title: Population distribution of Beta-lactamase conferring resistance to third-generation cephalosporins in human clinical Enterobacteriaceae in the Netherlands.
abstract: There is a global increase in infections caused by Enterobacteriaceae with plasmid-borne β-lactamases that confer resistance to third-generation cephalosporins. The epidemiology of these bacteria is not well understood, and was, therefore, investigated in a selection of 636 clinical Enterobacteriaceae with a minimal inhibitory concentration >1 mg/L for ceftazidime/ceftriaxone from a national survey (75% E. coli, 11% E. cloacae, 11% K. pneumoniae, 2% K. oxytoca, 2% P. mirabilis). Isolates were investigated for extended-spectrum β-lactamases (ESBLs) and ampC genes using microarray, PCR, gene sequencing and molecular straintyping (Diversilab and multi-locus sequence typing (MLST)). ESBL genes were demonstrated in 512 isolates (81%); of which 446 (87%) belonged to the CTX-M family. Among 314 randomly selected and sequenced isolates, bla(CTX-M-15) was most prevalent (n = 124, 39%), followed by bla(CTX-M-1) (n = 47, 15%), bla(CTX-M-14) (n = 15, 5%), bla(SHV-12) (n = 24, 8%) and bla(TEM-52) (n = 13, 4%). Among 181 isolates with MIC ≥16 mg/L for cefoxitin plasmid encoded AmpCs were detected in 32 and 27 were of the CMY-2 group. Among 102 E. coli isolates with MIC ≥16 mg/L for cefoxitin ampC promoter mutations were identified in 29 (28%). Based on Diversilab genotyping of 608 isolates (similarity cut-off >98%) discriminatory indices of bacteria with ESBL and/or ampC genes were 0.994, 0.985 and 0.994 for E. coli, K. pneumoniae and E. cloacae, respectively. Based on similarity cut-off >95% two large clusters of E. coli were apparent (of 43 and 30 isolates) and 21 of 21 that were typed by belonged to ST131 of which 13 contained bla(CTX-M-15). Our findings demonstrate that bla(CTX-M-15) is the most prevalent ESBL and we report a larger than previously reported prevalence of ampC genes among Enterobacteriaceae responsible for resistance to third-generation cephalosporins.
authors.affiliation: Department of Medical Microbiology, University Medical Centre Utrecht, Utrecht, The Netherlands. g.voets@umcutrecht.nl
authors.forename: Guido M
authors.initials: GM
authors.lastname: Voets
authors.forename: Tamara N
authors.initials: TN
authors.lastname: Platteel
authors.forename: Ad C
authors.initials: AC
authors.lastname: Fluit
authors.forename: Jelle
authors.initials: J
authors.lastname: Scharringa
authors.forename: Claudia M
authors.initials: CM
authors.lastname: Schapendonk
authors.forename: James Cohen
authors.initials: JC
authors.lastname: Stuart
authors.forename: Marc J M
authors.initials: MJ
authors.lastname: Bonten
authors.forename: Maurine A
authors.initials: MA
authors.lastname: Leverstein-van Hall
authors.forename: Maurine A L
authors.initials: MA
authors.lastname: Hall
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D015373:Bacterial Typing Techniques; D018550:Cephalosporin Resistance / Q000235:genetics*; D002511:Cephalosporins / Q000494:pharmacology*; D002648:Child; D002675:Child, Preschool; D004755:Enterobacteriaceae / Q000145:classification / Q000187:drug effects* / Q000235:genetics*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D009426:Netherlands; D055815:Young Adult; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002511:Cephalosporins; C048795:AmpC beta-lactamases; D001618:beta-Lactamases