[Molecular epidemiology of tuberculosis in Almeria (Spain). Factors associated with recent transmission]

Abstract

Background: Molecular epidemiology is used in tuberculosis (TB) to identify clusters in which the cases are assumed to belong to the same recent transmission chain. An endogenous reactivation of latent TB is considered when the Mycobacterium tuberculosis isolates have a unique genotype.

Objective: To describe factors associated with recent transmission of TB in Almeria, from 2003-2007.

Methods: We conducted an observational prospective study that included patients with Mycobacterium tuberculosis positive culture. The strains were genotyped by Restriction Fragment Length Polymorphism and spoligotyping. Adjusted odds ratio and 95% confidence intervals were calculated to study factors associated with cluster groups, using a multivariate logistic regression model.

Results: We analysed 427 isolates, of which 71% were from males and 56.2% of them belonged to foreign residents. Furthermore, 44% were classified as a cluster. The resistance to isoniazid was 8.4%. The factors associated with clusters were age, principally the group under 10 years (adjusted OR=12.75; 95% CI, 2.52-64.58) and the group aged between 50-59 years (adjusted OR=13.85; 95% CI, 3.04-63.17), and born in Spain (adjusted OR=2.17; 95% CI, 1.41-3.36).

Conclusions: In Almeria, native population, children under 10 years old and patients aged between 50-59 years have more probability to belong to the same recent transmission chain. The molecular epidemiology can be used to find out which population groups need more control and this information must be used in tuberculosis prevention programs.