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Natural extracts stimulate membrane‐associated mechanisms of resistance in Gram‐negative bacteria
Author(s) -
Fadli M.,
Chevalier J.,
Hassani L.,
Mezrioui N.E.,
Pagès J.M.
Publication year - 2014
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/lam.12216
Subject(s) - efflux , bacteria , microbiology and biotechnology , biology , escherichia coli , antibiotics , bacterial outer membrane , antibiotic resistance , antimicrobial , gram negative bacteria , carvacrol , thymol , biochemistry , gene , essential oil , genetics , food science
Abstract Several mechanisms are involved in the bacterial resistance towards antimicrobial agents. The membrane‐associated mechanisms of resistance were studied in E scherichia coli strains after incubation with T hymus maroccanus essential oil, its major components (carvacrol and thymol) or with certain antibiotics. The minimum inhibitory concentration ( MIC ) and the expression of membrane proteins, porins and efflux pumps were determined in wild type and derivative strains. Derivative strains adapted to different compounds displayed a high level of resistance to all tested antibiotics. The MIC increase is associated with an overexpression of an efflux pump immunorelated to A cr AB ‐ T ol C in various variants. Interestingly, the expression of outer membrane proteins slightly decreases in these strains. We demonstrate that the increase in antibiotic resistance correlates with membrane changes observed in the variants. This type of bacterial adaptation to natural compounds can occur in vivo providing the emergence/selection of bacteria less susceptible to clinically used antibiotics. Significance and Impact of the Study Thymus maroccanus essential oil and some major components are able to select variants that modify the expression of transporters involved in the influx (porins) and in the efflux ( A cr AB family) of various drugs. Importantly, these membrane proteins are involved in the transport of natural compounds and several antibiotic families. This special ‘membrane adaptation’ can explain the persistence of less susceptible/tolerant bacteria in the environment where natural compounds are present and the continuous stimulation of efflux systems in these bacteria.