RESEARCH ARTICLE


Molecular Characterization of Klebsiella pneumoniae Clinical Isolates with Elevated Resistance to Carbapenems



Rasha Barwa, Mona Shaaban*
Department of Microbiology and Immunology, Faculty of Pharmacy, Mansoura University, 35516, Mansoura, Egypt


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© 2017 Barwa and Shaaban.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Department of Microbiology and Immunology, Faculty of Pharmacy, Mansoura University, 35516, Mansoura, Egypt, Tel: (+2) 01001964899, Fax: (+2) 050-2200242; E-mails: mona_ibrahem@mans.edu.eg; sarafawzy2002@yahoo.com


Abstract

Background:

Emergence of carbapenems-resistant K. pneumoniae represents a serious challenge for antimicrobial therapy.

Objective:

The aim of this research is to determine different mechanisms mediating the emergence of K. pneumoniae isolates with high-level carbapenem resistance.

Method:

A total of 80 K. pneumoniae isolates were purified from sputum and urine specimens. The minimum inhibitory concentrations (MICs) of imipenem and meropenem were determined by broth microdilution method. Carbapenemases were detected by Modified Hodge test and PCR. Additionally, the copy numbers of the identified genes (blaVIM-1, blaNDM-1 and blaOXA-48) were quantified by RT-PCR. The outer membrane proteins OmpK35 and OmpK36 of the resistant isolates were analyzed.

Results:

Eight isolates were resistant to carbapenems; six of these isolates possessed elevated MICs to imipenem and meropenem (≥16 µg/ml). Carbapenem resistant isolates harbored blaNDM-1 (n=5), blaVIM-1 (n=4) and blaOXA-48 (n=1) with some isolates had multiple carbapenemases genes. Six isolates with high MICs to imipenem contained multi-copies of the carbapenemases genes along with the lack of OmpK35. Isolates with intermediate resistance to carbapenems (MIC; 4-8 µg/ml) did not exhibit multiple carbapenemases but lacked the OmpK35. Random amplified polymorphic DNA exhibited three different patterns and indicated that five isolates encoded the same pattern P1.

Conclusion:

This study elucidated that multiple carbapenemases genes, high copy number of carbapenemases and loss of the porin OmpK35 could collectively contribute to the emergence of K. pneumoniae isolates with high resistance to carbapenems. Hence, more restrictions should be applied on the use of carbapenems to reduce the emergence of the resistant clones.

Keywords: Carbapenem resistant, Klebsiella pneumoniae, Copy number of carbapenemases, Outer membrane proteins, RAPD.