Ambler Fungi

Question 1

general info re: fungi. Cell membrane contains what? Cell wall contains what?

Answer 1

Eukaryote
Obligate aerobes with some facultative anaerobes
Require carbon from environment (ie detritus)
Cell membrane has ergosterol which is site of some antifungal activity
Cell wall has chitin – a long chain polymer of n-acetylglucosamine (derived from glucose)
most can cause disease anywhere in the body

Question 2

enzyme common to fungal walls

Answer 2

beta(1,3) glucan synthase. Helps create big cell wall with cross-linking. Inhibition of this will cause cell wall destruction.

Question 3

Yeasts

Answer 3

candida, cryptococcus, malassezia, trichosporon

Only yeast form. Does not ‘mold’
Not uncommon infection when considering candidiasis

Question 4

dimorphs

Answer 4

histoplasma, blastomyces, coccidioides, paracoccidioides, penicillium, sporothrix

Question 5

molds

Answer 5

aspergillus, zygomycetes (mucor, rhizo, absidia), fusarium, pseudoallerscheria boydii/ scedosporium apiospermum

Question 6

sites of antifungal action

Answer 6

flucytosine and griseofulin act at the nucleus; evefything else acts on the cell wall (azols, amphotericin B, nystatin, echinodandins)

Question 7

most common bloodstream fungal infection

Answer 7

candida

Question 8

Candidiasis

Answer 8

Candida only endogenous fungal organism.
Found in GI and GU tracts
Invade when host imbalance/immune system dysregulation occurs.
a (1-3)β-D-Glucan test (Fungitell®) available

usually NOT a respiratory pathogen

Question 9

Mucocutaneous Candidiasis

Answer 9

Orophayngeal/Esophageal candidiasis
>90% C. albicans
HIV or other immune depressed state
?Abx but more so after systemic steroids

Vulvovaginitis
Non immune depressed state
Post Abx

Cutaneous candidiasis
Intertriginous areas. Abx, steroids, overall ill.

Question 10

Systemic Candidiasis

Answer 10

Bloodstream (candidemia)

• 4th most common nosocomial bloodstream infection. 22-38% mortality even with tx!
• Can be seen in severe immunocompromised (ie acute leukemia treatment or bone marrow xplant)
• Usually do not see manifestations until significant neutrophil recovery.
• Sticky. Rule is really remove catheters/devices but this has been slightly questioned recently.

Question 11

viruses and fungi are battled by

Answer 11

more of the cytotoxic system: T cells, lymphocytes.

Bacteria, on the other hand, by neutrophils.

Question 12

candida susceptibilities

Answer 12

albicans – most common, “germ tube”. Fluconazole tx.
glabrata - 2nd most common, flu experienced
parapsilosis – think central catheter
krusei – heavy fluconazole use/think heme malignancies
lusitaniea – not mentioned but ampho-b R

Question 13

Hepatosplenic (Chronic disseminated) Candidiasis

Answer 13

Seen with neutrophilic return from longstanding neutropenia.

High fever and usually RUQ pain with n/v and anorexia

Question 14

Endophthalmitis

Answer 14

Candidemia = eye exam
May need intraocular antifungals esp if it disseminates into posterior chamber or resistant species
Exam with ‘cotton ball’ appearance.

Question 15

Cryptococcus speces

Answer 15

C. neoformans – somewhat ubiquitous. HIV!
CD4 less than 200
C. gattii- seems more aggressive and also in non HIV people. NW USA/Vancouver
Capsule.
causes pulmonary, meningitis, skin, bone and joint

Question 16

cryptococcus

Answer 16

Capsule.
causes pulmonary, meningitis, skin, bone and joint

Pulmonary can be self limited.
Meningitis (more common HIV) causes a relatively non-inflammtory process with inc pressure.
Treatment is Ampho-B +/- flucytosine followed by fluconazole for a long time (6-12 months to life long)

India ink is a good prep that shows the capsule

Question 17

Malassezia furfur

Answer 17

board question is “spaghetti and meatballs” in a patient getting longterm TPN.
Also causes tinea veriscolor (pityriasis versicolor) with hypopigmentation
may play important role in seborrheic dermatitis

Question 18

Histoplasmosis

Answer 18

Histoplasma capsulatum
(2-4 μm dia)
soil, spore inhalation and flying animal guano
caves, chicken coops
“Ohio River Valley”,”Mississippi Valley”
diagnosis by ELISA but not consistent between labs. Will grow on culture.

Acute Pulmonary illness 		60%
Rheumatologic syndromes	10%
Pericarditis				10%
Chronic Pulmonary Symptoms	10%
Disseminating disease		10%
Fibrosing mediastinitis

Question 19

Blastomycosis

Answer 19

Blastomyces dermatididis
soil/environmental; similar to histo geography
size histology (8-15μm)
Pulmonary with infiltrates 60-70%
Cutaneous 40-50%
Osteoarticular 10-15%
GU (prostate) 10%
CNS

Question 20

Coccidioidomycosis immitis

Answer 20

“Valley Fever”
majority self limited respiratory illness
60% asymptomatic
40% with symptoms
can progress to pneumonia, nodules, cavities.
also can disseminate to skin, bones, tendons, CNS

Question 21

Paracoccidioides brasiliensis

Answer 21

South American Blasto
usually self-limited. can lay dormant until immunosuppression
more common to see non-lung symptoms even though lung portal of entry
bone marrow, organomegaly and Lymphadenopathy common. also intra-abdominal issues
CNS 10-25%

Question 22

Sporothrix schenckii

Answer 22

nodular lymphadenitis of the extremity in a rose gardener.
1-10 wk incubation
4 categories
lymphocutaneous; 75%
fixed cutaneous
disseminated
extracutaneous

Question 23

What is the function of the black/brown molds?

Answer 23

To return organic material from whence it came

Question 24

Aspergillus

Answer 24

ubiquitous.
major infection in severely immunocompromised and the fungus we worry about in neutropenics
lung portal of entry.
has an aspergillus galactomannan test
45 deg angle branching

Question 25

Acute Bronchopulmonary Aspergillosis (ABPA). AKA “Farmer’s Lung”

Answer 25

an allergic response/hypersensitivity pneumonitis to the spores/mold
cough, +/- fever, wheezing, productive sputum
High IGE levels ( more than 500)!; also goes with eosinophilia
treatment is avoidance, steroids like prednisone, +/- antifungal as this has been debated forever but it seems it may help in pts who need high dose or prolonged steroids

Question 26

Zygomycosis

Answer 26

Generally very fast growing and high mortality (nicknamed: lid-poppers)
Mucor, Rhizopus, Absidia are more commonly seen but this may be changing as there are numerous pathogenic zygomycetes.
Right angle (90 deg) branching hyphae *
Typical patient is an uncontrolled DM with sudden onset rhinocerebral necrotizing disease
Also can effect lung and GI
Treatment usually surgery, more surgery and then maybe some antifungal for good measure.

Question 27

Hyalohyphomycosis

Answer 27

Fusarium
Penicillium
Scedosporium/Pseudoallerscheria
others

Question 28

Fusarium

Answer 28

In normal host we see it in fungal keratitis as well as some other superficial infections
occasionally deep infections seen

more commonly we see in severely neutropenic hosts with 60-80% death

disseminated/fungemia*
skin*, pneumonia including hemoptysis

Question 29

sinus disease in uncontrolled diabetic? think…

Answer 29

mucor

cut to cure.

Question 30

old person suddenly develops asthma? think…

Answer 30

aspergillus

Question 31

Scedosporium apiospermum/Pseudoallersheria boydii

Answer 31

soil and contaminated water.
immunocompromised hosts tend to get CNS infection and if not aggressively treated upfront, has 75% mortality
Respiratory, keratitis/endophthalmitis and skin/bone infections can be seen.
also been implicated in sinusitis and lymphadenitis
Scedo is asexual (perfect) form and Pseudo is sexual (imperfect) form.

Question 32

Dermatophytes

Answer 32

Likes Keratin so think of nails, hair and skin.
Tinea and Trychophyton but others as well
“Ringworm”
Tinea sp. and called by descriptors
Tinea capitis – a cause of cradle cap-seen in young
Tinea pedis- athletes foot
Tinea corporis- body
Tinea cruris- jock itch
Tinea rubrum causes Majocchi’s granuloma
Tinea unguium – nails(onychomycosis)

Question 33

Pneumocystis jiroveci (carinii)

Answer 33

is it a fungus, no it’s a bacteria, wait. I think it really is a fungus…….
Need to know since it is one of the OI’s in HIV (and other immunocompromised pts) that still shows up regularly.

ubiquitous.
lung infection, interstitial pattern, esp with CD4 less than 200
dry hypoxic cough. LDH elevation common
often diagnosis of HIV/AIDS
treatment is antiBIOTIC, not antifungal. sulfa/tmp (Bactrim®).
dx with silver stain, dIF, pcr, (1,3)β-D-Glucan