Module 5 Path Continued: Fungi

Question 1

Candida Albicans (moniliasis) is normal flora of what parts of the body?

Answer 1

Mouth, vagina, oral cavity, esophagus

Question 2

what type of individuals typically get candida albicans?

Answer 2

Immunocompromised patients
Babies
elderly
Diabetics

Question 3

In babies where do they typically get candida albicans infections?

Answer 3

Diaper rash so the skin

Question 4

In the vagina, what is the presenation for a patient with candida albicans?

Answer 4

cheesy white vaginal discharge with puritis

additionally females on broad spectrum antibiotics are at risk for yeast infections

Question 5

Candida can invade the blood and go where?

Answer 5

lung, liver, heart and brain and you get abscesses in these four organs

Question 6

when you scrape the pseudomembrane -like off and look under the microscope what do you stain it with and what do you see?

Answer 6

PAS, Silver Stain and Mucicarmime

Budding yeast with pseudohyphae (Chinese letter appearance)

Question 7

What cells do you see in candida albicans?

Answer 7

PMNs + lymphocytes + monocytes + giant cells (mixture of acute and chronic always for fungi)

Question 8

What scenarios is candida albicans considered opportunistic ?

Answer 8

Diabetic patients, immunocompromised and patients on broad spectrum antibiotics

Question 9

Pneumocystis Jiroveci is considered an opportunistic infections in what kind of patients?

Answer 9

Immunocompromised patients with a CD4 count less then 200 (AIDS patients)

Question 10

How does a patient present with P. Jiroveci infection?

Answer 10

low grade Fever, SOB, dry cough (because the cotton candy exudate that is in the alveolar space is too thick to be coughed up), interstitial pneumonia, inflammation and thickening of alveolar wall with sparse mononuclear infiltrate

Question 11

What cells are present in P. Jiroveci infection?

Answer 11

PMNs + lymphocytes + monocytes + giant cells (again mixture of acute and chronic for all fungal infections)

Question 12

What is the best investigation for P. Jiroveci?

Answer 12

Bronchoalveolar lavage (this is how you get the actual sputum from the patient) 
and then silver stain the sputum and therefore fungus stains black and has a black cup shaped  cyst

Question 13

What is located in the alveolar space for P. Jiroveci?

Answer 13

Cotton candy exudate without cells ( just proteins and fibrin)

Question 14

The alveolar wall over time in P. Jiroveci what happens?

Answer 14

Cells (PMNs and lymphocytes and macrophages) overtime the alveolar wall becomes super thick

Question 15

What is the most common cause of death in P. Jiroveci?

Answer 15

Resp Failure due to V/Q mismatch
(ventilation is messed up because exudate is a diffusion barrier, no O2 in and no CO2 out)
so patient O2 levels in blood goes down (hypoxia) and CO2 levels goes up (hypercapnia) and pH in blood goes down (because of resp acidosis)

Question 16

What is the mode of infection in Aspergillus?

Answer 16

Inhalation of aspergillus (mycelial form)

Question 17

There are three types of Aspergillus, each card will go through the type. 1 –>

Answer 17

1. Aspergilloma: fungal ball –> colonize pre existing cavity from TB or a lung abscess or Wegener’s Granulomatosis
   the slide shows the fungal ball. this can happen in immunocompetent ppl

Question 18

2nd type of Aspergillus…

Answer 18

2. Allergic Bronchopulmonary Aspergillosis: type I (IgE from asthma) and type III (IgG and forms antigens to make immune complexes) hypersensitivity
   This is seen in immunocompetent patients with bronchial asthma (IgE) – inhale — colonzies —– causes wheezing, SOB, productive cough, fever —- exacerbation of asthma

Question 19

3rd type of Aspergillus…

Answer 19

3. Disseminated Aspergillosis: Immunocompromised patients get this one
   Angio-Invasive —- attacks the blood vessels and therefore you get thrombosis in the lumen and you get fibrinoid necrosis in the media of the vessel wall and coagulative necrosis of the actual organ

Question 20

What is fibrinoid necrosis?

Answer 20

Media in small or medium vessels gets its oxygen supply from the lumen but if you get endothelial damage and then thrombus in the lumen the media is going to become ischemic and therefore you get fibrinoid necrosis
(media is basically starving for oxygen)

Question 21

What do you stain Aspergillus with?

Answer 21

Well this is fungal so either silver stain, PAS or mucicarmine

Question 22

What does Aspergillus look like on histology?

Answer 22

Slender, septate hyphae that branch at acute angles

Question 23

What is a complication of Apergillus?

Answer 23

Meningitis

Question 24

What are the three Zygomycetes for mucormycosis?

Answer 24

Mucor, Rhizopus and Absidia

Question 25

Mucormycosis affects what types of individuals?

Answer 25

Diabetes who get DKA ( pH is low enough and favors growth of organism)
Opportunistic fungi in immunocompromised patients

Question 26

What is the pathogenesis for mucormycosis?

Answer 26

Inhalation of spores —– tropism for endothelial cells of blood vessels —- angio invasive —- disseminated —- endothelial damage —- thrombosis —– ischemia —- hypoxia —– coagulative necrosis

Question 27

Explain the coagulative necrosis for mucormycosis for the brain

Answer 27

Ischemia —– hypoxia —– coagulative necrosis (So this again will be the first 12-24 hours) —- red infarct
Once you see a hole in the brain then this is 48 hours and therefore this is liquefactive necrosis
Remember that gliosis is 2 weeks later and you are going to see astrocytes

Question 28

What is the most commonly affected part of mucormycosis?

Answer 28

Cerebral hemispheres (Thats why they call it rhino (because it goes through the sinuses) cerebral mucormycosis) 
In the picture in lab it shows the cerebellum affected but that is not the most common spot

Question 29

What other areas besides the brain can mucormycosis affect?

Answer 29

GI ( red infarct –coagulative necrosis — splenic flexures (watershed of GI)
Lungs
Sinuses

Question 30

What are the signs of mucormycosis?

Answer 30

Sero-sangrenous nasal discharge (Aka bloody discharge), fever, pain, and headache and rhino-facial-palatal necrosis

Question 31

What is the best investigation for mucormycosis?

Answer 31

Biopsy with PAS or silver stain
in the lab histology picture your looking at the blood vessel wall and again this type of necrosis would be fibrinoid necrosis

Question 32

What will you see on histological stain of mucormycosis?

Answer 32

Broad organisms with non septate hyphae branching at right angles

Question 33

Cryptococcus neoformans (Torulosis), what is the etiology and susceptible population?

Answer 33

• etiology - inhalation of soil with pigeon droppings

- Opportunistic infection in immunocompromised AIDS patients with CD4 less then 100

Question 34

Quick recap on AIDS, CD4 and infection

Answer 34

AIDS patient CD4 less then 50 = CMV retinitis
AIDS patient CD4 less then 200 = P. Jiroveci
AIDS patient CD4 less then 100 = crytococcal infection

Question 35

What is the pathogenesis for Crytococcus neoformans?

Answer 35

Spores in pigeon droppings — inhalation —– granulomas with giant cells
spores can go into the lungs and brain
if disseminated then meningitis

Question 36

In crytococcus Neoformans, if this fungus becomes disseminated it can lead to meningitis, what are the symptoms?

Answer 36

NO FEVER OR NECK STIFFNESS
headache, increased intracranial pressure, projectile vomiting ( caused by the increased intracranial pressure) and photophobia and blurred vision
symptoms are super vague because these are immunocompromised patients

Question 37

What would you see in the CSF of a patient with crytococcus neoformans?

Answer 37

MIXED (very minimal though because again these patients are immunocompromised so its hard for them to mount a response)
glucose goes down
protein will be elevated (highly)

Question 38

What are the best investigation for crytococcus neoformans?

Answer 38

1. Most accurate is latex agglutination looking for the antibodies
2. CSF – india ink stains polysaccharide of crytococcus — organism appears as clear halo — negative staining

Question 39

On autopsy, what do you find in a patient with crytococcus neoformans?

Answer 39

Use either a silver stain, PAS or mucicarmine (stains organism red in perivascular space or virchow robbin space)..directly stains the organism so this is not a negative stain
The brain will have cystic spaces called soap bubble lesions

Question 40

What are the three dimorphic fungi?

Answer 40

1. Coccoides Immitis – thick walled and non budding spherules (largest pathogenic fungus, southwestern and western US and Valley fever )
2. Blastomyces Dermatidis: round (broad based budding and endemic area overlaps with histoplasma)
3. Histoplasma capsulatum