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- Title
Efflux Pump Overexpression in Conjunction with Alternation of Outer Membrane Protein May Induce Acinetobacter baumannii Resistant to Imipenem.
- Authors
Luo, LiuLin; Jiang, XiaoFei; Wu, Qiong; Wei, LiMing; Li, JianHua; Ying, ChunMei
- Abstract
Background: To investigate the role of outer membrane proteins in Acinetobacter baumannii resistant to imipenem, 2 strains were procured from the same patient. Methods: The imipenem-resistant strain was obtained following a period of imipenem treatment in vivo. The multilocus sequence typing and repetitive extragenic palindromic PCR results indicated that the imipenem-resistant strain originated from the sensitive one. Results: Isoelectric focusing detected no carbapenemases, with neither OXA carbapenemases nor metallo-β-lactamases found. Mass spectrophotometric analysis revealed that 3 outer membrane proteins were expressed differentially in the 2 strains: 2 downregulated proteins (OprD and CarO) and 1 upregulated the 34-kDa efflux pump protein in the resistant strain. A 32-fold decrease in the MIC for imipenem in the presence of Phe-Arg-β-naphthylamide in the same strain indicated a possible involvement of the efflux pump mechanism in its resistance, which was consistent with the findings that the mRNA expression of the 34-kDa efflux pump gene was almost fivefold upregulated in the imipenem-resistant strain compared with that in the imipenem-sensitive strain. Such a significant difference, however, was not found in the expression of AdeB and AdeJ between the 2 strains, and AdeE was not detected. Conclusions: Our results suggested that downregulation of outer membrane proteins in conjunction with efflux pump overexpression might contribute to imipenem resistance induced in vivo in A. baumannii. Copyright © 2011 S. Karger AG, Basel
- Subjects
ACINETOBACTER; POLYMERASE chain reaction; MASS spectrometers; CARBAPENEMS; BETA lactamases; SPECTROPHOTOMETRY; PROTEINS; MESSENGER RNA
- Publication
Chemotherapy (0009-3157), 2011, Vol 57, Issue 1, p77
- ISSN
0009-3157
- Publication type
Article
- DOI
10.1159/000323620