Question | Answer |
What acid is unique to mycobacteria? | mycolic acid (remember iconazid targets) |
Can you culture m. leprae? | no. |
What type of granuloma are TB associated with? | caseating granuloma (center collapses, looks dead) Also Ghon complexes. |
Name the 5 members of the mycobacterium complex | 1) M. tuberculosis
2) M. bovis
3) BCG
4) M. cannetti
5) M. africanum |
What is the BCG vaccine made from? | M. Bovis. |
another name for leprosy? | Hansen's disease |
2 forms of leprosy. | 1) extreme tuberculoid-not lots of bacteria (t mediated), non-caseating granuloma
2) lepromatous-tons of bacteria (humoral), sheets of foamy macrophages. raised skin. |
Standard treatment for TB | "RIPE"
Rifampin
Isoniazid
Pyrazinamide
ethambutol |
does gram stain work for fungi? | not for most. Instead to NaOH wet mount or PAS/Gomori stains. |
what is the most important kind of immunity against fungi? | cell mediated. |
What is the most common infection caused by Candida? | diaper dermatitis (also see thrush--common in babies, cancer patients, AIDS patients) Also vaginitis is common. |
where does candida normally reside? | not in nature--endogenous, in host. |
How do you know you have candida albicans? | forms germ tubes from yeast in serum at 37 degrees within 1 hour. (this is hyphal form) "rapid germ tube" |
What allows hyphae to become covalently attached to host cells? | Hwp1 (can cause the white patches seen with thrus-tight adhesion of cadndia) |
What is the 2nd most common candida species? | glabrata. (note glabrata is less susceptible to azoles/amphotericin B then albicans is) |
What is the environmental and tissue forms in primary fungal pathogens? | environmental is hyphae
tissue is yeast |
are primary fungal pathogens transmitted from person to person? | no |
Does histoplasma capsulatum have a capsule? | no |
Where is histoplasma capsulatum located geographically? | Ohio River Valley (soil, bat guano) |
What is special about histoplasma capsulatum's morphology? | tuberculate chlamydospores (macroconidia) "spikes" (hyphael form)--yeast are small. |
How do we get histoplasma capsulatum? | inhaled from environment into lungs. Can be asymptomatic, acute pulmonary, chronic pulmonary or disseminated. (dissemination=carried by macrophages-can see in blood culture) |
What is a sign of disseminated histoplasma capsulatum infection? | skin lesion (coming from the inside) |
What are 3 virulence factors for hitoplasma capsulatum? | 1) Calcium binding protein-yeast phase
2) modulate ph of lysosome.
3) mask beta 1, 3 glucan with alpha glucan-hide from host defenses. |
How is geography of fungus determined? | skin test |
What is special about fungal pathogens growth in lab? | Can grow at 37 degrees. Most fungus can't. |
What fungal disease are dogs susceptible to? | blastomyces dermatitidis |
Key morphologic feature of blastomyces dermatitidis? | yeast form-buds have a broad base. |
What two organs do blastomyces dermatitidis have a tropism for? | skin and bone (inhaled and starts in respiratory) |
What surface protein is required for virulence with blastomyces dermatitids? | Bad1 (promotes uptake by macrophages) |
Geographic distribution of blastomyces dermatitidis? | Mississippi River Basin-wooded areas near waterways. |
Treatment for blastomyces dermatitids? | Treatment recommended for all, amphotericin B |
What is the geographic distribution of coccidioidomycosis? | Southwestern US |
What is morphology of coccidioidomycosis? | hyphal form is barrel shaped with thin structure between-easy to come apart.
yeast-see spherule with endospores (can see granulomas around spherules) |
What does disease with coccidiomycosis look like? | can be chronic or acute-affect skin, bone, meninges |
what is the only fungus with a capsule? What is capsule made of? | cryptococcus neoformans (note it is also monomorphic--not dimorphic) Capsule made of GXM. |
What kind of disease does type A cryptococcus neoformans lead to? | meningitis (can also see growth in lung) Good growth in CNS where there are catecholamines so cryptococcus can make melanin, be protected from host defense. |
What two special things can cryptococcus neoformans make (other than capsule?) | 1)melanin-help with protection
2) urease (note h.pylori and proteus can also make) |
Therapy for cryptococcus neoformans? | amphotericin B and 5-fluorocysteine for 6-10 weeks. |
What is the most prevelent airborne fungal pathogen? | aspergillus (neutropenic hospitalized patients are at high risk) Very high mortality rate. |
Morphology of aspergillus? | hyphael form only, highly sporulating--only inhalation form. Septate, branching at acute angles. Hyphae organized in same direction. |
Treatment of aspergilus? | amphotericin B. |
How are zygomycetes similar to aspergillus? (3 ways) | 1) ubiquitous
2) opportunistic
3) only hyphael growth form |
How is mucor different than aspergillus? | affinity for face, no septa. Common in diabetics. |
Can pneumocystis be cultured? | no (also no ergosterol). Confusion about if it was a parasite or a fungus. Leads to interstital pneumonia. See cysts in tissue.
Treat with trimethoprim. |
3 examples of subcutaneous mycoses | 1) sporothrix schenkii-thermal dimorphism
2) chromoblastomycosis-soil, splinters. Single lesion, slow growth. Sclerotic cells-cause granulomas.
3)mycetoma-introduced by trauma can be caused by either fungus or bacteria. Granuloma reaction |
3 examples of dermatophytes (fungal infections of skin, hair, nails) | 1) epidermophyton
2) microsporum
3) tricophyton |
What is a tinnea? | also called ringworm, meant to discuss infections with dermatophytes. |
How do dermatophytes grow? | as molds (can get as direct contacts from soil, animals, other people) |