INFECTION OF MICE WITH SINGLE SPORES OF HISTOPLASMA CAPSULATUM

Abstract

Mice are extremely susceptible to infection with the spores of H. capsulatum. Following insertion of single spores into the peritoneal cavity of mice, the fungus was recovered in a high percentage of tubes inoculated with liver, spleen, and adrenal glands. The rate of recovery was correlated directly with the length of time between inoculation and sacrifice and with inoculum size. With larger inocula, recovery was progressively greater in the shorter time intervals, but all approached 100% at the end of 8 weeks. The use of gastric mucin did not permit earlier recovery of the organism, and at the shorter time intervals, it lowered the isolation rates. Ground tissues for use in inoculation media tubes did not prove superior to unground inocula. Liver, spleen, and adrenals were equally effective in the isolation of H. capsulatum. The exptl. data would indicate the advisability of holding mice injected with soil suspensions four to eight weeks before sacrificing them and culturing their organs. With this schedule, chances for recovery of H. capsulatum from soil supernatants containing few spores would, in all probability, be greatly improved.