الفهرس 
Introduction
TaxanomyOnly 14 pages are availabe for public view
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Abstract
An investigation was conducted with the aim to illucidate
the presence of toxic substance, produced by various strains
of some species of Condida. 195 specimens were collected
from human cases of candidiasis in Assiut Governorate, and
55 strGins were isolated. Of these, 41 strains could be identified as such; 3 c. pseudotropicalis, 11 C. tropicalis,
10 Q. ~tilis, 4 S krusei, 7 C. albicans, 2 2:... parapsilosis, 3 ~ guilliermondii and one strain...s lipolytica.
The pathogenicity to mice of the identified strains was
determined by the intraperitoneal injection of a suspension containing 108 viable organisms. The most pathogenic strain of each of 6 species of Candida (~ pseudotropicalis, C.
ropicalis, C. utilis, C. krusei, C. a.lbicans and C.
parapsilosis) was selected for further studies together with a pathogenic strain of C. gtdlliermondii isolated in a
previous occasion.
Each strnin was cultured in fluid Sabouraud’s medium in
a special pattern, the grow~th was centrifuged and tested
for toxigenioity to mice. The cell-free supernatent was non-toxic while the deposit was toxic after being subjected to crushing and precipitation by alcohol. from certain evidences given it appears that the pathogenicity of Candida species depends on its power to produce a toxic substance
more related to endotoxin rather than to exotoxin.
The alcohol precipitate of each of the toxigenic strains was purified by using a cationic surface active agent. The LD50 of each purified substance was determined and no much diff2rence was noticed between the seven extracts. The
histopathological examinations of the internal organs of the
dead mj.ce were performed and the main changes were noticed
in the kidneys, liver and lungs while the heart was affected iD ~ase of C. guilliermondii. The physico-chemical characters of the purified toxic substances were recorded, no much
difference was obtained except for the thermolability of the
extracts of C. albicans and C. parapsilosis.
The chemical analysis of the 5 thermostable purified
substances revealed the presence of carbon, hydrogen, nitrogen and oxygen, and the absence of sulphur in all of them. The purified materials of ~ pseudotropicalis, ~ utilis and C. krusei were found to contain a measurable percentage of ilalogen in the form of chlorine. According to the percentage
of the chemical elements, the five extracts can be divided into 3 groups, each possesses a sim~ilar percentage. One group includes s... pseudotropicalis and ~ utilis, the second group includes C. tropicalis and S guilliermondii and the third
group includes C. krusei.
id
The five thermostable purified substances were found to
be devoid of nucleic acid, phosphoric acid and purine base
and to contain a polypeptide. The extracts of ~ tropicalis and C. krusei contained a polysaccharide. The presenoe of a
polypeptide indicates the protein nature of these extracts
combined with a polysaccharide in two of them. The absence
of nucleic acid is attributed to its loss during the process
of purification. The I.R. spectrum of the 5 thermostable
purified substances showed a similarity between ~ pseudootropicalis and C. utilis also Q.. tropicalis was similar to some extent to C. guilliermondii, C. krusei had a peculiar
intermediate position between the above two groups.
The results of the cross reactions between the five
thernlostable purified extracts of Candida species ffild their
ro1tisera prepared in rabbits showed the presence of 4 antigens.
C. pseudotropicalis possesses antigens (1) and (4); C. tropic8,lis antigens (2) and (3); ~ utilis antigen (4), S lcrusci antigens (1) and (2); S. guilliermondii antigen (3). The antigenic relationship between the five Candida species
\
would be as such: one related group is comprised of C.
--
pseudotropicalis ro1d C. utilis, another related group is
composed of c. tropicalis ffild C. guilliermondii and the last group is comprised of C. krusei which is related to only one of the two members of either the first or second group. It