Characterization of Escherichia coli isolated from wildlife in Iran: a comparative study with human isolates

Information on wildlife-derived bacteria, particularly in Iran, remains limited. This study determined the phenotypic and genotypic features of 103 fecal Escherichia coli ( E. coli ) isolates from wildlife in Bamou National Park, southern Iran, and compared them with 30 human fecal isolates (20 park rangers and 10 controls without wildlife contact). Wildlife isolates exhibited low resistance (< 15%) to only three of nine tested antibiotics (gentamicin, ciprofloxacin, and doxycycline), whereas resistance was more common in human isolates. Multidrug resistance occurred in < 2% of wildlife isolates but reached 20% in rangers. No wildlife isolate produced extended-spectrum beta-lactamases (ESBLs), compared with 25% of ranger isolates and 10% of controls. Class I integrons were detected in 12.6% of wildlife isolates, 35% of ranger isolates, and 30% of controls, while Class II integrons were identified only in 2.9% of wildlife isolates. Biofilm formation occurred in 13.6% of wildlife isolates, 5% of ranger isolates, and 40% of controls, predominantly as weak biofilms. Adhesion-related virulence genes were widely distributed with no significant differences among groups. The findings suggest the infiltration of antimicrobial resistance determinants into the wildlife microbiota. Also, biofilm-forming isolates and the high prevalence of adhesion-related virulence genes highlight their potential survival and transmissibility in natural ecosystems.