Korean J Clin Microbiol.  2011 Dec;14(4):131-137. 10.5145/KJCM.2011.14.4.131.

Chromosomal Mutations in oprD, gyrA, and parC in Carbapenem Resistant Pseudomonas aeruginosa

• Sung JY
• Cho HH
• Kwon KC
• Koo SH

• KMID: 1476034
• DOI: http://doi.org/10.5145/KJCM.2011.14.4.131

Abstract

BACKGROUND
Outbreaks of carbapenem resistant P. aeruginosa give rise to significant therapeutic challenges for treating nosocomial infections. In this study, we analyzed carbapenem resistance mechanisms in carbapenem resistant and clonally different P. aeruginosa strains. We analyzed chromosomal alterations in the genes of OprD and efflux system regulatory proteins (MexR, NalC, NalD, MexT, and MexZ). We also investigated chromosomal alterations in the quinolone resistance-determining region (QRDR) for quinolone resistance mechanisms.
METHODS
Twenty-one clonally different P. aeruginosa strains were isolated by repetitive extragenic palindromic sequence-based PCR (rep-PCR). PCR and DNA sequencing were conducted for the detection of beta-lactamase genes and chromosomal alterations of efflux pump regulatory genes, oprD, and QRDR in gyrA, gyrB, parC, and parE.
RESULTS
Only one (P28) of the 21 strains harbored bla VIM-2. Two isolates had mutations in nalD or mexZ that were associated with efflux pump overexpression. Chromosomal alterations causing loss of OprD were found in 4 out of 21 carbapenem resistant P. aeruginosa strains. Nine of 10 imipenem and ciprofloxacin resistant strains had alterations in gyrA and/or parC.
CONCLUSION
Carbapenem resistance in P. aeruginosa was mediated by several mechanisms, including loss of the OprD, overexpression of efflux systems, and production of carbapenemase. Resistance to quinolone is frequently caused by point mutations in gyrA and/or parC.

Keyword

Carbapenem resistant P. aeruginosa; OprD; Efflux system regulatory proteins; QRDR

MeSH Terms

Bacterial Proteins
beta-Lactamases
Ciprofloxacin
Cross Infection
Disease Outbreaks
Genes, Regulator
Imipenem
Point Mutation
Polymerase Chain Reaction
Proteins
Pseudomonas
Pseudomonas aeruginosa
Sequence Analysis, DNA
Bacterial Proteins
Ciprofloxacin
Imipenem
Proteins
beta-Lactamases

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