Typing of Mycobacterium tuberculosis strains isolated in Community Health Centers of Rio de Janeiro City, Brazil

Abstract

Fingerprinting of Mycobacterium tuberculosis strains from tuberculosis (TB) patients attended in Community Health Centers (CHCs) of Rio de Janeiro was performed to verify possible risk factors for TB transmission. A prospective community-based study was performed during the period of July 1996 to December 1996 by collecting sputum samples of 489 patients in 11 different CHCs in four different planning areas (APs) of the city. Bacteriological, clinical, and epidemiological information was collected and M. tuberculosis genotypes defined after restriction fragment length polymorphism (IS6110-RFLP) and double repetitive element (DRE) fingerprinting of RFLP-clustered cases. Risk factors for TB transmission were looked for using three levels of cluster stringency. Among 349 (71%) positive cultures obtained, IS6110-RFLP typing could be performed on strains from 153 different patients. When using identity of RFLP patterns as cluster definition, 49 (32%) of the strains belonged to a cluster and none of the clinical or epidemiologic characteristics was associated with higher clustering levels. However, higher clustering level was observed in the AP including the central region of the city when compared to others. This strongly suggests that more recent transmission occurs in that area and this may be related with higher incidence of TB and HIV in this region.Key words: tuberculosis -molecular epidemiology -IS6110-restriction fragment length polymorphism -double repetitive element It is generally accepted that one third of the world population is infected with Mycobacterium tuberculosis (Mtb), and the estimated mortality because of tuberculosis (TB) in 2004 was nearly 2 million, demonstrating that Mtb is among the most deadly human infectious agents. The majority (95%) of TB cases occur in developing countries, a scenario mainly responsible for negligence of the seriousness of the disease in richer countries. The latter however were obliged to reconsider the importance of the disease, due to the association between increased TB risk and HIV infection and the spreading of multi-drug resistant (MDR) strains all over the world (WHO 2006).In developed nations, epidemiologic investigations that incorporate genotyping of Mtb by restriction fragment length polymorphism (RFLP) have lead to novel information about the spread of Mtb in the community and during institutional outbreaks, to a better understanding of the transmission dynamics of TB and to the differentiation of (re)infection from reactivation (Barnes & Cave 2003, Seidler et al. 2004.Since the early nineties, definition of risk factors for TB transmission in high TB incidence areas has been complemented by information obtained by Mtb genotyping, the latter based on the recognition that clusters of fingerprints are a measure of recent transmission (Palittapongarnpim et al. 1997, Pineda-Garcia et al. 1997, Dale et al. 1999, Haas et al. 1999, Fandinho et al. 2000, Ferrazoli et al. 2000, Bruchfeld et al. 2002, Ferdinand et al. 2003, Easterbrook et al. 2004, Das et al. 2005. ...

Molecular diversity of Mycobacterium tuberculosis strains in a slum area of Rio de Janeiro, Brazil

“…Clustering has been associated with age, previous treatment and acid-fast bacilli (AFB)-positive smears, although epidemiological links have been difficult to establish. (10,13,14) In our study, being infected with a resistant strain and having an AFB-positive smear were not significantly associated with clustering. However, M. tuberculosis isolates were not available for all patients diagnosed in the period.…”

“…Nevertheless, our findings are in accordance with the proportions recently described for transmission in developing countries (20% to 38%), although epidemiological information linking clustered patients is usually unavailable. (9)(10)(11)(12) The presence of few strains presenting low copy numbers have been described in earlier studies conducted in Brazil as well in other countries. However, a study performed in India showed higher numbers.…”

“…However, a study performed in India showed higher numbers. (10,13) Tuberculosis (TB) remains a disease associated with overcrowding, poor nutrition and poor housing, occurring primarily in developing countries. Nevertheless, as long as there are individuals with active TB, Mycobacterium tuberculosis will prevail in the world, since, due to its airborne nature, the transmission of TB encounters few barriers inhibiting broad dissemination within the community.…”

Genotyping of Mycobacterium tuberculosis isolates from alow-endemic setting in northwestern state of Paraná in Southern Brazil

“…Particularly, there are few studies of this nature in Brazil (Borsuk et al 2005, Oelemann et al 2007b, Malaspina et al 2008, Malaghini et al 2009). To explore the molecular epidemiology of TB in northwestern PR, we chose to work with two effective and fast methodologies: spoligotyping and MIRU-VNTR typing (Malaghini et al 2009).…”

The Forest behind the Tree: Phylogenetic Exploration of a Dominant Mycobacterium tuberculosis Strain Lineage from a High Tuberculosis Burden Country

“…However, the applicability of this standardized system has so far not been tested in high TB-burden countries, except in a geographically restricted South African setting with extreme epidemiological conditions [17] or in certain Chinese regions with a specific M. tuberculosis Beijing strain population [18]. More specifically, only a few, limited molecular epidemiological studies have been performed in Brazil [19], [20], [21], [22], [23], [24].…”