[Experimental pathogenicity of isolates of Nocardia asteroides, Nocardia brasiliensis and Nocardia caviae from different sources]
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Abstract:
The experimental pathogenicity of 14 isolates of Nocardia brasiliensis, 15 of N. asteroides, and 5 of N. caviae was investigated for the white Swiss mice inoculated intraperitoneally and in the foot pad, and for the guinea-pig and the hamster (Mesocricetus auratus) both inoculated intratesticularly. The guinea-pig was remarkably sensitive to N. asteroides, with an apparent relationship between pathogenicity and thermotolerance, confirming previous observations. Mice were in general less susceptible to this species. In both guinea-pigs and hamsters it was possible to observe typical granules with or without clubs. N. caviae was highly pathogenic for the guinea-pig and the hamster but no mycetomas were produced in the mice inoculated in the foot pad. Isolates of N. brasiliensis from natural sources were scarcely virulent for the different animals. Those of human origin produced significant lesions in the mice inoculated intraperitoneally with granules. Foot pad inoculation of mice with N. brasiliensis caused mycetomas in several animals.
Insights
Nocardia species exhibit varied pathogenicity in animal models. Nocardia asteroides is highly virulent in guinea pigs, while Nocardia brasiliensis causes mycetomas in mice, highlighting species-specific host responses.
Area of Science:
- Microbiology
- Infectious Diseases
- Veterinary Pathology
Background:
- Nocardia species are aerobic actinomycetes known to cause opportunistic infections in humans and animals.
- Understanding the pathogenicity of different Nocardia species in various hosts is crucial for disease management and treatment strategies.
Purpose of the Study:
- To investigate the experimental pathogenicity of Nocardia brasiliensis, Nocardia asteroides, and Nocardia caviae in different animal models.
- To explore potential correlations between thermotolerance and pathogenicity in Nocardia asteroides infections.
- To characterize the formation of Nocardia granules in vivo.
Main Methods:
- Inoculation of white Swiss mice (intraperitoneal and foot pad) and guinea pigs and hamsters (intratesticular) with isolates of Nocardia brasiliensis, N. asteroides, and N. caviae.
- Observation and documentation of clinical signs, lesions, and granule formation.
Main Results:
- Nocardia asteroides demonstrated high pathogenicity in guinea pigs, with a correlation between pathogenicity and thermotolerance.
- Mice showed lower susceptibility to N. asteroides compared to guinea pigs.
- Nocardia caviae was highly pathogenic in guinea pigs and hamsters, but did not produce mycetomas in mice.
- Nocardia brasiliensis isolates from natural sources showed low virulence, while human-origin isolates caused significant lesions in mice, with foot pad inoculation leading to mycetoma formation.
Conclusions:
- Nocardia species exhibit distinct pathogenic profiles across different animal hosts.
- Guinea pigs are highly sensitive to Nocardia asteroides, suggesting a potential model for studying nocardiosis.
- Nocardia brasiliensis can induce mycetomas in mice, providing a model for studying this specific manifestation of nocardiosis.