Diagnosis of pulmonary and extrapulmonary tuberculosis using an in-house PCR method in clinical samples from a middle-income resource setting

1 GEPAMOL, Centro de Investigaciones Biomédicas, Universidad del Quindío, Armenia, Colombia 2 Maestría en Microbiología, Universidad de Cartagena, Cartagena de Indias, Colombia 3 Secretaría de Salud, Armenia, Colombia Abstract Introduction: PCR detection offers a good opportunity to obtain fast results which is a priority in tuberculosis control programs. Objectives: We assayed an in-house PCR method based on the detection of mycobaterial IS6110 gene in clinical samples of patients with pulmonary and extrapulmonary tuberculosis to demonstrate its usefulness and reliability in the setting of a middle-resource region with high tuberculosis prevalence. Materials and methods: Pulmonary (n=317) and extrapulmonary (n=41) samples were collected from 358 patients with clinical suspicion of tuberculosis. All samples were processed to detect acid-fast bacilli by microscopy, culture on solid media and PCR. To remove PCR inhibitors, three washing steps of the decontaminated pellet were included before mycobacterial cell lysis. Results: The overall sensitivity was 96% in clinical samples, and specificity was 100% for our in-house method in pulmonary and extrapulmonary samples. No inhibition was found among samples that were PCR negative, but culture positive for Mycobacterium tuberculosis. No false positives were found. Conclusions: In-house PCR in a middle-income setting region, with simple and strictly controlled methods, could efficiently complement conventional bacteriological tools for the rapid diagnosis of tuberculosis, especially in paucibacillary and extrapulmonary samples.