title: Multilocus sequence typing versus pulsed-field gel electrophoresis for characterization of extended-spectrum beta-lactamase-producing Escherichia coli isolates.
abstract: Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli strains are emerging pathogens. Molecular typing of ESBL-producing E. coli is useful for surveillance purposes, to monitor outbreaks and track nosocomial spread. Although pulsed-field gel electrophoresis (PFGE) is the current "gold standard" for bacterial molecular typing, multilocus sequence typing (MLST) may offer advantages. Forty ESBL-producing E. coli isolates were selected at random from a cohort of intensive care unit patients who had active surveillance perirectal cultures done. PFGE identified 19 unique PFGE types (PT) among the 40 isolates; MLST identified 22 unique sequence types. MLST had greater discriminatory ability than PFGE for ESBL-producing E. coli. Simpson's indices of diversity for PFGE and MLST were 0.895 and 0.956, respectively. There were five clonal complexes (CCs) (isolates with differences of no more than two loci) that each contained multiple PT, but each PT was found in only one CC, indicating genetic consistency within a CC. MLST has clear utility in studies of ESBL-producing E. coli, based on a greater discriminatory ability and reproducibility than PFGE and the ability to a priori define genetically related bacterial strains.
authors.affiliation: Department of Epidemiology and Preventive Medicine, University of Maryland School of Medicine, MSTF Building, Room 9-34, 10 South Pine Street, Baltimore, MD 21201, USA. lnemoy@epi.umaryland.edu
authors.forename: Lucia L
authors.initials: LL
authors.lastname: Nemoy
authors.forename: Mamuka
authors.initials: M
authors.lastname: Kotetishvili
authors.forename: Justine
authors.initials: J
authors.lastname: Tigno
authors.forename: Ananda
authors.initials: A
authors.lastname: Keefer-Norris
authors.forename: Anthony D
authors.initials: AD
authors.lastname: Harris
authors.forename: Eli N
authors.initials: EN
authors.lastname: Perencevich
authors.forename: Judith A
authors.initials: JA
authors.lastname: Johnson
authors.forename: Dave
authors.initials: D
authors.lastname: Torpey
authors.forename: Alexander
authors.initials: A
authors.lastname: Sulakvelidze
authors.forename: J Glenn
authors.initials: JG
authors.lastname: Morris
authors.forename: O Colin
authors.initials: OC
authors.lastname: Stine
mesh_terms: D015373:Bacterial Typing Techniques; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology; D004269:DNA, Bacterial / Q000032:analysis; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology; D029968:Escherichia coli Proteins / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D001618:beta-Lactamases