Dados do Trabalho

Título

High susceptibility of Mycobacterium africanum L6 to copper overload: understanding the bacterial response to nutritional immunity.

Introdução

Copper overload is a mechanism of nutritional immunity used by the host cell to kill bacteria of the Mycobacterium tuberculosis complex (MTBC). Recently, our laboratory identified that Mycobacterium africanum L6 presents a transcriptional profile of copper toxicity in vitro, most likely due to the deletion of the gene encoding MymT, a copper-metallothionein.

Objetivo (s)

To analyze the copper susceptibility of MTBC bacteria in the absence or presence of catalase using disk diffusion and plate assays.

Material e Métodos

 Two strains of Mycobacterium tuberculosis (H37Rv and a clinical isolate) and one strain each of M. africanum L5 (17458) and L6 (L12222) were tested for their susceptibility to different concentrations of copper sulfate using disk diffusion (400 mM to 2M) and plate assays (250 µM to 1 mM), with and without catalase.

Resultados e Conclusão

Our findings unveiled that the laboratory strain H37Rv has a pronounced sensitivity to copper compared to the other MTBC strains in both assays. The disk diffusion assay with catalase showed no difference in copper sensitivity among the remaining strains. In contrast, M. africanum L6 showed a higher susceptibility to copper when compared to L5 and the clinical isolate of M. tuberculosis when removing catalase from the plate assay. This sensitivity phenotype may be related to potential local Fenton-like reactions affecting the metabolism of M. africanum L6. These preliminary results suggest that exposure to copper can elicit different responses from ecotypes within the MTBC, which can have implications for virulence and drug tolerance.  

Palavras Chave

Mycobacterium africanum; copper; Tuberculosis; nutritional immunity.