Urine lipoarabinomannan testing for diagnosis of pulmonary tuberculosis in children: a prospective study

Background Urine tests for mycobacterial lipoarabinomannan might be useful for point-of-care diagnosis of tuberculosis in adults with advanced HIV infection, but have not been assessed in children. We assessed the accuracy of urine lipoarabinomannan testing for the diagnosis of pulmonary tuberculosis in HIV-positive and HIV-negative children. Methods We prospectively recruited children (aged ≤15 years) who presented with suspected tuberculosis at a primary health-care clinic and paediatric referral hospital in South Africa, between March 1, 2009, and April 30, 2012. We assessed the diagnostic accuracy of urine lipoarabinomannan testing with lateral fl ow assay and ELISA, with mycobacterial culture of two induced sputum samples as the reference standard. Positive cultures were identifi ed by acid-fast staining and tested to confi rm Mycobacterium tuberculosis and establish susceptibility to rifampicin and isoniazid. Findings 535 children (median age 42·5 months, IQR 19·1–66·3) had urine and two induced specimens available for testing. 89 (17%) had culture-confi rmed tuberculosis and 106 (20%) had HIV. The lateral fl ow lipoarabinomannan test showed poor accuracy against the reference standard, with sensitivity of 48·3% (95% CI 37·6–59·2), specifi city of 60·8% (56·1–65·3), and an area under the receiver operating characteristic curve of 0·53 (0·46–0·60) for children without HIV and 0·64 (0·51–0·76) for children with HIV. ELISA had poor sensitivity in children without HIV (sensitivity 3·0%, 95% CI 0·4–10·5) and children with HIV (0%, 0·0–14·3); overall specifi city was 95·7% (93·4–97·4). Interpretation Urine lipoarabinomannan tests have insuffi cient sensitivity and specifi city to diagnose HIV-positive and HIV-negative children with tuberculosis and should not be used in this patient population

Frequent Suboptimal Thermocycler Ramp Rate Usage Negatively Impacts GenoType MTBDRsl VER 2.0 Performance for Second-Line Drug-Resistant Tuberculosis Diagnosis

Strengthening second-line drug-resistant tuberculosis (TB) detection is a priority. GenoType MTBDRplus VER 2.0 performance is reduced with non-recommended ramp rate usage (temperature change speed between PCR cycles); however, ramp rate's effect on GenoType MTBDRsl VER 2.0 (MTBDRsl) performance, is unknown. Fifty-two Xpert MTB/RIF Ultra-positive rifampicin-resistant smear-negative sputa and a Mycobacterium tuberculosis dilution series were tested at a manufacturer-recommended (2.2°C/second) or suboptimal (4.0°C/second) ramp rate. M. tuberculosis-complex-DNA positivity, indeterminates, fluoroquinolone- and second-line injectable-resistance accuracy, banding differences, and, separately, inter-reader variability were assessed. Five (39%) of 13 re-surveyed laboratories did not use the manufacturer-recommended ramp rate. On sputum, 2.2°C/second improved indeterminates versus 4.0°C/second (0 of 52 versus 7 of 51; P = 0.006), incorrect drug-class diagnostic calls (0 of 104 versus 6 of 102; P = 0.013), and incorrect banding calls (0 of 1300 versus 54 of 1275; P < 0.001). Similarly, 2.2°C/second improved valid results [(52 of 52 versus 41 of 51; +21% (P = 0.001)] and banding call inter-reader variability [34 of 1300 (3%) versus 52 of 1300 (4%); P = 0.030]. At the suboptimal ramp rate, false-resistance and false-susceptible calls resulted from wild-type band absence rather than mutant band appearance, resulting in misclassification of moxifloxacin resistance level from high-to-low. Suboptimal ramp rate contributes to poor MTBDRsl performance. Laboratories must ensure that the manufacturer-recommended ramp rate is used

Urine lipoarabinomannan testing for diagnosis of pulmonary tuberculosis in children: a prospective study

Background: Urine tests for mycobacterial lipoarabinomannan might be useful for point-of-care diagnosis of tuberculosis in adults with advanced HIV infection, but have not been assessed in children. We assessed the accuracy of urine lipoarabinomannan testing for the diagnosis of pulmonary tuberculosis in HIV-positive and HIV-negative children. Methods: We prospectively recruited children (aged ≤15 years) who presented with suspected tuberculosis at a primary health-care clinic and paediatric referral hospital in South Africa, between March 1, 2009, and April 30, 2012. We assessed the diagnostic accuracy of urine lipoarabinomannan testing with lateral flow assay and ELISA, with mycobacterial culture of two induced sputum samples as the reference standard. Positive cultures were identified by acid-fast staining and tested to confirm Mycobacterium tuberculosis and establish susceptibility to rifampicin and isoniazid. Findings: 535 children (median age 42·5 months, IQR 19·1–66·3) had urine and two induced specimens available for testing. 89 (17%) had culture-confirmed tuberculosis and 106 (20%) had HIV. The lateral flow lipoarabinomannan test showed poor accuracy against the reference standard, with sensitivity of 48·3% (95% CI 37·6–59·2), specificity of 60·8% (56·1–65·3), and an area under the receiver operating characteristic curve of 0·53 (0·46–0·60) for children without HIV and 0·64 (0·51–0·76) for children with HIV. ELISA had poor sensitivity in children without HIV (sensitivity 3·0%, 95% CI 0·4–10·5) and children with HIV (0%, 0·0–14·3); overall specificity was 95·7% (93·4–97·4). Interpretation: Urine lipoarabinomannan tests have insufficient sensitivity and specificity to diagnose HIV-positive and HIV-negative children with tuberculosis and should not be used in this patient population. Funding: US National Institutes of Health, the National Health Laboratory Services Research Trust, the Medical Research Council of South Africa, and the Wellcome Trust