Molecular diagnosis of extrapulmonary tuberculosis and sensitivity to rifampicin with an automated real-time method.
BACKGROUND
Tuberculosis continues to be a global public health problem, the extrapulmonary form being estimated to occur in 10-20% of immunocompetent individuals, increasing in patients who are carriers of the human immunodeficiency virus (HIV); its diagnosis is difficult with conventional methods due to the paucibacillary nature of samples. The Xpert® MTB/RIF test represents an important development in the molecular detection of Mycobacterium tuberculosis and has been used with a variety of non-respiratory clinical samples.


OBJECTIVE
To determine the effectiveness of Xpert® MTB/RIF in the detection of M. tuberculosis and sensitivity to rifampicin in patients with suspected extrapulmonary tuberculosis attending Hospital Universitario de San Vicente Fundación in Medellín in 2013-2014.


METHODS
This was a descriptive, cross-sectional ambispective study of 372 consecutive samples from 301 patients with suspected extrapulmonary tuberculosis, who were subjected to bacilloscopy, followed by culture in Ogawa Kudoh and the Xpert® MTB/RIF molecular test.


RESULTS
The most frequent base diagnosis (60%) for the 182 patients was infection with HIV. Using the culture as reference, the sensitivity and general specificity of the molecular test was 94% (95% CI: 83-100) and 97% (95% CI: 95-99), respectively; for bacilloscopy it was 38.71(95% CI: 19-57) and 100% (95% CI: 99-100), respectively. Sensitivities higher than 75% were found in analyses stratified by samples. Thirty-seven of the isolates were sensitive and one resistant to rifampicin.


CONCLUSIONS
Xpert® MTB/RIF performed well in samples from different tissues and liquids, representing a significant advance in support of extrapulmonary tuberculosis diagnosis in terms of time and percentage positivity.
Unidad de Biología Molecular e Inmunogénetica de Trasplantes, Departamento de Microbiología, Hospital Universitario San Vicente Fundación, Medellín, Colombia. carlosadrianpb@gmail.com.
Adrián
A
Peñata
Richard
R
Salazar
Tatiana
T
Castaño
Julián
J
Bustamante
Sigifredo
S
Ospina
D000904:Antibiotics, Antitubercular / Q000737:chemistry / Q000494:pharmacology*; D003430:Cross-Sectional Studies; D015658:HIV Infections / Q000175:diagnosis* / Q000473:pathology; D006801:Humans; D009169:Mycobacterium tuberculosis / Q000737:chemistry / Q000302:isolation & purification*; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D012293:Rifampin / Q000737:chemistry / Q000494:pharmacology*; D018088:Tuberculosis, Multidrug-Resistant / Q000382:microbiology*; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000382:microbiology
D000904:Antibiotics, Antitubercular; D012293:Rifampin
DNA; Mycobacterium tuberculosis; miliary; polymerase chain reaction; rifampin.; tuberculosis