Occurrence of Extended Spectrum β-Lactamase (ESBL) Producing Bacteria in Urban Clinton River Habitat.

Research paper by Chithra C Muraleedharan, Deepa D Talreja, Mamta M Kanwar, Ashok A Kumar, Satish K SK Walia

Indexed on: 15 Oct '18Published on: 15 Oct '18Published in: Journal of Global Antimicrobial Resistance


Recently, we reported the presence of extended spectrum β-lactamase (ESBL) genes in Clinton River. Here, we determined whether Clinton River water (CRW) is contaminated with antibiotics and is a reservoir of antibiotic resistant bacteria. Water samples were taken from two sites of Clinton River. Antibiotic concentrations were determined using LC-MS/MS. Antibiotic-resistant bacteria were enumerated on agar plates amended with six commonly used antibiotics. ESBL producing bacteria were identified using Phoenix 100 system and 16S rRNA gene sequencing. Antibiotic resistance genes transfer was performed by conjugation studies and the location of genes was determined by Southern hybridization. Virulence properties of ESBL isolates were determined by assessing their ability to make biofilms, cause cellular toxicity, and induction of inflammatory response in intestinal epithelial cells (CaCo2 cell line). Mass spectrometry analysis detected the presence of tetracycline (10μgL) and ciprofloxacin (20μgL) in CRW. 16S rRNA analysis of water samples showed the presence of potentially pathogenic bacteria (e.g., Shigella flexneri, Klebsiella pneumoniae, Aeromonas punctate, and Pseudomonas aeruginosa). Among 136 cultivable bacterial isolates tested, 42% were resistant to cefotaxime (CTX), 32% were resistant to chloramphenicol (CHL), 9% to tetracycline (TET), 11% to ciprofloxacin (CIP), and 9% to gentamicin (GEN). Eleven (41%) out of 27 cefotaxime resistant bacteria were ESBL positive and possessed either the bla (n=9)bla (n=1), or bla (n=1) genes. Moreover, these ESBL positive isolates were multidrug resistant, ranging resistance from 2 to 19 antibiotics. The comparative analysis of ESBL gene sequences from CRW bacteria showed 98-100% identity with clinical isolates. ESBL isolates from CRW were found to make biofilms, induced inflammatory cytokines, and caused toxicity to epithelial cells, suggesting their ability to cause infection. Together, our study demonstrates the presence of ESBL bacteria in CRW which has sequence similarities with clinical isolates and possesses virulence properties, indicating the CRW could be a potential reservoir in causing human infections. Copyright © 2018. Published by Elsevier Ltd.