Fungal Respiratory Infections Flashcards
1) Know the 3 major systemic mycoses and how to diagnose/treat them 2) Know geographical distributions of systemic mycoses. 3) Know presentation of aspergillosis, its diagnosis, and need for urgent treatment 4) Know the medical emergency of mucormycosis (zygomycosis) 5) Know the protozoan nature of Pneumocystis and how it affects treatment.
Name the three major systemic mycoses and the three opportunistic mycoses.
Systemic:
1) Histoplasmosis
2) Blastomycosis
3) Coccidiodomycosis
Opportunistic
1) Aspergillosis
2) Mucormycosis (Zygomycosis)
3) Pneumocystosis
*BONUS: Not included in the packet but this is a systemic mycoses that we still need to know on boards. Its a fungus commonly spread by pigeons. It infects the lungs but can dessiminate into a very bad meningitis. What is it?
Cryptococcus neoformans.
Which two mycoses are endemic to the Mid-South?
1) Histoplasmosis (Ohio River Valley + Central America)
2) Blastomycosis (all through the Mid-South, SE, and MW)
**these fungi require an acidic and humid environment to live
How do fungi cause damage to the body?
They trigger damaging immune responses
When it says the systemic fungi are dymorphic, what does that mean?
Dimorphic = in the environment (lower temps) they are a MOLD, but when they are in the body (higher temps) they are in the TISSUE FORM, usually a yeast.
Classify histoplasmosis:
Histoplasma capsulatum
- -dimorphic fungus, seen as a mold in soil enriched from birds/bats. Mold is a distinct “tuburculate” (bumpy) conidia
- -anti-phagocytic small yeast in tissue that targets the reticuloendothelial system (RES)
Classify blastomycosis:
Blastomyces dermatitidis
- -dimorphic, mold in soil enriched by migratory birds
- -tissue yeast form cannot survive in macrophage
*Blasto = Broad-Based Budding yeast
Classify coccidiodomycosis:
Coccidioides immitis
- -dimorphic mold in soil in the SW US (desert valley fever)
- -tissure form is a SPHERULE, which releases hundreds of infectious spores (considered a bioweapon b/c of this)
What pathology can histoplasmosis cause?
Mostly asymptomatic to mild cough/fever.
Sometimes can cause chronic relapsing pneumonia, resembling TB symptoms
IC patients can develop RF, meningitis, abdominal masses/ulcers.
**highly fatal if untreated
What pathology can blastomycosis cause?
50% of infections are symptomatic, causing acute pneumona with brown or bloody sputum
Chronically mimics TB and lung cancer due to formation of mass-like lesions.
Warty skin lesions may form. Bones, GU tract, and prostate can be affected.
Meningitis is seen in IC patients
What pathology can coccidiodomycosis cause?
40% get valley fever if exposed.
Symptoms range from none > flu-like + widespread rash > skin/bone lesions > meningitis (1%)
*Fatigue lasts for months after resolution
Systemic infections more likely in IC patients, men, and dark-skinned races.
You’ve been swimming in the great Reelfoot Lake, a popular duck hunting lake in NW TN, and then come down with a bad cough with brown sputum and warty-like lesions on your skin. Whatcha got?
Blastomycosis infection. It grows where migratory birds poop.
You’ve been spelunking in Mammoth Cave, KY, and then two weeks later you’ve got flu-like symptoms. Whatcha got?
Histoplasmosis Grows where there are bats (caves).
You survived a massive earthquake in southern California. A week later, you’ve got a bad flu-like illness. Whatcha got?
Coccidiodomycoses. The earthquake stirred up the desert soil, releasing all the spherule endospores from this fungus.
How do you treat systemic mycoses?
1) DON”T. They’re mostly asymptomatic.
2) If infection persists for more than a month, treat with an AZOLE (Ketoconazole, itraconazole, or fluoroconazole)
3) If it’s really bad, treat with AMPHOTERICIN B
**IC patients are on lifelong azole therapy
Which fungus rapidly grows as a mold with branching 45* angle septate hyphae, commonly seen a lab contaminant but is a severe nosocomial infection (grows in hospital ducts)?
Aspergillus
*think of the septate hyphae forming Acute A’s
This fungus produces broad, nonseptate hyphae that branch at 90* angles, found commonly after environmental disturbances like tornadoes.
Zygomycetes (Mucormycosis infection)
Which mycoses is a fungal/protozoan hybrid that lacks hyphae, cannot be cultured, and uses cholesterol instead of ergosterol in it’s cell membrane?
Pneumocystis jerovici (carinii)
1) How does aspergillus present in asthma and CF patients?
2) Normal patients?
3) Immunocompromised patients?
1) Allergic bronchopulmonary aspergillosis (ABPA)
2) Allergic sinusitis
3) Invasive pulmonary infection
In patients with underlying pulmonary conditions (COPD, TB, etc), what might aspergillosis form in places where lung damage has occured?
Aspergilloma, a “fungal ball”
**presents with severe hemoptysis
How treatable is dessiminated aspergillus infection?
It is almost universally fatal. Usually gets into the CNS and it is then game-over.
Who is most likely to get mucormycosis?
Patients with diabetes mellitus or taking corticosteroids (IC + have acidosis)
How does mucormycosis present?
Acute, very invasive fungal pneumonia or a rhinocerebral form that rapidly leads to coma/death since sinus infections quickly penetrate the brain.
**this stuff looks horrible. Very disfiguring, very bad disease.
How does pneumocystis present?
In the IC patient (usually AIDS) as a diffuse interstitial pneumonia that can quickly asphyxiate the patient.
**used to be #1 cause of death in AIDS, but now it’s rarer due to HAART
How are all the mycoses similarly transmitted?
Inhalation of airborne conidia. No person-person transmission.
How are all mycoses generally diagnosed?
Observation of tissue structures obtained from sputum or bronchoalveolar lavage following treatment with KOH to remove everything but fungal cell wall.
Pneumocystis is different from the others in how it’s diagnosed. How so?
1) Must use bronchoalveolar lavage, not sputum.
2) Cannot be cultured (protozoan nature)
3) Silver-stain to reveal the sporozoite/trophozoite cysts
Which fungus can be detected serologically?
Coccidiodomycosis.
How are aspergillosis and mucormycosis similarly treated?
1) Surgical removal of infection (i.e. the aspergilloma)
2) Max dose Ampho B
3) Caspofungin if ampho resistant
How is pneumocystosis treated?
Why is it treated differently?
1) TMP-SMZ (sulfa’s!) or Pentamidine (anti-protozoal) + oxygen
2) Azoles/Ampho. B cannot work since it does not use ergosterol
