Background: Recurrent pulmonary tuberculosis has more drug resistance than in new case.
Objective: To study drug susceptibility test and outcomes of recurrent pulmonary tuberculosis in the Central Chest Institute
of Thailand.
Material and Method: Patients registered as recurrent pulmonary tuberculosis between 2011 and 2013 were retrospective reviewed.
Results: There were 102 cases, 76 males and 26 females. Mean age was 47.7 years old (range 18 to 79). Anti-HIV was done in 77 from 102 cases (75.5%) and one was HIV positive. All had pulmonary tuberculosis and five cases also had pleural
involvement. CXR showed cavity in 58.1%. The number of cases that had drug resistance to streptomycin, INH, rifampicin,
ethambutol, ofloxacin, kanamycin was 16, 11, 11, 5, 3, 1 (16.7, 11.5, 11.5, 5.2, 3.1, 1%) respectively. There were 74
pansusceptible (75.5%), six streptomycin monoresistance (6.1%), six multi-drug resistance (6.1%), three INH monoresistance (3.1%), three INH polyresistance (3.1%), three rifampicin monoresistance (3.1%), two rifampicin polyresistance (2 %), one ethambutol monoresistance (1%), and four cases that drug susceptibility test result was not available from both culture and Line probe assay. Average time after complete treatment from previous tuberculosis infection to recurrence was 10.9 years (range 1 month to 41 years). There were 67 cures (65.7%), one complete of treatment (1%), three failures (2.9%), one death (1%), 16 defaults (15.7%), and 14 transfers (13.7%).
Conclusion: Most recurrent pulmonary tuberculosis in the present study was pansusceptible. Streptomycin monoresistance, INH resistance (mono and poly drug resistance) and MDR-TB was the most common drug resistance. The number of MDRTB was more than in new case. INH polyresistance and rifampicin polyresistance had poor outcomes.

Keywords: Relapse, Reinfection, TB, DST, Drug resistance