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First identification and characterization of an AdeABC-like efflux pump in Acinetobacter genomospecies 13TU.

ABSTRACT: Non-Acinetobacter baumannii spp. are emerging among clinical Acinetobacter isolates causing nosocomial infections, and some (such as genomospecies 13TU) appear to be multidrug resistant. The prevalence of non-Acinetobacter baumannii spp. in the hospital setting is likely understated due to poor identification techniques. We report the first identification of an AdeABC-type efflux pump in an Acinetobacter genomospecies 13TU clinical isolate, its contribution to multidrug resistance, and the coexistence of three Ade-type efflux pumps in this strain.

SUBMITTER: Roca I

PROVIDER: S-EPMC3067064 | biostudies-literature | 2011 Mar

REPOSITORIES: biostudies-literature

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First identification and characterization of an AdeABC-like efflux pump in Acinetobacter genomospecies 13TU.

Roca Ignasi I Espinal Paula P Martí Sara S Vila Jordi J

Antimicrobial agents and chemotherapy 20110103 3

Non-Acinetobacter baumannii spp. are emerging among clinical Acinetobacter isolates causing nosocomial infections, and some (such as genomospecies 13TU) appear to be multidrug resistant. The prevalence of non-Acinetobacter baumannii spp. in the hospital setting is likely understated due to poor identification techniques. We report the first identification of an AdeABC-type efflux pump in an Acinetobacter genomospecies 13TU clinical isolate, its contribution to multidrug resistance, and the coexi ...[more]

PMID: 21199925

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Project description:IntroductionMultidrug-resistant Acinetobacter baumannii (A. baumannii) has become one of the greatest threats worldwide to the therapeutic management of infections. Our previous research confirmed an in vitro synergistic effect of amlodipine and imipenem against A. baumannii, and this study is designed to understand its mechanism.MethodsSixty-four non-duplicate A. baumannii isolates were collected and tested for antimicrobial susceptibility by the disk diffusion method. PCR amplification and sequencing were used to identify the presence of the adeB, adeE, adeH, adeJ, abeM and abeS efflux pump genes. The minimal inhibitory concentrations of imipenem, imipenem+amlodipine and imipenem+carbonyl cyanide m-chlorophenyl-hydrazone against these isolates were also determined by the broth microdilution method before and after siRNA silencing of the expression of the adeABC efflux pump.ResultsIn this study, the combination of amlodipine with imipenem showed synergistic antimicrobial activity against sixty-four A. baumannii isolates when compared with the activity of imipenem alone (p<0.025). In the multidrug-resistant group, AML was more effective than carbonyl cyanide m-chlorophenyl-hydrazone (p<0.001). The efflux pump genes adeB, adeE, adeH, adeJ, abeM and abeS were detected in 100% (4/64), 75% (48/64), 0% (0/64), 100% (64/64), 96.9% (62/64) and 96.9% (62/64) of the sixty-four A. baumannii isolates, respectively. The expression of the adeABC efflux pump genes in the multidrug-resistant group (5.05±19.25) is clearly higher than in the non-multidrug-resistant group (0.17±0.20), (p = 0.01). A gene silencing test verified that the mRNA expression levels of adeABC were decreased at 12 h and increased at 24 h, while the reversal of imipenem resistance by amlodipine disappeared at 12 h and reappeared at 24 h.ConclusionsThe combination of amlodipine with imipenem exhibits an in vitro synergistic antimicrobial effect on multidrug-resistant A. baumannii, which may be due to the inhibition of the AdeABC efflux pump.

Project description:Carbapenem-resistant Acinetobacter nosocomialis (CRAn) is a significant public health concern. Tigecycline non-susceptible CRAn (Tn-CRAn) isolates have emerged worldwide. Tigecycline resistance is mainly related to the overexpression of AdeABC efflux pump controlled by AdeRS two-component system (TCS). Two novel tetracycline derivatives, omadacycline and eravacycline, may present a treatment option for CRAn. This study investigated the in vitro antimicrobial activity of tigecycline, omadacycline and eravacycline against clinical CRAn isolates and the contribution of efflux pumps in their resistance. Eighty-nine clinical CRAn isolates, including 57 Tn-CRAn isolates were evaluated for minimum inhibitory concentrations (MICs) by the broth microdilution. The relationship between the antimicrobial resistance and efflux pump expression was assessed by their responses to the efflux pump inhibitor 1-(1-naphthylmethyl)-piperazine (NMP). The contribution of the AdeABC efflux pump in their resistance was determined by the complementation of the AdeRS two-component system in wild-type, adeRS operon and adeB gene knockout strains. Among the 89 isolates, omadacycline and eravacycline MICs were correlated closely with those of tigecycline. They demonstrated improved potency, based on MIC90 values, by showing a 4 to 8-fold greater potency than tigecycline. The synergetic effects of tigecycline, omadacycline and eravacycline with NMP were observed in 57 (100%), 13 (22.8%), and 51 (89.5%) of Tn-CRAn isolates, respectively. Further analysis showed that the laboratory strain carrying the Type 1 adeRS operon increased the tigecycline, omadacycline and eravacycline MICs by 4-8-folds, respectively. Eravacycline demonstrated improved potency over tigecycline against populations of CRAn, including Tn-CRAn isolates. The over-expression of AdeABC efflux pumps was directly activated by the AdeRS two-component system and simultaneously reduced the susceptibilities of tigecycline, eravacycline, and omadacycline. Omadacycline and eravacycline MICs were correlated closely with those of eravacycline.

Dataset Information

First identification and characterization of an AdeABC-like efflux pump in Acinetobacter genomospecies 13TU.

Publications

First identification and characterization of an AdeABC-like efflux pump in Acinetobacter genomospecies 13TU.

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