fungal infections Flashcards
3 types of fungi?
- yeast - unicellular
- molds - multicellular, forms hyphae - branching or tangled. tangled -> mycelium, with/without septa
- dimorphic fungi - either yeasts or molds, depends on environment
predisposing factors to mycotic infection?
congenital/acq T cell deficiences
corticosteroid tx
antineoplastic therapy
Endogenous fungi
- histoplasmosis
- coccidioidomycosis
- blastomycosis
- paracoccidioidomycocis = S. Am blastomycosis
histoplasmosis
histoplasma capsulatum: acute self limited, asx in immunocompetent
- however, if large inoculum –> large consolidation in lungs, spleen, liver, BM (systemic granulomatous dz): CALCIFIED FIBROCASEOUS NODULES….(LIKE TB)
- pts with impaired cell-mediated immunity (ICMI) and IC–> DISSEMINATED HISTOPLASMOSIS (infiltrates of macrophage filled with h.capatulum infiltrates: liver, spleen, lungs, intestines, meninges)
- from bird poop and soil, spread by INHALATION. goes into alv macrophages and cause PUL INFILTRATES, and LNs. remain in LNs til T cells activate the macrophages –> forms NECROTIZING GRANULOMAS at infection site.
-SX: if mild: fever, headache, cough –> no TX
if disseminated: weight loss, fever, headache, TX: systemic antifungals
coccidioidomycosis
caused by coccidioides immitis spores which are inhaled from SOIL (dry and windy weather lifts spores) (valley fever)
- INHALED SPORES form spherules and matures to sporangia. fills w. endospores and bursts and infect again.
- begins as focal bronchopna (macrophages and PMN), then activated –> necrotizing granuloma. most frequent COMPLICATION: CAVITATION IN PUL COCCI
SX: acute, self limited dz: FIBROCASEOUS NODULE BUT DO NOT NOT NOT NOT calcify like histoplasmosis…CHRONIC NECROTIZING MYCOTIC INF, RESEMBLES TB.
-in ICMI, IC, pregnant women –> desseminated coccidioidomycosis. could be primary inf or reactivation. poor prognosis if COCCIDIOIDO MENINGITIS - FATAL UNTX.
blastomycosis
caused by blastomyces dermatitidis: SOIL - INHALATION
-forms yeast (buds) –> FOCAL BRONCHOPNA (consolidation) -> activated macrophages –> neutrophilic abscesses/epitheloid granulomas (pul dz usually resolves by scarring)–> CHRONIC GRANULOMATOUS + SUPPURATIVE PUL DZ –> OFTEN LEADS TO DISSEMINATION TO SKIN AND BONE
- SKIN INF: PSEUDOEPITHELIOMATIOUS HYPERLASIA (resembles SCC of skin - most common signs of extrapul dissemination)
- PUL blastomycosis is limited in 1/3 of cases
paracoccidioidomycosis (s. Am blastomycosis)
caused by paracoccidioides brasilienis (mold in SOIL): suppurative or granulomatous.
- lesions are similar to BLASTOMYCOCCOS AND COCCIDIOIDOMYCOSIS.
- lungs alone (like TB) or skin, mucosal surfaces, LNs. men 15x more likely than women (hormonal influence)
-SELF LIMITED MILD DZ OF LUNG/SKIN
name the opportunistic fungi
- pneumocystis jiroveci pneumonia (PCP)
- candida
- aspergillosis (3)
- mucomycosis (zygomycosis)
- Cryptococcosis (C.neoformans)
PCP
DDx: get bronchoscopy, endobronchial washing or sputum sample. FATAL UNTX.
SX: fever, EXERTIONAL SOB, NONPRODUCTIVE COUGH, DIFFUSE PUL PROCESS ON CXR
-INHALED. progressive, often FATAL in ICMI, 80% AIDs (OI)
-targets TYPE 1 ALV lining cells –> reproduces in them and produce cysts that fill with trophozoites. daughters bursts and affects other TYPE 1s. ALV FILLS WITH ORGANISM AND PROTEINOUS FLUID –> SUFFOCATES IF UNTX.
-TX: TMP/SMX or pentamidine
candida
- many are endogenous flora. candida albican in vagina, GI, oropharynx
- predisposing: Ab use (most common), MACERATION (most common skin lesion that leads to candida inf), IV drug users/preexisting valvular dz –> candidal endocarditis (most serious complication: brain septic emboli)
- causes: intertrigol (armpits, inguinal, etc), paronychia (nail bed), diaper rash, vulvo vaginitis (normal flora alterations), IN ICMI: THRUSH AND ESOPHAGITIS. IF INFECT DEEPER ORGANS, IT IS FATAL IN IC/NEUTROPENIC PTS (SEPSIS, DISSEMINATED CANDIDIASIS)
aspergillosis - most freq is apergillosis fumigatus, a saprophyte from SOIL, decaying plants, dung, air has spores conidia.
in tissues: septate hyphae branching at acute angles
invasive aspergillosis: (in IC)high dose steroid/cytotoxic therapy/acute leukemia. spores –> lungs –> disseminate to blood –> THROMBOSIS and MULTIPLE NODULAR INFARCTS;;;
;;;OFTEN FATAL. early high doses of amphotericin B and antifungals may work
aspergilloma (fungus ball): in PREEXISTING OLD TUBERCULOUS CAVITIES OR BRONCHIECTASIS. inhaled spores grow there and dont invade. XRAY: dense round ball in cavity. best untx
allergic bronchopulmonary aspergillosis: complicates asthma
-esp in ppl with asthma. spore –> alv and aw, germinate and therefore causes long term exposure. 20% of asthmatics develop this and causes PUL INFILTRATES, EOSINOPHILIA, ASTHMA EXACERBATION
mucormycosis / zygomycosis
DIABETICS
- mucormycosis caused by Zygomycetes, ubiquitous in environment. SEVERE, NECROTIZING, OI THAT BEGINS IN NASAL SINUSES/LUNGS
- in IC: severe neutropenia, inc steroids, esp DIABETICS
- in tissue. hollow, septa-less hyphae in right angles
1. rhinocerebral mucormycosis - palate and nasal turbinates covered by BLACKCRUST, underlying tissue is friable and hemorrhagic , septic infarction.
2. pul mucormycosis - resembles invasive aspergillosis (fatal)
3. subcutaneous zygomycosis (limited to tropics, fungus grows slowly in panniculus –> hard mass)
cryptococcosis
-C. neoformans in PIGEON POOP that infects almost excl with ICMI (AIDs, lymphomas (esp Hodg), leukemias, sarcoidosis, inc steroids). AFFECTS MENINGES AND LUNGS.
-C. neoformans is unique: has proteoglycan capsule (pathogenic) that stains w. mucicarmine stain, h+e stain –> holes and bubbles
-enters via lungs –> CNS (most common site)
CRYPTOCOCCAL MENINGOENCEPHALITIS, thickeneing leptomeninges, minimal infl response in brains/lungs. FATAL UNTX, TX with prolonged antifungal
