Objectives: This study investigated the prevalence of extended-spectrum β-lactamase-producing Klebsiella pneumoniae (ESBL-KP) strains in the National Bone Marrow Transplant Center of Tunis between 2002 and 2011 as well as their associated antimicrobial resistance patterns and molecular features.
Methods: Antimicrobial susceptibility was determined by the disk diffusion method according to CA-SFM guidelines. All of the strains were screened for β-lactamase genes, plasmid-encoded AmpC genes and integrons. Carbapenemase genes were analysed by PCR and sequencing for strains showing reduced susceptibility to ertapenem. Genetic relatedness was determined by pulsed-field gel electrophoresis (PFGE) and multilocus sequencing typing (MLST).
Results: A total of 128 non-repetitive ESBL-KP strains (23.4%) responsible for infection or colonisation were recovered among 548 K. pneumoniae strains. The isolates were also multidrug-resistant. Molecular analysis revealed the prevalence of blaSHV-type (92.2%), followed by blaOXA-1 (81.3%) and blaCTX-M-1 group (73.4%). Four ertapenem-resistant ESBL-KP strains (3.1%) carried the blaOXA-48 gene associated with the blaCTX-M-15 gene. Class 1 integrons were the most prevalent among the isolates (85.2%). High diversity was demonstrated by PFGE with limited clonal dissemination of 1 major (n=13 strains) and 11 minor clusters (each comprising 2-3 strains). MLST of representative strains also showed high diversity with two main epidemic clones: ST15, associated with the major cluster; and ST101, associated with five minor clusters (n=11 strains).
Conclusions: This study provides relevant information on the epidemiology of ESBL-KP strains in oncohaematology patients, of which 18.8% belonged to the specific CTX-M-15 K. pneumoniae clones ST15 and ST101.
Keywords: CTX-M-15; Klebsiella pneumonia; OXA-48; Oncohaematology; ST101; ST15.
Copyright © 2018 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.