Survival and growth of Ajellomyces (Blastomyces) dermatitidis on oak leaves coated with saliva.

Yeast-form cells of Ajellomyces dermatitidis transferred to unsterilized and sterilized oak leaves in a humidity chamber failed to grow and produce mycelium. Transfers of these cells to Mycobiotic agar resulted in the growth of A. dermatitidis from all 5 autoclaved and 4 of the 11 unsterilized leaves. Soaking oak leaves with human airways secretions or saliva and inoculating them with yeast-form cells, and pouring sterile H2O on the leaves 10 days to 2 months later, permitted growth on 11 out of 36 leaves. It was concluded that these two natural substances, airways secretions and saliva, inhibited bacteria and furnished nutriment to A. dermatitidis.

Epidemiological studies on blastomycosis in the state of Wisconsin.

A study was made of 73 Wisconsin cases of canine blastomycosis. Each case was studied with respect to the life history of the animal. It was considered that a large percentage of the dogs were infected while in Wisconsin, since 40 had never left the state, and it was highly probable that in a large percentage of the other 33 cases the disease was contracted while the dog resided in Wisconsin. A study of the cases with respect to county of residence, birth and visitation revealed that there were three regions in the state where blastomycosis was prevalent: one region in the southeast and two regions in the northern parts of the state. An increase in the number of canine cases of blastomycosis over the years was considered to result from an increase in the skill of the veterinarian in diagnosing the disease. It was thought that a similar increase in number of human cases reported in recent years resulted from improvements in isolation techniques. The number of canine cases, 75, and human cases, 182, published up to now were considered to be minimum figures since many cases remain unpublished. A study of contiguous human and canine cases of blastomycosis lent support to the hypothesis that Ajellomyces (Blastomyces) dermatitidis conidia may be disseminated in fog or mist. Two cases of feline blastomycosis diagnosed in Wisconsin are reported for the first time. One cat acquired the disease in the state: the origin of the infection of the second cat was equivocal since it spent its summers in Wisconsin and its winters in another endemic state.

Dual infection by "+" and "-" mating types of Ajellomyces (Blastomyces) dermatitidis.

A culture of Blastomyces dermatitidis isolated via bronchial washing from a patient with blastomycosis was studied intensively. The primary isolate was shown to have contained both the "+" and "-" mating type determiners of Ajellomyces dermatitidis. This was evidenced by the observations that both a first and a second subculture, when paired with itself produced fertile ascocarps typical of A. dermatitidis. Both these subcultures determined the production of ascospores when paired individually with each of six testers, these testers not producing fertile fruiting bodies when selfed. Isolation by micromanipulation of "+" and "-" ascospores from ascocarps produced by selfing a subculture established the mixed ("+", "-") nature of the clinical isolate and of the infection. The mixed infection was considered to have resulted from inhalation of both the "+" and "-" ascospores or conidia of A. dermatitidis or from the inhalation of one spore that contained both the "+" and "-" mating type determiners.

Preliminary studies on conidial liberation of Blastomyces dermatitidis and Histoplasma capsulatum.

Controlled attempts to release viable conidia from cultures of Blastomyces dermatitidis and Histoplasma capsulatum with air samplers were unsuccessful. Air velocity was not fount to be a limiting factor since the conidia remained attached after conidiophores had been violently shaken by air currents in an observation chamber. Wetting these same conidiophores readily released the conidia. It is inferred that in nature conidia may be liberated by exposure to water and then dispersed by air currents.

Blastomyces dermatitidis: production of the sexual stage.

Growth of five combinations of strains of Blastomyces dermatitidis in paired cultures on yeast-extract agar, plus bone meal, yielded the perfect stage for the first time. These cleistothecia, apparently of a new genus, produced eight spored asci. Monoascospore cultures developed hyphae and conidia typical of B. dermatitidis. Mice were successfully infected with inocula from a monoascospore culture.