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J Infect Dis. 2016 Jan 1;213(1):149-55. doi: 10.1093/infdis/jiv347. Epub 2015 Jun 19.

Fitness Costs of Drug Resistance Mutations in Multidrug-Resistant Mycobacterium tuberculosis: A Household-Based Case-Control Study.

Author information

1
Department of Epidemiology, Harvard School of Public Health Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
2
Department of Global Health and Social Medicine, Harvard Medical School.
3
Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut.
4
Massachusetts Supranational TB Reference Laboratory, University of Massachusetts Medical School, Boston.

Abstract

BACKGROUND:

The projected long-term prevalence of multidrug-resistant (MDR) tuberculosis depends upon the relative fitness of MDR Mycobacterium tuberculosis strains, compared with non-MDR strains. While many experimental models have tested the in vitro or in vivo fitness costs of various drug resistance mutations, fewer epidemiologic studies have attempted to validate these experimental findings.

METHODS:

We performed a case-control study comparing drug resistance-associated mutations from MDR M. tuberculosis strains causing multiple cases in a household to matched MDR strains without evidence of secondary household cases.

RESULTS:

Eighty-eight multiple-case and 88 single-case household MDR strains were analyzed for 10 specific drug resistance-associated polymorphisms previously associated with fitness effects. We found that the isoniazid-resistant katG Ser315Thr mutation occurred more than twice as frequently in multiple-case households than in single-case households (odds ratio [OR], 2.39; 95% confidence interval [CI], 1.21-4.70), corroborating previous experimental findings. However, strains carrying both the katG Ser315Thr mutation and the rpsL Lys43Arg mutation were less likely to be found in multiple-case households (OR, 0.09; 95% CI, .01-.73), suggesting a negative epistatic interaction which contrasts previous findings.

CONCLUSIONS:

The case-control design presents a useful approach for assessing in vivo fitness effects of drug resistance mutations.

KEYWORDS:

Lima, Peru; MDR M. tuberculosis; antibiotic resistance; case-control study; epistasis; fitness cost; katG; rpsL; molecular epidemiology; transmission

PMID:
26092854
PMCID:
PMC4676541
DOI:
10.1093/infdis/jiv347
[Indexed for MEDLINE]
Free PMC Article

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