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Fungi and Parasites > Opportunistic Fungal Infections > Flashcards

Opportunistic Fungal Infections Flashcards

1
Q

List the opportunistic fungal infections (5)

A 
Candida albicans
Aspergillus fumigatus
Cryptococcus neoformans
Mucormycosis
Pneumocystis jirovecii
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2
Q

What is the most common cause of opportunistic mycoses?

A

Candida

If you have a patient who is neutropenic, has HIV/AIDS, or is diabetic and you suspect fungal infection - think Candida

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3
Q

Candida dimorphism

A

Yeast in the cold
Mold in the heat (dafuq??)

Forms pseudohyphae and budding yeast at 20C.

Forms germ tubes (hyphae) at 37C

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4
Q

What fungal infections are patients with chronic granulomatous disease especially susceptible to?

A

Candida and Aspergillus - catalase (+)

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5
Q

Where is Candida normally found?

A

It is normal GI flora (including oral cavity). It is present in about 40% of people. As long as host is immunocompetent it doesn’t usually pose any problems

Since it is so common in normal people, it commonly contaminates sputum cultures so WATCH OUT

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6
Q

Candida infection presentations (5)

A

1) Diaper rash in a characteristic distribution due to the heat and humidity within baby’s diaper
2) Oral candidiasis (thrush) is seen in immunocompromised patients or those using oral steroids.

Oral steroids (inhalers for example) must be followed by oral rinsing to avoid candidiasis

White patches form in mouth that can be scraped off (in leukoplakia you cannot scrape it off)

KOH is used to prep oral cavity scrapings to diagnosis oral candidiasis

3) Candidal esophagitis - white patches/pseudomembranes in esophagus

Associated with AIDS - it’s an AIDS-defining illness (CD4 4.5 it is NOT candida

Candidal vulvovaginitis is common in diabetes and in people who use antibiotics and birth control pills

5) Endocarditis - candida is an important cause of endocarditis

Commonly seen in drug users - Candida is often found growing in certain kinds of heroin. When injected IV, it seeds heart valves. The first valve they would encounter is tricuspid (commonly infected in IV drug users)

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7
Q

Candida Tx

A

Azoles for minor infection
Amphotericin B for severe, disseminated (in immunocompromised)

Oral or esophageal = Nystatin - a liquid taken as a swish/spit or swish/swallow respectively

For disseminated infection, if Candida is resistant to amphotericin, give capsofungin

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8
Q

Aspergillus flavus

A

Produces aflatoxins (associated with peanuts) that are extremely carcinogenic - esp for hepatocellular carcinoma

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9
Q

What does aspergillus look like?

A

Hyphae form acute angles in their branching

Septated

Aspergillus forms conidiophores with fruiting bodies - important for transmission. These conidiophores are released into the air and inhaled by humans. Kind of looks like the end of asparagus.

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10
Q

What are the 3 infections caused by Aspergillus?

A

1) Allergic Bronchopulmonary Aspergillosis - ABPA
2) Aspergillomas
3) Angioinvasive Aspergillosis

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11
Q

Allergic Bronchopulmonary Aspergillosis presentation

A

Caused by Aspergillus

Type 1 hypersensitivity

Causes wheezing, fever, migratory pulmonary infiltrate*

ABPA is associated with asthma and CF

Blood tests show high IgE

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12
Q

Aspergillomas presentation

A

Caused by Aspergilus

Responsible for formation of aspergillomas - fungus balls

These are solid balls of fungus within the lungs

People who are susceptible are those who may already have cavities in lungs (people with TB or Kleb Pneumo)

Aspergillomas are gravity dependent* - in upright CXR, fungus balls will be at bottom of the cavities

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13
Q

Angioinvasive aspergillosus

A

Worst infection caused by aspergillus

Affects the immunocompromised (Patients with neutropenia from leukemia/lymphoma)

Invades blood vessels and disseminates quickly throughout body.

Fever. Cough w/ hemoptysis.

Invasion of kidneys leads to kidney failure

Endocarditis

Ring enhancing lesions in brain

Could present with “seizures/focal deficits, has a cough and symptoms of pneumonia and in the past had TB” - Ring enhancing lesions gives us Aspergillus

Infection can also spread to paranasal sinuses and may cause necrosis around the nose (also seen in mucor)

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14
Q

Aspergillus Tx

A

Less serious - Voriconazole

Aspergillomas need to be surgically debrided in addition to treatment

For angioinvasive you need Amphotericin B

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15
Q

Cryptococcus capsule

A

It is heavily encapsulated

Capsule is made up of repeating polysachharide capsular antigens - main virulence factor making it anti-phagocytic - basis for a dx test

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16
Q

Cryptococcus transmission

A

Often in pigeon droppings/soil

After it is inhaled it settles in lung as primary focus

17
Q

Random unique fact about cryptococcus

A

It is urease (+)

18
Q

Who is most at risk for a cryptococcus infection?

A

It is an opportunistic infection!

Immunocompromised - esp in HIV, high dose steroids, malignancies

19
Q

What is the #1 cause of fungal meningitis?

A

Cryptococcus

20
Q

Cryptococcus presentation

A

Pulmonary symptoms:

Cough, dyspnea, other serious lung infections

Unlikely to be caught at this stage though and will progress to more worrisome symptoms

Can spread to CSF and cause meningitis - can lead to permanent neuro issues/death

Summary: Fever, pneumonia, meningitis

After invading brain, crypto has unique brain findings - Soap Bubble Lesions in gray matter of brain = crypto meningitis

21
Q

Cryptococcus diagnosis

A

Culture on Sabouraud agar (ALL FUNGI)
- This takes weeks to come back though

Use bronchopulmonary washings to diagnose - tissue samples are stained with mucicarmine (red) or methanamine silver stains

Lumbar puncture to dx crypto meningitis:

  • CSF stained with India Ink (This is a negative staining technique - background dark, organism transparent)
  • We will see the organism and its capsule as a halo

Latex Agglutination Test - detects the polysaccharide capsular antigen and causes agglutination - it detects its repeating capsular antigen

  • More sensitive
22
Q

Cryptococcus Tx

A

For crypto meningitis: Joint therapy with amphotericin B + Flucystosine

Followed by maintenance therapy with fluconazole

23
Q

What 2 fungi is mucormycosis caused by?

A

Mucor and Rhizopus (a bread mold)

24
Q

Mucormycosis transmission

A

Spore inhalation

25
Q

Who is most at risk of mucormycosis infection?

A

It is opportunistic! Immunocompromised (leukema and neutropenia especially) and diabetics

26
Q

What does mucormycosis look like?

A

Hyphae are not septated and have wide-angle (90 degrees) separation - looks like a tire iron

27
Q

Mucormycosis pathogenesis and presentation

A

After inhalation, the fungi like to proliferate in blood vessel walls, especially where there is excess glucose and ketones - explains why diabetics are at heightened risk

DKA is most common predisposing factor to this fungus

After invading blood vessels, the fungus likes to invade cribiform plate of skill and enter the brain

This causes necrosis of tissues leading to rhinocerebral mucormycosis and eventually to frontal cortex abscesses.

Patients present with black eschar on face and in nasal cavity. Prognosis if this is present is very poor. Necrosis of nasal cavity and eyes - bc it spreads so quickly through blood vessels it likely means that it has spread already to deep parts of brain causing neuro deficits and death

28
Q

What is the most common predisposing factor for mucormycosis infection?

A

DKA

29
Q

Mucormycosis Tx

A

Surgical debridement of dead tissue

Amphotericin B for medical management

30
Q

Pneumocystis transmission

A

respiratory transmission

31
Q

PCP presentation

A

Can infect normal people, but usually asymptomatic. Immunocompromised people are the only ones with signs of infection

PCP is an AIDS-defining illness CD4

32
Q

PCP Diagnosis

A

Confirm by getting good sample with brochoalveolar lavage (lung biopsy would work too, but it’s more invasive)

Get the sample, do methamine silver stain on tissue - PCP will look like disc-shaped yeast (ovoid)

33
Q

PCP Tx

A

Prophylaxis in HIV+ patient with CD4

Fungi and Parasites (5 decks)

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