The efflux pump inhibitor reserpine selects multidrug-resistant Streptococcus pneumoniae strains that overexpress the ABC transporters PatA and PatB - PubMed (original) (raw)

The efflux pump inhibitor reserpine selects multidrug-resistant Streptococcus pneumoniae strains that overexpress the ABC transporters PatA and PatB

Mark I Garvey et al. Antimicrob Agents Chemother. 2008 May.

Abstract

One way to combat multidrug-resistant microorganisms is the use of efflux pump inhibitors (EPIs). Spontaneous mutants resistant to the EPI reserpine selected from Streptococcus pneumoniae NCTC 7465 and R6 at a frequency suggestive of a single mutational event were also multidrug resistant. No mutations in pmrA (which encodes the efflux protein PmrA) were detected, and the expression of pmrA was unaltered in all mutants. In the reserpine-resistant multidrug-resistant mutants, the overexpression of both patA and patB, which encode ABC transporters, was associated with accumulation of low concentrations of antibiotics and dyes. The addition of sodium orthovanadate, an inhibitor of ABC efflux pumps, or the insertional inactivation of either gene restored wild-type antibiotic susceptibility and wild-type levels of accumulation. Only when patA was insertionally inactivated were both multidrug resistance and reserpine resistance lost. Strains in which patA was insertionally inactivated grew significantly more slowly than the wild type. These data indicate that the overexpression of both patA and patB confers multidrug resistance in S. pneumoniae but that only patA is involved in reserpine resistance. The selection of reserpine-resistant multidrug-resistant pneumococci has implications for analogous systems in other bacteria or in cancer.

PubMed Disclaimer

Figures

FIG. 1.

FIG. 1.

Accumulation of ciprofloxacin (CIP) with or without reserpine or sodium orthovanadate in S. pneumoniae strains R6, M169, M184, M186, M4, and M168. M186 was compared to R6 because M186 is a mutant of R6 transformed with DNA from M168. An asterisk indicates a P value of <0.05. R, reserpine; O, sodium orthovanadate.

FIG. 2.

FIG. 2.

Accumulation of ethidium bromide with or without sodium orthovanadate in S. pneumoniae. (A) Ethidium bromide kinetics over 10 min for strains R6 (⧫), M169 (□), M169 in the presence of sodium orthovanadate (▪), M184 (○), and M184 in the presence of sodium orthovanadate (•). Sodium orthovanadate was added after 5 min (as indicated by the arrow). (B) Ethidium bromide kinetics over 10 min for strains M4 (⧫), M168 (□), M168 in the presence of sodium orthovanadate (▪), M186 (○), and M186 in the presence of sodium orthovanadate (•). Sodium orthovanadate was added after 5 min (as indicated by the arrow).

FIG. 3.

FIG. 3.

Comparison of the levels of expression of patA (□) and patB (▪). The asterisks indicate values significantly different (P < 0.05) from those for R6.

FIG. 4.

FIG. 4.

Locations of SP2070, SP2071, SP2072, SP2073 (patA), SP2074, SP2075 (patB), SP2076, and SP2077 genes. patA and patB are colocalized in the S. pneumoniae (TIGR4) genome.

References

    1. Ahmed, M., C. M. Borsch, A. A. Neyfakh, and S. Schuldiner. 1993. Mutants of the Bacillus subtilis multidrug transporter Bmr with altered sensitivity to the antihypertensive alkaloid reserpine. J. Biol. Chem. 268**:**11086-11089. -PubMed
    1. Akerley, B. J., E. J. Rubin, A. Camilli, D. J. Lampe, H. M. Robertson, and J. J. Mekalanos. 1998. Systematic identification of essential genes by in vitro mariner mutagenesis. Proc. Natl. Acad. Sci. USA 95**:**8927-8932. -PMC -PubMed
    1. Andrews, J. M. 2001. The development of the BSAC standardized method of disc diffusion testing. J. Antimicrob. Chemother. 48(Suppl. 1)**:**29-42. -PubMed
    1. Aparicio, J. F., R. Fouces, M. V. Mendes, N. Olivera, and J. F. Martin. 2000. A complex multienzyme system encoded by five polyketide synthase genes is involved in the biosynthesis of the 26-membered polyene macrolide pimaricin in Streptomyces natalensis. Chem. Biol. 7**:**895-905. -PubMed
    1. Avery, O. T., C. M. MacLeod, and M. McCarty. 1944. Studies on the chemical nature of the substance inducing transformation of pneumococcal types. Induction of transformation by a desoxyribonucleic acid fraction isolated from Pneumococcus type III. J. Exp. Med. 79**:**137-158. -PMC -PubMed

Publication types

MeSH terms

Substances

LinkOut - more resources