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Over-expression of RND and MATE efflux pumps contribute to decreased susceptibility in clinical isolates of carbapenem resistant Acinetobacter baumannii.
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| Author:
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SUNIL KUMAR, LIPIKA SINGHAL, PALLAB RAY, VIKAS GAUTAM
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| Abstract:
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Objective: Acinetobacter baumannii is an opportunistic pathogen associated healthcare infections with high mortality in intensive care units all over the globe. Over-expression of efflux pumps has been reported as contributing factor in escalating drug resistance and renders the treatment ineffective. This study aimed to investigate the mechanism responsible for escalating resistance of carbapenem resistant A. baumannii (CRAB) retrieved from clinical isolates.
Methodology: A total of 64 CRAB isolates were enrolled in the present study from two tertiary care hospitals situated in North India from 2013 to 2016. Disk diffusion and agar dilution based MIC methods were used to determine the antimicrobial susceptibility pattern. Screening of Class-D and Class-B beta-lactamases was executed for all isolates using PCR. Relative gene expression of four RND, one MATE efflux pumps and outer membrane proteins’ genes were determined using RT-qPCR.
Results: All the isolates showed presence of efflux transporter and porin genes by PCR amplification method. Relative gene expressions for adeG, adeY and abeM were significantly found over-expressing (>2 fold) in all the 64 isolates followed by adeJ and adeB genes, which showed over-expression in 72% and 44% isolates respectively. Porin gene carO reported under-expression/downregulation (<0.5 fold) in 66% (42/64) isolates suggesting the resistant phenotypic nature of the isolates. The prevalence of adeB and oprD were absent in 92% and 93% respectively. High prevalence of OXA-23 (96.8%) observed amongst CRAB isolates followed by NDM-1 (29.7%) and OXA-58 (4.6%).
Conclusion: This study indicated the significant role of RND efflux transporters and carbapenemases in conferring carbapenem resistance to A. baumannii.
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| Keyword:
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Acinetobacter baumannii; Efflux pumps; Multidrug Resistance; RT-qPCR; Gene expression.
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| EOI:
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| DOI:
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https://doi.org/10.31838/ijpr/2020.12.03.050
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| Download:
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