AcrAB-TolC efflux pump system plays a role in carbapenem non-susceptibility in Escherichia coli

Shiela Chetri,Debadatta Dhar Chanda,Deepshikha Bhowmik,Piyush Pandey,Debajyoti Bora,Atanu Chakravarty,Deepjyoti Paul,Amitabha Bhattacharjee

doi:10.1186/s12866-019-1589-1

Shiela Chetri, Debadatta Dhar Chanda + Show 6 more

Open Access

https://doi.org/10.1186/s12866-019-1589-1

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Abstract

BackgroundEfflux pump mediated antibiotic resistance is an unnoticed and undetected mechanism in clinical microbiology laboratory. RND efflux systems are known for aminoglycoside and tetracycline resistance whereas their role in carbapenem non-susceptibility is not established. The study was undertaken to investigate the role of efflux pump in providing resistance against carbapenems and their response against concentration gradient carbapenem stress on the transcriptional level of the AcrAB gene in the clinical isolates of Escherichia coli from a tertiary referral hospital of Northeast India.ResultsOut of 298 non-susceptible Escherichia coli isolates 98 isolates were found to have efflux pump mediated carbapenem non-susceptibility. Among them thirty-five were non carbapenemase producers and their expressional levels were verified using qRT-PCR under concentration gradient carbapenem stress. In this study, a strong correlation between ertapenem resistance and AcrA overexpression was observed which has not been reported previously. Further, it was observed that imipenem stress increased AcrB expression in Escherichia coli which holds the novelty of this study. Additionally, the transcription of AcrR was insistently increased which is much higher than the transcriptional level of AcrA under concentration gradient carbapenem stress condition.ConclusionThe study established that AcrAB pump is a relevant antibiotic resistance determinant in bacterial pathogen, has an important role in developing resistance against carbapenem group of antibiotics.

Highlights

Efflux pump mediated antibiotic resistance is an unnoticed and undetected mechanism in clinical microbiology laboratory
Present study was undertaken to assess transcriptional response of AcrAB-TolC and AcrAD-TolC pump against sub-inhibitory concentration gradient stress of carbapenem antibiotics in clinical isolates of Escherichia coli
Minimum inhibitory concentration (MIC) result showed majority of the isolates were above the break point against ertapenem (88.5%) which is followed by imipenem (77%) and meropenem (60%) (Table 1) whereas all of them were susceptible to colistin and polymixin B

Summary

Introduction

Efflux pump mediated antibiotic resistance is an unnoticed and undetected mechanism in clinical microbiology laboratory. The study was undertaken to investigate the role of efflux pump in providing resistance against carbapenems and their response against concentration gradient carbapenem stress on the transcriptional level of the AcrAB gene in the clinical isolates of Escherichia coli from a tertiary referral hospital of Northeast India. Efflux pump mediated antibiotic resistance is an important intrinsic mechanism within bacteria which often remained unnoticed and undetected in clinical microbiology laboratory. Chetri et al BMC Microbiology (2019) 19:210 compounds of different size and physiochemical properties is well described [7,8,9] Their role in carbapenem resistance is still unknown. Present study was undertaken to assess transcriptional response of AcrAB-TolC and AcrAD-TolC pump against sub-inhibitory concentration gradient stress of carbapenem antibiotics in clinical isolates of Escherichia coli

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