title: Effect of chlorine exposure on the survival and antibiotic gene expression of multidrug resistant Acinetobacter baumannii in water.
abstract: Acinetobacter baumannii is a multidrug resistant pathogen capable of causing a wide spectrum of clinical conditions in humans. Acinetobacter spp. is ubiquitously found in different water sources. Chlorine being the most commonly used disinfectant in water, the study investigated the effect of chlorine on the survival of A. baumannii in water and transcription of genes conferring antibiotic resistance. Eight clinical isolates of A. baumannii, including a fatal meningitis isolate (ATCC 17978) (~108 CFU/mL) were separately exposed to free chlorine concentrations (0.2, 1, 2, 3 and 4 ppm) with a contact time of 30, 60, 90 and 120 second. The surviving pathogen counts at each specified contact time were determined using broth dilution assay. In addition, real-time quantitative PCR (RT-qPCR) analysis of the antibiotic resistance genes (efflux pump genes and those encoding resistance to specific antibiotics) of three selected A. baumannii strains following exposure to chlorine was performed. Results revealed that all eight A. baumannii isolates survived the tested chlorine levels during all exposure times (p > 0.05). Additionally, there was an up-regulation of all or some of the antibiotic resistance genes in A. baumannii, indicating a chlorine-associated induction of antibiotic resistance in the pathogen.
authors: Department of Animal Science, 3636 Horsebarn Hill Rd Ext., Unit 4040, University of Connecticut, Storrs, Connecticut, CT 06269, USA. deepti.karumathil@uconn.edu.
authors: Deepti Prasad
authors: DP
authors: Karumathil
authors: Department of Animal Science, 3636 Horsebarn Hill Rd Ext., Unit 4040, University of Connecticut, Storrs, Connecticut, CT 06269, USA. hsin-bai.yin@uconn.edu.
authors: Hsin-Bai
authors: HB
authors: Yin
authors: Department of Animal Science, University of Minnesota, St. Paul, Minnesota, MN 55108, USA. anupjohn@umn.edu.
authors: Anup
authors: A
authors: Kollanoor-Johny
authors: Department of Animal Science, 3636 Horsebarn Hill Rd Ext., Unit 4040, University of Connecticut, Storrs, Connecticut, CT 06269, USA. kumar.venkitanarayanan@uconn.edu.
authors: Kumar
authors: K
authors: Venkitanarayanan
mesh_terms: D040981:Acinetobacter baumannii / Q000235:genetics / Q000378:metabolism; D002713:Chlorine; D004203:Disinfection; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D014871:Water Microbiology
chemical_list: D002713:Chlorine