60. Opportunistic Mycoses Flashcards
opportunistic mycoses w/altered phagocytes (neutropenia)?
invasive candidiasis
aspergillus
zygomycosis
opportunistic mycoses w/altered T-cell function?
mucocutaneous candidiasis
cryptococcosis
pneumocystosis/pneumocystis carinii
likely pts to get mucocutaneous candidiasis?
Altered T-cell function
- underlying diseases (HIV, DM)
- corticosteroids
- pregnancy (progesterone)
- age (waning cell-mediated immunity)
- antibacterial antibiotics
- postpartum risk for cutaneous candidiasis
clinical disease of mucocutaneous candidiasis?
- oropharyngeal candidiasis (thrush)
- esophageal candidiasis (burning, dysphagia, good localization)
- candida epiglottitis
- cutaneous candidiasis (skin folds like groin or under breast, diaper dermatitis)
- onychomycosis (occasionally)
- vulvovaginal candidiasis
- mucocutaneous candidiasis = diabetes
- chronic mucocutaneous candidiasis (inherited disorder of cellular immunity w/ concomitant adrenal insufficiency and hypoarathyroidism, IDDM, hypothyroidism, hypogonadism = autoimmune polyendocrinopathy-candidosis-ectodermal dystrophy/APECED = autosomal recessive)
pathology of mucocutaneous candidiasis?
- lesions on oral, esophageal, epiglottal, GI, and vaginal mucosal surfaces w/white pseudomembranous plaque of Candida hyphae, pseudohyphae, and budding yeast cells
treatment of mucocutaneous candidiasis?
- keep diaper dry
- topical clotrimazole, miconazole, or nystatin
- PO fluconazole
- IV echinocandin for severe cases
invasive candidiasis susceptible patients?
Altered phagocytes (neutropenia) – major problem w/host defense : mucosal disruption, catheters, GI surgery, trauma, transplant and immune-suppressed
invasive candidiasis pathogenesis?
- adherence and colonization
- penetration through mucosal barriers and angioinvasion or access to vascular catheters
- hematogenous dissemination
- replicaoitn in tissue causes necrosis +/- abscess formation w/budding yeast and hyphae
invasive candidiasis clinical disease?
- candidemia
- endocarditis
- hepatosplenic candidiasis
- acute disseminated candidiasis (septic shock)
- renal candidiasis
invasive candidiasis treatment?
- echinocandins – esp if in eyes, need to QUICKLY KILL the fungi
- fluconazole
- AmB
candida albicans?
most virulent and common member of candida
germ tube w/chitin on the end
virulence:
surface receptors, cell wall can act as immunomodulator, hydrolytic enzymes, and host mimicry
aspergillus biology?
- filamentous fungi ubiquitous in the env’t
aspergillus pts at risk?
Altered phagocytes (Neurtopenia)
- CGD
- post-engraftment BMT
- organ transplant recipients
- corticosteroids
aspergillus pathogenesis?
- inhalation of conidia reach alveoli
- phagocytosis but no killing if compromised host
- germination w/hyphal invasion of lung parenchyma
- angioinvasion w/thrombosis, ischemia and infarction
- +/- hematogenous dissemination
aspergillis virulence factors?
- aflatoxins
- adherence receptors
- hydrolytic enzymes
- C’inhibitor
aspergillis clinical disesae?
- toxins re: aflatoxins
- allergic syndromes in atopic indivs
- fungal ball in old TB cavity
- keratitis following corneal trauma
- invasive disease (pulmonary +/- dissemination)
aspergillis pathology?
- angular dichotomously branching septate hyphae
halo sign or crescent sign
aspergillis treatment?
- first line therapy: voriconazole (isavuconazole, liposomal AmB)
- Second Line therapy: posaconazole, echinocandins, AmBLC
zygomycoses general biology?
- wide, ribbon-like, nonseptate hyphae that branch infrequently at right angles
- medical emergency! Can overwhelm the patient w/in hours
- rapid growing
- sporangiophores which bear a large sac-like structures called sporangia filled w/ sporangiospores produces internally
zygomycoses pts at risk?
Altered phagocytes (neutropenia)
- DM w/DKA -> rhinocerebral zygomycosis
- neutropenic -> pulmonary +/- dissemination
zygomycoses pathogenesis?
- inhalation/ contact w/asexual spores from env’t
Rhinocerebral zygomycosis: - infec begins in paranasal insuses (or nasal/oral mucosa)
- tissue invasion w/frequent invasion of nerves and BVs (cranial nerve palsies, thrombosis, and necrosis)
- invasion of orbit and eye
- direct extension to brain
Pulm: angioinvasion and hemorrhagic infarction
zygomycoses clinical disease/pathology?
- Saprophytic/Colonization: old TB lung cavity, no invasion of lung parenchyma
- Invasive: rhinocerebral zygomycosis
- invasive: pulmonary +/- dissemination
- easily spreads through lamina papyracea
- medial rectus affected = diplopia
- CN III, IV, V1, V2, V6, internal carotid (hemispheric infarction) affected if spreads to cavernous sinus
- invasion of BV walls and nerves w/extensive necrosis in advance of the fungus
zygomycoses treatement?
- First line therapy: AmB, recently approved isavuconazole
- adjunctive therapy: surgery, restitution of host defenses
cryptococcus neoformans general/biology?
- Encapsulated yeast
- neurotropic
- visualize capsule w/india ink stain
cryptococcus neoformans pts at risk?
Altered T-cell function:
- high dose corticosteroids
- organ transplant w/ immunusupp.
- HIV+**AIDS-defining infection
cryptococcus neoformans pathogenesis and virulence factors?
- inhalation of yeast from env’t
- replication in the lung
- recruitment of CD4 and CD8 cells
- clearance of pulm infection in most concomitant w/ development of specific cellular immune response OR progressive pulm infection in compromised pts
- +/- hematogenous dissemination or crossing of BBB
- replication of yeast w/gelatinous lesion due to capsule: tremendous pressue in CNS
- hetero-polysaccharide capsule: glucuronoxylomannan -> inhibits intracellular phagocytosis
- melanin inhibits oxygen dependent killing mechanisms
cryptococcus neoformans clinical disease/pathology?
- meningoencephalitis: memory impaired/confused
- pulmonary: asymptomatic to mild to progressive, depending on the pt and inoculum size…then spreads to the brain
- disseminated disease
- increased ICP can cause herniation and blindness so if see nothing on ophthalmic exam and pt experiencing blindness…think this.
- normal host: chronic inflammation and granulomatous responses, resolution w/out calcification
- compromised host = mild to non-inflammatory reaction
- gelatinous lesions (excess capsule)
- spherical yeasts: spherules
- stain w/PAS, GMS, or mucicarmine
cryptococcus neoformans treatment?
- first line therapy: Amb + 5FC then fluconazole maintenance
- Adjunctive therapy: relief of increased ICP
pneumocystis jirovecii general/biology?
- obligate parasite-fungus
pneumocystis jirovecii pts at risk?
Altered T-cell function
- immunosupp
- corticosteroid
- HIV
- age
pneumocystis jirovecii pathogenesis?
- proliferates w/in capillaries along alveolar epithelium and produces delicate proteinacious material that blocks capillary and prevents oxygenation of tissue
pneumocystis jirovecii clinical disease?
-alveolar-interstitial pna presents w/fever, dyspnea, and non-productive cough
- extrapulmonary disease rare
-
pneumocystis jirovecii tx?
- first line therapy: TMP-SMX
