Estimation of Absidia ramosa infection in the brain and kidneys of cortisone-treated mice by chitin assay

Effect of immunosuppression on the clinicopathological changes in experimental zygomycosis in rabbits

A study was undertaken to investigate the effect of immunosuppression by cyclophosphamide or methylprednisolone on the clinicopathological alterations in respiratory absidiosis in rabbits. Infected rabbits showed respiratory distress that was more severe in immunosuppressed groups. Leukocytosis due to neutrophilia was observed in the non-immunosuppressed group in the initial stages, whereas leukopenia was observed in both the immunosuppressed groups initially, owing to polymorphopenia in the cyclophosphamide-treated group and to lymphopenia in the methylprednisolone-treated group, followed by leukocytosis in both groups. Total serum proteins increased significantly in the non-immunosuppressed group but were significantly decreased in the immunosuppressed groups. Serum creatinine increased significantly in all the infected groups from 20 days post inoculation (DPI) onwards. Blood urea nitrogen increased significantly in the initial stages only in the methylprednisolone-treated group. AST and ALT also showed significant increases in the infected animals. Total serum immunoglobulins and circulating immune complexes increased gradually in all three infected groups, except for an initial significant drop in the immunosuppressed rabbits. Re-isolation of fungus was only achieved from the lungs of infected rabbits up to 15 DPI in the non-immunosuppressed group and 30 DPI in the immunosuppressed groups. Pathological lesions in all the infected groups were found mainly in the lungs and consisted of pyogranulomas. The lesions were most severe in the cyclophosphamide-treated group and least severe in the non-immunosuppressed group.

Experimental Absidia corymbifera infection in rabbits: clinicopathological studies

Absidiosis was produced experimentally in rabbits by intravenous inoculation of 1.4 x 10(5) spores of Absidia corymbifera. Infected rabbits exhibited a rise in body temperature, anorexia, dullness, listlessness, diarrhoea, occasional blindness, convulsions and death in some cases. Mortality occurred mainly between 6 to 9 days post infection (DPI) and overall mortality was 50 per cent during the three week observation period. No significant difference was observed in erythrocytic indices viz., Hb, PCV, TEC in control and infected rabbits. However, erythrocyte sedimentation rate was considerably increased in the infected rabbits. A state of leucocytosis was observed in the infected rabbits, which was due to increase in the relative percentage of neutrophils and decrease in lymphocytes. There was a significant increase in blood urea nitrogen concentrations of infected rabbits from 3 to 14 DPI as compared to controls, but serum creatinine values were not significantly altered at any stage of infection. The cause of death was attributed to kidney failure and uraemia in infected rabbits. The rabbit was found to be a suitable model for the study of absidiosis.

Comparison of the growth of virulent and attenuated strains of Candida albicans in the kidneys of normal and cortison-treated mice by chitin assay

Candida albicans strain 22114 was avirulent for mice compared with strain 19321 in that, administered intravenously, 10(6) blastospores of 22114 failed to kill whereas 10(6) blastospores of 19321 produced 100% mortality. Cortisone treatment rendered mice susceptible to killing by 22114. Chitin assay showed that cortisone stimulated the growth of both strains in the mouse kidney. Growth of 19321 was increased up to five-fold and 22114 up to forty-fold. The strains may have differential susceptibility to cortisone-sensitive host defences which control fungal growth in vivo.