Geographic Fungi/Opportunistic Fungi Flashcards
Candida clues and treatment:
Thrush, HIV, central venous catheter, dissemination
Treatment: fluconazole
Aspergillus clues and treatment:
Bone marrow transplant, cavitary lung lesion, sinusitis, galactomannan
Treatment: voriconazole, caspofungin or amphotericin (NOT fluconazole)
Cryptococcus clues and treatment:
Meningitis in an AIDS patient, pneumonia in the immunocompromised, CrAg
Treatment: Amphotericin B + flucytosine followed by fluconazole
Mucormycosis clues and treatment:
Burrowing necrotic sinus lesion, diabetes, iron overload, biopsy
Treatment: Surgery and posaconazole
Histoplasma clues and treatment:
Self-limited pneumonia, Mississippi and Ohio river valleys, urine antigen
Treatment: Fluconazole
Blastomycosis clues and treatment:
Bilateral pneumonia, pulmonary nodule, histoplasma region and further north
Treatment: Fluconazole
Coccidioides clues and treatment:
Self-limited pneumonia, pulmonary nodule, eosinophilia, AZ and CA.
Dimorphic fungi:
Fungi that exist in two forms: molds (in the environment) and yeasts (within the body). All geographic fungi are dimorphic fungi.
Histoplasmosis pathology:
Intracellular growth of tiny years within macrophages, leading to a GRANULOMATOUS reaction.
May produce mild flu-like illness with primary infection. Reinfection leads to acute pulmonary infiltrates.
Chronic pulmonary infection leads to nodular apical infiltrates, which cavitate.
Disseminated disease resembles miliary TB.
Histoplasmosis diagnosis:
Culture (fruiting bodies).
Histopathology (macrophages with small yeast)
Histoplasma urine antigen in active disease.
Histoplasmosis therapy:
Not all infections require treatment.
For severe infection, AMPHOTERICIN B.
For patients with abnormal immunity, AZOLES (Itraconazole)
Blastomycosis pathology:
Extracellular yeast (but may be seen within macrophages).
Thick-walled yeast with BROAD-BASED BUDS.
Non-caseating loose granulomas with neutrophils (PYOGRANULOMAS).
Causes pulmonary infection, rarely cutaneous lesions, BONE LESIONS, and disseminated infection.
Blastomycosis diagnosis:
Stain of pus/tissue
Culture
Blastomycosis treatment:
For serious disease, AMPHOTERICIN B.
For non-meningeal disease of moderate severity, ITRACONAZOLE.
Coccidioidomycosis pathology:
Inhalation of arthrospores, pulmonary infection, possible hematogenous dissemination.
Granulomatous response. Endospores in characteristic spherules of varying size.
Produces primary pulmonary illness (valley fever), may be associated with EOSINOPHILIA, Erythema nodosum. May disseminate to bone, skin, meninges.
Coccidioidomycosis diagnosis:
Serology, complement fixation, immunoprecipitin, ELISA
Culture (VERY HAZARDOUS)
Histopathology (visible endospores)
Coccidioidomycosis treatment:
Most primary disease is not treated.
AMPHOTERICIN B for progressive primary disease or immunosupressed patients. Intrathecal AMPHOTERICIN B for meningitis.
Sporotrichosis pathology:
Worldwide distribution. Local inoculation, frequently of the upper limb, with a pyogranulomatous response and LYMPHANGITIC spread.
Causes cutaneous lymphangitis with nodules. Rarely systemic symptoms. Pulmonary lesions can cavitate. May disseminate in the immunosuppressed.
Sporotrichosis diagnosis:
Culture
Histopathology (“cigar-shaped” yeast hard to find)
Sporotrichosis treatment:
Potassium iodide
Local heat for cutaneous lesions
ITRACONAZOLE
Immune defenses against Candida:
Mainly neutrophils (can damage pseudohyphae). Also, monocytes, macrophages, eosinophils, lymphocytes. The role of antibody and complement is uncertain.
Candidal infections:
1) Thrush (common). Plaques are pseudomembranes of fungus, PMNs, and epithelial debris. Risk factors are: inhaled steroids, dentures, cancer, antibiotics, HIV
Diagnosis: clinical appearance, KOH prep, Gram stain.
2) Esophagitis. Painful swallowing, substernal chest pain.
Risk factors: AIDS, chemotherapy
Diagnosis: endoscopy, biopsy
3) Vulvovaginitis (common). Thick, creamy discharge, intense itching and redness.
Risk factors: Diabetes, HIV, antibiotic therapy, pregnancy
Diagnosis: Exam and wet mount or KOH prep.
4) Cutaneous lesions (intertrigo, diaper rash, balanitis).
5) Candidemia. Spectrum from mild fever to sepsis.
Risk factors: Immunocompromised, ICUs, central IV catheters.
Diagnosis: Blood culture
6) Disseminated Candidiases. May effect: kidney, brain, myocardium, and eye. Diffuse microabscesses with acute suppurative and granulomatous reaction. AIDS PATIENTS RARELY GET DISSEMINATED CANDIDA.
Candida in the urine of a hospitalized person is rarely symptomatic and rarely indicates infection.
7) Candida cystitis. Causes pyuria, fever. Rarely disseminates.
8) Upper UTI. Usually a complication of disseminated disease, but may occur via ascending route.
Risk factors: diabetes, candidemia, anatomic or functional abnormalities.
Candida treatment:
Candidemia/disseminated candida: Removal of infected foreign bodies, antimicrobials (Amphotericin B, Caspofungin, or Fluconazole). Treatment should continue for 2 weeks after last positive culture. If there are persistently positive cultures, look for a nidus of infection.
Cystitis: Remove catheter (usually doesn’t require antifungals). Can use fluconazole or amphotericin bladder wash.
Thrush: nystatin
Aspergillus pathology:
Usually acquired by inhaling spores, or via trauma.
Phagocytosis and cell-mediated immunity are required for immune protection. Bronchopulmonary aspergillosis is an allergic reaction.
In the immunosuppressed patient, it may cause: VASCULAR INVASION (leading to infarction, necrosis, edema and/or hemorrhage), invasive sinusitis (acute and chronic), ASPERGILLOMAS, invasive pulmonary aspergillosis, disseminated aspergillosis (can affect any organ), or cutaneous aspergillosis.
