title: Prolonged clonal spreading and dynamic changes in antimicrobial resistance of Escherichia coli ST68 among patients who stayed in a respiratory care ward.
abstract: From 2007 to 2009, we collected a total of 83 bacteraemic isolates of Escherichia coli with reduced susceptibility or resistance to third-generation cephalosporins (TGCs). Isolates were genotyped by PFGE and multilocus sequence typing (MLST). The PFGE patterns revealed two highly correlated clusters (cluster E: nine isolates; cluster G: 22 isolates) associated with this prolonged clonal spreading. Compared with cluster E isolates, cluster G isolates were significantly more likely to harbour aac(6')-Ib-cr (P<0.05), and most of these isolates were isolated during a later year than cluster E isolates (P<0.05). By MLST analysis, 94% of cluster E and G isolates (29/31) were ST68. Although no time or space clustering could be identified by the conventional hospital-acquired infection monitoring system, E. coli cases caused by cluster E and G isolates were significantly associated with having stayed in our hospital's respiratory care ward (P<0.05). Isolates obtained from patients who had stayed in the respiratory care ward had a significantly higher rate of aac(6')-Ib-cr and blaCTX-M-14 positivity, and were more likely to belong to ST68/S68-like (all P<0.05). To our knowledge, this is the first report of prolonged clonal spreading caused by E. coli ST68 associated with a stay in a long-term care facility. Using epidemiological investigations and PFGE and MLST analyses, we have identified long-term clonal spreading caused by E. coli ST68, with extra antimicrobial-resistance genes possibly acquired during the prolonged spreading period.
authors.affiliation: Graduate Institute of Microbiology and Public Health, National Chung Hsing University, Taichung, Taiwan.|Division of Infectious Disease, Department of Internal Medicine, Tungs' Taichung MetroHarbor Hospital, Taichung, Taiwan.
authors.forename: Chih-Ming
authors.initials: CM
authors.lastname: Chen
authors.affiliation: Infection Control Office, Tungs' Taichung MetroHarbor Hospital, Taichung, Taiwan.
authors.forename: Se-Chin
authors.initials: SC
authors.lastname: Ke
authors.affiliation: Department of Medical Research, Tungs' Taichung MetroHarbor Hospital, Taichung, Taiwan.
authors.forename: Chia-Ru
authors.initials: CR
authors.lastname: Li
authors.affiliation: The Third Branch, Centers for Diseases Control, Taichung, Taiwan.
authors.forename: Chien-Shun
authors.initials: CS
authors.lastname: Chiou
authors.affiliation: Graduate Institute of Microbiology and Public Health, National Chung Hsing University, Taichung, Taiwan.
authors.forename: Chao-Chin
authors.initials: CC
authors.lastname: Chang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D016470:Bacteremia / Q000382:microbiology; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000235:genetics*; D004927:Escherichia coli Infections / Q000097:blood / Q000453:epidemiology / Q000382:microbiology*; D005260:Female; D014644:Genetic Variation; D006801:Humans; D008297:Male; D008875:Middle Aged; D012124:Respiratory Care Units; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents