Resumo

INTRODUCTION: The genotyping methods, spoligotyping and 24-loci Mycobacterial Interspersed Repetitive Units – Variable Number of Tamdem Repeats (MIRU-VNTR), combined with classical epidemiological investigations, has been suggested to constitute the new gold-standard for optimal TB surveillance at national, regional, and global levels by ‘‘universal genotyping’’ of patient isolates. OBJECTIVE: To use spoligotyping and MIRU-VNTR to confirm preliminaries information about the epidemiology of patients with family relationship and to understand the chain transmission of TB isolated from patients in the State of Pará, North of Brazil, in the period of 1998 and 2010. MATERIALS AND METHODS: The extraction of DNA was developed by purification and precipitation. Spoligotyping was performed by hybridization of the PCR product to the spoligo-membrane and the spoligotypes were reported using binary code. MIRU-VNTRs were performed by amplification of 24 loci. Genotype clustering was defined as having identical spoligo and miru-types. RESULTS AND DISCUSSION: We genotyped 63 isolates that belonged to 26 family groups (FG) and observed 16 strains with unique profiles and 17 clusters that belonged to 47 isolates demostrating a high clustering level in this population. Among the 26 FG, 18 (including 47 cases) demonstrated intra-family TB transmission (family contacts) because of identical spoligotypes and MIRU-VNTR profiles. Among six FG (11 cases), spoligotyping profiles were identical but MIRU-VNTR profiles were different in at least one locus. Two FG (five cases) showed different spoligo- and miru-types and one of these (wife and husband) showed a mixed infection. CONCLUSION: Genotype analysis confirm direct transmission of TB as defined by classical epidemioglogical investigation in 20 FG while in some six FG additional information is needed to understand the transmission. We also added to the definition of stringency needed for MIRU cluster definition in this population. We conclude that there is a high rate of TB transmission in the State of Pará and that this happens in a high frequency among household contacts. Strain typing may therefore help to interrupt the chain of transmission within and outside the home communities, as aid in the recognition of the principal clades responsible for spreading the disease.