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Biomedical subjects

G D Roberts

Publications and source records attributed to G D Roberts.

At least 145 records · Page 8Linked to original sources
PubMed1976

Recovery of pathogenic fungi from clinical specimens submitted for mycobacteriological culture.

A total of 332 major pathogenic fungi were isolated from specimens cultured onto both fungal culture media and media used for culturing mycobacteria from January 1968 to June 1975. Only 72 (21.7%) fungi were recovered on media used for culturing mycobacteria. The effect of sodium hydroxide treatment was evaluated and shown to be detrimental to the recovery of fungi. It is recommended that clinical laboratories not rely on mycobacteriological cultures to recover fungal pathogens.

Fungi↗
PubMed1976

Blocking effect of rheumatoid factor and cold agglutinins on complement fixation tests for histoplasmosis.

The blocking effect of rheumatoid factor (RF) and cold agglutinins (CA) on the detection of complement-fixing (CF) antibodies for Histoplasma capsulatum using a mycelial (histoplasmin) and a yeast antigen was studied. Sera from 213 patients serologically positive for histoplasmosis were screened for the presence of RF or CA. CF antibodies to H. capsulatum in sera containing RF or CA were studied before and after removal of these factors (RF and CA) by treatment with dithiothreitol. Results suggest that RF or CA may interfere with the CF reaction to the yeast antigen of H. capsulatum but not to the mycelial antigen (histoplasmin).

Agglutinins↗
PubMed1976

Evaluation of the API 20 c microtube system for the identification of clinically important yeasts.

The API 20 C microtube system containing 20 biochemical tests for the identification of yeasts was compared with conventional tests used in the Mayo Clinic mycology laboratory. Three hundred isolates of clinically important yeasts were studied, and agreement of the carbohydrate fermentation and assimilation tests between the systems was good. The API 20 C represents a useful, commercially available screening method for the identification of yeasts; however, it is not a complete system and must be used in conjunction with microscopic morphological features and, when appropriate, with other biochemical tests.

Carbohydrate Metabolism↗
PubMed1975

Comparison of four methods for determining nitrate utilization by cryptococci.

This study evaluated the following methods for determining nitrate utilization: Wickerham broth, a special nitrate broth, Delft plate, and nitrate strip. With 236 isolates of cryptococci as test organisms, the special nitrate broth method gave 99% correct results and the Wickerham broth method gave 98%. The nitrate strip and Delft plate methods gave correct results in 94 and 86% of tests, respectively. The special nitrate broth method is judged superior because it provides accurate results within 48 h, compared to 14 days with the Wickerham broth method.

Cryptococcus↗
PubMed1975

Detection of fungi in blood cultures.

In a retrospective study covering the period January 1972 to June 1974, recovery rates of bacteria and of fungi were generally equivalent with tryptic soy broth, Thiol, thioglycolate, and Columbia broth media (all under vacuum with carbon dioxide and sodium polyanetholesulfonate). An additional biphasic medium consisting of brain heart infusion broth and a brain heart infusion agar slant, which was inoculated only where fungal sepsis was suspected clinically, yielded significantly higher recovery rates of fungi. There were 29 instances of cultures with fungi in both the biphasic and broth media, 80 instances of cultures with fungi only in the biphasic medium, and no instances of fungi only in the broth media. The isolates were as follows: Candida albicans, 74; C. parapsilosis, 20; C. tropicalis, 16; Torulopsis glabrata, 18; Torulopsis sp., 1; Cryptococcus neoformans, 12; C. laurentii, 2; and Histoplasma capsulatum, 16. Despite routine subcultures of the broth media to chocolate blood agar within 24 h of inoculation and after 5 days of incubation, detection of fungemia was significantly improved by the use of a biphasic medium.

Bacteria↗
PubMed1975

Recovery of yeast from vented blood culture bottles.

Rates of isolation of yeasts from blood cultures were significantly enhanced by venting vacuum blood culture bottles in studies of both stimulated and patients' blood cultures; however, the time interval to detection of positivity of yeasts in the clinical studies was significantly (P less than 0.01) shorter in a vented bottle with biphasic brain heart infusion medium than in a vented bottle with soybean-casein digest broth. The mean time intervals to detection of positivity were 2.6 days in the former and 5.2 days in the latter.

Air↗
PubMed1975

Detection of fungi in clinical specimens by phase-contrast microscopy.

During 1973 and 1974, the following fungi were detected in clinical specimens by using phase-contrast microscopy: Blastomyces dermatitidis, 5; Coccidioides immitis, 3; Cryptococcus neoformans, 11; other yeasts 918; dermatophytes, 863; Mucor species, 1; and Aspergillus fumigatus, 16. This technique allows rapid detection and, in many instances, immediate identification of fungi in clinical specimens.

Arthrodermataceae↗
PubMed1974

Simplified approach to identification of aerobic actinomycetes by thin-layer chromatography.

A system has been developed for the identification of aerobic actinomycetes in the clinical laboratory based on analysis of whole cells for diaminopimelic acid and carbohydrates and on the ability of the organism to decompose casein, tyrosine, and xanthine media. The whole-cell analyses were performed by a simple thin-layer chromatographic procedure that is described. Eighteen reference cultures were correctly identified and, subsequently, 35 isolates from clinical material were grouped by using this system. The method is well suited for use in routine clinical laboratories.

Actinomycetales↗
PubMed1974

Immunocytoadherence during experimental histoplasmosis.

Immunocytoadherence was investigated as a method of detecting active histoplasmosis in two groups of infected New Zealand white rabbits. Yeast-phase Histoplasma capsulatum was given intravenously to one group and intratracheally to the other. There was a striking correlation between the clinical condition of the animals and the number of rosettes seen. This number increased as the infection progressed and decreased as it regressed. The immunocytoadherence technique might be of value in detecting active histoplasmosis, and investigation in humans is warranted.

Animals↗