Control of Mycobacterium fortuitum and Mycobacterium intracellulare infections with respect to distinct granuloma formations in livers of BALB/c mice

• Published in: Memórias do Instituto Oswaldo Cruz Vol. 105; no. 5
• Main Authors: da Silva, Tânia Regina Marques, de Oliveira Almeida Petersen, Antonio Luis, de Araújo Santos, Theo, de Almeida, Taís Fontoura, de Freitas, Luiz Antônio Rodrigues, Veras, Patrícia Sampaio Tavares
• Format: Journal Article
• Language: English
• Published: Fundação Oswaldo Cruz, Fiocruz 03-01-2011
• Subjects: Mycobacterium fortuitum - Mycobacterium intracellulare - granuloma - liver - control of infection
• ISSN: 1678-8060

Mycobacterium fortuitum is a rapidly growing nontuberculous
Mycobacterium that can cause a range of diseases in humans.
Complications from M. fortuitum infection have been associated with
numerous surgical procedures. A protective immune response against
pathogenic mycobacterial infections is dependent on the granuloma
formation. Within the granuloma, the macrophage effector response can
inhibit bacterial replication and mediate the intracellular killing of
bacteria. The granulomatous responses of BALB/c mice to rapidly and
slowly growing mycobacteria were assessed in vivo and the bacterial
loads in spleens and livers from M. fortuitum and Mycobacterium
intracellulare -infected mice, as well as the number and size of
granulomas in liver sections, were quantified. Bacterial loads were
found to be approximately two times lower in M. fortuitum -infected
mice than in M. intracellulare-infected mice and M. fortuitum -infected
mice presented fewer granulomas compared to M. intracellulare-infected
mice. These granulomas were characterized by the presence of Mac-1+ and
CD4+ cells. Additionally, IFN-γmRNA expression was higher in the
livers of M. fortuitum -infected mice than in those of M.
intracellulare-infected mice. These data clearly show that mice are
more capable of controlling an infection with M. fortuitum than M.
intracellulare. This capacity is likely related to distinct granuloma
formations in mice infected with M. fortuitum but not with M.
intracellulare.