Drug resistance pattern of mycobacterium tuberculosis complex at a medical center in central Taiwan, 2003-2007

Abstract

Background/purpose: Drug-resistant tuberculosis (TB) is an important issue for public health. This study was conducted to evaluate the prevalence of drug resistance to Mycobacterium tuberculosis complex at Changhua Christian Hospital in central Taiwan.

Methods: We retrospectively reviewed 1,961 non-duplicate isolates of M. tuberculosis complex from 2003 to 2007. The following data were collected: demographic characteristics, previous anti-TB therapy and drug susceptibility testing. Antimicrobial drug susceptibility testing was performed using the BACTEC MGIT 960 System from January 2003 to February 2005. Starting in March 2005, the agar proportion method was used for antimicrobial drug susceptibility testing.

Results: A total of the 1,961 patients were analyzed. The majority (66.5%) of cases were >/= 65 years of age. A total of 151 patients had undergone previous anti-TB treatment. Individual drug resistance was as follows: 229 isolates (11.7%) were resistant to isoniazid, 55 (2.8%) to rifampin, 49 (2.5%) to ethambutol, and 218 (11.1%) to streptomycin. The overall resistance to any drug was 19.1%, while 39 isolates (2.0%) were resistant at least to isoniazid and rifampin (multidrug-resistant). A significant decreasing trend in resistance rates to the four first-line anti-TB drugs, and any other drug, was observed during the 5-year period. Drug resistance was associated with a history of previous anti-TB treatment (p = 0.017).

Conclusion: The study found a significant decrease in drug resistance from 2003 to 2007. The multidrug resistance also decreased, although this was not statistically significant. This decreasing resistance rate may be due to the effect of the direct observed treatment, short-course strategy which was enhanced in Taiwan after 2006.