Degradation kinetics of antibiotic resistance gene (mecA) of Methicillin-resistant Staphylococcus aureus (MRSA) during water treatment with free available chlorine, ozone, and ultraviolet light

Abstract

Increasing antibiotic resistance is a global concern for public health. Antibiotic resistance bacteria (ARB) and genes (ARGs) can be disseminated through urban water cycle and disinfection processes in municipal water treatment plants can thus be an important barrier against ARB and ARGs. In this study, the efficiency of water chlorination was assessed to inactivate Methicillin Resistant Staphylococcus aureus (MRSA) and its mecA gene as the target ARB and ARG, respectively. During chlorination of MRSA, the concentration of cultivable and membrane-intact cells decreased rapidly at low chlorine exposure (< 0.4 mg/Lmin) while the degradation of mecA was much slower and required more than 50 mg/Lmin of chlorine exposure to achieve 3- logs reduction. Effects of initial chlorine concentration, solution pH, presence of mecA as extracellular vs. intracellular form, and target amplicon size of mecA on the degradation kinetics of mecA were systematically investigated.