Biomedical subjects
Publications and source records attributed to D L Greer.
A 32-year-old black woman presented in the emergency room with vaginal bleeding. Physical examination revealed a granulomatous lesion on the thigh and a breast abscess. Histopathologic examination and culture of an endometrial biopsy revealed Blastomyces dermatitidis. The breast abscess and thigh lesion were found to contain B. dermatitidis as well.
Cryptococcus neoformans yeast cells 40 to 60 micron in diameter were seen in an India ink preparation made from a human brain abscess specimen. In culture at 25 degrees C, uniform 5-micron-diameter yeast cells were produced. Inoculation into mice produced yeast cells up to 40 micron in diameter, and brain heart infusion broth culture at 35 degrees C produced yeast cells about 25 micron in diameter. A relationship of yeast cell diameter to incubation temperature is suggested.
Bifonazole 1% cream (Mycospor 1) was compared to its cream vehicle in the treatment of tinea versicolor, using a once-a-day application for 2 weeks. Patients were evaluated both clinically and mycologically in order to assess the efficacy and tolerance of the medication. 29 patients were evaluated by statistical analysis. Bifonazole cream 1% was shown to be significantly more effective in the treatment of tinea versicolor when used nightly for 2 weeks than was the vehicle cream.
Pooled normal bat serum was separated by gel filtration to give fractions rich in IgG-, Iga- and IgM-like proteins. These fractions were analogous to the corresponding human immunoglobulin classes by immunoelectrophoresis and SDS-polyacrylamide gel electrophoresis. Rabbits were immunized with the fractions and the antisera absorbed. Neotropical bats (Artibeus lituratus) were infected with Histoplasma capsulatum and serum samples were collected weekly and tested for specific serologic response to the fungus. A radial immunodiffusion test was devised to monitor changes in concentrations of IgG, IgA and IgM in the same sera. Bats infected with a low dose of fungus had significantly increased levels of IgM and IgA between 2-6 weeks post-infection. Bats receiving a high dose maintained elevated levels of IgM and IgA through the end of the study. Significantly elevated levels of IgG were not detected until late in the disease (8-9 weeks). In bats with histoplasmosis, IgM and IgA appeared to contribute primarily to the early positive serologies, while precipitating antibodies of the IgG class were detectable later in the disease. These results are similar to the serologic profile seen in human histoplasmosis, and extend our understanding of comparative immune responses in an important wildlife reservoir of human mycotic pathogens.
The pathogenesis of histoplasmosis was studied following intraperitoneal or intranasal infection of the neotropical bat, Artibeus lituratus. Groups of bats received either 10(4) or 10 viable mycelial fragments of Histoplasma capsulatum by intraperitoneal injection, or 10(6) or 10(4) viable mycelial particles by intranasal instillation. Intraperitoneal infection with the high dose resulted in rapid dissemination of the fungus to spleen, liver, lung and intestine, culminating in the death of some bats within 2-3 weeks. As few as 10 viable units of H. capsulatum produced systemic disease in about half of the bats, with the spleen and liver most frequently involved. In both groups the disease was characterized by gross pathologic abnormalities, numerous viable fungi in the tissue, and histologic lesions compatible with a chronic inflammatory process. Following intranasal exposure to 10(6) viable fungi, the primary pulmonary infection disseminated to the spleen, liver, and intestine within 2 weeks. Gross lesions were rarely observed in the viscera, and only one death resulted from the disease. The chronic disseminated nature of histoplasmosis in A. lituratus, especially following the more natural route of infection, suggests the means by which these bats could acquire and harbor H. capsulatum in nature. The frequent involvement of the gastrointestinal tract provides the mechanism by which these reservoirs might seed their environment with the fungus. The similarities between the pathogenesis of histoplasmosis in humans and bats provide a strong rationale for the use of this model in basic histoplasmosis research.
Groups of neotropical bats (Artibeus lituratus) were inoculated by the intraperitoneal or intranasal routes with varying doses of yeast phase Paracoccidioides brasiliensis. Bats infected with 10(6) viable yeast cells intraperitoneally developed fatal, disseminated disease, with delayed hypersensitivity appearing within 2 weeks. No precipitating antibodies were detected up to 7 weeks post-exposure. After intranasal instillation of 10(5) viable P. brasiliensis, the disease spread from the lung to the spleen by 3 weeks and to the liver by 9 weeks. As few as 10 viable cells were capable of causing pulmonary disease. Antibodies were detected at 5 weeks and persisted for several weeks thereafter. No viable P. brasiliensis was recovered from the intestines or fecal contents of any bats. Artibeus lituratus appears to be very susceptible to paracoccidioidomycosis by the respiratory route. The resulting immune response is characterized by delay appearance of precipitating antibodies and a moderate degree of delayed hypersensitivity. The pathogenesis of the resulting disease is similar to that observed in humans. The absence of intestinal involvement, even in chronic systemic disease, suggests that bats do not play a direct role in dissemination of this fungus in nature.
Groups of bats (Artibeus lituratus) were infected by the intranasal instillation of a suspension of mycelia and spore particles of Histoplasma capsulatum containing either 10(4) or 10(6) viable units. Bats infected with the high dose had viable H. capsulatum in the lungs, liver, spleen and gut as early as 2 weeks post-infection. Complement-fixing antibodies to the organism were detectable 3 weeks after infection, whereas precipitating antibodies were not persent until 5 weeks. Significantly delayed hypersensitivity to histoplasmin was noted at 2 and 4 weeks after infection. By 9 weeks, delayed hypersensitivity had waned, while antibodies could still be demonstrated. The observation that bats are susceptible to respiratory infection with H. capsulatum suggests a mechanism by which the disease may be maintained within a colony. Delayed hypersensitivity appears to be a sensitive, but transient, indicator of active histoplasmosis in bats.
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The humoral and cell-mediated immune responses of the large, frugivorus bat, Artibeus lituratus, were studied following intraperitoneal injection of 10 or 10(4) viable mycelial particles of Histoplasma capsulatum. Most bats had both cultural and histologic evidence of disease at autopsy. Utilizing a technique designed to measure the volume of footpad swelling in hypersensitive bats a significant degree of delayed hypersensitivity to histoplasmin was evident in both groups 4 to 6 wk after infection. Precipitating antibodies first appeared in the serum 3 wk after infection, but only in the animals infected with 10(4) viable organisms. Both the double diffusion and counterimmunoelectrophoresis techniques for antibody gave identical results. These findings suggest that A. lituratus is very susceptible to infection with H. capsulatum, and that a mild infection will stimulate delayed hypersensitivity to the organism but only low levels of antibody. The footpad test utilized in this study may be a sensitive and practical method for detecting natural infection in bats.
The fruit-eating bat, Artibeus lituratus, was fed known quantities of viable yeast cells and mycelial particles of Paracoccidioides brasiliensis in an attempt to assess the role of this animal in the distribution of this agent in nature. Results of mycosal cultures of the stomach, upper intestine, lower intestine and rectum clearly showed that the fungal cells were unable to survive more than 8 hours in the digestive tract of the bat. The mycelial particles were more susceptible than the yeast and were killed before passing to the rectum. The fungus died rapidly in the voided fecal material. These findings indicate the improbability of isolating P. brasiliensis from the digestive tract of wild captured bats and show that A. lituratus probably plays no role in the distribution of this fungus in nature.
We tested the hypothesis that symptomatic infection with Paracoccidioides brasiliensis caused impaired host cellular immune responses. In a cross-sectional study in Colombia, the immune responses of thirty-six patients with paracoccidioidomycosis were compared with those of sixty normal individuals. Patients demonstrated increased skin sensitivity to paracoccidioidin (para) and histoplasmin, and reduced reactivity to candidin and dinitrochlorobenzene as compared to controls. The skin test response to tuberculin (PPD) was similar to that of controls. In vitro lymphocyte transformation (LT) and leucocyte migration responses to phytohaemagglutinin and PPD did not differ in patients and controls; these responses to PPD correlated with skin sensitivity in controls, but not in patients. LT and inhibition of leucocyte migration to para were seen in more patients than controls; the latter response correlated with skin sensitivity in controls only. Positive LT to para was associated with absence of antibodies to P. brasiliensis. Analysis of symptomatic patients suggests that the prevalence of para skin test positivity was lowest in patients with the longest duration of disease; this implies decrease in specific cell-mediated immunity with prolonged active infection. Analysis of clinically cured patients suggests that the prevalence of para skin sensitivity and LT to para and PPD increased with time elapsed since diagnosis; this implies development or restoration of immunocompetence upon clinical recovery. Results of a preliminary longitudinal study on the immunological responses of six patients with active paracoccidioidomycosis are compatible with the above observations.
One hundred eighty children hospitalized for acute respiratory disease were studied in Cali, Colombia. In the majority of patients, pneumonia was the reason for hospitalization and remained the final diagnosis. Fifty-one cases of pneumonia of indeterminate etiology comprised the largest single diagnostic category, followed by 38 cases of pneumonia associated with measles, and 22 cases assocaited with serologic evidence of infection with other viral agents or Mycoplasma pneumoniae. Etiologic diagnosis could be assigned with a reasonable degree of confidence in 116 of the 180 patients (64%). The laboratory procedure found most likely to provide the etiologic diagnosis in this series was paired sera specimens for demonstration of rise in antibody titer against the common viral respiratory pathogens. Those most frequently implicated serologically as etiologic agents in the cases studied were, in order of decreasing frequency, measles, influenza, parainfluenza, and adenoviruses.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.