Clinico-microbiological profile and treatment outcomes in patients with isoniazid monoresistant tuberculosis in South India

Isoniazid (INH) is an important first-line medication for the treatment of tuberculosis. The impact that tuberculosis drug resistance has on treatment outcomes is a topic that is receiving a lot of attention these days because of the rising incidence of INH-resistant cases. Study involves a single group of patients who have been diagnosed with Isoniazid monoresistant tuberculosis. Treatment history and demographic data of the patients were obtained after informed consent. The mutation patterns of isoniazid were observed after multiplex PCR and Line Probe Assay (LPA). A total of 101 patient (M,F) records at the IRL, Puducherry were analyzed. The predominant gene responsible for TB was KATG (67.3%). The KATG Mut1 was a prime mutation observed in the present study population (58.41%). Study showed positive association with males (74%), occupation as coolie (88%), diabetes as comorbidity (33%), pulmonary tuberculosis as the TB site (98.01%), history of previous ATT intake in 43 patients (42.6%), katG mutation (67.3%), katG Mut 1 was the prime mutation (58.4%).The cure rate was high in INH high concentration resistance patients which was statistically significant (p=0.0167). INH monoresistance mutations seen in 64.3% of the patients with katG, compared to inhA (34.65%). Similar to katG mutations, inhA mutations also have MUT1 as their most frequent gene pattern. There is a significant association between males, diabetes, smoking and alcohol addictions were associated with high risk of developing high dose INH monoresistance (katG). High prevalence of recurrent tuberculosis was seen in high dose INH monoresistance tuberculosis. Patients who are microbiologically confirmed pulmonary tuberculosis and diabetes with rifampicin sensitive status needs to be checked for LPA for isoniazid sensitivity status to prevent treatment failure and relapse. It is crucial to understand the gene pattern in each of these patients since these mutations are closely associated to high or low-degree resistance to INH