Pathoanatomical Pattern of Brain Damage of White Mice Infected with Experimental Anthrax

Background. Bacillus anthracis is a microorganism that causes anthrax. Because of irrational therapy, this particularly dangerous infectious disease leads to a systemic spread of bacteria in the body through histohematological barriers. Bacilli entering the brain subsequently lead to hemorrhagic meningitis. Despite intensive antibiotic therapy, that kind of meningitis is difficult to cure and therefore highly lethal. Studying characteristics of anthrax’s isolates of different origin and genotype is an actual area of research.

The aim of the study is searching for pathomorphological and histological changes in the brain regions of experimental animals with anthrax infection, caused by B. anthracis with different plasmid spectrum.

Materials and methods: The study was conducted on 200 certified white mice, three B. anthracis strains were used as research objects: B. anthracis I-323 (рХО1^– /рХО2^– ), B. anthracis I-275 (рХО1^- /рХО2^- ), and B. anthracis I-217 (рХО1⁺ / рХО2^– ). The material for histological examination was the brain of mice, embedded in paraffin, and then sections were prepared using a microtome and stained with hematoxylin-eosin and Nissl toluidine blue. The degree of neuronal damage was assessed by calculating the semi-quantitative factor and determining the average size of the neuron nuclei, and the numerical density of cells in 1mm² was studied. Microphotography and quantitative analysis was performed using the Motic Images Plus 2.0 application package. Statistical processing of the results was performed using the program “Statistica 6.0”.

The results of the study showed that the brain of infected mice shows signs of hemorrhagic leptomeningitis, the manifestations of which are more pronounced in mice infected with weakly virulent plasmid strains of B. anthracis and fallen mice.

Conclusion. Multicomponent exotoxin and specialized proteins, encoded in the pathogenicity plasmid of microorganisms, allow B. anthracis to easily overcome histohematological barriers and cause severe septic anthrax. The results obtained during the study supplement the available information on the pathogenesis of anthrax and indicate the need for further research in this direction.

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