Spread of an OmpK36-modified ST15 Klebsiella pneumoniae variant during an outbreak involving multiple carbapenem-resistant Enterobacteriaceae species and clones.
We aim to characterise multiple ertapenem-resistant (ERT-R, n = 15) Enterobacteriaceae isolates identified as presumptive carbapenemase producers in a Portuguese hospital in a short period of time (March-July 2010). Antibiotic susceptibility patterns, β-lactamases, genetic relatedness [pulsed-field gel electrophoresis (PFGE), multi-locus sequence typing (MLST)], plasmid content and major enterobacterial porins were investigated. Ertapenem resistance was associated with deficiencies in major porins and, in some cases, extended-spectrum β-lactamase (ESBL) or AmpC β-lactamase production among outbreak and non-outbreak clones. Most isolates (n = 8) corresponded to two ERT-R Klebsiella pneumoniae ST15 PFGE-types: (i) a sporadic variant (Kp-A-ERT, n = 1) presenting a premature stop codon in ompK36 and (ii) an epidemic variant (Kp-B-ERT, n = 7) exhibiting a new OmpK36 porin variant, which differed additionally in plasmid and antibiotic susceptibility profiles. ST14 (n = 1) and ST45 (n = 1) K. pneumoniae, ST131 (n = 1) and ST354 (n = 1) Escherichia coli, Enterobacter asburiae (n = 1), Enterobacter cloacae (n = 1) and Enterobacter aerogenes (n = 1) ERT-R clones were also sporadically detected. Porin changes in these isolates included non-sense mutations [ompK35, ompK36, ompF; minimum inhibitory concentration (MIC) = 4-32 mg/l], IS-mediated porin disruptions (ompK36, ompC; MIC = 12->32 mg/l) or alterations in the L3 loop (ompK36; MIC = 4-16 mg/l). We describe, for the first time in Portugal, the simultaneous emergence of multiple ERT-R Enterobacteriaceae species and clones in a short period of time. Moreover, our results support that a CTX-M-15-producing ST15 K. pneumoniae with an OmpK36-modified porin might successfully spread in the nosocomial setting.
REQUIMTE, Laboratório de Microbiologia, Faculdade Farmácia, Universidade do Porto, Rua Jorge Viterbo Ferreira, 228, 4050-313, Porto, Portugal.
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Novais
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Rodrigues
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Branquinho
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Antunes
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Grosso
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Boaventura
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Ribeiro
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Peixe
D001426:Bacterial Proteins / Q000235:genetics*; D015780:Carbapenems / Q000494:pharmacology*; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004196:Disease Outbreaks; D016521:Electrophoresis, Gel, Pulsed-Field; D004755:Enterobacteriaceae / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000453:epidemiology* / Q000382:microbiology; D006761:Hospitals; D006801:Humans; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D058885:Multilocus Sequence Typing; D010957:Plasmids / Q000032:analysis; D018272:Porins / Q000235:genetics*; D011174:Portugal / Q000453:epidemiology; D017422:Sequence Analysis, DNA; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000032:analysis
D001426:Bacterial Proteins; D015780:Carbapenems; D004269:DNA, Bacterial; C092233:OmpK36 protein, Klebsiella pneumoniae; D018272:Porins; D001618:beta-Lactamases