Comparison of Culture, Direct Microscopy, and Polymerase Chain Reaction Results for Detection of Mycobacterium Tuberculosis Complex in Clinical Specimens
Abstract
Aim: Tuberculosis is a chronic, necrotizing disease known since prehistoric times. The most important stage of the tuberculosis control program is the microbiological identification, typing and detection of drug resistance of the Mycobacterium tuberculosis complex for the detection of active cases. The aim of this study is to compare the results of the methods used in the detection of M.tuberculosis complex in clinical samples.
Materials and Methods: The presence of M. tuberculosis complex in various clinical specimens sent to the Medical Microbiology Laboratory from patients with a pre-diagnosis of tuberculosis between January 2016 and January 2022 was investigated retrospectively. In microbiological diagnosis, Ehrlich-Ziehl-Neelsen (EZN) staining method, culture (BACTEC MGIT 320 automated system and Löwenstein Jensen (LJ) medium, and polymerase chain reaction (PCR) tests were used.
Results: A total of 1706 samples were evaluated. The mean age of the patients was 46.49±25.77 years and 1025 (60.1%) were male. EZN method was positive in 32 (1.9%), culture in 48 (2.8%), and PCR in 40 (2.3%) samples. Samples were mostly sent from the departments of chest diseases (52.8%) and pediatrics (24.2%).
Conclusion: Culture, which is the gold standard method, was found to be the most reliable method for demonstrating the presence of M. tuberculosis complex. In the rapid diagnosis of tuberculosis, PCR method gives more reliable results than EZN method. As a result, since the culture method, gives late results, extensive routine use of molecular tests such as PCR is needed for accurate diagnosis of tuberculosis in a short time and to detect drug resistance.
Keywords
Mycobacterium tuberculosis, EZN, Löwenstein Jensen Medium, TB-DNA
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