TITLE:
Study of OmpK35 and OmpK36 Expression in Carbapenem Resistant ESBL Producing Clinical Isolates of Klebsiella pneumoniae
AUTHORS:
Amina Amal Mahmoud Nour El Din, Reem Abdel Hameed Harfoush, Hadir Ahmed Said Okasha, Dina Aly El Sayed Kholeif
KEYWORDS:
OmpK35, OmpK36, K. pneumoniae, Carbapenem Resistant
JOURNAL NAME:
Advances in Microbiology,
Vol.6 No.9,
August
11,
2016
ABSTRACT: Background: Carbapenem resistant extended spectrum β-lactamase (ESBL) producing Klebsiella pneumoniae (K.
pneumoniae) is increasing worldwide. Carbapenem resistance (CR) has been attributed
not only to production of carbapenemases but also to permeability barriers due
to outer membrane proteins (OmpK35 and OmpK36) disruption. Objective: Phenotypic
detection of CR among ESBL producing K. pneumoniae isolates, followed by
the evaluation of the role of ompK35
and ompK36 gene
expression among carbapenem resistant K. pneumoniae (CR-KP) isolates.
Methods: 100 ESBL producing K. pneumoniae isolates were included in this
study. Minimum inhibitory concentration (MIC) of imipenem was performed for all
isolates by broth microdilution method. For CR-KP isolates, phenotypic
detection of K. pneumoniae carbapenemase (KPC), metallo-β-lactamase (MBL) and AmpC enzymes was
performed followed by Realtime qRT-PCR to detect and quantify ompK35 and ompK36 gene expression. Results: 42% of
our isolates were carbapenem resistant, and all of them were KPC producers
either singly or in combination with MBL and/or AmpC production. Reduced
expression of both ompK35
and ompK36 was detected
in (52.38%) of CR-KP isolates, while reduced expression of ompK36 or ompK35 alone was found in (2.38%) and
(33.33%) respectively. Twenty of 42 CR-KP isolates (47.62%), showing reduced ompK35 and ompK36 expression, exhibited high level
resistance (HLR) (>32 μg/ml) to imipenem. There was a significant
correlation between reduced expression of ompK36 and increase MIC values (p ompK35
and/or ompK36 resulted
in significant increase in imipenem MIC (p K. pneumoniae showing carbapenemase and/or AmpC
production together with loss of OmpK35 and/or OmpK36.