Effect of concentration gradient carbapenem exposure on expression of blaNDM-1 and acrA in carbapenem resistant Escherichia coli.

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Effect of concentration gradient carbapenem exposure on expression of blaNDM-1 and acrA in carbapenem resistant Escherichia coli.

Infect Genet Evol. 2019 Jun 03;:

Authors: Chetri S, Bhowmik D, Dhar D, Chakravarty A, Bhattacharjee A

Abstract
Escherichia coli, one of the major pathogens, frequently exhibits carbapenem resistance. It would be of interest to investigate which of the mechanisms responds when a strain that carries both blaNDM-1 and over expressed AcrAB-TolC efflux pump system is exposed against carbapenem under differential concentration gradient stress. Four different sets of strains were used in the study; (i) Strain that have blaNDM-1 and over expressed AcrAB-TolC system (ii) Strain that harbour blaNDM-1 and express AcrAB-TolC at basal level (iii) the strain that is devoid of blaNDM-1 but having over expressed AcrAB-TolC systems and (iv) E. coli AG100A (ΔAcrAB) and E. coli HUE 1 (ΔAcrAB-TolC) where blaNDM-1was cloned. The Quantitative Real time PCR showed blaNDM-1 was over expressed under meropenem and imipenem stress irrespective of concentration gradient. In case of ertapenem, at lower concentration AcrA were over expressed whereas, at higher concentration blaNDM-1 showed elevated expression. A consistent elevated expression of AcrA and AcrB was observed against all carbapenems in the strains devoid of blaNDM-1 where as in case of the strain with basal level expression of AcrA, no significant over expression could be observed for blaNDM-1. In case of clones in group IV, expression of blaNDM-1 was elevated in the presence of carbapenem stress.

PMID: 31170528 [PubMed - as supplied by publisher]