Histopathological and immunohistochemical characterization of Burkholderia pseudomallei lesions in an acute model of infection with BALB/c mice.

Organ tissue damage is a key contributor to host morbidity and mortality following infection with microbial agents. Severe immune responses, excessive cellular recruitment and necrosis of cells all play a role in disease pathology. Understanding the pathogenesis of disease can aid in identifying potential new therapeutic targets or simply act as a diagnostic tool. Burkholderia pseudomallei is a Gram-negative bacterium that can cause acute and chronic diseases. The BALB/c mouse has been shown to be highly susceptible to aerosol challenge with B. pseudomallei and hence acts as a good model to study the acute and potentially lethal form of the disease melioidosis. In our study, BALB/c mice were challenged and culled at predetermined time points to generate a pathological time course of infection. Lung, liver and spleen were subjected to pathological and immunohistochemical analysis. The number and type of microscopic lesions within each organ, as well as the location and the mean percentage of neutrophils, B cells, T cells and Burkholderia capsule antigen within the lesions, were all characterized during the time course. Neutrophils were determined as the key player in tissue pathology and generation of lesions, with B cells playing an insignificant role. This detailed pathological assessment increases our understanding of B. pseudomallei disease.