PLASMID-MEDIATED QUINOLONE RESISTANCE IN MUNICIPAL WASTEWATER BIOSOLIDS

Ella Kaplan ^1,3 Noa Sela ² Edouard Jurkevitch ³ Eddie Cytryn ¹

¹Department of SoilChemistry, Plant Nutrition and Microbiology, Institute of Soil, Water and Environmental Sciences,The Volcani Center, Agricultural Research Organization, Beit Dagan
²Department of Plant Pathology and Weed Research, The Volcani Center, Agricultural Research Organization, Beit Dagan
³Agroecology and Plant Health, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot

Antibiotic resistance is a growing global concern due to development of multidrug resistant strains associated with the extensive use, and misuse of antibiotic compounds. Although antibiotic resistance genes (ARGs) are commonly found in natural habitats, anthropogenic activity increased their abundance significantly. Wastewater treatment plants (WWTP) are large-scale man-made reservoirs in which human associated bacteria come in close and prolonged proximity with environmental strains allowing horizontal gene transfer to occur, therefore considered as major hotspots for evolution and dispersal of ARGs. Among resistance mechanisms, those harbored on mobile genetic elements are maybe the most significant public health hazards because of their capacity to horizontally transfer resistance mechanisms within and between phylogenetic groups. Fluoroquinolones are commonly prescribed antibacterial drugs used in humans. Resistance was traditionally associated with mutations in bacterial gyrase/topoisomerase IV but in the past decade several plasmid-associated quinolone resistance mechanisms have been detected. In this study we isolated a large collection (N=112) of ciprofloxacin-resistant Enterobacteriaceae from WWTP biosolids. Many of these isolates were multidrug resistant and several of them contained plasmid-associated quinolone resistance genes. We successfully extracted plasmids (n=8) which confer resistance to fluoroquinolones and analyzed their resistance pattern. One of the plasmids is a large, multi-drug resistance, IncF-type plasmid, about 160kbp in size that contains 8 different resistance genes conferring resistance to 4 different antibiotic families. It is highly similar to the pKPN3 plasmid family that have been detected in multidrug resistant clinical Klebsiella isolates. The other 7 plasmids are much smaller and were limited to qnrS-type plasmid associated quinolone resistance gene and show high similarity to each other.