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Review / Wrong Answers > DIT review - Micro 9 > Flashcards

DIT review - Micro 9 Flashcards

1
Q

What agar is used to culture fungi?

A

Sabouraud

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2
Q

What are the 4 systemic mycoses

A

Histoplasmosis

Blastomycosis

Coccidioidomycosis

Paracoccidiodomycosis

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3
Q

Describe histology of Histoplasmosis including size compared to RBC

A
  • Intracellular oval bodies within macrophages
  • Smaller than RBC
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4
Q

HIstology of blastomycosis including size compared to RBC

A
  • Broad based budding
  • Same size as RBC
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5
Q

Histology of Coccidiodomycosis including size compared to RBC

A
  • Spherules (filled with endospores)
  • Larger than RBC - tubleweed bigger than sombrero
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6
Q

HIstology of paracoccidiodomycosis including size compared to RBC

A
  • Captains wheel
  • Larger than RBC - wheel larger than red spot in center of wheel
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7
Q

Describe the location of each of the systemic mycoses

A

Histo - Mississippi and Ohio river valley (midwest/central US)

Blasto - Eastern US

Coccidio - Southwest US, California

Paracoccidio - Latin america

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8
Q

What is the cuase of Pityriasis versicolor

A

Malessezia furfur

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9
Q

PResentation of Pityriasis versicolor

A
  • More common in summer (fungus survives in hot/humid conditions)
  • Hypopigmented patches
    • Due to degradation of lipids that produces acids that damage melanocytes
    • Confined to the stratum corneum (superficial layer)
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10
Q

Histology of Malessezia

A
  • Spaghetti and meatball appearance
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11
Q

Treatment of Pityriasis versicolor

A
  • Selenium Sulfide aka Selsun blue
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12
Q

Treatmtne of tinea (dermatophyte) aka ring worm

A
  • Topical azoles
  • Griseofulvin for more severe infections
  • Onychomycosis – oral Terinafine
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13
Q

Presentation and treatment of Sporothrix Schenckii

A
  • “Rose gardener’s disease”
  • Dimorphic
  • Cigar-shaped yeast
  • Presentation:
    • Local pustule or ulcer at site of trauma
    • Ascending lymphangitis (nodules along draining lymph nodes)
  • Treatment:
    • Itraconazole
    • Potassium iodide (THINK: plant a rose in the pot”)
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14
Q

What are the only catalase positive fungi

A

Candida, Aspergillus

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15
Q

Histology of Candida at 20 C

A
  • 20C – yeast: pseudohyphae and budding yeasts
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16
Q

Histology of candida at 37 C

A
  • 37C – mold: germ tubes
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17
Q

Describe risk factors and pH of candida vulvovaginosis

A
  • Vulvovaginitis
    • Associated with diabetes and antibiotic use
    • Normal vaginal pH (vs. Gardnerella and Trichomonas which have pH > 4.5)
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18
Q

Describe histology of Aspergillus

A
  • Septate hyphae branching at 45 acute angle
  • Produces conidia in radiating chains at end of conidiophore
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19
Q

Presentation of Aspergillus

A
  • Allergic bronchopulmonary aspergillus (wheezing, fever, pulmonary infiltrate) – HSR Type I
    • Associated with asthma and cystic fibrosis
  • Aspergillomas (solid balls of fungi) in pre-existing cavities
  • Angioinvasive aspergillosis (fever, cough, hemoptysis)
    • Kidney failure, ring enhancing brain lesions, paranasal necrosis
  • Aflatoxin can cause hepatocellular carcinoma
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20
Q

Characteristics of Cyptococcus neoformans

A
  • Heavily encapsulated
  • Urease positive
  • Found in soil and pigeon droppings
21
Q

Presentaton of crytococcus

A
  • Pneumonia, meningitis, encephalitis (“soap bubble” lesions in brain)
22
Q

Name 3 different ways to diagnose Cryptococcus

A
  • Bronchopulmonary washing of lung tissue
    • Stain sample with mucicarmine red methanamine silver stain
  • Lumbar puncture
    • Stain with India ink – will show clear halo
  • Latex agglutination
    • Detects polysaccharide capsular antigen
23
Q

Treatment of cryptococcus

A
  • Amphotericin B + Flucytosine, followed by maintenance with Fluconazole
24
Q

MOA and uses of Amphotericin B

A
  • MOA:
    • Binds Ergosterol in cell membrane and forms pores leading to fungal cell death
    • Usually given IV
    • Can also be given intrathecally (into spinal theca) for CNS infections
  • Uses:
    • Serious, systemic mycoses
    • Cryptococcus, blastomycosis, coccidiodomycosis, aspergillosis, histoplasmosis, mucormycosis
      *
25
Q

Adverse effects of Amphotericin B

A
  • Fever/chills, hypotension. IV phlebitis, Nephrotoxicity, Hypokalemia, hypomagnesemia, Arrhythmias, anemia
26
Q

MOA and uses of Nystatin

A
  • MOA:
    • Binds Ergosterol in cell membrane and forms pores leading to fungal cell death
    • Usually given topically (too toxic for IV use)
  • Uses:
    • Cutaneous candidiasis – diaper rash, vulvovaginitis
    • Oropharyngeal candidiasis – “swish and swallow”
27
Q

MOA, uses, and adverse effects of Flucytosine

A
  • MOA:
    • Inhibits DNA and RNA biosynthesis by being converted to 5-fluorouracil by cytosine deaminase
  • Uses:
    • Used in combo with Amphotericin B to treat Cryptococcus and systemic candida
  • Adverse effects:
    • Bone marrow suppression
28
Q

MOA of Azoles

A
  • Inhibits synthesis of Ergosterol in cell wall
    • Inhibits P450 enzyme that converts Lanosterol to Ergosterol
29
Q

Specific uses of each to the following azoles:

  • Fluconazole
  • Itraconazole
  • Voriconazole
  • Clotrimazole
  • Miconazole
A
  • ses:
    • Fluconazole – cryptococcal meningitis
    • Itraconazole – dimorphic fungi: blastomycosis, Histoplasma, coccidiodes
    • Voriconazole – asperigillus
    • Clotrimazole – tinea
    • Miconazole – tinea
30
Q

Adverse effects of azole

A
  • Liver dysfunction – CYP-450 inhibitor
  • Testosterone synthesis inhibition (gynecomastia) – especially with ketoconazole
  • Blurry vision, changes in vision color, flashes of light (Voriconazole)
31
Q

MOA of Echinocandins

A
  • Drugs:
    • Caspofungin
  • MOA:
    • Inhibits cell wall synthesis by inhibit synthesis of beta-glucan
      • Vs. other drugs which affect cell membrane
32
Q

Uses and adverse effects of Echinocandin

A
  • Uses:
    • Invasive aspergillosis, candida infection
      • THINK: cASPogungin = ASPergillus
  • Adverse effects:
    • GI upset
    • Flushing (due to histamine)
33
Q

MOA, uses, and adverse effects of Terbinafine

A
  • MOA:
    • Inhibits fungal enzyme squalene epoxidase, leading to decreased Ergosterol synthesis (cell membrane)
      • Squalene epoxidase catalyzes squalene to lanosterol (lanosterol is then converted to Ergosterol)
  • Uses:
    • Dermatophytes
      • Topical = tinea pedis and corporis
      • Oral = onychomycosis and tinea capitis
  • Adverse effects:
    • GI upset
    • Hepatotoxicity
34
Q

MOA, uses, and adverse effects of Griseofulvin

A
  • MOA:
    • Targets microtubule function, inhibiting mitosis
    • Deposits in keratin-containing tissue (e.g. skin, hair, nails)
  • Uses:
    • Dermatophytes
  • Adverse effects:
    • Teratogen
    • Confusion, HA
    • Carcinogenic
    • CYP-450 inducer
35
Q

Transmission of giardia

A
  • Cysts in water (fecal-oral)
36
Q

Diagnosis of giardia

A
  • Multinucleated trophozoites in stool
  • Cysts in stools (image)
37
Q

Transmission and presentation of entamoeba histolytica

A
  • Transmission:
    • Cysts in water
  • Presentation:
    • Causes amebiasis
    • Bloody diarrhea
    • Liver abscess – RUQ pain with “anchovy paste” exudate
    • Flask-shaped ulcers in colon on histology
38
Q

Describe trophozoites of entamoeba

A
  • Trophozoite with engulfed RBCs in stool
39
Q

Describe cysts of entamoeba

A
  • Cysts with up to 4 nuclei in stool
40
Q

Treatment of entamoeba

A
  • Metronidazole – kills trophozoites
  • Paramycin – luminal agent to kill cysts
  • Iodoquinol – luminal agent to kill cysts
41
Q

Transmission and presentation of cryptosporidium

A
  • Transmission:
    • Oocysts in water
  • Presentation:
    • Severe diarrhea in HIV patients
    • Mild watery diarrhea in immunocompetent
42
Q

Diagnosis of cryptosporidium

A
  • Oocyts in acid-fast stain
43
Q

Treatment of cryptosporidium

A
  • Prevention via water filtering
  • Nitazoxanide in immunocompetent hosts
  • Spiramycin (macrolide)
44
Q

3 modes of transmission of Toxoplasma gondii

A
  • Cysts in raw/undercooked meat
  • Oocyst in cat feces
  • Crosses the placenta
45
Q

Presentation of congenital toxo?

A
  • Triad: chorioretinitis, hydrocephalus, intracranial calcifications
    • Also deafness
46
Q

Presentation of toxo in AIDs patients

A

HIV – brain abscess with ring-enhancing lesions

Brain biopsy to differentiate from CNS lymphoma (other cause of ring-enhancing lesion

47
Q

Treatment of Toxo

A
  • Sulfadiazine + pyrimethamine
  • TMP-SMX prophylaxis CD4 < 100 + IgG positive for Toxo
48
Q

Transmission and presentation of Trypanosoma bruceii

A
  • Transmission:
    • Tsetse fly (painful bite)
  • Presentation:
    • African sleeping sickness
      • Enlarged lymph nodes, recurring fever, somnolence, coma
      • Recurring fevers due to antigenic variation, preventing host from forming immune response
49
Q

Diagnosis and treatment of trypanosoma bruceii

A
  • Diagnosis:
    • Trypomastigote on blood smear
    • Have a single flagella
  • Treatment:
    • Suramin = blood borne disease
    • Melarsoprol = CNS penetration

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