Objective: In this study, it was aimed to evaluate the performance of GeneXpert MTB/RIF (GX) assay used for the identification of Mycobacterium tuberculosis complex (MTC) and detection of rifampicin (RIF) resistance in the Central Laboratory of Dokuz Eylul University Hospital between June 2012, and November 2016 by comparing microscopic, and culture methods.

Method: The results of 4.199 patient samples (1361 pulmonary and 2838 extrapulmonary) using Kinyoun?s staining method for microscopic examinztion, culture methods and GX test as requested by clinics were retrospectively included in t he study.

Results: By using culture as the reference method for the detection of MTC; sensitivity and specificity of GX assay were determined as 74.5% and 99.1% for all specimens; 82.7% and 98.7% for pulmonary specimens; 67.2% and 99.3% for extrapulmonary specimens, respectively. The sensitivity and specificity of microscopic examination were found to be 16.4% and 99.7% for all specimens; 28.8% and 99.2% for pulmonary specimens; and 5.2% and 99.9% for extrapulmonary specimens, respectively. The difference between the sensitivities of the GX assay and the microscopic examination was found statistically significant for all samples and for the pulmonary and extrapulmonary samples (p<0.001). By using the drug susceptibility test results of the MGT SIRE as a reference; the sensitivity and specificity of the GX test for detecting RIF resistance was 100% and 95.8%, respectively.

Conclusion: In conclusion, GX assay is useful for rapid diagnosis of TB considering that the test is easily applicable and directly detects MTC DNA and resistance to RIF within 2 hours and is superior in sensitivity than microscopic examination. However, test results should always be confirmed by culture methods.