Studies on the biology of pathogenic fungi

1. An introduction to the subject of medical mycology is given with a brief indication of its scope and the organisms concerned. The nature of the Experimental Mycoses Unit is described and the objects of the present work defined.2. The first part of the work is a survey of the fungi occur -1 :ring in a variety of human sources, with especial reference to the yeasts. 1,004 samples were examined from urine, sputum, throat, high vaginal, wound, stool and other sources. 289 fungi (28.8%) were obtained; 248 (86%) of the isolates were yeasts.3. Candida albicans was the most common species and was isolated on 141 occasions (56% of the total number of yeasts). Other species were Torulopsis glabrata (31); Rhodotorula mucilaginosa (16); Candida tropicalis (12); Candida parapsilosis (7); Saccharomyces cerevisiae (4); Candida zeylanoides (4); Cryptococcus albidus (4); Saccharomyces fragilis (3); Candida krusei (3); Hansenula anomola (2); Pichia membranaefaciens (2); Saccharomyces carlsbergensis (1); Trichosporon cutaneum (1); Candida robusta (1)i Candida guilliermondii (1); Torulopsis famata (1); Torulopsis candida (1); Cryptococcus laurentii (1); Cryptococcus diffluens (1).4. Torulopsis glabrata is shown to be a significant member of the flora of the sources examined.5. A description of 11 isolates which were atypical is given with a discussion on their taxonomic affinities.6. Rhodotorula mucilaginosa was obtained from decaying vegetation; Candida guilliermondii was isolated from soil.7. A description is given of a strain of Candida tropicalis which was responsible for a fatal septicaemia.8. An evaluation of the methods used in the survey is provided.9. Tissue culture techniques were used to demonstrate phagocytosis of Candida albicans and Candida tropicalis.10. In vivo experiments showed that Candida albicans rapidly forms pseudomycelium. After 12 hours verticillate branching occurs. An association between branching and the presence of polymorpho- :nuclear leukocytes is indicated. Candida tropicalis also forms pseudómyycelium in vivo, but a check is evident after 4 hours. Pseudomycelial strands are branched and production of blastospores is not entirely suppressed.11. Blastospores of Torulopsis glabrata were predominantly intracellular within host phagocytes after 12 hours.12. Abortive pseudomycelium is demonstrated in Saccharomyces fragilis