Isolation and Antibiotic Resistance Rates of Mycobacterium tuberculosis complex in Mycolor TK^® System

Tuberculosis (TB) is a public health problem. This study aimed to determine the growth rates and drug susceptibility levels of patients with Mycobacterium tuberculosis complex (MTC) growth in cultures obtained and to compare the results with the growth rates and drug susceptibility levels found in our country and other countries. It also aimed to evaluate the results of supplementing classical methods such as Lowenstein-Jensen (LJ) with liquid TK MEDIUM^® and to determine the relationship between the growth rates obtained with both methods.

The study included patients who were Erlich Ziehl Neelsen (EZN) positive or negative and whose samples showed MTC growth in culture and susceptibility to the main drugs used in the treatment of TB, including streptomycin (SM), isoniazid (INH), rifampicin (RIF) and ethambutol (EMB). Patient samples were inoculated simultaneously into liquid TK^® MEDIUM based on color change and LJ solid medium. TB identification and antimicrobial susceptibility testing were performed using the TK ANTI TB and PNB KIT^® for the Mycolor TK^® automated mycobacterial culture system.

The study found resistance to dual drugs at 5.4%, INH+RIF at 1.35%, INH at 6.8%, RIF at 14.8%, EMB at 17.6%, and SM at 1.35%. Out of 69 samples cultured in LJ medium, three failed to grow in liquid TK^® MEDIUM, and two of 71 samples cultured in liquid TK^® MEDIUM gave negative results in solid LJ medium.

We found that the drug resistance rates we obtained in our study were similar to the results of the Republic of Türkiye Ministry of Health and other studies conducted in our country. In a joint study conducted with liquid and solid media, no difference was found in the detection of TB bacilli. Mycolor TK^® automated system can enable rapid mycobacterial culture in laboratories with limited resources.