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Occurrence of Ciprofloxacin‐, Trimethoprim‐Sulfamethoxazole‐, and Vancomycin‐Resistant Bacteria in a Municipal Wastewater Treatment Plant
Author(s) -
Nagulapally Sujatha R.,
Ahmad Aqeel,
Henry Adam,
Marchin George L.,
Zurek Ludek,
Bhandari Alok
Publication year - 2009
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143008x304596
Subject(s) - ciprofloxacin , sulfamethoxazole , trimethoprim , wastewater , vancomycin , bacteria , sewage treatment , microbiology and biotechnology , antibiotics , environmental science , biology , environmental engineering , staphylococcus aureus , genetics
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 × 10 5 colony‐forming units (CFU)/100 mL for fecal coliforms, nondetectable to 5 × 10 4 CFU/100 mL for E. coli , and nondetectable to 6 × 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 .