Increase in primary drug resistance of Mycobacterium tuberculosis in younger birth cohorts in France

SummaryBackgroundMonitoring of primary drug resistance is of interest for long-term evaluation of the efficacy of a national tuberculosis program. The objective was to describe changes over time in primary drug resistance among new tuberculosis patients.MethodsStratified analysis by birth cohorts, region of birth, HIV-coinfection of data from 14,610 culture-positive new tuberculosis patients diagnosed by a network of university hospitals between 1995 and 2008.ResultsHalf of the patients were foreign-born, and 9% HIV-coinfected. For foreign-born and French-born patients, there was an upward trend in resistance rates to streptomycin, isoniazid, and rifampicin from the oldest to the youngest cohorts. For a same age at tuberculosis diagnosis, the risk of isoniazid resistance was higher in younger cohorts, revealing a cohort effect. Among French-born patients, the only factor independently associated with primary resistance to streptomycin, or isoniazid was birth after 1950, and particularly after 1980. Risk of streptomycin resistance increased in youngest cohorts among European-born patients. HIV-coinfection was associated to rifampicin resistance among foreign-born and French-born patients,ConclusionsTheses results indicate that among French-born patients, isoniazid-resistant strains are currently circulating in younger patients that are more likely to be infected recently, and that among foreign-born patients, HIV-coinfection is a strong risk factor for primary resistance.