RESUMO
Mycobacterium avium complex (MAC) is ubiquitous throughout the world. It is an opportunistic pathogen in AIDS patients but the number of cases in HIV negative patients is also increasing. The aim of this study was to determine whether patients were being infected with different MAC strains or whether one strain was dominant. DNA obtained from isolates in Brazil and England were compared using pulsed field gel electrophoresis (PFGE). Strains from 22 Brazilian patients clustered into 7 groups but 68/90 patients had a unique strain. In all patients, Brazilian and English, the same strain was isolated repeatedly over time, some over several years. This study shows that it is most likely that Man is infected from the environment and that one strain can survive without change for many years both in the environment and in Man.
Assuntos
Infecções Oportunistas Relacionadas com a AIDS/epidemiologia , DNA Bacteriano/química , Complexo Mycobacterium avium/classificação , Infecção por Mycobacterium avium-intracellulare/epidemiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Brasil/epidemiologia , DNA Bacteriano/metabolismo , Eletroforese em Gel de Campo Pulsado , Inglaterra/epidemiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Complexo Mycobacterium avium/genética , Complexo Mycobacterium avium/isolamento & purificaçãoRESUMO
SETTING: The incidence of Mycobacterioses is increasing annually, especially in patients with AIDS. There is no clear correlation between in vitro drug susceptibility testing of mycobacteria other than the tubercle (MOTT) bacilli and the in vivo response. Although in vitro, MOTT bacilli appear resistant, some patients respond to treatment possibly as a result of a synergistic action between the drugs being used. OBJECTIVE: To produce a simple method to determine which individual drugs or combinations of drugs will be effective in killing the causative organism. DESIGN: A broth microdilution method, using microtitre plates, was used to determine the minimum inhibitory concentration (MIC) of the drugs alone and then in combination. RESULTS: It was found that the MIC values of the test drugs varied between but were constant within each of the species. Mycobacterium xenopi, M. malmoense and M. kansasii showed a large amount of susceptibility while M. avium complex, M. fortuitum and M. chelonae were limited in their response. These results were reproducible. The test was also easy to perform. The drug combination studies showed that each strain of the M. avium complex tested exhibited synergy between different combinations of drugs. CONCLUSION: This method, therefore, can be used to indicate individual or combinations of drugs that will or will not act upon the Mycobacterium species isolated. The method was also very rapid, giving a result within 7 days.