Diversity of fecal coliforms and their antimicrobial resistance patterns in wastewater treatment model plant

摘要

The occurrence of resistance patterns among wastewater fecal coliforms was determined in thenstudy. Susceptibility of the isolates was tested against 19 antimicrobial agents: aminoglycosides,naztreonam, carbapenems, cephalosporines, b-lactam/b-lactamase inhibitors, penicillines,ntetracycline, trimethoprim/sulfamethoxazole, and fluoroquinolones. Additionally the removal ofnresistant isolates was evaluated in the laboratory-scale wastewater treatment model plantn(M-WWTP), continuously supplied with the wastewater obtained from the full-scale WWTP.nNumber of fecal coliforms in raw (after mechanical treatment) and treated wastewater, as well asnin aerobic chamber effluent was determined using selective medium. The selected strains werenidentified and examined for antibiotic resistance using Phoenix Automated Microbiology Systemn(BD Biosciences, USA). The strains were identified as Escherichia coli (n ¼ 222), Klebsiellanpneumoniae ssp. ozaenae (n ¼ 9), and Pantoea agglomerans (n ¼ 1). The isolate of P. agglomeransnas well as 48% of E. coli isolates were sensitive to all antimicrobials tested. The most frequentnresistance patterns were found for ampicillin: 100% of K. pneumoniae ssp. ozaenae and 41% ofnE. coli isolates. Among E. coli isolates 12% was regarded as multiple antimicrobial resistantn(MAR). In the studied M-WWTP, the applied activated sludge processes reduced considerablynthe number of fecal coliforms, but increased the ratio of antimicrobial-resistant E. coli isolatesnto sensitive ones, especially among strains with MAR patterns.