs and Zone Diameters. Version 13.1. 2023. Available online: http://www.eucast.org (accessed on 17 July 2023).
  89. Clinical and Laboratory Standards Institute (CLSI). Performance Standards for Antimicrobial Susceptibility Testing, 33rd ed.; CLSI supplement M100; CLSI: Wayne, PA, USA, 2023. [Google Scholar]
  90. Argimón, S.; Abudahab, K.; Goater, R.J.E.; Fedosejev, A.; Bhai, J.; Glasner, C.; Feil, E.J.; Holden, M.T.G.; Yeats, C.A.; Grundmann, H.; et al. Microreact: Visualizing and Sharing Data for Genomic Epidemiology and Phylogeography. Microb. Genom. 2016, 2, e000093. [Google Scholar] [CrossRef] [PubMed] [Green Version]
Antibiotics 12 01301 g001
Figure 1. Midpoint-rooted maximum-likelihood distance tree of partial rpoB sequences from clinical isolates and reference strains of Anb species. The various species identified in this study are shown with the colored inner clades, according to the legend. Reference strains are marked with black triangles. Species of the A. calcoaceticus-baumannii complex are shown with red branches. Concentric rings show (from the center to the outside): (i) the accuracy of the species identification with the Autobio and Bruker MALDI-TOF MS systems; (ii) the infection type; (iii) the antibiotic resistance profiles; and (iv) the presence of acquired carbapenemase genes (see legends).
Figure 1. Midpoint-rooted maximum-likelihood distance tree of partial rpoB sequences from clinical isolates and reference strains of Anb species. The various species identified in this study are shown with the colored inner clades, according to the legend. Reference strains are marked with black triangles. Species of the A. calcoaceticus-baumannii complex are shown with red branches. Concentric rings show (from the center to the outside): (i) the accuracy of the species identification with the Autobio and Bruker MALDI-TOF MS systems; (ii) the infection type; (iii) the antibiotic resistance profiles; and (iv) the presence of acquired carbapenemase genes (see legends).
Antibiotics 12 01301 g001
Table 1. Accuracy of the species identification of Anb isolates using MALDI-TOF MS systems.
Table 1. Accuracy of the species identification of Anb isolates using MALDI-TOF MS systems.
Anb Species 1No. of IsolatesNo. (Percent) Correctly Identified
Autobio AutofBruker Biotyper
A. bereziniae180 (0%)18 (100%)
A. calcoaceticus/oleivorans2117 (81%)21 (100%)
A. courvalinii10 (0%)1 (100%)
A. geminorum140 (0%)0 (0%)
A. haemolyticus33 (100%)3 (100%)
A. johnsonii77 (100%)7 (100%)
A. junii99 (100%)9 (100%)
A. lwoffii55 (100%)5 (100%)
A. nosocomialis3232 (100%)30 (93.8%)
A. pittii100100 (100%)89 (89%)
A. radioresistens22 (100%)2 (100%)
A. seifertii80 (0%)8 (100%)
A. soli99 (100%)9 (100%)
A. ursingii/septicus55 (100%)5 (100%)
1 as determined by rpoB gene sequence analysis.
Table 2. Minimum inhibitory concentration (MIC) range, MIC50, MIC90, and proportion of Anb isolates by category of susceptibility to 11 antibiotics.
Table 2. Minimum inhibitory concentration (MIC) range, MIC50, MIC90, and proportion of Anb isolates by category of susceptibility to 11 antibiotics.
AntibioticMIC, mg/LPercent by Category 1
Range50%90%SIR
Amikacin≤0.5–≥2561890.1-9.9
Cefepime 2≤0.5–≥25621688.75.75.7
Ciprofloxacin≤0.06–≥1280.1250.5-92.67.4
Colistin≤0.06–≥640.5297.0-3.0
Gentamicin≤0.25–≥2560.5888.8-11.2
Imipenem≤0.06–≥1280.1250.595.7-4.3
Meropenem≤0.06–≥1280.250.595.20.93.9
Sulbactam 3≤0.25–≥2561492.22.25.6
Tigecycline 4≤0.03–≥160.251---
Tobramycin≤0.25–≥2560.25291.3-8.7
Trimethoprim–
sulfamethoxazole (1:19) 5		≤0.125–≥2560.125489.61.78.7
1 S, susceptible; I, susceptible, increased exposure (EUCAST), or intermediate resistant (CLSI); R, resistant. EUCAST v13.0 MIC clinical breakpoints were used unless otherwise stated. 2 For cefepime, CLSI M100 ED33 MIC breakpoints were used. 3 For sulbactam, the MIC breakpoints (S ≤ 4 mg/L, I 8 mg/L, R ≥ 16 mg/L) were based on CLSI M100 ED33 ampicillin–sulbactam (2:1) MIC breakpoints (S ≤ 8/4 mg/L, I 16/8 mg/L, R ≥ 32/16 mg/L), where sulbactam comprises the active component of the combination against Acinetobacter. 4 For tigecycline, no MIC breakpoints were established by either EUCAST or CLSI. 5 MIC values refer to trimethoprim.
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Sheck, E.; Romanov, A.; Shapovalova, V.; Shaidullina, E.; Martinovich, A.; Ivanchik, N.; Mikotina, A.; Skleenova, E.; Oloviannikov, V.; Azizov, I.; et al. Acinetobacter Non-baumannii Species: Occurrence in Infections in Hospitalized Patients, Identification, and Antibiotic Resistance. Antibiotics 2023, 12, 1301. https://doi.org/10.3390/antibiotics12081301

AMA Style

Sheck E, Romanov A, Shapovalova V, Shaidullina E, Martinovich A, Ivanchik N, Mikotina A, Skleenova E, Oloviannikov V, Azizov I, et al. Acinetobacter Non-baumannii Species: Occurrence in Infections in Hospitalized Patients, Identification, and Antibiotic Resistance. Antibiotics. 2023; 12(8):1301. https://doi.org/10.3390/antibiotics12081301

Chicago/Turabian Style

Sheck, Eugene, Andrey Romanov, Valeria Shapovalova, Elvira Shaidullina, Alexey Martinovich, Natali Ivanchik, Anna Mikotina, Elena Skleenova, Vladimir Oloviannikov, Ilya Azizov, and et al. 2023. "Acinetobacter Non-baumannii Species: Occurrence in Infections in Hospitalized Patients, Identification, and Antibiotic Resistance" Antibiotics 12, no. 8: 1301. https://doi.org/10.3390/antibiotics12081301

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