Opportunistic Mycosis
-
Upload
api-19969058 -
Category
Documents
-
view
377 -
download
18
Transcript of Opportunistic Mycosis
Opportunistic Fungi
Opportunistic fungi are able to causes disease
in immunocompromised patients.
Opportunistic fungi includes:
a. Candida albicans.
b. Cryptococcus neoformans.
c. Aspergillus fumigatus.
d. Mucor & Rhizopus species.
e. Pneumocystis carinii.
Candida albicans Characteristics:
● Normal flora of mucous membranes of upper respiratory tract, gastrointestinal tract and genital tract.
● Yeast as normal flora, Pseudohyphae and hyphae when invade tissue.
Candida albicans
Transmission: As part of normal flora, no need of transmission.
Clinical findings: Thrush: Over growth of C. albicans occurs in
the mouth and produces white patches. Common in infants, immunocompromised patients.
Vulvovaginitis: Itching and whitish discharge.
Candida albicans
Disseminated infection: Such as
endocarditis, esophagitis, &
endophthalmitis can occur.
Chonic mucocutaneous
candidiasis: Occurs in children
with T- cell defect immunity.
Skin lesion: Warm & moist areas become red and weeping. Fingers and nails of persons employed as dish washers are involved.
mucocutaneous candidiasis
Laboratory diagnosis
Sample: According to the site of lesion. Microscopy: Microscpic examination of tissue
reveals yeast and pseudohyphae. The yeast is gram-positive.
Culture: On sabouraud’s agar media colonies are formed. Germ tube formation and production of chlamydospores distinguish C. albicans from other species of Candida.
Laboratory diagnosis
Germ tube test: Inoculate yeast into
serum Results in germinated
hyphae (within 2 hrs at 37OC for C.albicans)
Specific for C.albicans although C.tropicalis sometimes (rarely) produces germ tubes
Germ tube test
Candida albicans
Colony on SDA
Candida albicans
Mycelium and blastospores
in urine
Vaginal swab
Cryptococcus neofornans Characteristic:
Oval budding yeast.
Have a wide polysaccharide
capsule.
Habitat in the soil containing
bird dropping.
Transmission: by inhalation.
Cryptococcus neofornans
Clinical feature:
Lung infection is often asymptomatic or may ٭ produce flu-like disease or pneumonia.
They spread via blood stream to the ٭ meninges and other system in patients with reduced cell mediated immunity.
.But some cases of meningitis may occur ٭
Laboratory Identification Microscopy: Visualization of encapsulated
yeast in India ink preparation. Gram stain is unreliable but stains such as methenamine-silver, periodic acid-Schiff will allow the organism to be visualized.
Culture: On sabouraud’s agar produces colonies of yeast.
Serlogy: Capsular polysaccharide antigen can be detected by latex-agglutination test.
Cryptococcus neoformans
Colonies on SDA CSF, India ink, capsule
India ink, phase contrastLung section, ecapsulated cells
Aspergillus
Common species: A. fumigatus, A. flavus, A.
niger.
Medical importance: Aspergillus species
especially, A. fumigatus cause infections of skin,
ears, eyes, “fungus ball” in the lungs.
Aspergillus Transmission: Inhalation of airborne spores. Clinical feature: Can colonize and invade
abraded skin, wound, burn, cornea, ear and paranasal sinuses.
In immunocompromised persons invade blood vessels causing thrombosis and infarction.
A person with lung cavity e.g; from tuberculosis may develop a fungal ball.
Laboratory Identification Microscopy: Biopsy specimen shows septate,
branching hyphae. Culture: On sabouraud’s agar produces colonies with
characteristic radiating chains of conidia from central stalk.
Colony on SDA Hyphae in lung section
Aspergillus
Detection of antibody: Patients with allergic
bronchopulmonary aspergillosis have high titer
of specific IgE antibody.
Detection of antigen: Patients with invasive
aspergillosis, their may be high titer of
galactomannan antigen.
Pneumocystis carinii
Trophozoite and cyst forms, therefore thought to be a protozoan
Responds to protozoan drugs, not to fungal drugs
But now classified as a fungus (by rRNA sequencing)
Pneumonia-like disease, especially in immunocompromised
Common killer in AIDS