RESUMO
Bacterial resistance to antibiotics is often plasmid-mediated and the associated resistance genes encoded by transposable elements. Mycobacteria, including the human pathogens Mycobacterium tuberculosis and M. leprae, are resistant to many antibiotics, and their cell-surface structure is believed to be largely responsible for the wide range of resistance phenotypes. Antibiotic-resistance plasmids have so far not been implicated in resistance of mycobacteria to antibiotics. Nevertheless, antibiotic-modifying activities such as aminoglycoside acetyltransferases and phosphotransferases have been detected in fast-growing species. beta-lactamases have also been found in most fast- and slow-growing mycobacteria. To date no mycobacterial antibiotic-resistance genes have been isolated and characterized. We now report the isolation, cloning and sequencing of a genetic region responsible for resistance to sulphonamides in M. fortuitum. This region also contains an open reading frame homologous to one present in Tn1696 (member of the Tn21 family) which encodes a site-specific integrase. The mycobacterial resistance element is flanked by repeated sequences of 880 base pairs similar to the insertion elements of the IS6 family found in Gram+ and Gram- bacteria. The insertion element is shown to transpose to different sites in the chromosome of a related fast-growing species, M. smegmatis. The characterization of this element should permit transposon mutagenesis in the analysis of mycobacterial virulence and related problems.
Assuntos
Mycobacterium/genética , Fatores R/genética , Sulfonamidas , Sequência de Aminoácidos , Sequência de Bases , Clonagem Molecular , Códon , Elementos de DNA Transponíveis/genética , Escherichia coli/genética , Dados de Sequência Molecular , Hibridização de Ácido Nucleico , Homologia de Sequência do Ácido Nucleico , Transformação GenéticaAssuntos
Antibacterianos/farmacologia , Mycobacterium avium/genética , Mycobacterium/genética , Micobactérias não Tuberculosas/genética , Fatores R , Animais , DNA Bacteriano/análise , Resistência Microbiana a Medicamentos , Humanos , Canamicina/farmacologia , Mycobacterium/efeitos dos fármacos , Mycobacterium avium/efeitos dos fármacos , Mycobacterium leprae/efeitos dos fármacos , Mycobacterium leprae/genética , Mycobacterium lepraemurium/efeitos dos fármacos , Mycobacterium lepraemurium/genética , Micobactérias não Tuberculosas/efeitos dos fármacos , Rifampina/farmacologia , Estreptomicina/farmacologiaRESUMO
The author did researchs of acid-fast bacillus in 19 human exhumed corpses of with of lepers and founds always great quantity of acid-fast bacterias with a polimorphism entirely identic to the Hansen and Koch's bacteria: short bacterias, long, grained, more or less great agglomerated, fuchsinophilic or cyanomingle forms. He does to lesp again the fact of these bacterias to agglomerate themselves in great groups like the constituted by the leprosy's bacteria. The corpses had of 1 to 4 1/2 years of inhumation; the material for examinationwas drawed of the bones and colored by the Ziehl-Neelssen. He does not know to say if the corps leper's bacterias were Hansen's bacillus or purely corpses acid fast, why they confused himselves easily with the bacillus of other corpses. At last he has exhumed 2 dogs corpses whose matarials heve presented the same bacterioscopic squares. His study does porsue for tentatives of culture and inoculations, what, he is effecting. He remember the MANALANG, WLADIMIROFF and WALTER'S theories on the saprophytism of the Mycobacterium leprae, and he askes if this don't should himself develop in that place where products derived of the action of other bacterias on the living and dead tissues existed.