GeneXpert MTB/RIF Testing in the Management of Patients with Active Tuberculosis; A Real Life Experience from Saudi Arabia

Abstract

BackgroundGeneXpert MTB/RIF is a real-time PCR assay with established diagnostic performance in pulmonary and extra-pulmonary forms of tuberculosis. The aim of this study was to assess the contribution of GeneXpert MTB/RIF assay to the management of patients with any form of active tuberculosis in a single large tertiary center in Saudi Arabia, with a special focus on the impact on time to start of antituberculous therapy compared with Ziehl-Neelsen (ZN) smears and mycobacterial cultures.Materials and MethodsClinical, radiological and laboratory records for all patients who were commenced on antituberculous therapy between March 2011 and February 2013 were retrospectively reviewed.ResultsA total of 140 patients were included, 38.6% of which had pulmonary tuberculosis. GeneXpert MTB/RIF was requested for only 39.2% of patients and was the only reason for starting antituberculous therapy for only 12.1%. The median time to a positive GeneXpert MTB/RIF result was 0 days (IQR 3) compared with 0 day (IQR 1) for smear microscopy (P > 0.999) and 22 days (IQR 21) for mycobacterial cultures (P < 0.001). No patients discontinued antituberculous therapy because of a negative GeneXpert MTB/RIF result.ConclusionsIn a setting wherein physicians are highly experienced in the diagnosis and treatment of tuberculosis, GeneXpert MTB/RIF was remarkably under-utilized and had only a limited impact on decisions related to starting or stopping antituberculous therapy. Cost-effectiveness and clinical utility of routine testing of all smear-negative clinical samples submitted for tuberculosis investigations by GeneXpert MTB/RIF warrant further study.

Genomic analysis of the emergence of drug-resistant strains of Mycobacterium tuberculosis in the Middle East

“…Finally, the GeneXpert Dx automated system (Cepheid AB, Solana, Sweden) was used to detect MTBC and rifampicin resistant genotypes at the KAUH following the manufacturer’s instructions as previously described 52 – 55 . GenoType MTBDRplus (Hain Lifescience GmbH, Nerhren, Germany) was also used to detect MTBC and rifampicin as well as isoniazid resistant genotypes 56 .…”

Diagnosis of Human Immunodeficiency Virus Infection

“…The WHO reported the underutilization of conventional VL platforms, with only a 36.5% capacity of the existing platforms being used in the reported countries (224). Similarly, other studies have reported underutilization of POC or near-POC instruments (222,225). Decentralized VL testing, if properly planned, offers several advantages, including (i) cost-efficient, flexible, and close monitoring of patients; (ii) faster turnaround times for patient results; and (iii) early detection of treatment failures for better patient management.…”

Lymphadenopathy: Differentiation between Tuberculosis and Other Non-Tuberculosis Causes like Follicular Lymphoma

“…According to a systematic review by Smith et al, GeneXpert test is likely to be of greatest utility when testing lymph node or tissue samples (besides CSF), and differentiating tuberculous from non-tuberculous mycobacteria in smear positive samples ( 43 ). A study has reported that the GeneXpert test reduced the time to begin ATT by 4 weeks in both pulmonary and extrapulmonary TB cases with a negative sputum AFB smear ( 45 ). The positive and negative predictive values of this test are 90–100 and 70–85%, respectively, since it has a specificity of almost 98–100% ( 42 , 46 – 48 ).…”