Micro - Fungal (histo, blasto, coccidomycoses, aspergillus, zygomycoses, pneumocystis) Flashcards
Systemic mycoses
Histo
Blasto
Cocciodio
Opportunistic mycoses
Aspergillus
Zygomycosis
Pneumocystis
How are fungal respiratory infections transmitted?
Inhalation of spores
Extremely serious fungal infection which must be treated aggressively as soon as suscpected
Aspergillosis
Has fungal and protozoal properties
Pneumocystis
What causes symptoms of fungal respiratory infections?
Damage from immune response
Why are immunocompromised patients at greatest risk for fungal infections (specifically)?
Most fungi can be handled by PMNs but immunocompromised pt ain’t got em
Characteristics of the systemic fungi
Dimorphic
Endemic
Environmental v. tissue forms of systemic fungi
Tissue form is able to evade immune system, env. form can’t
Reservoir for histo
Soil laden with bird and bat feces
Endemic region for histo
Ohio-Mississippi River valley
Central America
Morphology of histo
Tuberculate (bumpy) conidia
Histo/blasto tissue forms vs. coccidioides tissue form
Histo/blasto = yeasts Coccidioides = spherule
Cells targeted by histo
RES
Reservoirs of blasto and coccidioides
Soil
Morphology of aspergillus
A-shaped (45 degree) branching septate hyphae
Where is aspergillus found? Buzz word?
Everywhere
Hospital air ducts
Fungus that commonly contaminates cell cultures
Aspergillus
think: it’s ubiquitous
Morphology of zygomycetes
Broad, nonseptate hyphae that branch at 90 degree angles
When do people develop mucormycosis?
After soil disturbance
think: AIDS pt with pneumonia or rhinocerebral sx after tornado, earthquake
Which fungus can’t be grown in culture? How can it be ID’d? Which must be cultures from BAL only?
Pneumocystis - use silver stain to look for cysts
Aspergillus - ubiquitous so it’s a common contaminant
What is unique about Pneumocystis structure? Implication?
Has cholesterol instead of ergosterol in membrane; can’t use amphotericin B or azoles
Valley Fever
Coccidioidomycosis - found in San Joaquin River Valley in California
Sx of most histo infections
None
Sx of histo infection in infants/immunocompromised
Disseminated infection leading to renal failure, meningitis, encephalitis
Complication of histo in AIDS pt
Abd masses
Histo sx in other healthy pt
Chronic and relapsing pneumonia resembling TB
Fatality of histoplasmosis
25%
Sx of blastomycosis
50% asymptomatic
Acute pneumonia with brown, purulent or bloody sputum
Blasto often confused with:
Lung CA or TB because of masses in lung
Sx of disseminated blasto
Prostate infection
Warty skin lesions
Meningitis
Sx of coccidioidomycosis/Valley fever
Fever, arthralgia, fatigue and rash
Fatigue can last for months
Who is most likely to get disseminated coccidioidomycosis/Valley fever
Men
Dark-skinned pts
Immunocompromised
Which fungus associated with pre-existing lung disease?
Aspergillosis
think: ABPA in asthma, cystic fibrosis
Characteristic lesion of aspergillosis
Fungal ball = aspergilloma
causes severe hemoptysis
Fatality of disseminated aspergillosis
Universally fatal
Who gets mucormycosis?
Pt in DKA or on corticosteroids
Two forms of mucormycosis
Pneumonia
Rhinocerebral form
Pneumocystis causes what type of pneumonia
Diffuse interstitial pneumonia
What PFT would be lowered in pneumocystis pneumonia?
O2 sat
Endemic area for blasto
Mid-south
Southeast
Mid-west
Who’s more likely to get blasto?
Middle-aged and older men
Endemic area for coccidioidomycetes
Arid climates in southwest US
San Joaquin River Valley in California
Which fungal infection is extremely contagious?
Valley fever (coccidiodo)
Which fungal infection has widespread seropositivity?
Pneumocystis - most people infected by age 4
however, infections in AIDS pts aren’t reactivation but new infections with different serotypes
What has greatly reduced the incidence of pneumocystis pneumonia?
HAART tx
AIDS is #1 predisposing factor
First step in culturing fungi
Treatment with KOH to remove everything but fungal cell walls
Tuberculate macroconidia
Histo
Spherules
Coccidioidomycosis
Broad-based budding yeasts
Blasto
Tx of healthy pt with fungal systemic infection
Watch for one month
If persists –> azoles for 6-12 weeks
If persists –> ampho B until it’s gone then azoles for 1-2 years
Tx of immunocompromised pt with fungal systemic infection
Ampho B until it’s gone then azoles for life
Tx of aspergillosis
Ampho B + removal of aspergilloma
Tx of mucormycosis
Ampho B + debridement (really disfiguring)
Tx of pneumocystis pneumonia
Trimethoprim+sulfamethoxazole (remember no ergosterol so can’t use ampho B or azoles)
Pentamidine (anti-protozoal) 2nd line
Most common fungal infection
Candidiasis
