The genus Prototheca is composed of microscopic achlorophyllous organisms has a life cycle similar to that of Chlorella and is widespread in nature. Prototheca species are considered adventitious pathogens. The genus is reviewed on the basis of life cycle, morphology and physiology. Colony morphology and physiological identification keys are given. All eleven known epithets published on Prototheca are listed and a literature review is provided.

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Arthrospores of Trichophyton mentagrophytes were inoculated onto the plantar part of a guinea pig foot by the wet disc inoculation method.
Anthropophilic strain NTM-105 and zoophilic strain SM-110 required 280 arthrospores (or 315 microconidia) and 80 arthrospores to infect 50% of the inoculated feet, respectively. After inoculation of 5×10³ arthrospores, all feet were infected, even 50 arthrospores were shown to be infective in some cases.
Some arthrospores of NTM-105 inoculated on plantar parts of guinea pig feet germinated in 6 hours and the hyphae invaded horny cells in 12 hours, but histological examination revealed no fungal elements in the horny layer of 24-hour feet. After 3 days, one-third of the horny layer was invaded by fungi and after 7 days this had increased to two-thirds.
Anthropophilic strain NTM-105 invaded only the upper two-thirds of the horny layer and induced no inflammatory response. On the other hand, zoophilic strain SM-110 invaded the whole horny layer and provoked strong inflammatory response and clinical manifestations.
Infecting fungi were demonstrated in the horny layer of all inoculated feet for more than 6 months.
The experimental infection indicated herein will be a useful model to analyse tinea pedis, because it is quite similar to human tinea pedis histologically, clinically and in terms of its chronicity. Precise experimental studies using this model may open the way to an elucidation of fungal infection mechanisms against host defense activities and an evaluation of antifungal treatments.

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We prepared two models of infection most similar to candidiasis in humans, with the main purpose of determining the significance of the indigenous bacterial flora in the development of infection.
1. Systemic candidiasis by Candida albicans colonizing in the gastrointestinal tract of mice.
C. albicans is seldom present in the gastrointestinal tract of rodents, and cannot colonize in specific pathogen-free mice after oral inoculation. It was revealed that its colonization in the murine gastrointestinal tract requires a disturbance of the anaerobic indigenous bacterial flora by antibacterial antibiotics, and that the presence of lactobacilli, which multiply in the nonglandular stomach in the same way as Candida, is especially significant for antagonization. In mice administered the broad-spectrum antibacterial agent; mezlocillin, C. albicans colonized well irrespective of its virulence, and in mice in which a highly virulent strain was established, it disseminated from the intestine to the other organs after the animals were treated with cortisone acetate, and fatal infection developed.
These systemic or local candidiasis models using invasive routes by which candidal infection can be caused in humans, rather than on artificial route such as intravenous or intraperitoneal inoculation, enabled colonization and multiplication in the experimental animal, as well as development of fatal infection. In addition, these animal models correspond well to the human pathologic condition in that the severity of infection increases as the degree of virulence of challenged organisms increases and host defense declines.
2. Colonization of C. albicans in the vagina of pregnant mice and transfer to suckling mice.
The number of bacteria in the vagina in late pregnancy decreases markedly. When human isolated C. albicans was inoculated into the vagina of such mice, it colonized well without the necessity of treatment with estrogen, remained fluent until delivery, and was transferred to suckling mice.

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The occurrence of pulmonary cryptococcosis in humans has been recognized by a large body of clinical and pathological evidence. Primary foci of a cryptococcal infection usually appear to be established in the lung and, cryptococci then often disseminate to the central nervous system. To learn the details of the pathogenesis of pulmonary cryptococcosis, histopathological studies were carried out with mice experimentally infected with Cryptococcus neoformans through an intranasal route. This route of inoculation was chosen because it is considered to be the most common route of a human cryptococcal infection. Two clinical isolates of Cr. neoformans with different virulence were chosen and several strains of inbred mice were employed to produce the experimental models of pulmonary cryptococcosis in which a respiratory infection was induced by an intranasal instillation of saline suspension of cryptococci.
When ICR mice were inoculated with yeast cells of a low-virulent, heavily encapsulated strain (TIMM 0372), nonfatal pulmonary cryptococcosis was established within one week postinfection. Histopathological studies with the infected mice revealed that numerous granulomatous lesions, containing la antigen-expressing histiocytes, developed in the lung. By contrast, in the ICR mice inoculated with yeast cells of a high-virulent, weakly encapsulated strain (TIMM 0362), fatal infection was established, involving not only the lung but also the brain and several other organs. The most prominent histopathological findings were characterized by both delay of the response of histiocytes against the invading organism in alveoli and nonsuppurative destruction of pulmonary tissue, as well as subsequent development of cerebral cystic lesions.
Histopathological studies of pulmonary cryptococcosis were also carried out using murine models produced in BALB/c, C3H/He, CBA/J, DBA/2 and C57BL/6 mice. The animal models were intranasally inoculated with both strains of Cr. neoformans to develop pulmonary lesions. In result, marked proliferation of yeast cells was recognized in the lung of animals infected with either strain of Cr. neoformans. In addition, there was a tendency for the groups of animals infected with a low-virulent strain (TIMM 0372) to show more evident response of alveolar macrophages against the invading organism despite the mouse strain.
The above results suggest that the variety of cryptococcal lesions produced in the lung stems from the host defense mechanism against invading cryptococci, which is determined by immunological competence of the host, on the one hand, and virulence of the infecting cryptococci, on the other. Occurrence of a histiocytic response to a certain strain of cryptococci seems to play the major role in inducing cryptococcal lesions of the lung.

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Spores of Absidia corymbifera were inoculated orally into sheep with ruminal acidosis produced by feeding on barley. Lesions, which developed in the forestomachs of all four inoculated cases, included desquamation of superficial layers of the mucosae and focal necrosis from the lamina propria to muscular layers. Granulomatous lesions were found in the submucosa of three sheep. Lesions in the abomasum (two sheep) included focal necrosis, diffuse hemorrhages, and infiltration of neutrophils. All lesions were accompanied by mycotic proliferation. These results show that A. corymbifera can invade forestomach mucosae through degenerated epithelium resulting from ruminal acidosis.

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The main target organ of Aspergillus fumigatus is the lung, and therefore, and it is natural that many medical mycologists have tried to make animal models of pulmonary aspergillosis. However, A. fumigatus also has a predilection for the brain. Even though the frequency of cerebral aspergillosis is approximately 6%, almost all patients die within a few months. The study of animal models of cerebral aspergillosis is thus very important for prevention and therapy of the disease.
In 1969, the authors isolated a strain of A. fumigatus which has a remarkable predilection for the mouse brain. Their successive studies revealed a few other strains of A. fumigatus also having a predilection for the mouse brain. This property is genetically stable and passed on to the new generation. When the strains possessing this property are inoculated on brain heart infusion agar medium supplemented with skim milk at a rate of 2%, their growth rates slow down and clear melting rings appear around their colonies. There is thus a definite relationship between the invasiveness of the mouse brain by A. fumigatus and its proteolytic activity.
It is important from the standpoint of preventive medicine to understand the percentage of such strains existing in nature. This time, the authors investigated 149 strains of A. fumigatus which consist of 26 strains stored at the Research Center, 83 isolated from soil in Japan and given to them by Dr. Y. Horie, and 40 isolated from soil in Colombia. All the strains were inoculated on brain heart infusion agar medium supplemented with skim milk and incubated at 37°C for 6 days. Clear melting rings appeared around the colonies of only two strains which had been isolated from patients with aspergillosis. When the conidia of the two strains were inoculated intravenously into mice, they affected the mouse brain remarkably within 4 days.

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Spleen cells from mice were shown to be capable of killing Cryptococcus neoformans cells in the absence of active complement. The number of viable C. neoformans cells did not vary significantly during the first 5hr of incubation period either in the presence or absence of spleen cells, but after 15hr incubation with spleen cells a considerable reduction in the number of viable yeast cells was observed. No significant difference related to age, sex or genetic background of mice in the killing activity of spleen cells was found. Cells with killing activity were plastic- and nylon wool-adherent. Treatment of spleen cells with carbonyl iron powder and magnet modestly reduced their activity. The activity of spleen cells was fairly diminished when they were treated with anti-mouse IgG antiserum plus complement. In contrast, anti-mouse IgM, anti-Thy 1, 2 and anti-asialo GM₁ antisera, each in the presence of complement, had no effect. These results appear to indicate that the majority, if not all, of the effector cells belong to B lymphocyte lineage. The results obtained in the present study suggest that effector cells of the natural killing activity play a role in primary host defense against C. neoformans infection.

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In order to elucidate whether Pityrosporum oribiculare (ovale), a lipophilic yeast-like fungus and one of the cutaneous flora, plays some etiologic role in neonatal seborrheic dermatitis or acne-like eruption, we examined periodically the prevalence and the parasitic morphology of the fungus on the facial skin surface of newborn infants. Experimental provocation was also examined. The results are were as follows.
1. Pityrosporum was found by direct examination in about 50% of 410 neonates within 24 hours after birth, in over 80% of those aged 5 to 7 days, and in more than 90% of 106 infants from 2 to 6 weeks of age. 2. Pityrosporum was cultured from 7 out of 224 newborn infants (3%) within 24 hours after birth. 3. Pityrosporum showing spores intermingled with hyphal fungus element was noted in 56% of 43 infants with apparent skin change. This was a significantly higher incidence (p<0.01) than the 22% of 63 infants without skin change. 4. Experimental provocation of skin change with filtrate of olive oil after culture was done in 32 neonates within 3 days after birth. Two showed a slightly inflammatory reaction and seven others showed a mild scale formation on the patch-test site. 5. It is inferred that Pityrosporum may play a somewhat etiologic role in the development of neonatal seborrheic dermatitis or acne-like eruption.

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A three-year-old girl and her sixty-two-year-old grandmother, living in Niigata Prefecture of Japan, had a black dot ringworm form of tinea capitis about one year ago. Recently a five-month-old boy, a cousin of the girl, also contracted tinea corporis. In the cultures of affected hairs and scales, violetcolored fungi grew on the Sabouraud's media, and subcultured colonies of these fungi showed a white suede-like surface. These fungi were identified to be Trichophyton tonsurans from the above mentioned and following characteristics: no hair perforation, positive urease test, no pigment production on the cornmeal and oatmeal agar and the ability to produce abundant microconidia, intercalary chlamydospores and rare macroconidia. These are the first reports of T. tonsurans infection observed in Niigata Prefecture. In addition, the grandmother and mother of the boy had previous histories of tinea corporis, and violet-colored fungi were isolated from the lesions at that time. Since further identification of these fungi was not performed, it is not clear whether they were T. tonsurans or not. T. tonsurans has been isolated almost exclusively in Kyushu Island and only a few cases of tinea capitis due to T. tonsurans have been reported in other areas of Japan. Although it was found that, a family originating from Kyushu Island had been living until about two years previously in the neighborhood of the girl in the present case, we were not able to clarify the invading course of the causative fungi of the current cases.

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A 67-year-old man was admitted to our hospital with complaints of cough, excessive sputum and dyspnea. Increased erythrocyte sedimentation rate and marked eosinophilia in peripheral blood (26%) were observed. Chest X-rays showed infiltrates in the lower paramediastinal field of the right lung. Tomograms showed central bronchiectasis in the infiltrated area.
Using Aspergillus fumigatus antigens, positive immediate and Arthus skin reactions and serum precipitins were demonstrated. Serum IgE (ETA) was elevated (50, 321IU/ml) and Aspergillus-specific IgE (BAST) antibody was positive. Sputum cultures revealed A. fumigatus.
These findings were consistent with a diagnosis of allergic bronchopulmonary aspergillosis (ABPA).
The patient probably had been suffering from ABPA for more than 22 years according to retrospective observations of his chest films.

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