E. S. McDonough

Isolation of Blastomyces dermatitidis from Soil

Through the intravenous inoculation of soil suspensions in the tail vein of mice, Blastomyces dermatitidis was recovered from a Lexington, Kentucky, soil sample. The positive specimen was collected in a tobacco-stripping barn. The shed had sheltered a dog that died of blastomycosis 2 years before the sample was collected.

Blastomycosis-epidemiology and biology of its etiologic agent Ajellomyces dermatitidis

From this review of previous publications and unpublished data it was concluded that there was little evidence that blastomycosis is contagious. Yet in spite of some reports thatB. dermatitidis has been isolated from soil no claim has been made that the ecologic niche in nature has been found. The logical assumption that soil is the natural habitat of the pathogen has been made less certain by demonstrations that this fungus, unlikeHistoplasma capsulatum, soon disappears from natural soils into which it is introduced. Furthermore,B. dermatitidis is lysed by microorganisms obtained from such soils. Therefore it was considered to be questionable how much epidemiologic significance is to be applied to chance contaminations of soil by animals with blastomycosis. Only one species ofAjellomyces dermatitidis, the heterothallic, perfect stage ofB. dermatitidis, may exist in the United States of America. Evidence for this was obtained through pairing cultures isolated in that country since ascospores were produced when an isolate from a dog was paired with an isolate from a person and fertile cleistothecia were produced by pairing isolates from widely distributed geographic regions. Individual pairings of 6 African isolates with testorB. dermatitidis strains from the U.S.A. resulted in each case in production of ascocarps. However, unquestioned ascospore production has not been obtained, although a few spherical cells having the dimensions of ascospores have been found in some cleistothecia. On this, and the other evidence so far obtained, it was concluded that the African isolates are closely related to the American isolates and could belong to the same species. Von dieser Übersicht vorheriger Veröffentlichungen und unveröffentlicher Angaben wird der Schluß gezogen, daß wenig Beweis vorhanden ist, daß Blastomykose ansteckend ist. Trotz mancher Berichte, daßB. dermatitidis vom Erdboden isoliert worden ist, ist kein Anspruch gemacht, daß das ekologische Habitat in der Natur gefunden worden ist. Die logische Annahme, daß der Erdboden das natürliche Habitat des Pathogens sei, wurde durch die Demonstration weniger sicher gemacht, daß dieser Pilz, ungleichH. capsulatum, nach Einführung in den natürlichen Erdboden bald verschwindet. Weiterhin wirdB. dermatitidis durch Mikroorganismen vom natürlichen Erdboden aufgelöst. Deshalb ist es fraglich, wieviel epidemiologische Bedeutung einer zufälligen Ansteckung des Erdbodens durch Tiere mit Blastomykose zukommt. Nur eine Art vonAjellomyces dermatitidis, die heterothallische, perfekte Phase vonB. dermatitidis, mag in den Vereinigten Staaten vorkommen. Beweise hierfür sind durch Paarung (Kreuzung) von Kulturen erhalten worden, die hier isoliert worden sind, da Askospores produziert wurden, wenn ein Isolate von einem Hund mit einem Isolate einer Person gekreuzt worden ist. Fertile Kleistothezia sind produziert worden durch Kreuzung von Isolaten von weit zerstreuten geographischen Gegenden. Individuelle Kreuzung von sechs afrikanischen Isolaten mit Testers vonB. dermatitidis von U.S.A. führte zur Produktion von Askokarpen. Jedoch ist eine unzweifelhafte Produktion von Askosporen nicht erhalten worden. obwohl einige spherische Zellen mit der Größe von Askosporen in einigen Kleistothezien gefunden worden sind. Auf Grund von bisher erhaltenen Beweisen ist beschlossen, daß die afrikanischen Isolaten nahe verwandt sind mit den Amerikanischen und wohl zu derselben Art gehören.

The discovery of Histoplasma capsulatum in Connecticut soil incidental to the investigation of a case of feline cryptococcosis.

The seventh case of cryptococcosis in a cat is described. The animal involved was a five-year-old Maltese short hair that had lived in Connecticut all of its life. An investigation was carried out to discover the point source of this feline infection. This search was unsuccessful but it did result in the isolation ofH. capsulatum for the first time from Connecticut soil. In addition, the preliminary findings of a study to evaluate the use of the fluorescent antibody technique for the rapid detection ofH. capsulatum in soil are reported. Round to oval forms measuring 1.5 to 3.5 microns in diameter were demonstrated in smears of the positive Connecticut soil that had been stained with fluorescein labeled anti-H. capsulatum globulins. The morphology of these elements was similar to that of the microconidia ofH. capsulatum. Through the use of this immune conjugate five additional positive soil samples from other areas were also shown to contain these forms. None of these six soils showed stained elements when treated with normal conjugates. The implications of these findings are discussed.

Epidemiology of 46 wisconsin cases of north american blastomycosis, 1960–1964

In an attempt to find the source of infection 45 Wisconsin North American blastomycosis patients or their immediate relatives were interviewed and the records studied. B. dermatitidis was considered to have been proved to be endemic in Wisconsin, since infection took place in several parts of the state, and a large proportion of the patients were shown to have been infected while living in the state. A study of the yearly occurrence of cases of blastomycosis in Wisconsin, 1960–1964, revealed an unequal distribution. A noticeably small number of cases occurred in 1963. Since this was the driest year in Milwaukee and many other parts of the state in 30 years, further work on a possible relationship between the disease and annual precipitation was suggested. The seasonal distributions of both onset and diagnosis were found to differ significantly from an even distribution among the seasons. The distributions were found to be compatible with the hypothesis that infection took place toward the end of the growing season. Evidence was presented that the American Indian in Wisconsin may have a racial susceptibility or an environmental relationship favoring infection byB. dermatitidis. When compared with other published series of blastomycosis cases, an unusually large number of women patients was found resulting in a 3.5 : 1 male to female ratio. The study failed to show an occupational connection with the disease.

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.