Global expansion of Mycobacterium tuberculosis lineage 4 shaped by colonial migration and local adaptation

On the basis of population genomic and phylogeographic analyses of 1669 Mycobacterium tuberculosis lineage 4 (L4) genomes, we find that dispersal of L4 has been completely dominated by historical migrations out of Europe. We demonstrate an intimate temporal relationship between European colonial expansion into Africa and the Americas and the spread of L4 tuberculosis (TB). Markedly, in the age of antibiotics, mutations conferring antimicrobial resistance overwhelmingly emerged locally (at the level of nations), with minimal cross-border transmission of resistance. The latter finding was found to reflect the relatively recent emergence of these mutations, as a similar degree of local restriction was observed for susceptible variants emerging on comparable time scales. The restricted international transmission of drug-resistant TB suggests that containment efforts at the level of individual countries could be successful.

Effectiveness and safety of clofazimine in multidrug-resistant tuberculosis: a nationwide report from Brazil

Although clofazimine is used to treat multidrug-resistant tuberculosis (MDR-TB), there is scant information on its effectiveness and safety. The aim of this retrospective, observational study was to evaluate these factors as well as the tolerability of clofazimine in populations in Brazil, where it was administered at a daily dose of 100 mg·day−1 (body weight ≥45 kg) as part of a standardised MDR-TB treatment regimen until 2006 (thereafter pyrazinamide was used).

All MDR-TB patients included in the Sistema de Informação de Tratamentos Especiais da Tuberculose (SITETB) individual electronic register were analysed. The effectiveness of clofazimine was assessed by comparing the treatment outcomes of patients undergoing clofazimine-containing regimens against those undergoing clofazimine-free regimens and its safety by describing clofazimine-attributed adverse events. A total of 1446 patients were treated with clofazimine-containing regimens and 1096 with pyrazinamide-containing regimens.

Although success rates were similar in patients treated with clofazimine versus those treated with pyrazinamide (880 out of 1446, 60.9%, versus 708 out of 1096, 64.6%; p=0.054), clofazimine-treated cases exhibited higher death rates due to tuberculosis than pyrazinamide-treated ones (314 out of 1446, 21.7%, versus 120 out of 1096, 10.9%) but fewer failures (78 out of 1446, 5.4%, versus 95 out of 1096, 8.7%) and less loss to follow-up (144 out of 1446, 10.0%, versus 151 out of 1096, 13.8%). No relevant differences were detected when comparing adverse events in patients treated with clofazimine-containing regimens to those treated with clofazimine-free regimens. However, the incidence of side-effects was less than previously reported (gastro-intestinal complaints: 10.5%; hyper-pigmentation: 50.2%; neurological disturbances: 9–13%).

IS1245 genotypic analysis of Mycobacterium avium isolates from patients in Brazil

OBJECTIVE

Disseminated Mycobacterium avium infection is an emerging opportunistic disease among patients with acquired immunodeficiency syndrome (AIDS) in Brazil. The mode of transmission of M. avium in a developing country setting needs to be better characterized.

METHODS

Mycobacterium avium strain collections in São Paulo and Rio de Janeiro were analyzed according to the strains' IS1245 DNA gel electrophoretic migration patterns. Medical records of the patients from whom M. avium isolates were available were reviewed, and their demographic characteristics were stratified according to the isolates' IS1245 DNA fingerprint patterns.

RESULTS

Of 105 patients, 33 (31%) with M. avium isolated between 1990 and 1994 had strains having IS1245 patterns identical in patterns seen in isolates from two or more patients (designated as cluster pattern strains). Cluster pattern strains were isolated from 21 (39%) of 54 patients with disseminated infection (defined as infection due to M. avium isolated from a sterile site in an adult patient). Six of the cluster pattern strains were isolated only from sterile sites. In São Paulo, cluster pattern strains were significantly more likely to be isolated from patients with disseminated disease.

CONCLUSIONS

These preliminary observations suggest that in large cities of Brazil, a high proportion (at least 39%) of disseminated M. avium infections in patients with AIDS results from a recent transmission. Some strains of M. avium may be more likely to cause disseminated disease than others after an infection.

Drug resistance patterns among hospitalized tuberculous patients in Rio de Janeiro, Brazil, 1993-1994

The purpose of this study was to analyze the prevalence and risk factors for drug resistance among hospitalized patients in two tertiary care centers, an acquired immunodeficiency syndrome (AIDS) reference center and a sanatorium, in Rio de Janeiro, Brazil. From 1993-1994, 389 patients were diagnosed as having tuberculosis (TB). Isolates from 265 patients were tested for in vitro susceptibility to rifampin and isoniazid. Resistance to one or more drugs was detected in 44 patients (16.6%) and was significantly more common among recurrent cases in both hospitals (p=0.03 in the AIDS center and p=0.001 in the sanatorium). Twenty seven patients (10.2%) had isolates resistant to both isoniazid and rifampin. Multi-drug resistance was associated with human immunodeficiency virus (HIV) infection among patients who had never been treated for TB. In conclusion, drug-resistant TB is high in hospitalized patients in Rio de Janeiro, especially among HIV infected patients. Therefore, measures to control TB and prevent nosocomial transmission need urgently to be set up in the Brazilian hospitals.