Dear Colleagues,

This Special Issue is a continuation of our previous Special Issue, “Antimicrobial Compounds from Alternative Sources”.

Antimicrobial therapy revolutionized both human and veterinary medicine, leading to a spectacular decrease in infection rates and a dramatic reduction in epidemics. Diseases such as tuberculosis found their “therapeutic golden standard” when streptomycin was discovered in 1944. Numerous antibiotic groups were subsequently discovered, such as tetracycline (1945), rifamycin (1957), quinolones and streptogramins (1962), cephalexin (1968), carbapenem (1976), norfloxacin (1986), linezolid (1989), and others.

Nevertheless, if one looks into the efficacy of these drugs, many of which are also approved for veterinary or human use, it is obvious that resistance develops soon after their introduction in therapy. Thus, only five years after the introduction of penicillin, the first resistant strain of S. aureus was identified. Similarly, only three years (or one, according to other authors) elapsed between the introduction of erythromycin and linezolid in humans and reports of resistance to these drugs. Additionally, an increasing number of bacterial strains, some pathogenic and some ubiquitous, have been reported to acquire multiple resistance to antibiotics, further complicating the therapeutic approach in both human and animal patients.

Such laboratory and clinical research results led WHO and OIE to consider antibiotic resistance “one of the biggest threats to global health, food security, and development today”. Bacteria, pathogenic or epiphytic, gain their antibiotic resistance under natural circumstances. Nevertheless, the changes that occur in the resistome are accelerated and broadened by either misuse or inappropriate/exaggerated treatment with antimicrobials in both humans and animals. The subsequent pollution of the surrounding habitats/broader environment with resistance genes and also poor infection prevention and control may pose risks for humans, livestock, and wildlife. The “ESKAPE” group (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter species) represents one of the best examples of the threat to “one health”. Since new antibiotic resistance mechanisms are continuously developed by bacteria, we cannot expect that antibiotics yet to be synthesized will cope with multiresistant microbial strains in the post-antibiotic era.

Nature has been very generous in providing humankind with numerous resources for its survival and fight against diseases. Medicinal and aromatic plants have represented the center of traditional therapeutic practices for millennia, being cited in the oldest written evidence for their healing power. Nonetheless, modern science relies on traditional preparations, as extracts from these plants are difficult to standardize. Therefore, combinations of plant extracts and allopathic drugs, due to their synergistic effects, have been suggested. Bee products have numerous proven health-directed properties, including antimicrobial ones mainly allocated to propolis and Manuka honey. Numerous other marine and terrestrial organisms, along the entire phylogenetic scale, have also been mentioned as a source of antimicrobials by researchers. Finally, other natural mineral compounds, such as clay or coal, lignite, or zeolites, have been tested and found to be efficient antimicrobials, directly or indirectly, due to their diverse properties.

This Special Issue aims at providing an updated overview of research results for alternative sources of antimicrobial drugs and therapies, their laboratory or clinical use, preparation technologies, factors influencing their efficacy in medicine, and their impact on preserving “One Health” and “”One Welfare”. Submissions of perspectives, opinions, commentaries, and data reports are also welcome.

Potential topics include, but are not limited to, the following:

• Antimicrobial compounds from plants: their preparation, use, and biological effects;
• Bee products: their role in obtaining novel antimicrobials;
• Antimicrobial compounds from mineral sources: obtainment methodology, standardization, and biological effects;
• Antimicrobials from other sources (marine or terrestrial, microorganisms, etc.): obtainment methodology, effects, and biological uses;
• Impact of alternative antimicrobials on antibiotic resistance gene transfer;
• Farming technologies and alternative antibiotic uses;
• Potential role of alternative antimicrobial in controlling environment pollution;
• Prevention and control of antibiotic resistance by use of alternative antimicrobials.

Dr. Marina Spinu
Dr. Pall Emoke
Guest Editors

Manuscript Submission Information

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• antimicrobial compounds from plants: their preparation, use, and biological effects
• bee products: their role in obtaining novel antimicrobials
• antimicrobial compounds from mineral sources: obtainment methodology, standardization, biological effects
• antimicrobials from other sources (marine or terrestrial, microorganisms, etc.): obtainment methodology, effects, biological uses
• impact of alternative antimicrobials on antibiotic resistance gene transfer
• farming technologies and alternative antibiotic uses
• potential role of alternative antimicrobial to control environment pollution
• prevention and control of antibiotic resistance by use of alternative antimicrobials