Clinical Performances of Pure TB-Lamp Kit for <i>M. tuberculosis</i> Complex Detection in Sputum Samples

Abstract

Tuberculosis represents a main concern for public health worldwide. In poor countries, the most prevalent method for bacteriological confirmation remains Smear Sputum Microscopy (SSM). This study objective was to assess clinical performances of Loop Mediated Isothermal Amplification for TB detection (Lamp-TB). Sputum of patients presenting symptoms consistent with tuberculosis were collected according to the National Tuberculosis Control Programme guidelines in Centre Antituberculeux de Yopougon. SSM after Ziehl-Neelsen staining and TB-Lamp were blindly performed with spot sputum specimen. Samples, transported at Institut Pasteur de Côte d'Ivoire were decontaminated according to N-acetyl-L -cystein (NALC) method. In Mycobacteria Growth Indicator Tube (MGIT), 500 µl of pellet were inoculated and incubated in MGIT 960 instrument. MPT64 antigen was detected on positive culture. Of 500 patients enrolled, 469 were included. Clinical isolates of M. tuberculosis Complex were detected for 157 (33.5%). Comparatively to culture, Sensitivity and Specificity of SSM were 86% (95% Confidence interval (CI): 81% -91%) 96% (95%IC: 94% -98%) respectively. TB-Lamp Sensitivity was 92% (95%CI: 88% -96%), and Specificity 94% (95%CI: 91% -97%). Positive Predictive Value of SSM and TB-Lamp was 91.8% and 88.8% respectively. Negative Predictive Value of TB-Lamp assay was 95.7% whereas this of SSM was 93.3%. Positive Likelihood Ratio was 15.3 for TB-Lamp and 21.5 for SSM 21.5 whereas negative Likelihood of TB-Lamp was lower than SSM. Active tuberculosis was detected in162/469 (34.5%) with TB-Lamp and 147 (31.3%) with SSM. TB-Lamp assay performances estimated from sputum samples may improve detection of active TB cases in routine.

Innovations in Molecular Identification of Mycobacterium tuberculosis

“…69 According to research, 68 the sensitivity of the test is 55.6% in patients with a negative smear and 98.2% in patients with a positive smear. According to N'guessan et al, 6 the PURE-LAMP test has a greater sensitivity than that of smear microscopy. However, the specificity of the smear microscopy was greater than that of PURE-LAMP.…”

“…5 Alternatively, Lowenstein-Jensen culture, which is often considered the gold standard in presumptive respiratory infections, looks to be more specific than smear microscopy, however, it is more timeconsuming (4-8 weeks in culture). It demands appropriate infrastructure and possibly the best laboratory personnel 6 which can cause delays in efficient medical treatments. Therefore, the demand for novel, quick, and reliable diagnostic procedures has arisen.…”

Rapid molecular assays for detection of tuberculosis

“…Moreover, a positive result by this test does not discriminate between the Mycobacterium species [ 7 ]. Otherwise, Lowenstein-Jensen culture, generally used as the gold standard in suspected pulmonary cases, is more sensitive than smear microscopy, but it is time consuming (may take 4–8 weeks in solid media culture), and it requires adapted infrastructures and well-trained laboratory staff [ 8 ], which can delay effective medical interventions; therefore, the need for new rapid and accurate diagnostic methods has emerged. With the rapid evolution of molecular techniques, a wide variety of nucleic amplification tests (NAATs) such as polymerase chain reaction (PCR), real-time PCR, and loop-mediated isothermal amplification (LAMP), are available for the diagnosis of TB .…”

“…Several studies showed that PURE-LAMP has very high sensitivity and specificity, which makes it economic, cost effective and rapid method for the diagnosis of tuberculosis [ 8 , 89 ]. Mitarai et al [ 88 ] reported the sensitivity of PURE-LAMP in smear-negative TB patients to be 55.6%, and 98.2% among smear positive TB patients.…”

“…Kouzaki et al [ 90 ] showed that PURE-LAMP may potentially be a valuable tool for the diagnosis of extrapulmonary TB. N’guessan et al [ 8 ] compared the performances of sputum smear microscopy (SSM) after Ziehl-Neelsen staining and PURE TB-LAMP assay. The results of this study show that the sensitivity of TB-LAMP assay is higher than SSM.…”