Nosocomial Fungi

Nosocomial Fungi I. Pathophysiology A. Common Settings for Nosocomial Fungal Infections 1. Neonatal intensive care unit 2. Neutropenic cancer patients 3. Bone marrow transplant patients 4. HIV infection 5. Intravascular catheters 6. Other predisposing conditions a. Hyperalimentation b. Hyperglycemia c. Intralipids d. Steroids e. Prolonged antibiotic therapy f. Breach of epithelial barrier B. Infections with Candida Species 1. Predisposing conditions a. Change in intestinal flora (1) Prolonged antibiotic therapy (2) Oral contraceptives b. Breach of Epithelial Barrier (1) Catheters -intravascular, intraperitoneal, urinary (2) Burns (3) Surgery c. Hyperglycemia (1) Diabetes (2) Steroids (3) Hyperalimentation d. Immunocompromise (1) Prematurity (2) Chemotherapy (3) Neutropenia e. Genetic Defects of Neutrophil Function (1) Chronic granulomatous disease (2) Myeloperoxidase deficiency 2. Order of Frequency a. C albicans b. C tropicalis -catheters c. C. parapsilosis -NICU c. C krusei-Bone marrow transplant patients on fluconazole prophylaxis d. C glabrata, lusitaneii, guillermondii 3. Associated Physical Findings a. Rash -isolated subcutaneous nodules b. Eyes -endophthalmitis c. Liver and spleen d. Kidneys e. Bones f. Rarely meningitis, especially in neonates g. Pneumonia extremely rare 4. Microbiology a. Fungal isolator b. Induction of germ tubes in 20% serum -C. albicans c. Fungal sensitivities -test Amphotericin B, fluconazole, 5-FC 5. Anti-fungal therapy -choice must be tied to gravity of infection and degree of immunocompromise a. local infection a. Stoma site: Clotrimazole powder b. Vaginitis: Clotrimazole trochees or ointment 6. Locally Invasive Disease a. Esophagitis: (1) Amphotericin B, 0.3 mg/kg/day (2) Fluconazole if sensitive b. Peritonitis 2E dialysis catheter c. Cystitis in catheterized patient -irrigation with 50 mg/L 7. Systemic Disease a. Amphotericin B at 1.0 mg/kg b. Remove catheterc. Ascertain degree of dissemination: ophthalmologic exam, liver/spleen renal ultrasound C. Aspergillus 1. Pre-disposing conditions a. Bone marrow transplant b. Prolonged neutropenia c. Asthma for allergic bronchopulmonary aspergillosis d. Cavitary lung disease for aspergilloma 2. Species Encountered a. Aspergillus niger b. Aspergillus flavus c. Aspergillus terreus 3. Associated Physical Findings a. Black eschar on exam of nares b. Black eschar at skin site c. Tachypnea and dyspnea 4. Diagnostic Issues a. Requires >7 days to grow b. biopsy most rapid means of diagnosis -look for septate hyphae c. CT of chest more sensitive for nodular infiltrates than CXR d. sinus films and ENT exam 5. Anti-fungal Therapya. Amphotericin B -1.5 mg/kg/day b. addition of 5 FC or Rifampin now displaced by Itraconazole D. Mucormycoses 1. Predisposing conditions a. Diabetes and acidosis b. Steroids c. Adhesive tape and Elastoplast d. Neutropenia e. Dirt in wound 2. Species Encountered a. Rhizopus b. Mucor 3. Associated Physical Findings a. Black eschar in nose b. Black eschar on skin c. Direct inhalation: pneumonia 4. Diagnostic Issues a. Biopsy required -look for non-septate hyphae 5. Anti-fungal Therapy a. Successful therapy requires wide surgical debridement b. Amphotericin B at 1.0-1.5 mg/kg/day c. Imidazoles are not effectiveE. Other Opportunistic Pathogens 1. Fusarium -neutropenic cancer patient with papular rash a. Portals of entry -respiratory and skin, especially feet b. Physical Findings (1) Rash -subcutaneous nodules, painful papules with central infarction and target lesions (2) Cellulitis of toe or finger c. Culture required to differentiate from Aspergillus: septate hyphae on biopsy d. Can be recovered from blood e. Resistant to most anti-fungal agents 2. Pseudallescheria boydii a. Sinusitis, endophthalmitis, pneumonia in immunocompromised b. Involvement of CNS common c. Typically resistant to Amphotericin B but susceptible to azoles 3. Malassezia furfur -NICU baby a. Intralipid therapy b. Same organism as in Tinea versicolor c. Must be cultured with lipid supplements -Sabouraud's overlaid with olive oil d. Treatment requires removal of catheter but antifungal therapy is not necessary4. Penicillium marneffei a. Risk factors: cancer, AIDS, exposure to adreno corticosteroid therapy b. Physical findings include fever, weight loss, papular skin lesions resembling molluscum contagiosum, lymphadenopathy 5. Dematiaceous fungi -Curvularia, Alternaria a. Yeast-like cells or swollen septate hyphae b. Stain with Fontana-Masson (melanin-specific stain) c. Abscesses (1) Subcutaneous (2) Sinusitis (3) Cerebral 6. Trichosporon beigelii a. Endogenous colonization of the GI tract b. Hosts with neutropenia or steroid use are susceptible c. Multiple cutaneous lesions, fungemia, renal involvement (hematuria) d. Cryptococcal antigen test may be positive -shared cellsurrfac antigen e. "Tolerant" to Amphotericin B -use 1.5 mg/kg/day plus 5 FC f. Add fluconazole if fungemia persists or lesions progress within 24 hours