Dear Colleagues,

Antimicrobial therapy revolutionized, at its beginnings, both human and veterinary medicine, with a spectacular decrease in infection rate and dramatic reduction of epidemics. Diseases such as tuberculosis, known for millennia, 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, 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 and reports of resistance to erythromycin and linezolid in humans. Additionally, more and more bacterial strains, some pathogenic and some ubiquitous, were reported to acquire multiple resistance to antibiotics, further complicating the therapeutic approach in either human or animal patients.

Such results of the laboratory and clinical research 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 and threatens “one health”. Since new antibiotic resistance mechanisms are 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 with 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, cited in the oldest written evidence for their healing power. Nonetheless, modern science relies on traditional preparations, the extracts from these being difficult to standardize. Therefore, sometimes, combinations of plant extracts and allopathic drugs, due to their synergistic effects, have been suggested. Bee products have proven numerous health-directed properties, including antimicrobial ones mainly allocated to propolis and Manuka honey, throughout history. Other, numerous marine or terrestrial organisms along the entire phylogenetic scale have also been mentioned as a source for antimicrobials by researchers. Finally, other natural mineral compounds, such as clay or coal, lignite or zeolites, have been tested and found to be efficient directly or indirectly acting antimicrobials, due to their diverse properties.

This Research Topic aims at updating research results on alternative sources for antimicrobial drugs and therapies, their laboratory or clinical use, preparation technologies, factors influencing their efficacy in medicine, and their impact in 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, 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.

Prof. Marina Spinu
Guest Editor

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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.