Opportunistic mycoses Opportunistic mycoses are infections due to fungi with low inherent virulence. The main opportunistic fungi and the diseases caused by them are the followings. Candida albicans and other species Candidiasis Cryptococcus neoformans Cryptococcosis Aspergillus species Aspergillosis. Rhizopus and mucor species Mucormycosis.
Candida Species There are more than 150 species of Candida, about 10 of them cause diseases in human. Candida are thin- walled, small yeasts that reproduce by budding. The main species is Candida albicans. They can be found in soil, inanimate object, food, and hospital environment. Candida species are normal commensals of human skin and mucous membrane. Candidiasis (moniliasis) is the disease caused by species of Candida.
Clinical types (disease caused by Candida spp). Oral candidiasis (thrush) Common disease in newborns.
At birth, new born do not have a normal flora in the oropharyngeal area. The lesion, mainly in adult may extend to the esophagus, and is strongly connected with prolonged use of broad spectrum antibiotics, with diabetes mellitus, and impaired . T- cell immunity. It is one of the first indication in the development of AIDS.
Intertriginous candidiasis Involve those areas of the body that are warm and moist. Cutaneous or Intertriginous candidasis, also is a common cause of diaper rash in infants (Napkin candidiasis). Obesity, diabetes and alcoholism are predisposing factors. Conditions leading to maceration of skin, such as frequent and continued immersion in water as in house wives and fruit canner are important environmental factors.
Vuluovaginitis (Vuluovaginal candidiasis) Occurs most commonly in postpubertal women who have : a- diabetes mellitus, b- have been taking systemic antibacterial agents, c- and in the third trimester of pregnancy, d- also estrogen contraceptive therapy probably predispose women to the infections. Candida albicans transmited to male during intercourse and lead to balanitis, this considered sexually transmited disease.
Onychomycosis (paronychia ,infection of the nail)
Urinary tract candidiasis. Rare, manifesting as cystitis and pyelonphritis either ascending from a bladder infection or from hematogenous spread. Ocular candidiasis. Respiratory tract candidiasis. Septicaemia. Endocarditis. Meningitis.Laboratory diagnosis The clinical specimens depending on the type of clinical symptom. Skin or nail scraping, mucous material from mouth, vagina, sputum, blood, CSF, stool and urine should be collected in sterile container.
Culture of the specimens on Sabouraud's agar with P/S, but no actidione. The production of chlamydospores and germ tube on special media by C. albicans is usually sufficient to differentiat it from other candida species. Assimilation test used to differentiat other species. Chrom agar (enzymatic) use for. Candida identification, inaddition to API - C system. No completely specific immunologic procedure for diagnosis is present. Treatment Cutaneous lesions treated with topical agents as nystatin powder or suspension. Creams or lotions with clotrimazole, econazole, miconazole. for systemic candidcasis. Amphotericin B, fluconazole, Itraconazole.
Cryptococcus neoformans There are 37 species within the genus Cryptococcus. The organism exists as a yeast in both nature and tissue. Cryptococcus neoformans possesses a polysaccharide capsule that is essential for virulence. The major environmental sources of C. neoformans include aged pigeon dropping and pigeon nesting areas. It is not part of the normal human flora. The disease caused by C. neoformans known as cryptococcosis Human who are exposed to dust containing birds droppings are particularly at risk for contracting cryptococcosis.
Clinical types Pulmonary. C.N.S. Cutaneous. Osseous. (bone and joints). visceral or disseminated. Ocular. Laboratory diagnosis Direct examination
Culture Niger seed (bird seed) agar also used as selective media. Cryptococcus neoformans produce phenoloxidase, which oxidizes the caffeic acid in the niger seed extract into melanine. As a result, C. neoformans is selectively indicated by the brown colonies it produces on the medium.