Declining drug resistance of Mycobacterium tuberculosis isolates from elderly patients in Taiwan, 2000–2008

We retrospectively investigated the prevalence of drug resistance in Mycobacterium tuberculosis (MTB) isolates recovered from elderly patients and compared the drug resistance patterns between the elderly (≥65 years old) and adult (15–64 years old) patients. Data on the prevalence of drug resistance in clinical and non-duplicate isolates of MTB recovered from 2000 to 2008 were evaluated. Among the 3,186 non-duplicate MTB isolates found during the study period, 1,497 isolates were recovered from elderly patients. Thirty-eight (2.54%) isolates were multidrug-resistant tuberculosis (MDRTB). The rates of resistance to isoniazid (INH), rifampicin (RIF), ethambutol (EMB), streptomycin (SM), ofloxacin, rifabutin, any one drug-resistant (ADR), and multidrug-resistant (MDR) were significantly lower in isolates from the elderly than from adults (p < 0.05). Significant decreasing trends in resistance rates to EMB, SM, at least any one of the four first-line agents (ADR), and MDRTB were observed (p < 0.05) . In conclusion, elderly patients had a lower rate of anti-TB drug resistance than adults and a decreasing overall trend of anti-TB drug resistance was found in the elderly in recent years, but the higher rate of MDRTB in Taiwan continues to present a challenge for the control of TB in the elderly.