Emerging antibiotic resistance in Plesiomonasshigelloides: insights from surface waters in Southwest Nigeria

Abstract

Abstract This study aimed to investigate the antibiotic resistance pattern, extended-spectrum β-lactamase (ESBL) production, and biofilm formation potential of Plesiomonas shigelloides in selected surface waters in southwestern Nigeria. Isolates were identified using the spread plate technique on inositol brilliant green bile agar and confirmed molecularly by polymerase chain reaction. Antibiotic susceptibility was determined using the Kirby–Bauer disc diffusion method, ESBL production by the double disc synergistic test, and biofilm formation by the test tube method. A total of 111 P. shigelloides isolates were identified and confirmed. Significant resistance rates were observed against cefuroxime (71%), cefotaxime (92%), and ceftazidime (92%), while high susceptibility was noted for ciprofloxacin (94%), gentamicin (96%), and chloramphenicol (100%). A higher prevalence of multiple drug resistant phenotypes was observed during the dry season, reaching 79% and 60% along sampled rivers. Biofilm-producing phenotypes exhibited robust homogeneous biofilm formation. In this study, P. shigelloides exhibited high resistance to critical antibiotics such as third-generation cephalosporins. However, isolates displayed susceptibility to ciprofloxacin, gentamicin, and chloramphenicol. The presence of ESBL phenotypes and strong biofilm formation emphasizes the potential threat of P. shigelloides as an emerging environmental pathogen, highlighting the importance of monitoring and understanding antibiotic resistance patterns for effective public health management strategies.