Objective: Tuberculosis remains a significant public health challenge worldwide, with drug resistance being one of the primary factors influencing treatment success. In this study, we retrospectively evaluated the isolation rates of Mycobacterium tuberculosis complex (MTBC) and non-tuberculous mycobacteria (NTM) from clinical samples submitted to the Microbiology Laboratory of Sivas Cumhuriyet University Faculty of Medicine Research and Training Hospital for suspected tuberculosis between 2019 and 2023. Additionally, we analyzed the results of acid-fast bacillus (AFB) microscopy and the susceptibility profiles of MTBC isolates to first-line anti-tuberculosis drugs.

Methods: We retrospectively analyzed 8,540 samples from suspected TB cases between 2019 and 2023. Cultures were performed using the BD-BACTEC-MGIT-960 system and Löwenstein-Jensen medium. Ziehl-Neelsen staining was used for AFB microscopy. Drug susceptibility testing of culture-positive MTBC isolates against isoniazid, rifampicin, streptomycin, and ethambutol was performed retrospectively using an automated system.

Results: Culture positivity was observed in 2.06% of the total 8,540 samples. Among these, 150 were MTBC and 26 were NTM. A significant correlation was found between ARB and culture results (p<0.0001). Among MTBC isolates, 117 (78.0%) were fully susceptible, while 33 (22.0%) showed resistance to at least one drug. Resistance rates were 8.7% for isoniazid, 5.3% for streptomycin, 2% for rifampicin, and 1.3% for ethambutol. Resistance to one, two, and three drugs was found in 17.3%, 4.0%, and 0.7% of isolates, respectively. Multidrug resistance was observed in 4.7%.

Conclusion: The increase in TB drug resistance in the post-pandemic era is concerning. Joint use of culture and microscopy improve diagnostic reliability. Our study contributes to local empirical treatment planning by updating the resistance data in our hospital.