Evaluation influence of the treatment directly observed (DOT) with and without Prophylaxis in the transmission of the tuberculosis in medical centers of health of the city of Rio De Janeiro, using tuberculosis techniques of molecular typing in cepas of M. tuberculosis

by Foschiani Dias, Ida Maria

Abstract (Summary)
Tuberculosis (TB) is a major cause of morbidity and mortality worldwide, particularly in developing countries. In the city of Rio de Janeiro, 7,000 new TB cases are reported annually, for an incidence de 105 per 100,000 inhabitants. In three Community Health Centers (CHCs) of Planning Area 1 (AP-1.0) of Rio de Janeiro, the section of the city with the highest case rate of TB, an evaluation of the influence of directly observed treatment (DOT) without or with (DOT-A) prophylaxis of risk contacts was performed; contacts of the latter group were also actively evaluated for active or latent TB. For this purpose, four communities received the DOT regimen while other four communities received DOT-A. A prospective community-based study was performed during the period 2001 to 2004 and we received strains of 353 patients, equally distributed among the neighborhoods with the two DOT schemes. Bacteriological, clinical and epidemiological data were collected and Mycobacterium tuberculosis genotypes defined through MIRU-VNTR (mycobacterial interspersed repetitive units - variable number tandem repeats) typing, spoligotyping and IS6110 restriction fragment length polymorphism (IS6110-RFLP). Also, the use of the left-hand side probe and a right-hand side probe of the PvuII site in the IS6110 was evaluated. All samples were typed by both PCR typing methods while a large fraction of the 2001 samples was submitted to IS6110-RFLP. Clustering results between the three methods were compared and cluster rates were, respectively, 20%, 29% and 72 % for IS6110-RFLP, MIRU-VNTR typing and spoligotyping. The combination of MIRU-VNTR and spoligotyping techniques for the definition of genotypes reduced the number of clusters to 7.8% and initial data were obtained suggesting that clusters formed by IS6110-RFLP are respected by MIRU-VNTR. However, IS6110-RFLP typing should be performed of all isolates to have a more solid comparison of this technique with MIRU-VNTR and spoligotyping. The biggest cluster obtained with MIRU-VNTR was only observed in 2001 and could suggest a local temporary outbreak. Risk factor determination for TB was evaluated through association of cluster formation of isolates with recent transmission of TB between patients. This was performed for the three typing methods and for the combined MIRU-VNTR and spoligotyping procedure. The only risk factor that was consistently related with recent transmission was being infected with a resistant or multi-drug resistant strain. No difference in clustering rates was observed between the two DOT procedures suggesting either the absence of association between clustering of genotypes and recent transmission of TB or the lack of influence of the additional procedures inherent to DOT-A in relation to DOT on TB transmission in the investigated population. Additional approaches of data analysis should however be performed and are underway.
This document abstract is also available in Portuguese.
Bibliographical Information:

Advisor:Philip Noel Suffys

School:Faculdades Oswaldo Cruz

School Location:Brazil

Source Type:Master's Thesis

Keywords:Mycobacterium tuberculosis Tuberculosis Bacterial Typing Techniques


Date of Publication:06/06/2006

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