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44 Cards in this Set

  • Front
  • Back
Characterisitcs of fungi
- eukaryotic cells
- lack chlorophyll (no photosynthesis)
- require an aerobic envt
Which sub category fungi are unicellular, spherical (elipsoidal), budding reproduction OR pseudohyphae (no budding)?
Yeast
Which sub category of fungi are threadlike, branching, cylindrical, tubular (attached end-to-end) and reproduced/grow by extending length tips?
Hyphae
Which sub category of fungi form multicellular colonies, clumps of intertwined branching hyphae and grow by longitudinal extensino and produce spores?
Molds (aka mycelia)
Which sub category of fungi are the reporducing bodies of molds?
Spores
Which sub category of fungi grow as either yeast or mold depdnign on environmental conditions?
Dimorphic fungi
Which sub category of fungi life in and utilize organic matter (soil, rotten veg) as their energy source?
Saprophytes
What is unique about fungi cell membranes? Which antifungals target this feature?
bilayered w sterols (ergosterol)
"-azoles" and echinocandins prevent synthesis or ergosterol --> no cell membrane --> no fungi can grow
Do fungi have cell walls?
yes
What does the fungal coating consist of?
Polysaccaride capsule surrounds cell wall.
- antiphagocytic visualized using india ink stain
How are fungi classified?
based on the degree of tissue involvement and mode of entry
3 classifications of fungi?
1. Superficial: skin, hair, nails, mucous membrane (ex dermatophytes and yeast)
2. Deep systemic mycoses: deep infectiosn of the internal organs (ex histoplasma capsulatam, coccidioides immitis- dimorphic)
3. Opportunistic: cause infection only in immunocompromised patients (ex candida spp, cryptococcus spp, asperigillus spp, pneumocystis spp)
Opportunistic vs Primary pathogens.
Opportunistic: only cause infection when there are disruptions in the protective barriers of skin and mucous membranes, or when defects in the hose immune system allow them to penetrate, colonize and reproduce in host (ex candida)

Primary: are capable of initiating infection in a normal, apparently immunocompetant host. Colonize --> niche --> multiply (ex dimorphic fungi)
Characteristics of dermatophytes?
- live in dead, horny layer of skin, hair and nails
- secrete enzymes called keratinase (digests keratin) --> causes hair loss, scaling of skin, crumbling of nails
- chronic process ( months to years)
- most are resident organism
Which fungi are transmitted directly/indirectly to infected sites and invade horny layer of skin causing inflammation on skin that look ring shaped, red and raised? What
Tinea corporis (corporis=body... think corpse!)
AKA Ringworm
Which fungi causes athletes foot?
Tinea pedis (pedis = feet)
Which fungi infects between the toes and causes cracking and peeling of skin which may spread to the groin/medial thigh, buttocks?
Tinea pedis AKA athletes foot
pedis = feet

If spread to groin/medial thigh is considered Tinea cruis
Which fungi infects the hair and scalp --> grows --> scaly red lesions --> loss of hair?
Tinea capitus
Capitus = scalp ( thinking cap?)
How to Dx and Tx dermatophyte infections?
Dx: sample from affected area --> culture (slow) and direct microscopy (use KOH to digest keratin, calcoflour stain)

Tx: depend on types and severity
- singe uncomplicated cutaneous lesion --> topical antifungal
- chronic or diffuse infection, acute inflammatory --> systemic antifungal
Which fungi is an opportunisitc pathogen that normally resides on our skin and when given the opportunity will cause multiple macules/papules of variable appearance (back chest abdomen neck upper limbs) and can also cause total parenteral nutrition (neonates)?
Tinea Versicolar
aka Malassezia furfur
Are dimorphic fungi primary or opportunistic pathogens? Why?
Primary
Are capable of causing infection in an immunocompetant host
Name the 2 major groups of dimorphic fungi (that we need to know for HDI..)
1. Histoplasma
2. Coccidiodes
Which fungi whos natural habitat is soil, vegetation or bird dropping (where it grows as mycelia aka mold) produce spores that can be inhaled by humans and grow as yeast in the lungs (37degrees) causing local infection (pneumonia) and can also diseminated within macrophages?
Histoplasma
Which fungi is similar to TB in the sense that it can lead to formation of granulomas w calcifications following infection?
Histoplasma
Which fungi, if disseminated, can lead to organ lesions, meningitis, bone lytic granulomas and skin granulomas (that can break down into ulcers)?
Histoplasma
Compare Histoplasma to TB?
Similaries:
- inhaled primary infection in lung
- asymptomatic, mild, seer, or chronic lung infection
- lung granulomas, calcifications, and/or cavitations
- can disseminate hematogenously to distant sites
- skin tests like PPD

Differences:
- no person-to-person transmission
- fungi w spores NOT acid fast bacteria
Which fungi can cause sever pneumonia --> chronic cavitary pneumonia --> weightloss/low grade fever?
Histoplasma
Tx and Dx for Histoplasma and Coccidiodes?
Biopsy affected tissue, skin test (not very helpful..), serological tests, or urine histoplasma antigen test
Tx: Acute pulmonary histomlamosis and coccidiod casis usually require no treatment. Chronic or disseminated disease - Intraconazole or Amphotericin B (antifungals)
What is the organism responsible for valley fever? Where is this endemic to?
Coccidioide immitis
- SW USA
Which fungi form arthrospores (asexual, thick walled spores) in soil and can be inhaled into lungs where they become infective endospores at 37 degrees, potentially disseminate within macrophages (spores form budding yeast inside M0) causing local infections throughout the body, granulomas, or sever granulomatous disease throughout the body?
C. immitis
Which fungi is found in histocytes (ie macrophages)? .. the answer is in the questions
Histoplasma
Which organism causes symptoms clinically similar to miliary TB in HIV+ve and AIDs patients?
Histoplasma
Which fungi are resident flora of the mucous membranes (resp, GI, female genital tracts)?
Candida
Which organism is responsible for oral thrush, diaper rash, vaginitis, or esophagitis?
Candida
How to Dx and Tx Candida?
Dx: pseudohyphae and budding yeast observed in tissue scrapping (local); disseminated infection exibits +ve blood cultures
Tx: thrush/esophagitis - Nyastatin mouth wash, fluconaszole,
vaginitis - fluconazole, topical antifungal
-systemic: antifungals
Which fungus is found as yeast in pigeon droppings and can infect lungs if inhaled leading to pneumonia (local), fungemia (bony lesions, ulcers, meningitis can caused increased pressure)?
Cryptococcus
How to Dx and Tx Cryptococcus?
Dx: CSF (elevated opening pressure; budding yeast w halo);
CSF or serum cryptococcal Ag
Tx: amphtericin B and Flucytosine (for meningitis); Fluconazole for lifetime suppresion in AIDs patients
Which fungi grows as a mold in decaying vegetation and can produce spores --> inhaled --> produce aflotoxin --> liver damage/cancer?
Asperigillus
Which fungi ( inhaled as spored from decaying vegetation) can deposit in the lung caviity formed by previous TB --> fungemia (in immunocompromised) --> vessel occlusion --> pumonary infartion?
Asperigillus
Which organism can grow within cavities in lung made from previous TB and grow hyphea within cavity (wo invading) --> aspergilloma?
Asperigillus
How to Dx and Tx asperigillus?
Dx: tissue biopsy (branching hyphae with septa); septum culture (radiating chain of spores); serology or xray
Tx: ABPA= corticosteroids to lessen IgE reponse
Asperilloma = surgery,
invasive asperilloma: antifungals
- blood eosinophilia and IgE antibodies may be preset
Which fungi can stimulate IgE reponse (type I hypersenitivity rxn) and cause bronchospasm and allergiv bronchopulmonary asperillosis?
Asperigillus
Which organism is inhaled as a cyst by most in childhood --> asymptomatic or mild pneumonia --> asymptomatic latent infection in lungs --> immunocompromised --> uncontrolled growth --> inflammatory response --> pneumonia?
Pneumocystis jirovecii
- causes Pneumocyctis pnemonia PCP
Dx of PCP?
silver stain of induced sputum, bronchoalveolar lavage or lung biopsy