title: Outbreak caused by an ertapenem-resistant, CTX-M-15-producing Klebsiella pneumoniae sequence type 101 clone carrying an OmpK36 porin variant.
abstract: Although numerous studies have documented outbreaks of carbapenem-resistant Klebsiella pneumoniae (CRKP) possessing various carbapenemases, reports on outbreaks due to CRKP possessing extended-spectrum β-lactamases (ESBLs) and/or AmpCs with porin lesions have been limited. Here, we describe an outbreak caused by an ertapenem-resistant, CTX-M-15-producing clonal K. pneumoniae strain expressing an OmpK36 porin variant. From May 2012 to November 2012, 37 ertapenem-resistant K. pneumoniae isolates phenotypically negative for carbapenemase production were recovered from 19 patients hospitalized in the intensive care unit of a Greek hospital. The isolates were either susceptible or intermediate to other carbapenems and resistant to all remaining β-lactams but cefotetan. Phenotypic and molecular analysis revealed the presence in all isolates of the blaCTX-M-15 gene on a conjugative 100-kb plasmid, disruption in the expression of the ompK35 gene, and the production of an Ompk36 porin variant. The index case was a patient admitted from another hospital. Active surveillance upon admission and on a weekly basis was immediately initiated; environmental samples were also periodically tested. Molecular typing showed that all clinical isolates as well as two ertapenem-resistant environmental K. pneumoniae isolates belonged to the same clonal type and were assigned to multilocus sequence typing (MLST) sequence type 101 (ST101). As all colonized/infected patients were hospitalized during overlapping periods, cross-infection was considered the main route for the dissemination of the outbreak strain. Despite reinforcement of infection control measures and active surveillance, the outbreak lasted approximately 7 months. Identification of hidden carriers upon admission and by screening on a weekly basis was found valuable for early recognition and subsequent successful management of the outbreak.
authors.affiliation: Department of Microbiology, Serres General Hospital, Serres, Greece.
authors.forename: Aggeliki
authors.initials: A
authors.lastname: Poulou
authors.forename: Evangelia
authors.initials: E
authors.lastname: Voulgari
authors.forename: Georgia
authors.initials: G
authors.lastname: Vrioni
authors.forename: Vasiliki
authors.initials: V
authors.lastname: Koumaki
authors.forename: Grigorios
authors.initials: G
authors.lastname: Xidopoulos
authors.forename: Vasiliki
authors.initials: V
authors.lastname: Chatzipantazi
authors.forename: Fani
authors.initials: F
authors.lastname: Markou
authors.forename: Athanassios
authors.initials: A
authors.lastname: Tsakris
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics*; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000235:genetics; D004196:Disease Outbreaks; D000077727:Ertapenem; D005260:Female; D005838:Genotype; D006115:Greece / Q000453:epidemiology; D006761:Hospitals; D006801:Humans; D007710:Klebsiella Infections / Q000453:epidemiology / Q000382:microbiology*; D007711:Klebsiella pneumoniae / Q000145:classification / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D058889:Molecular Typing; D010957:Plasmids / Q000032:analysis; D018272:Porins / Q000235:genetics*; D055815:Young Adult; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism; D047090:beta-Lactams / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; C092233:OmpK36 protein, Klebsiella pneumoniae; D018272:Porins; D047090:beta-Lactams; C473109:beta-lactamase CTX-M-15; D001618:beta-Lactamases; D000077727:Ertapenem