open access

Vol 54, No 2 (2016)
REVIEW
Published online: 2016-06-06
Submitted: 2015-08-07
Accepted: 2016-05-18
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Acinetobacter baumannii: biology and drug resistance — role of carbapenemases

Pawel Nowak, Paulina Paluchowska
DOI: 10.5603/FHC.a2016.0009
·
Pubmed: 27270503
·
Folia Histochem Cytobiol 2016;54(2):61-74.

open access

Vol 54, No 2 (2016)
REVIEW
Published online: 2016-06-06
Submitted: 2015-08-07
Accepted: 2016-05-18

Abstract

Acinetobacter baumannii is a Gram-negative, glucose-non-fermenting, oxidase-negative coccobacillus, most commonly associated with the hospital settings. The ability to survive in adverse environmental conditions as well as high level of natural and acquired antimicrobial resistance make A. baumannii one of the most important nosocomial pathogens. While carbapenems have long been considered as antimicrobials of last-resort, the rates of clinical A. baumannii strains resistant to these antibiotics are increasing worldwide. Carbapenem resistance among A. baumannii is conferred by coexisting mechanisms including: decrease in permeability of the outer membrane, efflux pumps, production of beta-lactamases, and modification of penicillin-binding proteins. The most prevalent mechanism of carbapenem resistance among A. baumannii is associated with carbapenem-hydro­lysing enzymes that belong to Ambler class D and B beta-lactamases. In addition, there have also been reports of resistance mediated by selected Ambler class A carbapenemases among A. baumannii strains. Resistance determinants in A. baumannii are located on chromosome and plasmids, while acquisition of new mechanisms can be mediated by insertion sequences, integrons, transposons, and plasmids. Clinical relevance of carbapen­em resistance among strains isolated from infected patients, carriers and hospital environment underlines the need for carbapenemase screening. Currently available methods vary in principle, accuracy and efficiency. The techniques that deserve particular attention belong to both easily accessible unsophisticated methods as well as advanced techniques based on mass spectrometry or molecular biology. While carbapenemases limit the therapeutic options in A. baumannii infections, studies concerning novel beta-lactamase inhibitors offer a new insight into effective therapy.

Abstract

Acinetobacter baumannii is a Gram-negative, glucose-non-fermenting, oxidase-negative coccobacillus, most commonly associated with the hospital settings. The ability to survive in adverse environmental conditions as well as high level of natural and acquired antimicrobial resistance make A. baumannii one of the most important nosocomial pathogens. While carbapenems have long been considered as antimicrobials of last-resort, the rates of clinical A. baumannii strains resistant to these antibiotics are increasing worldwide. Carbapenem resistance among A. baumannii is conferred by coexisting mechanisms including: decrease in permeability of the outer membrane, efflux pumps, production of beta-lactamases, and modification of penicillin-binding proteins. The most prevalent mechanism of carbapenem resistance among A. baumannii is associated with carbapenem-hydro­lysing enzymes that belong to Ambler class D and B beta-lactamases. In addition, there have also been reports of resistance mediated by selected Ambler class A carbapenemases among A. baumannii strains. Resistance determinants in A. baumannii are located on chromosome and plasmids, while acquisition of new mechanisms can be mediated by insertion sequences, integrons, transposons, and plasmids. Clinical relevance of carbapen­em resistance among strains isolated from infected patients, carriers and hospital environment underlines the need for carbapenemase screening. Currently available methods vary in principle, accuracy and efficiency. The techniques that deserve particular attention belong to both easily accessible unsophisticated methods as well as advanced techniques based on mass spectrometry or molecular biology. While carbapenemases limit the therapeutic options in A. baumannii infections, studies concerning novel beta-lactamase inhibitors offer a new insight into effective therapy.

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Keywords

Acinetobacter baumannii; virulence factors; drug resistance; carbapenems; carbapenemases; metallo-beta-lactamases; oxacillinases; CHDL; resistance detection; carbapenemase inhibitors

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About this article
Title

Acinetobacter baumannii: biology and drug resistance — role of carbapenemases

Journal

Folia Histochemica et Cytobiologica

Issue

Vol 54, No 2 (2016)

Pages

61-74

Published online

2016-06-06

DOI

10.5603/FHC.a2016.0009

Pubmed

27270503

Bibliographic record

Folia Histochem Cytobiol 2016;54(2):61-74.

Keywords

Acinetobacter baumannii
virulence factors
drug resistance
carbapenems
carbapenemases
metallo-beta-lactamases
oxacillinases
CHDL
resistance detection
carbapenemase inhibitors

Authors

Pawel Nowak
Paulina Paluchowska

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