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

Tuberculosis represents a main concern for public health worldwide. In poor countries, the most prevalent method for bacteriological confirmation re- mains 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 Cote 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.

Molecular Detection of Resistance to Rifampin and Isoniazid among Patients Eligible for Retreatment Regimen in Côte d’Ivoire in 2012

Drug-resistant tuberculosis is an important health problem in Cote d’Ivoire. Patients of category I treatment are based on 2RHZE/4RH regimen. For the patients of category II, the 2RHZES/1RHZE/5HRE regimen is systematically initiated. Study objective was to describe the susceptibility profile to Rifampin and Isoniazid among previously treated patients who are eligible for retreatment and who had received the 2RHZES/1RHZE/5HRE regimen in Cote d’Ivoire with a molecular method in 2012. Two sputum samples were collected to each patient recruited in the reference regional centres for tuberculosis. Sputum samples were decontaminated by NALC method. The DNA extraction was realized with 500 μl of decontaminated sputum sample with smear-positive. MTBDRplus assay version 1.0 was performed according to the manufacturer’s instruction. An internal quality control program with positive and negative controls was implemented for interpretation of results. A total of 278 patients were enrolled, 148 (53.2%) were recurrent TB cases, 118 (42.5%) failure cases, and 12 (4.3%) defaulters. From sputum of previously treated patients, mutli-drug resistant tuberculosis was diagnosed for 60 (69.8%, 95% IC, 60% - 80%) treated with the 2RHZE/4RH regimen, 24 (75%, 95% IC, 60% - 90%) with the 2RHZES/1RHZE/5HRE regimen, 60 (41%, 95% IC, 33% - 49%) recurrent TB cases, and 4 (33.3%) defaulters. The comparison of resistance rates to Rifampin estimated from sputum samples in the categories of treatment failures and the recurrence TB cases showed a statistically significant difference. In Cote d’Ivoire, genotype? MTBDRplus assay has permitted to estimate the prevalence of MDR-TB in categories of previously treated patients for tuberculosis.

QBC ParaLens^(TM) LED fluorescent microscope attachment with QBC F.A.S.T.^(TM) AFB staining system

This study was designed to evaluate the QBC ParaLensTM LED fluorescent microscope attachment and the QBC F.A.S.T.TM AFB staining system for the detection of Acid Fast Bacilli in pathological samples in Abidjan, Cote d’Ivoire. A total of 50 patients were tested using direct smear specimens with both Ziehl-Neelsen (ZN) light microscopy and LED fluorescence microscopy with QBC F.A.S.T. AFB stain. The samples were also cultured and tested using an immunochromatograpic test for detection of antigen MPT 64 and the results were compared to direct examination. ZN light microscopy detected 20 positive cases and LED fluorescent microscopy with QBC F.A.S.T. AFB stain detected 21. The sensitivity and specificity of ZN light microscopy was determined to be 84.2% and 87.1% respectively. The sensitivity and specificity of LED fluorescent microscopy with QBC F.A.S.T. AFB stain was determined to be 94.7% and 90.3% respectively. Compared to ZN light microscopy, LED fluorescent microscopy with QBC F.A.S.T. AFB stain increased the sensitivity of direct examination without concentration by 10.5%.