Opportunistic Fungal Infections Flashcards
Characteristics of opportunistic fungal infections
All able to grow at body temperature, normal cell defenses of host can destroy them, and ubiquitous in nature. Disease depends on altered host resistance.
germ tubes
unique feature of Candida albicans
Oropharyngeal candidiasis (thrush)
Most frequent finding in HIV patients with CD4 lt 200. May also be caused by oral antibiotics, hyperglycemia in diabetics or pregnancy.
Candida parapsilosis
Associated with infected devices
Candida krusei
Rare, inherently resistant to fluconazole
Candida glabrata
Increasing in frequency, reduced susceptibility to fluconazole
Candida lusitaniae
rare, variable susceptibility to amphotericin
Esophageal candidiasis
In immunocompromised individuals, should be considered systemic so requires systemic admin of oral fluconazole or IV antifungal therapy.
Candida vulvovaginitis
Same predisposing factors as thrush. Creamy white exudate that is odorless but may be pruritic.
Systemic candidiasis
Severely impaired immunity allows candida to invade deep tissues. Hepatosplenic candidiasis, candidemia (via catheter), endophthalmitis (do an eye exam of patient has candidemia)
Aspergillus lab identification
Cannot use blood culture isolation.
In tissue: acute 45 degree angle branching, septation of hyphae. Stain best with PAS or methenamine silver.
Aspergillus species most common in human disease
Aspergillus fumigatus and flavus
Allergic bronchopulmonary aspergillosis
Respiratory disease in patients with asthma. Aspergillus is an antigen, increases IgE levels. Treat with avoiding provoking environments and steroid therapy.
Aspergilloma
Mycelia, results from colonization of preformed cavities or ma result de novo in invasive disease.
Invasive aspergillosis
Angioinvasive, results in thrombosis and necrosis of surrounding tissue. Two patterns:
1) Chronic necrotizing pulmonary aspergillosis: slowly progressive course
2) Acute/fulminant necrotizing: With greater degrees of immunosuppression.
Disseminated aspergillosis
Organism no longer contained in lung, find lesions in brain, kidney and other vascularized structures.
Aspergillus treatment
IV amphotericin for invasive aspergillus used to be used, but now voriconazole is the drug of choice.
Cryptococcus neoformans testing
Serologic tests for antigen in serum and CSF are highly sensitive and accurate
Where is cryptococcus found?
In soil contaminated by pigeon droppings
Cryptococcus pathogensis
Usually non-specific characterized by a headache. Pulmonary infection, can progress to CNS and cause meningitis. Important reservoir for latent infection is prostate gland. Lesions characteristically gelatinous at first but then become mixed cell granulomas.
Cryptococcus lab procedure
Direct examination with India ink stain.
Histology: Capsule stains with mucicarmine
Serology: Latex agglutination test for capsular antigen should always be performed, much more sensitive than above two.
Cryptococcus treatment
- Amphotericin B, often combined with 5-fluorocytosine for synergy
- Fluconazole can penetrate CSP and can be used after a 2 week course of ampho induction
- Since cell wall does NOT contain glucan, cannot use echinocandins
BE CAREFUL TO MONITOR INTRACRANIAL PRESSURE
Zygomycosis predisposing factors
diabetes, metabolic acidosis, corticosteroids, hematologic malignancies, transplants
Zygomycosis presentation
Severe acute sinus infection, nasal ulceration or necrosis/palatal necrosis.
