title: Outbreak of nosocomial infections due to extended-spectrum beta-lactamase-producing strains of enteric group 137, a new member of the family Enterobacteriaceae closely related to Citrobacter farmeri and Citrobacter amalonaticus.
abstract: A member of the Enterobacteriaceae initially identified as Kluyvera cryocrescens by the MicroScan Gram-Negative Combo 13 panel caused an outbreak of nosocomial infections in four patients (pneumonia, n = 2; urinary tract infection, n = 1; wound infection, n = 1) and urinary tract colonization in one patient. When the strains were tested by the Enteric Reference Laboratory of the Centers for Disease Control and Prevention, biochemical results were most compatible with Yersinia intermedia, Kluyvera cryocrescens, and Citrobacter farmeri but identification scores were low and test results were discrepant. However, when the biochemical test profile was placed in the computer database as a new organism, all strains were identified as the organism with high identification scores (0. 999968 to 0.999997) and no discrepant test results. By 16S rRNA sequence analysis the organism clustered most closely with, but was distinct from, Citrobacter farmeri and Citrobacter amalonaticus. Based on its unique biochemical profile and rRNA sequence, this organism is designated Enteric Group 137. Restriction endonuclease analysis and taxonomic antibiograms of strains causing the outbreak demonstrated a single clone of Enteric Group 137, and antibiotic susceptibility testing revealed the presence of extended-spectrum beta-lactamase (ESBL) resistance. Enteric Group 137 appears to be a new opportunistic pathogen that can serve as a source of ESBL resistance in the hospital.
authors.affiliation: Departments of Pathology and Medicine, Northwestern University Medical School, and the Clinical Microbiology Laboratory, Veterans Administration Chicago Health Care System Lakeside Division, Chicago, Illinois 60611, USA.
authors.forename: J R
authors.initials: JR
authors.lastname: Warren
authors.forename: J J
authors.initials: JJ
authors.lastname: Farmer
authors.forename: F E
authors.initials: FE
authors.lastname: Dewhirst
authors.forename: K
authors.initials: K
authors.lastname: Birkhead
authors.forename: T
authors.initials: T
authors.lastname: Zembower
authors.forename: L R
authors.initials: LR
authors.lastname: Peterson
authors.forename: L
authors.initials: L
authors.lastname: Sims
authors.forename: M
authors.initials: M
authors.lastname: Bhattacharya
mesh_terms: D000368:Aged; D015373:Bacterial Typing Techniques / Q000379:methods; D002487:Centers for Disease Control and Prevention, U.S.; D002954:Citrobacter / Q000145:classification / Q000235:genetics; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology*; D004196:Disease Outbreaks; D004755:Enterobacteriaceae / Q000145:classification* / Q000201:enzymology / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000453:epidemiology* / Q000382:microbiology; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests / Q000379:methods; D008875:Middle Aged; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D014481:United States; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D012336:RNA, Ribosomal, 16S; D001618:beta-Lactamases