Surveillance of antimicrobial resistant Gram negative bacteria in water and wastewater sources of human exposure in Singapore and evaluation of monitoring methods (2016)

Undergraduates: Katherine Mulligan, Laurence Glass-Haller, Karina Gin Yew-Hoong, Thai Hoang Le

Faculty Advisor: Mark Sobsey
Department: Biology

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The alarming proliferation and widespread presence of antibiotic resistant bacteria and antibiotic resistance gene transfer in the environment, potentially originating from human sewage, hospital effluent, and treated municipal sewage effluent, coupled with the lack of integrated and cohesive global surveillance methods, has created a need for improved and harmonized detection and analysis methods. As part of a larger study that aims to compare different bacteriological media and methods used by different laboratories to see if they provide comparable information and to test clinical diagnostic microbiology bacteriological media for direct detection and enumeration of antimicrobial resistant E coli and related coliform bacteria in environmental samples, this study assesses the susceptibility of bacterial isolates from the waste waters of Singapore hospitals to seven different antibiotics using the Kirby-Bauer disc-diffusion method to determine bacterial phenotype (resistant, intermediate, or susceptible) and compare to apparent susceptibilities as based on growth on CHROMagar KPC and CHROMagar ESBL medias. As expected, the majority of bacterial samples cultured on CHROMagar KPC media were resistant to carbapenems (imipenem and meropenem). Likewise, the majority of bacteria grown and isolated on CHROMagar ESBL media were determined to be resistant to beta lactam antibiotics (cephalosporins ¿¿¿ ceftazidime, ceftrizoxime, and ceftriaxone).