Drug resistance in extra-pulmonary tuberculosis in South Korea: comparison with pulmonary tuberculosis

Objective To compare the prevalence of and trends in drug resistance in extra-pulmonary tuberculosis (EPTB) and pulmonary tuberculosis (PTB). Methods We retrospectively analysed the results of phenotypic drug susceptibility testing (DST) in culture-confirmed TB patients from January 2010 to December 2014 at seven university hospitals in South Korea. Results Of 5599 patients included, 320 (5.7%) were classified in the EPTB group and 5279 (94.3%) in the PTB group. The proportion of EPTB among all TB cases had gradually increased from 2010 to 2014 ( P = 0.004). Among both new and previously treated patients, there were no significant differences in rates of resistance to any kind of anti-tuberculosis drug between the EPTB and PTB groups. The trends in drug resistance rates among new patients were similar in both the EPTB and PTB groups. The rates of multidrug-resistant TB among new patients gradually decreased in both groups ( P = 0.031 and P = 0.001, respectively). Conclusion The prevalence of and trends in drug resistance among new patients are not significantly different between patients with EPTB and those with PTB.