Kostas Konstantinidis
Georgia Institute of Technology, Georgia
Title: Do disinfectants promote bacterial antibiotic resistance?
Biography
Biography: Kostas Konstantinidis
Abstract
Whether disinfectant exposure promotes antibiotic resistance (AbR) has been a long debate with major practical consequences. To obtain insights into this issue, we exposed a microbial community originating from River sediment (Calcasieu River, USA) to benzalkonium chlorides (BAC; a family of quaternary ammonium disinfectants) for 3 years in a fed-batch bioreactor receiving Dextrin Peptone plus BAC as the sole carbon source (DPB bioeractor). A bioreactor receiving only Dextrin Peptone (DP) served as control. Bacterial isolates, representing the same ancestral population in the original inoculum were also obtained from both bioreactors and used to study adaptive evolution in response to increasingly higher BAC concentrations. Metagenomics of the bioreactors and genetic manipulation of isolates revealed that BAC exposure induced the spread of AbR in several species via horizontal transfer of mobile DNA elements that encode a BAC efflux pump together with AbR genes. Although several BAC-exposed isolates exhibited higher resistance to certain antibiotics, others did not, presumably due to their intrinsic resistance mechanisms. Nonetheless, genomics and transcriptomics analysis of Pseudomonas aeruginosa isolates revealed several fixed mutations in BAC-evolved populations such as in the histidine kinase A domain of the pmrB, which regulates resistance to polymyxin B, consistent with higher MIC values for polymyxin B and the overexpression of genes regulating tetracycline and ciprofloxacin resistance in response to BAC exposure. Collectively, this result revealed that there is a significant link between disinfectants and AbR antibiotics, providing new insights into the long-standing debate and have implications for biotechnological solutions to this problem.