RESUMO
Assuntos
Antituberculosos/farmacologia , Mycobacterium tuberculosis/efeitos dos fármacos , Tuberculose Resistente a Múltiplos Medicamentos/tratamento farmacológico , Farmacorresistência Bacteriana Múltipla/genética , Genótipo , Ensaios de Triagem em Larga Escala/métodos , Humanos , Isoniazida/farmacologia , Testes de Sensibilidade Microbiana/métodos , Mutação , Mycobacterium tuberculosis/genética , Fenótipo , Rifampina/farmacologia , Sensibilidade e Especificidade , Tuberculose Resistente a Múltiplos Medicamentos/microbiologiaRESUMO
SETTING: Xpert® MTB/RIF is the most widely used molecular assay for rapid diagnosis of tuberculosis (TB). The number of polymerase chain reaction cycles after which detectable product is generated (cycle threshold value, CT) correlates with the bacillary burden.OBJECTIVE To investigate the association between Xpert CT values and smear status through a systematic review and individual-level data meta-analysis. DESIGN: Studies on the association between CT values and smear status were included in a descriptive systematic review. Authors of studies including smear, culture and Xpert results were asked for individual-level data, and receiver operating characteristic curves were calculated. RESULTS: Of 918 citations, 10 were included in the descriptive systematic review. Fifteen data sets from studies potentially relevant for individual-level data meta-analysis provided individual-level data (7511 samples from 4447 patients); 1212 patients had positive Xpert results for at least one respiratory sample (1859 samples overall). ROC analysis revealed an area under the curve (AUC) of 0.85 (95%CI 0.82-0.87). Cut-off CT values of 27.7 and 31.8 yielded sensitivities of 85% (95%CI 83-87) and 95% (95%CI 94-96) and specificities of 67% (95%CI 66-77) and 35% (95%CI 30-41) for smear-positive samples. CONCLUSION: Xpert CT values and smear status were strongly associated. However, diagnostic accuracy at set cut-off CT values of 27.7 or 31.8 would not replace smear microscopy. How CT values compare with smear microscopy in predicting infectiousness remains to be seen.
Assuntos
Reação em Cadeia da Polimerase/métodos , Escarro/microbiologia , Tuberculose/diagnóstico , Humanos , Microscopia/métodos , Sensibilidade e EspecificidadeRESUMO
INTRODUCTION: In July 2012, the United States Agency for International Development (USAID) Quality Health Care Project introduced the Xpert® MTB/RIF assay at the facility level of the primary health care system in Kyrgyzstan. This study analysed the results of the implementation of Xpert. MATERIALS AND METHODS: Test results from 2734 patients from July 2012 to December 2014 were analysed. The sensitivity and specificity of Xpert in routine programme conditions were evaluated using culture and phenotypic drug susceptibility testing (DST) as gold standard. Contribution to early start of treatment for multidrug-resistant tuberculosis (MDR-TB) was expressed as the median time between availability of the test result and start of treatment. RESULTS: Compared to culture, the sensitivity and specificity of Xpert were respectively 92.7% and 90.4%. For the detection of rifampicin (RMP) resistance, Xpert sensitivity and specificity were respectively 90.1% and 90.7%. The median time to initiation of MDR-TB treatment decreased to 10 days (interquartile range [IQR] 6-16) in 2014 from 20 days (IQR 12-40, P < 0.001) in 2013. CONCLUSION: The Xpert assay demonstrated good agreement in the detection of both Mycobacterium tuberculosis and RMP-resistant pulmonary TB in routine clinical practice. Although Xpert improved the time to treatment initiation from 2013 to 2014, more efforts are needed to further reduce this delay.