title: Prevalence and characteristics of lactose non-fermenting Escherichia coli in urinary isolates.
abstract: Recently, serotype O75 was found to be prominent among the non-ST131 ciprofloxacin-resistant Escherichia coli, and they were all lactose non-fermenters. In this study, we investigated the prevalence and characteristics of lactose non-fermenters in urinary isolates of E. coli. A total of 167 E. coli isolates was collected. Antimicrobial susceptibility tests were determined by VITEK 2 (bioMerieux, France). The lactose non-fermenters underwent PCR-based O typing, multilocus sequence typing (MLST) analysis, phylogenetic grouping. For ciprofloxacin-resistant isolates, the resistance mechanisms were investigated. Thirty-three (19.7%) isolates were lactose non-fermenters and the ciprofloxacin resistance rate was significantly higher than in lactose fermenters (66.7% vs. 31.6%, P = 0.0002). According to the serotype, O75 was the most common (42.4%, 14/33) and was followed by O16 (5/33), O2 (4/33), O25b (3/33), O15 (1/33), O6 (1/33), O1 (1/33). All the O75 isolates were ciprofloxacin-resistant and belonged to ST1193. By MLST, they were resolved into 11 STs. ST1193 was the most common (14/33) and was followed by ST131 (8/33). Interestingly, 8 isolates of ST131 were divided into three O types [O16 (4 isolates), O25b (3), and non-typeable (1)]. The ciprofloxacin resistance rate was high in isolates of O75-ST1193 and O25b-ST131 but low in O16-ST131 and O2-ST95. All the ciprofloxacin-resistant isolates showed identical triple mutations in gyrA and parC but the serotype O25b isolates had an additional mutation in parC (E84V). Only one isolate harbored aac(6')-Ib-cr variant and no qnr gene was detected. Continuous monitoring of the prevalence and clonal composition of the lactose non-fermenters is needed.
authors.affiliation: Department of Laboratory Medicine, Seoul St. Mary's Hospital, School of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Jiyoung
authors.initials: J
authors.lastname: Chang
authors.affiliation: Department of Laboratory Medicine, Seoul St. Mary's Hospital, School of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Jinkyung
authors.initials: J
authors.lastname: Yu
authors.affiliation: Department of Laboratory Medicine, Seoul St. Mary's Hospital, School of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Hyeyoung
authors.initials: H
authors.lastname: Lee
authors.affiliation: Department of Laboratory Medicine, Seoul St. Mary's Hospital, School of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Hyejin
authors.initials: H
authors.lastname: Ryu
authors.affiliation: Department of Laboratory Medicine, Seoul St. Mary's Hospital, School of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Kanggyun
authors.initials: K
authors.lastname: Park
authors.affiliation: Department of Laboratory Medicine, Seoul St. Mary's Hospital, School of Medicine, The Catholic University of Korea, Seoul, Republic of Korea. Electronic address: yjpk@catholic.ac.kr.
authors.forename: Yeon-Joon
authors.initials: YJ
authors.lastname: Park
mesh_terms: D002939:Ciprofloxacin / Q000494:pharmacology; D027081:DNA Gyrase / Q000235:genetics; D027101:DNA Topoisomerase IV / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000145:classification / Q000235:genetics* / Q000378:metabolism*; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000382:microbiology* / Q000652:urine; D006801:Humans; D007785:Lactose / Q000378:metabolism*; D017720:Molecular Epidemiology; D058885:Multilocus Sequence Typing; D015995:Prevalence; D065288:Serogroup; D014556:Urine / Q000382:microbiology
chemical_list: D002939:Ciprofloxacin; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase; D007785:Lactose
keywords: Ciprofloxacin; O75; Resistance; ST1193