Opportunistic mycoses
Opportunistic mycoses are infections due to fungi with low inherent virulence.
cause
disaese in debiated or immunecomprmised or patient carry intravascular or prosthetic
devise
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
1. Candida are thin- walled, small yeasts that reproduce by budding.
2. The main species is Candida albicans.
3. Candida species are normal commensals of human skin and mucous membrane.
4. Candidiasis (moniliasis) is the disease caused by species of Candida.
can be acute or
chronic , superficial or deep , and clinical spectrum is wide .
Clinical types (disease caused by Candida spp).
1. Oral candidiasis (thrush)
1. Common disease in newborns. white patches apear inside the sturctues of the mouth
with fissuring on it is corrner
2. At birth, new born do not have a normal flora in the oropharyngeal area. so if mother
vaginal coloniztion of candida is heavy the infant respiratory tract becom infected .
3. The lesion, mainly in adult may extend to the esophagus, and is strongly connected with :
A. prolonged use of broad spectrum antibiotics,
B. diabetes mellitus,
C. impaired . T- cell immunity.
D. It is one of the first indication in the development of AIDS.
2. Intertriginous candidiasis
1. Involve those areas of the body that are warm and moist.
as axillae and grion .
2. Cutaneous or Intertriginous candidasis, also is a common cause of diaper rash in infants
(Napkin candidiasis).
3. Obesity, diabetes and alcoholism are predisposing factors. Conditions leading to
maceration of skin, are important environmental factors.
3. Vuluovaginitis (Vuluovaginal candidiasis)
Occurs most commonly in postpubertal women who have :
a- diabetes mellitus,
b- have been taking systemic antibacterial agents,
c- in the third trimester of pregnancy,
d- estrogen contraceptive therapy
Vagainal discharge is the most common symptom
Candida albicans transmited to male during intercourse and lead to balanitis, this
considered sexually transmited disease.
4. Onychomycosis (paronychia ,infection of the nail)
Inflammation of the nail but the debris does not acculmalte benathe the nail
5. Urinary tract candidiasis.
Rare, manifesting as cystitis and pyelonphritis
6. Ocular candidiasis.
7. Respiratory tract candidiasis.
8. Septicaemia.
9. Endocarditis.
10. Meningitis.
Laboratory diagnosis
1. The clinical specimens depending on the type of clinical symptom. Microscopically
apearing of budding yeast cell and pseudohyphae
2. 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.
3. Assimilation test used to differentiat other species.
4. Chrom agar (enzymatic) use for. Candida identification, inaddition to API - C system.
5. No completely specific immunologic procedure for diagnosis is present.
Treatment
A. Cutaneous lesions treated with topical agents as nystatin powder or suspension.
Creams or lotions with clotrimazole, econazole, miconazole.
B. for systemic candidcasis. Amphotericin B, fluconazole, Itraconazole.
Cryptococcus neoformans
1. The organism exists as a yeast in both nature and tissue.
2.
Cryptococcus neoformans possesses a polysaccharide capsule that is essential for
virulence.
3. The major environmental sources of C. neoformans include aged pigeon dropping and
pigeon nesting areas.
4.
It is not part of the normal human flora.
5.
The disease caused by C. neoformans known as cryptococcosis
6.
Human who are exposed to dust containing birds droppings are particularly at risk for
contracting cryptococcosis.
Clinical types
1. Pulmonary.
2. C.N.S.
3. Cutaneous.
4. Osseous. (bone and joints).
5. visceral or disseminated.
6. Ocular.
Laboratory diagnosis
1. Direct examination of specimen obsorving capsulated singly budding yeast cell
2. Culture on sabouraud agar or brain heart infusion agar BHI
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.
3. Serodignosis
a. Latex agglutination test with high sensitivity used to detect the polysaccharide capsule
antigen in serum and CSF but not other body ftuid.
b. As enzyme immunoassay (ELISA)
Treatment
A. Combination of Amphotericin B1 and Fluorocytosine.
B. Itraconazole (sporanox).