The association between diabetes mellitus and rate of sputum culture conversion among patients with multi-drug resistant pulmonary tuberculosis at the Zamboanga City Medical Center: A cross sectional analytical study.

BACKGROUND: Diabetes Mellitus (DM) is a risk factor for active tuberculosis (TB) but little is known about the effect of DM on culture conversion among patients with Multidrug-Resistant Tuberculosis. Conversion of serial sputum cultures from positive to negative is an important indicator of treatment response and declining infectiousness. The knowledge of associated risk factors to delay in sputum culture conversion at the end of the initiation phase of anti-tuberculosis treatment is necessary for care providers to prevent unfavorable outcomes. 

OBJECTIVES: This study identifies the risk factors of sputum culture non-conversion at the end of the intensive phase of treatment, and the effects of culture and smear non-conversion on the outcome treatment especially among MDRTB patients afflicted with Diabetes Mellitus. 

METHODS: A cross-sectional analytical design has been used and includes all >15 years of age (n=171) Multi-Drug Resistant Pulmonary Tuberculosis patients who started treatment between January 1, 2011 until June 30, 2015 at the Zamboanga City Medical Center - Programmatic Management for Drug Resistant Tuberculosis (ZCC-PMDT). Measure of Association is computed between MDRTB with DM patients ad sputum conversion rate.

RESULTS: Diabetes Mellitus is associated with delayed culture conversion and poor treatment outcome. MDRTB patients with Diabetes are found to have a culture conversion rate of 89% compared to 95% among MDRTB patients without diabetes. Diabetes Mellitus (OR=2.12, p-0.04), positive sputum smear (OR=2.44, p-0.04), and positive sputum culture at start of treatment (OR=4.54, p-0.03) are significant risk factors for delayed sputum culture conversion. Gender (being female OR=3.02, p-0.03) is associated with poor treatment outcome.

CONCLUSION: Poor treatment outcomes for TB is influenced by gender (being female) and co-morbidity of DM. Diabetes Mellitus with a positive sputum smear and culture at the start of treatment is in turn associated with delayed sputum conversion. Knowing these factors, a physician is guided to effectively manage PTB patients in minimizing poor treatment outcomes.