Age-stratified anti-tuberculosis drug resistance profiles in South Korea: a multicenter retrospective study

Abstract Background: The emergence of drug-resistant tuberculosis (DR-TB) is a major healthcare concern worldwide. Here, we analyzed age-related trends in DR-TB rates in South Korea. Methods: Drug susceptibility test results were collected from patients with culture-confirmed TB between 2015 and 2018 from eight university-affiliated hospitals. Patients were divided into three subgroups: younger (15–34 years), middle (35–59 years), and older (≥60 years) to compare drug-resistance patterns. Results: Among the 4,417 cases investigated, 179 (4.1%), 53 (1.2%), and 316 (7.2%) were multidrug-resistant TB (MDR-TB), rifampicin-mono-resistant TB (RR-TB), and isoniazid-mono-resistant TB (Hr-TB), respectively. Proportions of Hr-TB cases were similar among the three groups (11.2%, 12.2%, and 10.4% in the younger, middle, and older groups, respectively). MDR/RR-TB case numbers decreased significantly as age increased (8.6%, 6.3%, 3.3%, respectively). Proportions of MDR/RR-TB among retreated patients in the younger generation decreased from 50.0% to 18.2%, but remained higher than that in the older generation. Fluoroquinolone resistance was highest among second-line drugs, and there were no differences in resistance to fluoroquinolones and second-line injectable drugs among the three age groups. Conclusions: The number of MDR/RR-TB cases was highest in young patients. Effective public health interventions should include increased focus on rifampicin resistance in young patients.