Recurrent tuberculosis from 1992 to 2004 in the metropolitan area of Madrid, Spain

¹ Servicio de Microbiología, Hospital Universitario de Getafe, Madrid
² Servicio de Salud Pública, Comunidad de Madrid, Madrid
³ Servicio de Neumología, Hospital Universitario de Getafe, Madrid
⁴ Mycobacteria Genetics Group of the University of Zaragoza

^* To whom correspondence should be addressed. E-mail: jcacho.hugf{at}salud.madrid.org.

	Abstract

The proportion of recurrent tuberculosis cases caused by reinfection has varied widely in previous study. Our aim was to determine the relative frequency of relapse and exogenous reinfection in patients with second episodes of tuberculosis, by means of DNA fingerprinting.

A population-based retrospective longitudinal descriptive study was conducted in Madrid from 1992 to 2004. The study consisted of 645 patients with culture-confirmed tuberculosis. Twenty (3.1%) patients were retained because they presented a second isolate of M. tuberculosis. Finally, twelve of these cases were excluded because they did not complete the full treatment prescribed. All strains were typed by restriction fragment length polymorphism (RFLP) and some of them by mycobacterial interspersed repetitive units (MIRU-VNTR). The patients with recurrent tuberculosis were compared with patients without recurrent tuberculosis.

For seven of the eight patients, the RFLP patterns of the M. tuberculosis strains from the episode of recurrent disease had identical initial and final genotypes, indicating relapse, the remaining recurrente case showed different genotypes, suggesting exogenous reinfection.

Reinfection is possible among people in developed countries, but the rates are lower than those in high-risk areas. The risk factors of recurrent tuberculosis might be taken into account in following up of treatment and tuberculosis control strategies.

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