Increasing drug resistance of Mycobacterium tuberculosis in Sinaloa, Mexico, 1997–2005

SummaryBackgroundIn 1997 the US Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) reported high proportions of drug-resistant Mycobacterium tuberculosis in three Mexican states: Sinaloa, Baja California, and Oaxaca. In 2006, we showed that resistance to anti-tuberculosis drugs remained frequent in Sinaloa.ObjectivesThe objectives of this study were to describe drug-resistant tuberculosis (TB) trends and to investigate the probability that patients acquire resistance to first-line anti-TB drugs on recurrence after treatment in Sinaloa.MethodsSputum specimens were collected from patients diagnosed with TB at all the health care institutions of Sinaloa during 1997–2005. Isolates were tested for susceptibility to first-line drugs.ResultsAmong 671 isolates tested from 1997 to 2002, the overall resistance rate was 34.9% (95% confidence interval (CI) 31.2–38.4) with a 1.2% increase per year (Chi-square = 4.258, p = 0.03906). The prevalence of multi-drug resistance (MDR) was 17.9% (95% CI 14.9–20.7) with a 1.2% increase per year (Chi-square = 8.352, p = 0.00385). Of 50 patients registered twice between 1997 and 2005, 15 were fully susceptible at first registration, of whom six (40%) acquired drug resistance. Of 35 cases with any drug resistance at first registration, 21 (60%) came to acquire resistance to at least one other drug.ConclusionsThe proportion of drug-resistant TB increased during 1997–2005 in Sinaloa. Major efforts are needed to prevent the further rise and spread of drug-resistant and MDR TB.