GENOTYPIC CHARACTERIZATION OF THE MYCOBACTERIUM TUBERCULOSIS COMPLEX RESISTANT TO ANTI-TUBERCULOSIS DRUGS ISOLATED FROM BREEDERS IN SIX TOWNS IN SOUTHERN CHAD

Monitoring risk factors associated with tuberculosis transmission and identifying the genetic basis of Mycobacterium tuberculosis complex strains resistant to first-line anti-tuberculosis drugs could help provide important information to optimize care and reduce family contact. tuberculosis among breeders. The present study was an observational, cross-sectional and analytical study aimed at determining the prevalence of resistance genes of strains of the Mycobacterium tuberculosis complex circulating in the environments of breeders practicing nomadism and transhumance in Chad. Microscopy using the Ziehl Neelsen staining technique made it possible to identify 274 (21.8%) strains of Mycobacterium tuberculosis complex among 1256 breeders consulted for the search for tuberculosis including 67 cases in relapse and 207 new cases under treatment or not without clinical improvement. The average age of the patients was 47.5 years with the extremes ranging from 15 to 80 years. The M/F sex ratio was 1.6 in favorof the male sex. The GeneXpert MTB/RIF detected 268 Mycobacterium tuberculosisout of the 274 cases of tuberculosis that microscopy identified. Of 268 Mycobacterium tuberculosis, 24 (9%) were rifampicin resistant (RR-TB) and 244 (91%) rifampicin susceptible. Culture on MGIT (mycobacteria growth indicator tube) medium confirmed the isolation of 274 strains of mycobacteria. Molecular typing of the 274 strains of the Mycobacterium complex by Spoligotyping made it possible to detect 268 (98%) Mycobacterium tuberculosis and 6 (22%) Mycobacterium bovis. Spoligotyping also made it possible to detect three lines from Mycobacterium tuberculosis isolates (Lineage, Lineage 3 and Lineage 4 (L1, L3 and L4). Thirteen genotypic markers were detected by the Spoligotyping technique and Mycobacterium tuberculosis Cameroon (MtbCam) was predominant (27%) The GenoType MTBDR plus made it possible to detect the genes which code for resistance to rifampicin and isoniazid: rpoB (n=24), inhA (n=13) as well as the mutation genes associated with second-line anti-tuberculosis drugs(gyrA (n=5), gyrB (n=6), rrs (n=3), eis (n=3)). TB/HIV co-infection represented 5%. This study highlighted the emergence of lineages of strains of the Mycobacterium tuberculosis complex resistant to rifampicin and isoniazid as well as strains of Mycobacterium bovis transmitted from cattle to breeders. It raises the need to implement an effective surveillance system to detect the different lines of Mycobacterium tuberculosis resistant to anti-tuberculosis drugs in Chad, in Africa and even in the world.