Evaluation of GeneXpert assay performance for pulmonary tuberculosis at King Abdulaziz University Hospital: A two years’ surveillance study

Document Type : Original Article


1 Diagnostic Molecular biology Laboratory, King Abdulaziz University Hospital, Jeddah, Kingdom of Saudi Arabia.

2 Department of Medical Microbiology and Parasitology, Faculty of Medicine, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia

3 Associate professor of Medical Microbiology and Immunology, Faculty of Medicine, Zagazig University

4 Medical microbiology and immunology Department, Faculty of Medicine, zagazig university, Egypt.


Background: Tuberculosis (TB) is one of the deadliest health problems. Accurate rapid diagnosis and prompt treatment are crucial for cure. The aim of this study was to investigate the role of GeneXpert PCR in the rapid detection of MTBC directly from clinical samples and to determine the anti-TB drug resistance patterns in pulmonary tuberculosis. Methods: This is a cross-section analysis, involving a total of 92 patients with pulmonary TB (primary TB resistance); 37 Saudis and 55 non-Saudis. Respiratory specimens were processed, and examined by flurochrome stain. Culture and susceptibility testing was performed by VersaTREK , a liquid culture system. Adding, Mycobacterium tuberculosis complex (MTBC) was directly detected from the sample by GeneXpert PCR. Results: GeneXpert assay achieved 96 % sensitivity and 100 % specificity for the detection of MTBC in sputum. Resistance to pyrazinamide was (6.5 %), followed by rifampicin (2.2 %), streptomycin and isoniazid (1.1 %). Mono-resistance to pyrazinamide and streptomycin (5.4%) and (1.1%) respectively. MDR-TB was (1.1%) and there was no substantial difference in anti-TB resistance between Saudi and non-Saudi TB patients. Conclusions: The GeneXpert PCR is a very helpful tool for the detection of MTBC in respiratory specimens with a high sensitivity, specificity and accuracy within a shorter time as compared to conventional methods.
Recommendations: Costs-benefit analysis of GeneXpert versus other recently deployed TB diagnostic systems may be required on a wider scale.


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