Systemic Mycoses Flashcards
What are the types of opportunistic pathogens that cause systemic mycoses?
1) Candida–>most common (yeast)
2) Cryptococcus neoformans (yeast)
3) Aspergillus (mold)
4) Pneumocystis jiroveci
What type of pathogen can become an opportunistic pathogen?
Zygomycetes
What are the species of Candida?
1) Candida albicans
2) C.tropicalis
3) C. parapsilosis
4) C. glabrata (cannot form pseudohyphae or true hyphae)
Which species of Candida cannot form pseudohyphae or true hyphae?
C. glabrata
What is used to differentiate C. albicans from all other yeasts?
Germ tubes that are formed at normal body temp (37 celcius)
What medium is used to identify Candida species?
Chrome agar
Candida Epidemiology
- Grows everywhere
- Major source of nosocomial infections
- Grows very well on plastics
Candida Risk Factors
- Hematological malignancy
- Neutropenia
- GI surgery
- Extremes of age
- Exposures
Candida Pathogenesis
Use adhesins like Fibronectin to attach to the cell surface and then use proteases that sit on hyphae and germ tubes to burrow inside
Immunity to Candida
Neutrophils and a working Th1 response is critical
What are some clinical manifestations of Candida?
- Diaper Rash
- Oropharyngeal Infection (Thrush)
- Vulvovaginitis (Yeast infection)
- Cutaneous disease…can affect scrotum, nails, in between digits
How would you treat a mucosal or cutaneous Candida infection?
Topical nystatin or oral azoles
How would you treat a deep-seated Candida infection?
Oral or IV azoles or Echinocandin
How would you treat C. galbrata?
Amphotericin B plus Echinocandin
-It is resistant to Azoles
What are the species of Aspergillus?
1) Flavus
2) Niger
3) Terreus
What kind of patients are highly susceptible to Aspergillus infections?
Patients with previous lung problems.
What are the species of Zygomyces?
1) Rhizopus
2) Mucor
Zygomyces Morphology
Asexual conidia found within sporangium
Sparsely septated hyphae
-Rhizoids are present
Which species of Rhizopus is the most common cause of human disease?
Rhizopus arrhizus
What are the zygomycoses mentioned in class?
Rhinocerebral zygomycoses, Pulmonary zygomycoses, cutaneous zygomycoses
What is the major organism that causes Pneumocystosis?
Pneumocystis jiroveci
What can Pneumocystis jiroveci cause?
- Pneumocystis jiroveci pneumonia (PJP)
- Penumocystis carinii pneumonia (PCP)
- Interstitial pneumonitis
How is Pneumocystosis diagnosed?
“Crushed Ping-Pong balls”
How is Pneumocystosis treated?
Trimethoprim-Sulfamethoxazole (Anti-biotic)
Pentamidine (anti-parasitic)
Morphology of Cryptococcus neoformans
Budding from a narrow/thin base
Cryptococcus neoformans is associated with…
Soil contaminated by pigeons
Cryptococcus gatti is found…
In the Pacific Northwest, associated with trees
In immunocompromised patients, C. neoformans and C. gatti cause what disease?
Meningo-encephalitis. Results in increased intracranial pressure. Will be a chronic infection, and symptoms may wax and wane.
Endemic fungi are of what morphology?
Dimorphic
Endemic fungi are often found in…
soil and bat feces
What is the morphology of Histoplasma capsulatum
Thermally dimorphic
Room temp: Mold with thick-walled macroconidia and oval microcinidia
Body temp (37 C): Intracellular thin-walled yeast
Pathology of Histoplasma capsulatum
Microconidia are phagocytosed by macrophages and it germinates into yeast
What regions is Histoplasma capsulatum endemic to?
Ohio and Mississippi river valleys, Mexico, Central and South America
Symptoms of Histoplasmosis
Light antigen load–> no symptoms
Heavy antigen load–> Flu-like symptoms
Rare complications: ARDS, mediastinal fibrosis, pericarditis, arthritis
1/100,000 people infected with Histoplasma capsulatum get?
Chronic pulmonary disease
1/2,000 people infected with Histoplasma capsulatum get?
Disseminated infection.
Chronic: weight loss, fatigue, oral ulcers, hepatosplenomegaly
Subacute: Same as chronic but with fever, CNS probs, adrenals and heart valves
Acute: Septic shock-like syndrome, oral&GI bleeding, meningitis, endocarditis
Diagnosis of Histoplasma capsulatum
Serological test for histoplasmin antigen in serum or urine
Treatment of Histoplasma capsulatum
Oral azoles and Amphotericin B..especially for chronic disseminated disease
What is the morphology of Blastomyces Dermatitidis?
Room temp: White to tan mold with oval conidia found on terminal hyphae branches
Body temp: Non-encapsulated yeast
What is the distinctive feature of Blastomyces?
Broad-based budding
Where is Blastomyces Dermatitidis found?
MS and Ohio River Valleys and Bogalusa, Louisiana
Conidia breathed in when soil and leaves are disturbed
What are the symptoms of Pulmonary Blastomyces?
Acute: Spectrum of symptoms
Chronic: Resembles cancer or TB
What are the symptoms of Cutaneous Blastomyces?
Painless lesions that can resemble a squamous cell carcinoma in the skin and bones
How do you diagnose Blastomyces Dermatitidis?
Broad-based budding in the tissue
Immunological test to look for antibodies
Treatment for Blastomyces
Amphotericin B, Itraconazole, Fluconazole
What is the morphology of Coccidiomycosis?
Room Temp: Barrel shaped arthrocondida
Body Temp: Anthrocondida become rounded spherules
What is the epidemiology of Coccidiomycosis?
Endemic to SW USA, Northern Mexico, and South America
-Referred to as Valley Fever or San Joaquin Fever
What kinds of infections do people with Coccidiomycoses get?
Primary infection: Asymptomatic pulmonary disease. 10% develop macular rash.
Secondary infection: Symptomatic after 6 wks. Nodular cavitary disease in the lungs. Resembles military TB or disseminated TB.
What are the risk factors for Coccidiomycoses?
HIV+ men of Filipino, African-American, Native American, or HIspanic origen
-Mortality is 90% without treatment
Diagnosis for Coccidiomycoses
Endosporulating spherules in sputum, exudates, or tissue
Most commonly made via biopsy
Treatment of Coccidiomycoses
Amphotericin B, Itraconazole, Ketoconazole
