JOURNAL OF CLINICAL MICROBIOLOGY, Jan. 2009, p. 198–204 0095-1137/09/$08.00⫹0 doi:10.1128/JCM.00507-08 Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Vol. 47, No. 1

Factors Associated with Differences between Conventional Contact Tracing and Molecular Epidemiology in Study of Tuberculosis Transmission and Analysis in the City of Barcelona, Spain䌤 ` ngels Orcau,3 Griselda Tudo So `nia Borrell,1 Montserrat Espan ˜ol,2 A ´,1 Francesca March,2 Joan A. Cayla`,3 3 4 Josep Maria Jansa`, Fernando Alcaide, Nu ´ria Martín-Casabona,5 Margarita Salvado ´,6 7 8 9 10 Jose´ Antonio Martı´nez, Rafael Vidal, Francesca Sa´nchez, Neus Altet, Pere Coll,11 and Julia`n Gonza´lez-Martín1* Servei de Microbiologia, CDB, H. Clínic de Barcelona-IDIBAPS, Universitat de Barcelona,1 Servei de Microbiologia, H. U. Sant Pau (HSCSP),2 Servei d’Epidemiologia, Age`ncia de Salut Pu ´blica de Barcelona,3 Servei de Microbiologia, H. U. Bellvitge-IDIBELL, L’Hospitalet de Llobregat,4 Servei de Microbiologia, Hospital Universitari Vall d’Hebron, Universitat Auto `noma de Barcelona,5 Laboratori de 6 Refere`ncia de Catalunya, El Prat de Llobregat, Servei de Malalties Infeccioses, ICMID, Hospital Clínic-IDIBAPS,7 Servei de Pneumologia, Hospital Universitari Vall d’Hebron,8 Servei de Malalties Infeccioses, Hospital del Mar,9 Unitat de Prevencio ´i Control de la Tuberculosi,10 and Servei de Microbiologia, Hospital de la Santa Creu i Sant Pau, Departament de Gene`tica i Microbiologia, Universitat Auto `noma de Barcelona,11 Barcelona, Spain Received 14 March 2008/Returned for modification 6 July 2008/Accepted 11 November 2008

The aim of this study was to analyze the factors associated with conventional contact tracing (CCT) and molecular epidemiology (ME) methods in assessing tuberculosis (TB) transmission, comparing the populations studied and the epidemiological links established by both methods. Data were obtained from TB case and CCT registries, and ME was performed using IS6110-based restriction fragment length polymorphism (RFLP) analysis and mycobacterial interspersed repetitive unit 12 (MIRU12) typing as a secondary typing method. During two years (2003 and 2004), 892 cases of TB were reported, of which 687 (77%) were confirmed by culture. RFLP analysis was performed with 463 (67.4%) of the 687 isolated strains, and MIRU12 types in 75 strains were evaluated; 280 strains (60.5%) had a unique RFLP pattern, and 183 (39.5%) shared patterns, grouping into 65 clusters. CCT of 613 (68.7%) of 892 cases detected 44 clusters involving 101 patients. The results of both CCT and ME methods yielded 96 clusters involving 255 patients. The household link was the one most frequently identified by CCT (corresponding to 80.7% of the cases clustered by this method), whereas nonhousehold and unknown links were associated with 94.1% of the strains clustered by ME. When both methods were used in 351 cases (39.3%), they showed the same results in 214 cases (61%). Of the remainder, 106 (30.2%) were clustered only by ME, 19 (5.5%) were clustered only by CCT, and 12 (3.4%) were clustered by both methods but into different clusters. Patients with factors potentially associated with social problems were less frequently studied by CCT (P ⴝ 0.002), whereas patients of