RESUMO
SETTING: The epidemiology of tuberculosis (TB) in urban populations is changing. Combining conventional epidemiological techniques with DNA fingerprinting of Mycobacterium tuberculosis can improve our understanding of how TB is transmitted. OBJECTIVE: To improve the definition of molecular epidemiology of TB over 10 years in an area of Europe not previously studied. DESIGN: A population-based retrospective study was conducted in the Autonomous Community of Madrid, Spain, from 1992 to 1998; from 1999 to 2001, the study was prospective. The study population consisted of all patients for whom positive culture and full clinical and demographic data were available. All strains were typed by RFLP. Non-clustered patients were compared with clustered patients and studied using univariate analysis and a logistic regression model. RESULTS: Of 448 patients studied, 228 (50.7%) were clustered. Youth was the strongest risk factor associated with clustering. Pleural effusion was also found to be associated with clustering. An epidemiological link was found in only 85 (37.4%) of the 228 patients belonging to a cluster. CONCLUSION: Youth and pleural effusion were identified as risk factors for clustering. These findings may help adjust TB control and contact tracing strategies.
