Virology and Mycology (2) Flashcards
Explain opportunistic mycoses
What species are common causes? (3)
Caused by endogenous or ubiquitous organisms of LOW virulence that cause infection in immunocompromised patients
Species
- Candida
- Cryptococcus
- Aspergillus
Can candida be part of normal flora?
Yes
Candida can produce pseudohyphae and hypae. Define pseudohyphae
Pseudohyphae:
Form when buds continue to grow but fail to detach
What group of patients are cutaneous candidiasis common in?
location
Who: obese, diabetic
Location: skin fold, groin, axillae
What group of patients are candidal onychomycosis common in?
location?
Who: chronic CUTANEOUS candidiasis
Location: nails
Which candida causes bloodstream infections, wound infections, or ear infections and are often multidrug-resistant
Candida Auris
How to diagnose candidiasis (3)
microscope: KOH mount of skin/nails scrapings
- will show psuedohyphae/true hyphae
Culture at 37C
Tissue biopses, gram-staining
Explain what gram-positive and gram-negative stains of fungi look like?
Gram-positive
- Intact YEAST cells
Gram-negative
- broken/disrupted cells during the dye process
How do Fungi stain gram-positive if they don’t have peptidoglycan?
Other structures can retain the stain such as:
- chitin
- beta-glucan
- Mannoprotein
Cryptococcosis
Causative fungi
Location?
What group of patients?
Type of capsule?
Found in?
Causative fungi
- Cryptococcus neoformans
Location?
- Lungs, meninges
What group of patients?
- AIDS patients
Type of capsule?
- polysaccharide capsule
Found in?
- vegetation, soil
- pigeon feces
What is the lab diagnosis of cryptococcosis? (3)
- Specimens: blood, urine
- Microscopic examination
- wet mounts using INDIA INK (capsule stays white (bright)) - Culture at 37C
NOT SEROLOGY
Aspergillosis
Pathogens (2)
Produce (morphology)
Pathogens
- aspergillus fumigatus
- Aspergillus flavus
Produce
- small conidia that is easily aerosolized
- rapidly produce aerial hyphae that have long conidiophores with terminal vesicles
Define the following forms of aspergillosis:
Allergic bronchopulmonary aspergillosis
Aspergilloma
Invasive pulmonary aspergillosis
Allergic bronchopulmonary aspergillosis
- diagnosed by high titres of IgE antibody to aspergillus
Aspergilloma
- spherical growth of aspergillys in pre-existing lung cavities
Invasive pulmonary aspergillosis
- disease start in lungs and move to other organs
- produces abscesses and necrotic (cell death) lesions
Lab diagnosis of Aspergillosis? (4)
- Specimens
- Microscopic examination w KOH or calcofluor
- branched septate hyphae - Culture at room temperature
- Serology (IgE)
Pneumocystis pneumo
Pathogen
Spread?
Morphology?
Who is at risk?
Location?
Pathogen
- pneumocystis jiroveci
Spread?
- by inhalation
Morphology?
- thin-walled trophozoites + thick cysts
Who is at risk?
- AIDS, immunocompromised, malnourished
Location?
- Lungs, human
- cannot culture ex-vivo
