Fungal Infections Flashcards
1
Q
Predispositions to fungal infection
A
- corticosteroids, antineoplastic therapy, T-cell deficiencies
2
Q
Yeast
A
- unicellular
- round or oval cells that reproduce by budding
- can form pseudohyphae
3
Q
Molds
A
- multicellular filamentous colonies with branching tubules (hyphae)
- mass of tangled hyphae = mycelium
4
Q
Pneumocystis jiroveci pneumonia
A
- opportunistic pathogen seen in AIDS or someone with compromised cell-mediated immunity
- reproduces with alveolar type 1 cells, active disease confined to lungs
- trophozoites feed on host cells and form cysts
- progressive consolidation of lungs preventing exchange of air and suffocates patients
5
Q
Candida
A
- most common opportunistic pathogens
- interigo: infection of opposed skin surfaces
- paronychia: infection of the nail bed
- diaper rash
- vulvovaginitis
- thrush: oral infection
- esophagitis
- sepsis and dissemination
- endocarditis
- deep infections are less common but life threatening
- resident bacteria normally limit fungal organisms by blocking attachment to epithelial cells, competing for nutrients, or preventing tissue-invasive forms
- most commonly precipitated by antibiotic use
6
Q
Aspergillosis
A
- environmental fungi causing opportunistic infection involving the lungs
- can cause allergic bronchopulmonary, colonization of preexisting cavity, or invasive aspergillosis
- inhale conidia spores which go straight to alveoli
- fungal antigens cause infiltrate of lymphocytes, plasma cells, and eosinophils (allergic)
- can germinate in hollows and form aspergilloma, especially old TB cavities (preexisting cavities)
- in neutropenic patients, spores germinate to produce hyphae which invade lung parenchyma
7
Q
Mucormycosis (Zygomycosis)
A
- related fungi : Rhizopus, Mucor, Phizomucor, Absidia
- produce severe necrotizing invasive opportunistic infections
- have large hyphae that branch at right angles
- spores are inhaled and disease begins in lungs
- predispositions: neutropenia, glucocorticoid use, severe diabetes
- RHINOCEREBRAL: palate or nasal turbinates covered by black crust, can cause septic infarction of tissues, may lead to encephalitis
- PULMONARY: resembles invasive pulmonary aspergillosis with vascular invasion and multiple areas of septic infarction
- SUBCUTANEOUS: limited to tropics, caused by B. haptosporus, produces a gradually englarging hard inflammatory mass on shoulder, trunk, butt, or thigh
8
Q
Cryptococcus
A
- systemic mycosis by C. neoformans which affects meninges and lungs
- main reservoir is pigeon droppings
- has proteoglycan capsule
- affects people with impaired cell mediated immunity
- usually enters lungs but CNS is most common point of disease because it loves CSF
9
Q
Histoplasmosis
A
- H. capsulatum, a dimorphic fungi
- usually self lmiited but can lead to systemic granulomatous disease
- acute, self-limiting disease forms necrotizing granulomas in the lungs that are surround by macrophages which eventually calcifies
- disseminated disease has progressive organ infiltration
10
Q
Coccidioidomycosis
A
- C. immitis clinically and pathologically resembles TB
- California = valley fever
- dimorphic fungi, forms spores that are inhaled
- mature to form sporangia which form endospores that rupture and repeat cycle
- begins with focal bronchopneumonia
- disseminates in immunocompromised people
- risk of dissemination in Filipinos 175x’s greater than whites
- necrotizing, caseous granulomas develop
11
Q
Blastomycosis
A
- B. dermatitidis, dimorphic fungus
- acquired by inhalation of infected spores
- form yeasts, focal bronchopneumonia (usually confined to the lungs)
- skin and bones are most common site of extrapulmonary involvement
- pathologically rings with sharply definted cell walls
12
Q
Paracoccidioidomycosis
(South American Blastomycosis)
A
- P. brasiliensis, dimorphic fungi, mold in soil
- mixed suppurative and granulomatous response in lungs
13
Q
Sporotrichosis
A
- Sporothrix schenckii, dimorphic fungus in soil
- usually from cutaneous entry, proliferates locally eliciting an inflammatory response in dermis or subq tissue
- periphery is granulomatous, center is suppurative
- Splendore-Hoeppli substance surrounding yeast is probably Ag-Ab complex
14
Q
Chromomycosis
A
- chronic skin infection
- fungi likened to copper pennies
- most common in barefooted agricultural workers in tropics
15
Q
Dermatophyte Infections
A
- cause localized superficial infections of keratinized tissue
- Trichophyton, Microsporum, and Epidermophyton
- proliferate within tissues and spread centrifugally from initial site which produces round, expanding lesions with sharp margins
- ringworm/tinea
