Occurrence of ciprofloxacin-, trimethoprim-sulfamethoxazole-, and vancomycin-resistant bacteria in a municipal wastewater treatment plant.
The occurrence of antibiotic-resistant bacteria was evaluated in aqueous samples obtained from a municipal wastewater treatment plant. Samples collected from the influent, clarifier effluent, and disinfected effluent were assayed for fecal coliforms, E. coli, and enterococci exhibiting resistance to ciprofloxacin, trimethoprim-sulfamethoxazole, and vancomycin. Membrane filtration of samples was followed by plating on growth media containing various concentrations of antibiotic. Bacterial colonies on plates with antibiotic exposures greater than the clinical minimum inhibitory concentrations were counted and considered resistant. The numbers of drug-resistant organisms in influent ranged from nondetectable to 7 x 10(5) colony-forming units (CFU)/100 mL for fecal coliforms, nondetectable to 5 x 10(4) CFU/100 mL for E. coli, and nondetectable to 6 x 10(5) CFU/100 mL for enterococci. Fecal coliforms, E. coli, and enterococci with reduced susceptibility to antibiotics were also detected in influent and clarifier effluent; however, the disinfected effluent did not contain resistant bacteria. Species-level identification of enterococci revealed that resistant enterococci were predominantly E. faecalis.
Nagulapally
Sujatha R
SR
Department of Civil Engineering, Kansas State University (KSU), Manhattan, Kansas, USA.
Ahmad
Aqeel
A
Henry
Adam
A
Marchin
George L
GL
Zurek
Ludek
L
Bhandari
Alok
A
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002939:Ciprofloxacin / Q000494:pharmacology; D024901:Drug Resistance, Multiple, Bacterial; D004755:Enterobacteriaceae / Q000187:drug effects / Q000302:isolation & purification*; D016983:Enterococcus / Q000187:drug effects / Q000302:isolation & purification*; D004926:Escherichia coli / Q000187:drug effects / Q000302:isolation & purification*; D008826:Microbial Sensitivity Tests; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000494:pharmacology; D014640:Vancomycin / Q000494:pharmacology; D014865:Waste Disposal, Fluid; D014871:Water Microbiology
D000900:Anti-Bacterial Agents; D002939:Ciprofloxacin; D014640:Vancomycin; D015662:Trimethoprim, Sulfamethoxazole Drug Combination