Carbapenem-resistant and carbapenem-susceptible isogenic isolates of Klebsiella pneumoniae ST101 causing infection in a tertiary hospital.

M. Ángeles Dominguez,Lucía Gallego,Guillermo Cuervo,Sara Martí,Carmen Ardanuy,Carmen Peña,Fe Tubau,Meritxell Cubero,Josefina Liñares,Josefina Ayats,Elena Sevillano,Miquel Pujol

doi:10.1186/s12866-015-0510-9

Abstract

BackgroundIn this study we describe the clinical and molecular characteristics of an outbreak due to carbapenem-resistant Klebsiella pneumoniae (CR-KP) producing CTX-M-15 and OXA-48 carbapenemase. Isogenic strains, carbapenem-susceptible K. pneumoniae (CS-KP) producing CTX-M-15, were also involved in the outbreak.ResultsFrom October 2010 to December 2012 a total of 62 CR-KP and 23 CS-KP were isolated from clinical samples of 42 patients (22 had resistant isolates, 14 had susceptible isolates, and 6 had both CR and CS isolates). All patients had underlying diseases and 17 of them (14 patients with CR-KP and 3 with CS-KP) had received carbapenems previously. The range of carbapenem MICs for total isolates were: imipenem: 2 to >32 μg/ml vs. <2 μg/ml; meropenem: 4 to >32 μg/ml vs. <2 μg/ml; and ertapenem: 8 to >32 μg/ml vs. <2 μg/ml. All the isolates were also resistant to gentamicin, ciprofloxacin, and cotrimoxazole. Both types of isolates shared a common PFGE pattern associated with the multilocus sequence type 101 (ST101). The blaCTX-M-15 gene was detected in all the isolates, whereas the blaOXA-48 gene was only detected in CR-KP isolates on a 70 kb plasmid.ConclusionsThe clonal spread of K. pneumoniae ST101 expressing the OXA-48 and CTX-M-15 beta-lactamases was the cause of an outbreak of CR-KP infections. CTX-M-15-producing isolates lacking the blaOXA-48 gene coexisted during the outbreak.

Highlights

In this study we describe the clinical and molecular characteristics of an outbreak due to carbapenem-resistant Klebsiella pneumoniae (CR-KP) producing CTX-M-15 and OXA-48 carbapenemase
In this study we describe the clinical and molecular epidemiology of a nosocomial outbreak due to a K. pneumoniae clone producing CTX-M-15 and OXA-48
The outbreak was initially restricted to the Digestive Surgery Unit but it was subsequently spread throughout the Intensive Care Unit (ICU)

Summary

Introduction

In this study we describe the clinical and molecular characteristics of an outbreak due to carbapenem-resistant Klebsiella pneumoniae (CR-KP) producing CTX-M-15 and OXA-48 carbapenemase. Nosocomial outbreaks due to multidrug-resistant enterobacteria have become a serious problem worldwide, especially due to the spread of extended spectrum betalactamase (ESBL)-producing strains and to the posterior emergence of carbapenemases [1]. In Spain, carbapenem-resistant K. pneumoniae (CR-KP) strains have been described sporadically due to production of VIM-type enzymes and, more recently, OXA-48 [2, 3]. After whole genome sequencing of a ST101 OXA-48-producing K. pneumoniae, revealed that the blaOXA-48 gene was recently found in IncL/M plasmids previously described [4, 5]. In this study we describe the clinical and molecular epidemiology of a nosocomial outbreak due to a K. pneumoniae clone producing CTX-M-15 and OXA-48. Isogenic K. pneumoniae isolates producing the CTX-M-15 enzyme but lacking the blaOXA-48 gene were detected during the same period of time

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