Ambler Fungi Flashcards
general info re: fungi. Cell membrane contains what? Cell wall contains what?
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
enzyme common to fungal walls
beta(1,3) glucan synthase. Helps create big cell wall with cross-linking. Inhibition of this will cause cell wall destruction.
Yeasts
candida, cryptococcus, malassezia, trichosporon
Only yeast form. Does not ‘mold’
Not uncommon infection when considering candidiasis
dimorphs
histoplasma, blastomyces, coccidioides, paracoccidioides, penicillium, sporothrix
molds
aspergillus, zygomycetes (mucor, rhizo, absidia), fusarium, pseudoallerscheria boydii/ scedosporium apiospermum
sites of antifungal action
flucytosine and griseofulin act at the nucleus; evefything else acts on the cell wall (azols, amphotericin B, nystatin, echinodandins)
most common bloodstream fungal infection
candida
Candidiasis
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
Mucocutaneous Candidiasis
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.
Systemic Candidiasis
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.
viruses and fungi are battled by
more of the cytotoxic system: T cells, lymphocytes.
Bacteria, on the other hand, by neutrophils.
candida susceptibilities
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
Hepatosplenic (Chronic disseminated) Candidiasis
Seen with neutrophilic return from longstanding neutropenia.
High fever and usually RUQ pain with n/v and anorexia
Endophthalmitis
Candidemia = eye exam
May need intraocular antifungals esp if it disseminates into posterior chamber or resistant species
Exam with ‘cotton ball’ appearance.
Cryptococcus speces
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
cryptococcus
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
Malassezia furfur
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
Histoplasmosis
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
Blastomycosis
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
Coccidioidomycosis immitis
“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
Paracoccidioides brasiliensis
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%
Sporothrix schenckii
nodular lymphadenitis of the extremity in a rose gardener. 1-10 wk incubation 4 categories lymphocutaneous; 75% fixed cutaneous disseminated extracutaneous
What is the function of the black/brown molds?
To return organic material from whence it came
Aspergillus
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
Acute Bronchopulmonary Aspergillosis (ABPA). AKA “Farmer’s Lung”
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
Zygomycosis
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.
Hyalohyphomycosis
Fusarium
Penicillium
Scedosporium/Pseudoallerscheria
others
Fusarium
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
sinus disease in uncontrolled diabetic? think…
mucor
cut to cure.
old person suddenly develops asthma? think…
aspergillus
Scedosporium apiospermum/Pseudoallersheria boydii
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.
Dermatophytes
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)
Pneumocystis jiroveci (carinii)
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
