Elucidating Environmental Reservoir of Antimicrobial Resistance: A Phenotypic Characterization of Gut Microbiota from Aquatic Coleoptera in a Low-Anthropogenic Impact Zone

Introduction and objectiveThe present study concentrated on reviving bacterial isolates from the gut microbiota of particularinsects (Coleoptera: Hydrophilidae and Helophoridae) collected in water bodies in the vicinity ofErzurum, Turkey. This area is characterised by a low level of human impact, thereby providing aunique opportunity to investigate the baseline microbial diversity and ecological roles within relativelypristine aquatic environments.Material and methodsThe antimicrobial susceptibility of the isolates was then assessed using disc diffusion and minimuminhibitory concentration (MIC) methods. The analysis encompassed 30 Gram-negative bacteriabelonging to the genera Aeromonas, Acinetobacter, Vibrio, Pseudomonas, Escherichia and Yersinia.ResultsThe results indicated that the most resistant bacteria were Aeromonas, Pseudomonas andAcinetobacter, while enteric bacteria demonstrated greater sensitivity. It is noteworthy thatnitrofurantoin, a commonly used antibiotic for treating urinary tract infections, exhibited the highestlevel of resistance among the antibiotics tested by disc diffusion, followed by cephalosporins andpenicillins.ConclusionsThe MIC testing with DKGM and NF kits demonstrated high resistance to cephalosporins,sulfonamides, polymyxins and monobactams. Furthermore, two multidrug-resistant (MDR) isolatesexhibited resistance to at least two antibiotic classes. These findings underscore the necessity forexpanded antimicrobial resistance surveillance beyond clinical settings, extending into environmentalsamples, and contributing to ongoing research on resistance mechanisms.