A gonococcal efflux pump system enhances bacterial survival in a female mouse model of genital tract infection - PubMed (original) (raw)

A gonococcal efflux pump system enhances bacterial survival in a female mouse model of genital tract infection

Ann E Jerse et al. Infect Immun. 2003 Oct.

Abstract

Active efflux of antimicrobial substances is likely to be an important bacterial defense against inhibitory host factors inherent to different body sites. Two well-characterized multidrug resistance efflux systems (MtrCDE and FarAB-MtrE) exist in Neisseria gonorrhoeae, a bacterial pathogen of the human genital mucosae. In vitro studies suggest that the MtrCDE and FarAB-MtrE efflux systems protect the gonococcus from hydrophobic antimicrobial substances that are likely to be present on mucosal surfaces. Here we report that a functional MtrCDE efflux system, but not a functional FarAB-MtrE system, enhances experimental gonococcal genital tract infection in female mice. Specifically, the recovery of mtrD and mtrE mutants, but not a farB mutant, from mice inoculated with mutant or wild-type gonococci was reduced compared with that of the wild-type strain. Competitive-infection experiments confirmed the survival disadvantage of MtrCDE-deficient gonococci. This report is the first direct evidence that a multidrug resistance efflux system enhances survival of a bacterial pathogen in the genital tract. Additionally, experiments using ovariectomized mice showed that MtrCDE-deficient gonococci were more rapidly cleared from mice that were capable of secreting gonadal hormones. MtrCDE-deficient gonococci were more sensitive to nonphysiological concentrations of progesterone in vitro than were wild-type or FarAB-MtrE-deficient gonococci. These results suggest that progesterone may play an inhibitory role in vivo. However, hormonally regulated factors rather than progesterone itself may be responsible for the more rapid clearance of mtr-deficient gonococci from intact mice.

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Figures

FIG. 1.

FIG. 1.

Recovery of wild-type and efflux pump-deficient N. gonorrhoeae from estradiol-treated mice. Results are expressed as the average number of CFU (expressed as log10) recovered from vaginal swab suspensions over a 12-day period. P = 0.012 and 0.024 for KH14-Sm and RD1-Sm, respectively, compared with the wild-type strain. The experiment was performed twice, and the results were similar.

FIG. 2.

FIG. 2.

Recovery of efflux pump-deficient gonococci relative to that of the wild-type strain in competitive infections. The frequency of the mutant in the total population of gonococci recovered for each mouse in each experimental group on day 4 postinoculation is shown on the y axis. The frequency of mutant CFU within the inocula ranged from 0.35 to 0.59. The medians are represented by horizontal bars. P = 0.003 for RD1-Sm and KH14-Sm when compared with the recovery of EL1-Sm (as determined by the Mann-Whitney test). The experiment was performed three times using four to seven mice per group, and the results were similar.

FIG. 3.

FIG. 3.

Plating efficiency of efflux pump-deficient N. gonorrhoeae on agar containing progesterone. GC agar contained 0, 5, 10, 20, and 40 μg of progesterone/ml. The experiment was performed twice, and the results were similar.

FIG. 4.

FIG. 4.

Inhibition of Mtr-deficient N. gonorrhoeae by progesterone in mixed broth cultures. Mutants RD1-Sm and EL1-Sm were cocultured with wild-type FA19-Sm in GC broth containing 0 to 20 μg of progesterone/ml. (A) Recovery of bacteria on solid agar without antibiotic selection (closed circles, total CFU) versus that on agar containing kanamycin (open circles, mutant CFU) from FA19-Sm-RD1-Sm mixed cultures containing progesterone at the concentrations indicated on each graph. (B) Recovery of mutant EL1-Sm (open circles) when cocultured with FA19-Sm in the presence of 10 μg of progesterone/ml (closed circles, total CFU) and the change in absorbency of this culture over time (inset). (C) Total bacterial growth within FA19-Sm-RD1-Sm mixed cultures in the presence of increasing concentrations of progesterone as measured by change in absorbency at 600 nm. The experiments were performed twice, and the results were similar.

FIG. 5.

FIG. 5.

Recovery of efflux pump-deficient gonococci relative to that of the wild-type strain in competitive-infection experiments using intact versus ovariectomized mice. Results are expressed as the total number of CFU (closed circles) and the number of Kmr CFU (mutant) (open circles) recovered from mice inoculated with mixed suspensions containing a 1:1 ratio of wild-type FA19 to mutant RD1-Sm (A) or mutant EL1-Sm (B). Asterisks indicate time points at which significant differences in the recovery of RD1-Sm gonococci were detected in intact versus ovariectomized mice (P = 0.012 and 0.013 on days 2 and 3, respectively). The experiment was performed twice with six to nine mice per group, and the results were similar.

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References

    1. Bina, J. E., and J. J. Mekalanos. 2001. Vibrio cholerae tolC is required for bile resistance and colonization. Infect. Immun. 69:4681-4685. - PMC - PubMed
    1. Brabin, L. 2002. Interactions of the female hormonal environment, susceptibility to viral infection, and disease progression. AIDS Patient Care STDs 16:211-221. - PubMed
    1. Braude, A. I., L. B. Corbeil, S. Levine, J. Ito, and J. A. McCutchan. 1978. Possible influence of cyclic menstrual changes on resistance to the gonococcus, p. 328-337. In G. F. Brooks, E. C. Gotschlich, K. K. Holmes, W. D. Sawyer, and F. E. Young (ed.), Immunobiology of Neisseria gonorrhoeae. American Society for Microbiology, Washington, D.C.
    1. Chattoraj, S. C. 1976. Endocrine function, p. 699-823. In N. W. Tietz (ed.), Fundamentals of clinical chemistry. W. B. Saunders Company, Philadelphia, Pa.
    1. Critchley, H. O. D., R. W. Kelly, R. M. Brenner, and D. T. Baird. 2001. The endocrinology of menstruation—a role for the immune system. Clin. Endocrinol. 55:701-710. - PubMed

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