Version 1: Genotypic study of isolated resistance to isoniazid in the Mycobacterium tuberculosis complex in  a Moroccan hospital

Introduction:

Despite the introduction 40 years ago of effective and low-cost treatment for tuberculosis, morbidity and mortality from this disease remain substantial worldwide. The World Health Organization (WHO) estimates that 10.6 million people contracted tuberculosis, with 1.3 million deaths in 2022. The increasing number of multidrug-resistant strains of Mycobacterium tuberculosis raises concerns

Materials and Methods :

This is a retrospective study conducted at the Bacteriology Department of Mohammed V Military Instruction Hospital over a period of 3 years. Data were collected via the laboratory information system. Clinical samples underwent treatment using both conventional bacteriological methods and molecular techniques. The study of resistance to major anti-tuberculosis drugs was performed using the reverse hybridization technique, specifically the HAIN method (GenoType® MTBDRplus by Hain Lifescience). Statistical analysis of the data was carried out using Excel software     

Results :  

The study involved 464 patients treated for pulmonary and extrapulmonary tuberculosis, including both new cases and those previously treated with positive cultures. The mean age of the patients was 42.2 years, with a range from 8 to 88 years. There was a predominance of males at 74%, with a sex ratio of 2.8. 

Pulmonary sputum samples accounted for 84.8% of the cases, whereas extrapulmonary samples representedonly15.2% , the positivity rates for direct examination and culture across all samples were74%and100%,respectively.Isoniazid resistance had a prevalence of 9% (43/464). Genetic mutations observed indicated that 63% of the clinical isolates resistant to INH had mutations in the KATG gene, while 37% had mutations in the inhA gene

Conclusion :

The increasing prevalence of Mycobacterium tuberculosis complex strains resistant to one or more first-line anti-tuberculosis drugs necessitates regular epidemiological surveillance to limit the spread of these strains in the general population