Invasive Fungal Infections (Kays) Flashcards
Define “prophylaxis”.
administration of antifungal agents prior to and throughout periods of neutropenia (ANC ≤ 1,000 cells/mm3)
Define “early empiric therapy”.
administration of systemic antifungal agents at the onset of fever and neutropenia
Define “empiric therapy”.
administration of systemic antifungal agents to neutropenic patients with persistent or recurrent fever despite appropriate antimicrobial therapy
Define “secondary prophylaxis (suppressive therapy)”.
administration of systemic antifungal agents to prevent relapse of a documented invasive fungal infection treated during a previous episode of neutropenia
What is the causative agent for histoplasmosis?
Histoplasma capsulatum
Explain the pathophysiology of histoplasmosis.
- Conidia aerosolize when soil is disturbed
- Conidia aerosoles are inhaled, reach bronchioles and alveoli
- Conidia germinate within 2-3 days, releasing yeast forms that begin multiplying
- Over the next 9-15 days, organisms are phagocytized by macrophages but not killed
- Infected macrophages migrate to lymph nodes and other sites (liver, spleen) via blood stream
- Onset of specific T-cell immunity in non-immune host activates macrophages (fungicidal)
- Over next 2-4 months, tissue granulomas form with central caseation and necrosis
- These areas become encapsulated and calcified over several years with viable organisms trapped within the necrotic tissue (unable to multiple except in immunocompromised patients)
In acute pulmonary histoplasmosis, low inoculum exposure results in ______________________.
mild/asymptomatic pulmonary infection; benign disease course and symptoms gone within a few weeks
In acute pulmonary histoplasmosis, high inoculum exposure results in _____________________.
acute, self-limited illness with flu-like pulmonary symptoms (fever, chills, headache, myalgias, non-productive cough)
True or false: patients with diffuse pulmonary histoplasmosis will never require mechanical ventilation.
false; can have diffuse radiographic changes and become hypoxic, leading to need for ventilation
Chronic pulmonary histoplasmosis presents as an ____________ infection imposed on a pre-existing medical condition (e.g., emphysema).
opportunistic
True or false: patients with early, non-cavitary chronic pulmonary histoplasmosis usually recover without treatment.
true
Disseminated histoplasmosis may be seen in patients exposed to large inoculum or an immunocompromised host, especially if there is decreased ___________________.
cell-mediated immunity
In disseminated histoplasmosis, what may occur if there is NOT successful containment of the organism with macrophages?
progressive illness characterized by persistent yeast-filled macrophages and inability to form granulomas
Most adults have mild, chronic form of disseminated histoplasmosis; untreated patients may be ill for 1-20 years with long periods of asymptomatic periods interrupted by clinical illness characterized by ___________, ____________, and _____________.
weight loss; weakness; fatigue
What are some symptoms of progressive disseminated histoplasmosis (PDH) in HIV-infected patients?
- fever
- chills
- fatigue
- weight loss
- night sweats
- hepatosplenomegaly
- cough, chest pain, dyspnea in 50% of patients
