Gene Xpert

GeneXpert is a cartridge-based molecular diagnostic system that detects DNA or RNA of infectious agents using real-time PCR. It automates sample processing, amplification and detection, giving rapid results (often 30–90 minutes). Versions include Xpert MTB/RIF for tuberculosis and rifampicin resistance and SARS-CoV-2 tests. It's used in clinics and labs for accurate, point-of-care pathogen diagnosis and drug-resistance screening.

GeneXpert (Xpert MTB/RIF) is a rapid, highly sensitive and specific molecular test that detects Mycobacterium tuberculosis DNA and rifampicin resistance. A positive GeneXpert result is strongly diagnostic and guides treatment, but culture remains the definitive gold standard and clinical and radiological correlation is needed. A negative result does not fully exclude TB, especially in paucibacillary disease.

GeneXpert assays accept a wide range of clinical specimens depending on the test: respiratory samples (sputum, induced sputum, bronchoalveolar lavage, tracheal aspirate, nasopharyngeal/oropharyngeal swabs), cerebrospinal fluid, blood/plasma, urine, stool, cervicovaginal or endocervical swabs, and tissue or lymph node aspirates. The appropriate specimen type depends on the specific GeneXpert cartridge and diagnostic indication.

Sputum is respiratory mucus coughed up from the airways and serves as the clinical specimen for diagnosing lung infections. GeneXpert is an automated molecular (PCR) test performed on sputum that rapidly detects Mycobacterium tuberculosis DNA and rifampicin resistance (about two hours). In short, sputum is the sample; GeneXpert is the diagnostic test run on that sample for fast, sensitive TB detection.

There's no single best test for all cases. For suspected active pulmonary TB, rapid molecular tests (e.g., Xpert MTB/RIF) offer sensitive detection and rifampicin-resistance results; mycobacterial culture remains the diagnostic gold standard and is needed for full drug-susceptibility testing. For latent TB, use the Tuberculin Skin Test or Interferon-Gamma Release Assays (IGRAs), with IGRAs preferred after BCG vaccination.

GeneXpert instrument prices vary widely: small 1–4‑module systems typically cost roughly $15,000–$25,000, while larger multi‑module platforms can exceed $50,000–$100,000. Per‑test cartridges range from about $10 (concessional TB cartridges) to $100–150 or more for commercial assays. Additional expenses—shipping, installation, maintenance and staffing—raise overall program costs.