Elucidating environmental reservoir of antimicrobial resistance - a phenotypic characterization of gut microbiota from aquatic coleoptera in a low-anthropogenic impact zone.

INTRODUCTION AND

OBJECTIVE

This study investigated the antibiotic resistance of bacterial isolates obtained from the gut microbiota of certain insects (Coleoptera: Hydrophilidae and Helophoridae), which were collected from aquatic areas in Erzurum Province, Türkiye. This area is characterised by a low level of human impact, thereby providing a unique opportunity to investigate the baseline microbial diversity and ecological roles within relatively pristine aquatic environments.

MATERIAL AND

METHODS

The antimicrobial susceptibility of the isolates was assessed using disc diffusion and minimum inhibitory concentration (MIC) methods. The analysis encompassed 30 Gram-negative bacteria belonging to the genera Aeromonas, Acinetobacter, Vibrio, Pseudomonas, Escherichia and Yersinia.

RESULTS

The results indicated that the most resistant bacteria were Aeromonas, Pseudomonas and Acinetobacter, while enteric bacteria demonstrated greater sensitivity. It is noteworthy that nitrofurantoin, a commonly used antibiotic for treating urinary tract infections, exhibited the highest level of resistance among the antibiotics tested by disc diffusion, followed by cephalosporins and penicillins.

CONCLUSIONS

The MIC testing with DKGM and NF kits demonstrated high resistance to cephalosporins, sulfonamides, polymyxins and monobactams. Furthermore, two multidrug-resistant (MDR) isolates exhibited resistance to at least two antibiotic classes. These findings underscore the necessity for expanded antimicrobial resistance surveillance beyond clinical settings, extending into environmental samples, and contributing to ongoing research on resistance mechanisms.