Surveillance of antibiotic persistence adaptation of emerging antibiotic-resistant bacteria in wastewater treatment processes: Comparison between domestic and hospital wastewaters

Abstract

This study aims to investigate the survival and antimicrobial resistance (AMR) adaptation of the emerging antibiotic-resistant bacteria (ARB) in a common wastewater treatment process (activated sludge (AS) + chlorination (if any)) treating domestic and hospital wastewater in Thailand. The selected Gram-negative AMR indicators were E. coli (EC), coliforms (CF), and Acinetobacter spp. (AC) which resist carbapenem and extended spectrum beta-lactamase (ESBL). Meanwhile, the selected Gram-positive ARBs were methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant Enterococcus (VRE). The viable population of those ARB was enumerated via standard plate count using selective/differential media comparison between added antibiotic (resistant population) and none (total population). The results showed that E. coli, coliforms, Acinetobacter spp., S. aureus, and Enterococci spp. appeared in similar ranges (4.20 – 5.05 log CFU ml −1) in both types of wastewaters. The ESBL resistance population of EC, CF, AC; and MRSA appeared similarly in both types of wastewaters. However, the ARB percentages of carbapenem resistance of EC, CF, and AC including VRE were higher in the hospital wastewater. In treatment processes, all ARB could survive in AS processes differently, but only MRSA, carbapenem- and ESBL-resistant Acinetobacter spp. might reproduce in the aeration tanks. Moreover, carbapenem and ESBL-resistant Acinetobacter spp., MRSA, and VRE showed remarkably high AMR prevalences in the chlorinated effluent. The findings suggest that carbapenem- and ESBL-resistant Acinetobacter spp., MRSA, and VRE could be the AMR indicators of hospital-discharged wastewater.