Study of Direct Tb-Lamp using Non-Centrifugal Sputums about Efficiency for Rapid Diagnosis of Tuberculosis
Yoshida, H.; Onohara, K.; Tazawa, T.; Kawahara, K.; Tsurinaga, Y.; Han, Y.; Tamura, Y.; Nagai, T.; Hashimoto, S.; Kawase, I.
Kekkaku 90(5): 497-502
2015
ISSN/ISBN: 0022-9776 PMID: 26489152 Document Number: 682647
To analyze the results of the external quality assessments (EQA) for anti-tuberculosis drug susceptibility testing (DST) and to set-up its rational passing criterion. Each participating laboratory in EQA performed DST, and the sensitivity, specificity, agreement (efficiency) and kappa coefficient were calculated from the results. We analysed the data of seven EQA results for DST from 2004 to 2010. A total of 20, 20, 10, 5, 10, 10, and 10 strains of M. tuberculosis with known susceptibility were sent to each participating laboratory in 2004, 2005, 2006, 2007, 2008, 2009, and 2010, respectively. The total of participating laboratories was 564. Each laboratory was asked to perform DST with its routine methods and reported 25,100 test results in these seven years. The laboratories showed relatively high specificity than sensitivity, and an improving sensitivity through the years. Sixteen laboratories participated the EQA continuously, and the sensitivity and specificity to isoniazid (INH), rifampicin (RFP), streptomycin (SM) and ethambutol (EB) were 0.999 (95% CI 0.992-1.000) and 0.998 (95% CI 0.991-1.000), 0.985 (95% CI 0.973-0.992) and 0.997 (95% CI 0.989-0.999), 0.932 (95% CI 0.912-0.948) and 0.977 (95% CI 0.962-0.986), and 0.965 (95% CI 0.947-0.977) and 0.978 (95% CI 0.966-0.986), respectively. The analyses revealed that the accuracy of DST for INH and RFP was highly maintained throughout the years. However, SM showed a high unevenness of performance quality and required situational considerations for evaluation. In conclusion, the EQA for DST would require a minimum number of 10 strains for each assessment, and INH and RFP should show over 95% of sensitivity and specificity with over 90% of efficiency to SM and EB as passing remark. To evaluate the efficiency of the direct tuberculosis-loop-mediated isothermal amplification (TB-LAMP) assay by using non-centrifuged sputum samples. STUDY PERIOD AND METHODS: The study was conducted between June 2013 and February 2014. We collected 111 sputum samples from patients who had been radiographically diagnosed with tuberculosis and had not received any treatments for longer than 5 days. In the direct TB-LAMP assay, a loop-mediated isothermal amplification kit and 60-μL sputum samples were used. A direct smear microscopy test was used as the smear test. Then, the same sputum samples were processed with a CCE pretreatment reagent, and 100 μL of the solution samples were cultured by using the mycobacterial growth indicator tube (MGIT) culture method. Forty-six of the 111 samples were positive in the smear microscopy tests. All the smear-positive samples were positive in both the MGIT and direct TB-LAMP assay (100%). The mean positive detection time with the direct TB-LAMP assay was 13 minutes 55 seconds. Of 56 smear-negative and MGIT positive samples, 44 (78.6%) were judged to be positive using the direct TB-LAMP assay, with a mean positive detection time of 15 minutes 59 seconds. The direct TB-LAMP assay using non-centrifuged sputum samples was demonstrated to have a high detection rate and thus may be considered useful for rapid and effective tuberculosis diagnosis.