EC Pulmonology and Respiratory Medicine

Introduction: Tuberculosis is an infectious disease and leading cause of death globally. The disease majorly affects the lungs and it can also affect other sites of the body. Drug resistant tuberculosis (TB) continues to be a public threat globally. Isoniazid and rifampicin are the two most effective first line TB drugs and their resistance status is paramount. For more than 10 years documented tuberculosis cases with multi-drug and rifampicin resistant tuberculosis (MDR-RR/TB) for the first time was 3 - 4% while those previously treated for TB remained at 18 - 21%. Detection of drug resistance requires bacteriological confirmation of TB and testing for drug resistance. Isoniazid preventive therapy (IPT) is one of the major interventions used to reduce the risk of TB infection progressing to TB disease. The World health organization recommends IPT treatment for people living with the human immunodeficiency virus (HIV), household contacts of bacteriologically confirmed pulmonary tuberculosis cases and people undergoing dialysis.

Objective: This study sought to document resistance patterns to first line TB drugs among the study participants.

Materials and Methods: A retrospective cohort study was carried out among 346 people with human immunodeficiency virus. Mycobacterium tuberculosis was detected and isolated from patient sputa using Xpert MTB/RIF assay and BACTEC MGIT 960 machine, drug susceptibility testing for first line TB drugs was done using BACTEC MGIT 960 machine. Collected data was analyzed using statistical package for the social sciences version 20.0.

Results: Of the 72 isolates subjected to drug susceptibility testing, those sensitive to all drugs under test were 17 (23.6%). The portion of isolates sensitive to all first line TB drugs among IPT and non-IPT cases was 1 (10%) and 16 (25.8%) respectively (OR = 0.319 [95% C.I = 0.037-2.723]; P = 0.297. Resistance to any of the drugs tested among IPT patients was; Streptomycin 7 (70%), isoniazid 2 (20%), rifampicin 1 (10%), ethambutol 3 (30%), Pyrazinamide 3 (30%). While among non-IPT patients the resistance patterns were; streptomycin 18 (29%), isoniazid 26 (41.9%), rifampicin 8 (12.9%), ethambutol 22 (35.5%) Pyrazinamide 4 (6.5%). Multi-drug resistant TB cases were IPT 1 (3.2%) and non-IPT 2 (4.2%). There were no significant differences regarding MDR-TB cases in relation to IPT status IPT 1 (3.2%) Non-IPT 2 (4.2%) (P = 0.689)

Conclusion: There was statistical significance in relation to resistance to pyrazinamide (P = 0.034) and streptomycin (P = 0.019), suggesting resistant strains to these drugs circulation in the community. Resistance to isoniazid was statistically insignificant suggesting that IPT does not amplify resistance to the drug (P = 0.202). On the other hand strains showing resistance to rifampicin (P = 0.797) and ethambutol (P = 0.736) were statistically insignificant.

 Keywords: Tuberculosis; Drug Resistance; Human Immunodeficiency; Preventive-Therapy

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