Widespread use and significant availability of antibiotics in the environment led bacterial adaptability to antibiotics. Even at low concentrations (ng/L), long term exposure of antibiotics to the microbe rich environment could create a selection pressure on bacteria for resistance development. Sewage treatment plants (STP) are one of the places where favorable conditions like plentiful of oxygen and nutrients are made available for bacteria to grow and degrade the organic content at faster rates. Studies say around 60% of antibiotics used during therapy are excreted from the body in an un-metabolised state and ultimately found their way to STP’s through wastewater. This could expose bacteria to sub inhibitory levels of antibiotics in the STP’s and create a selection pressure on bacteria to become resistant and play a critical role in spreading resistant bacteria to the environment. This study focused on identification and fate of the flouroquinolone (FQ) resistant bacteria in an Indian STP. Samples were collected from different points of STP and analyzed for the presence of FQ resistant bacteria. FQ resistant bacteria ranged from 5.4X103 to 5.7X103 in the influent and 2.5X102 to 4X102 in the effluent stream. An increase in the fraction of FQ resistant bacteria over total bacteria was observed after the biological treatment indicating the selection pressure. Antibiotic susceptibility tests showed that isolated bacteria were multidrug resistant in nature and increase in the MAR (Multiple antibiotic resistance) index was also observed after the biological treatment indicating bacteria have undergone certain selection pressure in the STP. Ribosomal DNA sequencing revealed that the resistant bacteria belonged to Enterobacteriaceae family (Escherichia, Shigella and Salmonella).

Occurrence and fate of Fluoroquinolone resistant bacteria in a sewage treatment plant in India

2019 Spring National Meeting

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