ABSTRACT
Objective/background: tuberculosis remains an important cause of mortality worldwide. Previous tuberculosis treatment is a strong determinant of multi-drug resistant tuberculosis. The study objective was to describe the mutations detected of Mycobacterium tuberculosis [MTB] complex clinical strains screened with GeneXpert isolated from previously treated patients in Cote d' Ivoire
Methods: sputum collected and decontaminated by the n-acetyl-L-cysteine method was used to perform Ziehl-Neelsen staining, GeneXpert MTB/ rifampicin, and culture on LowensteinJensen medium. Drug susceptibility testing [DST] for first-line drugs was performed in a Baetee 960 Automated System. After strain identification by antigen MPT64 detection, DNA extraction, and genotyping with MTBDRplus assay was performed and interpreted. The strains muted in rpoB without a specific protein identified and were sequenced
Results: mutant sequences were detected in 60 sputum samples with GeneXpert MTB/ rifampicin of which 55 were confirmed multi-drug resistant MTB strains after DST. The most frequent mutations responsible for rifampin resistance were detected with MTBDR plus assay for 49 [81.7%] clinical strains, while sequencing was required for 11 [18.3%]. H526Qmutation, L533P, and D516V associated respectively with L533P, A532A, and S522L, and were observed for three relapse cases. For these cases, GeneXpert and sequencing results were concordant. Discrepancies between GeneXpert and mycobacteria growth indicator tube-DST for rifampin were observed for three strains, on which D516Y, H526C, and L533P were identified
Conclusion: in the setting of a high prevalence of drug resistance, characterization of the genetic basis of MTB strains resistant to rifampin could be screened first with MTBDR plus
ABSTRACT
Tuberculosis is explicitly recognized as a major global public health problem. In Cote d'Ivoire, relapse cases represent 66.5% of patients eligible for retreatment according to the National Tuberculosis Control Program. This study objective was to detect multidrug-resistance tuberculosis among relapse cases. Patients were recruited in tuberculosis centers in routine. A standardized questioning was administrated. Two sputum samples were collected and transported at Institut Pasteur. Sputum samples were decontaminated by NALC method. The DNA extraction was realized with 500 microl of decontaminated sputum sample with smear-positive. MTBDRplus assay version 2.0 was performed according to the manufacturer's instruction. An internal quality control program with positive and negative controls was implemented for interpretation of results. In total 146 relapse cases with smear positive were studied. Out of selected patients, 130 had received the 2RHZE/4RH regimen and 16, the 2RHZES/1RHZE/5HRE. In group of relapse cases previously treated with 2RHZE/4RH regimen, 40 [31.3%, IC95%: [0.23; 0.39]] had punctual mutations at codon 526 in rpoB gene. Although, in patients under treated with 2RHZES/1RHZE/5HRE, a mutation in rpoB gene was identified in 12 of 16 sputum samples. Thirteen mutations conferring a resistance to Isoniazid were observed of which 9 in katG gene and 4 in katG and promoter region of inhA gene. The comparison [Chi-square with Yates correction] of resistance rates to Rifampin estimated showed a statistically significant difference. Use of a rapid method to detect drug-resistance in recurrent TB cases has permitted to identify patients eligible for first-line drugs or not.