This site is 100% ad supported. Please add an exception to adblock for this site.

Block V, Week VI


undefined, object
copy deck
what is the "hygiene hypothesis?"
the idea that at a young age we are exposed to nonpathogenic organisms and make antibidies to them. These antibodies can crossreact with pathogenic organisms encountered later in life. When a child grows up in a clean, hygenic house it is hypothesized that they are more prone to infection.
regarding AIDS:
1. what is the "top" viral opportunistic infection?
2. what is the "top" bacterial opportunistic infection?
1. Cytomegalovirus (CMV) retinitis
2. MAC (mycobacterium avium-intracellular complex)
regarding AIDS:
1. what is the "top" protozoal oppportunistic infection?
2. what is the "top" fungal opportunistic infection?
1. Toxoplasmosis of the brain
2. PcP - Pneumocystis jirovecii pneumonia
which bacterial opportunistic infection is very similar to TB but only causes symptoms in the immunocompromised host?
MAC (Mycobacterium avium-intracellular complex)
what are 6 characteristics of fungi?
1. eukaryotic
2. non-photosynthetic
3. chitin cell walls
4. Spores (asexual or sexual)
5. can be single celled (yeast)
6. can be filamentous (molds, hyphae, mycelium)
what are the 4 classes of fungi?
1. Ascomycetes
2. Basidiomycetes
3. Zygomycetes
4. Deuteromycetes
what are the sexual spores of Zygomycetes called and are they internal or external spores?
Zygospores (external)
what are the asexual spores of Zygomycetes called and are they internal or external spores?
Sporangiospores (internal)
what are the sexual spores of Ascomycetes called and are they internal or external spores?
Ascospores (internal)
what are the asexual spores of Ascomycetes called and are they internal or external spores?
Conidiospores (external)
"ascus" - "little sac"
what are the sexual spores of Basidiomycetes called and are they internal or external spores?
Basidiospores (external)
"basidio" = stick
what are the asexual spores of Basidiomycetes called and are they internal or external spores?
Conidiospores (external)
What are the asexual spores of Deuteromycetes called and are they internal or external spores?
Conidiospores (external)
In summary:which classes of fungi have asexual spores that are CONIDIOSPORES and are EXTERNAL?
(all but Zygomycetes)
How would a fungal disease...
1. cause allergies?
2. manifest in the skin?
3. manifest in the respiratory system?
1. airborne spores
2. athelete's foot, ringworm
3. similar to and often confused w/ TB
How does a KOH mount help us identify fungi?
the acid disintegrates the tissue, leaving only the fungal hyphae to see.(this is due to acid resistance by their chitin walls)
what is the name of the stain that causes fungi to fluoresce green or blue-green?
Calcofluor white
India Ink (nigrosin) is useful to identify which fungi in which fluid?
THE CAPSULE OF Cryptococcus neoformans in CSF
India ink is essentially what kind of stain? (what does it "pick out")
India ink is a negative stain for fungal capsules.
What does PAS (Periodic Acid Schiff) stain?
PAS stains carbohydrates in the chitin cell wall
What color do fungi stain in a Gomori-Silver stain?
black or deep brown
What are the 6 antifungal antibiotics available?
1. Amphotericin B (and derivatives)
2. 5-fluorocytosine
3. Azoles
4. KI
5. Topicals
6. Griseofulvin
What is the MOA of amphotericin B?
destroys membrane function by binding sterols
What is the drawback of amphotericin B?
(be specific)
(kidneys have lots of sterols)
what are the two derivatives of amphotericin B?
1. ABLC (Amphotericin B Lipid Complex)
2. ABCD (Amphotericin C Colloidal Dispersion)
What are the advantages of using amphotericin B derivatives (ABLC, ABCD) instead of amphotericin B?
less nephrotoxicity
Which fungus is ABCD as effective as amphotericin B against?
1. what is the MOA of 5-fluorocystine?
2. what are the advantages and drawbacks?
1. Inhibits DNA synthesis
2. less toxic,
only effective against a limited range of fungi.
Name 2 commonly used Azoles
MOA of Azoles?
inhibits ergosterel synthesis
(ergosterel is specifically made in the fungal membrane)
What is the only organism KI is effective against?
1. Topicals are good against?
2. example of a topical?
1. dermatophytoses
2. tolnaftate
What is the name of the oral drug used for severe systemic dermatophytoses?
MOA of Griseofulvin?
interferes with microtubule function
1. which organism causes Pneumocystis pneumonia (PcP)?
2. what is significant about this organism?
1. Pneumocystis jirovecii
2. It only causes pneumonia in immunocompromised persons.
what is a typical microscopic observation seen when diagnosing PcP?
dark black cysts in lung
(seen with Grocott silver stain)
what is the recommended treatment for PcP?
cotrimoxazole or pentamidine
which antifungal can be administered prophylactically to prevent PcP?
Along with PcP, what is one of the most frequent fungal diseases?
(Candida albicans ~60%)
Structural characteristics of Candidiasis?
pseudomycelial form
"germ tube" formation at 37 deg.C
what is the normal habitat/reservoir for Candida?
large intestine
what three lab tests are used to diagnose Candidiasis?
1. germ tube test
2. cornmeal test
3. sugar assimilation
what is the name of the Candidiasis infection in the...
1. mouth
2. Skin
3. Vagina
4. corners of mouth
1. Thrush
2. Cutaneous Candidiasis (dermatocandidiasis)
3. Vaginitis
4. perleche
What is the treatment for:
1. Thrush
2. Cutaneous candidiasis
3. Systemic candidiasis
1. restore normal flora (lactobacilli in yogurt)
2. topical Tx: clotrimazole or nystatin
3. Amphotericin B
why is Candida albicans considered an opportunistic fungi?
in the immunocompromised person it can cause systemic Candidiasis
Cryptococcosis usually begins with _1__ and can spead to the __2__ or __3__ to cause __4__ or __5__.
1. lung infection
2. blood
3. lymph
4. meningitis
5. skin lesions
what is the treatment regimen for cryptococcosis?
- what for lung inf. and meningitis
- what for skin lesions
- Amphotericin B (lung infection and meningitis)
- fluconazole (skin lesion)
when cryptococcosis is seen in the clinic what kind of suspicion should be raised?
80-90% of cases worldwide
>50% of cases in U.S.
where is Cryptococcosis more common than PcP as an opportunistic pathogen?
Africa and Southeast Asia
what is the habitat/reservoir of Cryptococcosis neoformans?
pigeon or other bird droppings
eucalyptus trees
describe the physical characteristics of Cryptococcus neoformans
filamentous mycelium at room temp.

at 37 deg. C yeast produces a VERY LARGE CAPSULE (this capsule is easily seen with India ink negative stain)
1. What is the method of transmission for Cryptococcosis?
2. What contributes to its virulence?
1. inhalation of spores
2. antiphagocytic capsule
How is Cryptococcosis diagnosed in the lab?
1. in meningitis cases: direct examination of CSF
2. in pneumonia cases: direct examination of sputum and tissue
3. brown colonies on birdseed (niger) agar
Which class of fungi (1) and specific genera (2) cause phycomycosis (mucormycosis)?
Fungi - Zygomycetes
Genera - Rhizopus, Mucor
1. Which organism causes Aspergillosis?
2. Describe the organism structure
3. Which other fungal organism has a similar structure?
1. Aspergillus fumigatis
2. structure - filamentous "bread mold"
3. Penicillin
1. What is a potential complication of Aspergillosis?
2. How often does this occur in Aspergillosis cases?
1. spread to heart and CNS
2. 25% of cases
what would you prescribe to treat Phycomycosis, Aspergillosis and Penicillinosis?
Amphotericin B
a systemic rash that is an allergic reaction (to circulating antigen that originated from a primary dermatophyte infection) is known as?
dermatophytid (ID) reaction
In diagnosing a dermatophytosis, which causative organism will show up on a PAS stain?
Pityriasis versicolor
Which species of fungi fluoresces under a Wood's light?
fill in the following for the Microsporum species:
1. Infection site
2. # of Macroconidia
3. wall type of macroconidia
4. # of Microconidia
1. skin, hair
2. lots
3. thick, rough
4. lots
fill in the following for the Trichophyton species:
1. Infection site
2. # of Macroconidia
3. wall type of macroconidia
4. # of Microconidia
1. skin, hair, nails
2. few
3. thin, smooth
4. few
fill in the following for the Epidermophyton species:
1. Infection site
2. # of Macroconidia
3. wall type of macroconidia
4. # of Microcondia
1. skin, nails
2. in 2's and 3's
3. thick, smooth
4. none
What are the three classes of dermatophytes?
1. Microsporum
2. Trichophyton
3. Epidermophyton
Describe the hallmark symptoms of Sporotrichosis
"Gardener's disease"
1. begins as a primary lesion, usually on hands or feet
2. chain of lesions move along the lymphatics up the arm
what is the etiologic agent of Sporotrichosis?
Sporothrix shenckii
Describe the morphology of Sporothrix shenckii
filamentous hyphal form at room temp. ("floret" conidiospores)
"cigar" form yeast, often in "cigar packets"
Chromomycosis is often confused with what subcutaneous mycosis because they present similarly?
Bacterial mycetoma
what is the clinical presentation of both chromomycosis and bacterial mycetoma?
large, distended swelling of the infected area
What are the casuative agents of Chromomycosis (2) and what type of fungi are they?
1. Cladosporium
2. Phialophora
Both are "dematiaceous" (dark colored) fungi
What is the main diagnostic feature of chromomycosis?
can see brown to black hyphae without using any tissue stain
which organism is responsible for bacterial mycetoma (namely Madura foot and Lumpy jaw)
Actinomyces israelii
what are the diagnostic features of (A. israelii caused) bacterial mycetoma?
1. "sulfur granules" (bacterial colonies)are present in the exudate and visible to the human eye
2. dark filaments seen microscopically
which two stains are commonly used in diagnosis of (A. israelii caused) bacterial mycetoma?
1. Brown & Benn stain
2. Gomori methamanine silver stain
how can you tell the difference between a bacterial mycetoma caused by Actinomyces israelii or Nocardia asteroides?
A. isrealii - anaerobic
N. asteroides - aerobic
(both are Gram + branching rods)
what are the 2 fungal caused subcutaneous mycoses?
1. Sporotrichosis
2. Chromocycosis
what are the 3 fungal caused systemic mycoses?
1. Histoplasmosis
2. Blastomycosis
3. Coccidiomycosis
what are the general morphological characteristics of organisms causing systemic mycosis?
filamentous at room temp.
yeast form at 37 deg. C
what is the general method of transmission of systemic mycosis infections?
*no known human to human transmission*
which fungus causes Histoplasmosis?
Histoplasma capsulatum
regarding H. capsulatum:
1. at room temp. it resembles?
2. at 37 deg. C it resembles a yeast that divides how?
1. "tuberculate" macroconidia (looks like thing on the end of a mace)
2. with a narrow neck between daughters
what contributes to the virulence of Histoplasma capsulatum? (how does it infect the host cells)?
it is an intracellular macrophage parasite
what is the habitat/reservoirs of H. capsulatum?
bird droppings
where is H. capsulatum geographically prevalent?
in the Midwestern U.S.
(around Mississippi and Ohio rivers)
Histoplasmosis often begins as __1___. It can then disseminate to which organs?
1. pneumonia or TB mimic (flu-like symptoms)
2. organs with macrophages (blood, bone marrow, spleen, liver, lung)
what is the recommended treatment for Histoplasmosis?
Amphotericin B
What is the organism that causes Blastomycosis?
Blastomyces dermatitidis
what is the dimorphic difference between blastomycosis and histoplasmosis?
at 37 deg. C:

histo-narrow neck between daughters
blasto-thick neck between daughters (Blasto=BroadBasedBuds)
how does blastomycosis present?
1. pulmonary, "flu-like" symptoms
2. acute pneumonia or TB mimic
3. dissemination (cutaneous or any other organ - bones, urogenital, CNS etc)
what is the organism that causes Coccidioidomycosis?
Coccidioides immitis
describe the morphology of C. immitis
filamentous arthrospores (barrel-shaped spores in hyphae) at room temp.
spherules (large spheres filled with spores)seen at body temp.
where is Coccidioidomycosis commonly seen and where is it prevalent?
commonly seen (free-living) in SW US deserts
prevalent in San Jaoquin Valley, CA (hence "San Joaquin Valley Fever")
what is the mode of transmission of coccidioidomycosis?
VERY EASILY AEROSOLIZED, arthrospores are inhaled, cause spherules to grow in the lung.
describe the clinical course of coccidiomycosis
1. "San Joaquin Valley Fever" - pneumonia, flu-like symptoms
2. can disseminate to any organ, VERY DANGEROUS
what is notable about coccidioidomycosis?
what is the diagnostic feature of coccidioidomycosis?
spherules in sputum
what is the preferred treatment for all the systemic mycoses?
Amphotericin B
define mycelium
the mass of hyphae that make up the body of a fungus
what is an arthrospore?
a spore resulting from the fragmentation of a hypha
define conidia
asexual spores produced by fungi
(have Micro- and Macro-)
What are the four forms of possible transplant rejection?
1. Hyperacute
2. Acute
3. Chronic
4. Graft-vs-host
which immunodeficiency disorder is caused by a failure of B cells to mature?
Brutons agammaglobulinemia
what is the heredity of Bruton's agammaglobulinema?
X linked recessive
Boys get it
what is the cause of Bruton's agammaglobulinema?
mutation in tyrosine kinase - B cells never mature
Hallmark of Bruton's agammaglobulinema?
recurrent bacterial infections
In Bruton's agammaglobulinema: Describe B cell levels in
1. serum
2. bone marrow
3. What about T cells?
4. What about plasma cells?
1. Decreased
2. B cell precursors are present
3. T cells are uneffected
4. Plasma cells are nonexistant
What is the treatment for Bruton's agammaglobulinema?
Prophylactic IV Immunoglobulin
Describe symptoms seen in an IgA deficiency (4)
(remember most patients are asymptomatic)
1. low levels of serum and secretory IgA
2. recurrent pulmonary infections, diarrhea
3. allergies
4. other autoimmune diseases
What is the thing to watch out for in patients with an IgA deficiency?
Many patients have serum Antibodies to IgA: this can cause a serious rxn. in tranfusion of blood with normal IgA antibodies in it.
What are the serum B cell levels in CVID?
B cells just don't differentiate into plasma cells
compare the pathology of lymphoid follicles seen in:
2. Bruton's agammaglobulinema
1. hyperplastic lymphoid follicles
2. NO lymphoid follicles
describe the pathophysiology of hyper-IgM syndrome
- T cell disorder
- failure to isotype switch, therefore the only antibodies made are IgM
- results in immunodeficiency
what is the hallmark presenting symptom of hyper-IgM syndrome?
Recurrent pyogenic infections
in hyper-IgM syndrome describe:
1. the serum B and T cell levels
2. Serum of the levels of different types of antibodies?
1. B and T cells levels normal
2. Increased IgM
very little IgA, IgE, IgG
what is the cause of DiGeorge syndrome (Thymic aplasia)
Thymus and parathyroid glands fail to develop (because 2nd and 3rd pharyngeal pouches did not develop correctly)
Result: No T cells and hypocalcemia
what do patients with DiGeorge syndrome (thymic aplasia) present with?
recurrent fungal and viral infections (due to loss of T cell mediated immunity)
describe severe combined immunodeficiency (SCID)
NO T cells or B cells
therefore a defect in humoral and cell mediated response
What is the treatment for an individual with SCID?
Bone marrow transplant
describe the pathology of Wiscott-Aldrich Syndrome
X linked defect
- loss of cell mediated and humoral immunity
- still have a thymus
in Wiscott-Aldrich Syndrome what are the levels of the following:
1. IgM
2. IgG
3. IgE
4. IgA
1. low
2. normal
3. elevated
4. elevated
presenting symptoms of a patient with Wiscott-Aldrich Syndrome?
(also thrombocytopenia)
what are the symptoms of a person who has a deficiency of C5,6,7,8,9 (complement mediators)?
Recurrent Neisserial infections
what are the symptoms of a person who has a deficiency of C1 inhibitor?
Hereditary angioedema
(overactive complement)
compliment defends against what kind of bacteria?
Gram negative
which antibodies activate the classic pathway of compliment?
(GM makes CLASSIC cars)
what activates the alternate pathway of compliment?
molecules on the surfaces of microbes (esp. endotoxin)
which type of transplant rejection am I?
* Occurs weeks after transplantation
*Cell mediated due to cytotoxic T cells reacting against foreign MHCs
Acute Rejection
Which type of transplant rejection am I?
* Antibody mediated vascular damage (fibrinoid necrosis)
*occurs months to years after transplant
Chronic rejection
which type of transplant rejection am I?
* antibody mediated due to already present anti-donor antibodies in the recipient.
*occurs within minutes of transplantation
Hyperacute Rejection
which type of transplant rejection am I?
* Grafted T cells reject host cells
* results in severe organ dysfunction
Graft-versus-Host disease
What are some symptoms of Graft-versus-Host disease? (4)
maculopapular rash
what are the 5 groups at risk of contracting AIDS?
1. homosexuals
2. IV drug users
3. Blood recipients
4. hemophiliacs (recieve factor VII or IX)
5. heterosexuals making contact with high risk groups
How can vertical transmission of HIV occur? (3)
- transplacental
- via birth canal
- via breast milk

Deck Info