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USMLE > Microbiology Superset RidEZ - Part 2 (1) > Flashcards

Microbiology Superset RidEZ - Part 2 (1) Flashcards

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USMLE® Step 1 flashcards
1
Q

Disease states caused by Legionella (list only)

A
  1. Asymptomatic infection
  2. Pontiac fever
  3. Legionnaires disease
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2
Q

Describe Pontiac fever

A

Caused by Legionella. Presents like influenza. Strikes suddenly and completely resolves in one week. Originally described in the Pontiac Michigan government AC.

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3
Q

Describe Legionnaires’ disease

A

Very high fever with severe pneumonia

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4
Q

Treatment for Legionella

A

Has a beta-lacatamase (penicillin-resistant)

  1. Erythromycin
  2. Rifampin
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5
Q

Diagnosis: Pneumonia in a smoker >50 years of age. Gram stain of pus shows many neutrophils with few microbes.

A

Legionella

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6
Q

Special culture requirements for: Legionella

A

Grows on charcoal yeast extract culture with iron and cysteine
Mnemonic: French legionnaire with silver helmet, sitting around a campfire (charcoal medium) with a canteen of water (water transmission) and his iron dagger-he is no sissy (cysteine).

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7
Q

Legionella: Gram stain

A

Gram negative. Gram stains poorly (use silver stain)

Mnemonic: French legionnaire with silver helmet, sitting around a campfire (charcoal medium) with his iron dagger-he is no sissy (cysteine).

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8
Q

Legionella: How transmitted?

A

Aerosol transmission from environmental water sources (AC, Showers, whirlpools, cooling towers, supermarket produce mist)

Mnemonic: French legionnaire with silver helmet, sitting around a campfire (charcoal medium) with a canteen of water (water transmission) and his iron dagger-he is no sissy (cysteine).

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9
Q

Pseudomonas: Disease states

A

PSEUDDOburnnas

  1. Pneumonia (especially in CF)
  2. Sepsis (black lesions on skin)
  3. External otitis (swimmer’s ear)
  4. UTI (nosocomial and drug-resistant)
  5. Drug use
  6. Diabetic Osteomyelitis
  7. Burns and wound infections
  8. Hot tub folliculitis
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10
Q

Pseudomonas: Organism characterization

A
  1. Gram-negative rod
  2. non-lactose fermenting
  3. Aerobic (think AERuginosa) and oxidase positive (cytochrome c oxidase for oxidative phosphorylation)
  4. Produces pyocyanin (blue-green) pigment
  5. Fruity odor
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11
Q

What to know about exotoxins produced by: Pseudomonas aeruginosa

A

Exotoxin A is an ADP ribosylating A-B toxin (similar to Diphtheria toxin)

Mechanism:
Inactivates elongation
factor 2 (EF-2)

Also has endotoxin (as it is gram negative) which produces fever and shock.

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12
Q

Diagnosis: Sepsis in burn victim

A

Most likely Pseudomonas

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13
Q

Treatment for pseudomonas

A

Aminoglycoside

plus

Extended-spectrum penicillin (eg piperacillin, ticarcillin)

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14
Q

Helicobacter pylori: Disease states

A

Causes:

  1. Gastritis
  2. 90% of duodenal ulcers

Risk factor for:

  1. Peptic ulcer
  2. Gastric carcinoma
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15
Q

Helicobacter pylori: Characterization

A
  1. Gram negative rod
  2. Urease-positive
  3. Creates alkaline environment
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16
Q

Treatment for Helicobacter Pylori

A

Triple treatment

  1. Metronidazole with one of the two combos below

$:

  1. Bismuth (eg Pepto-Bismol)
  2. Either Tetracycline or Amoxicillin

$$:

  1. Omeprazole
  2. Clarithromycin
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17
Q

What bug?: Urease-positive gram-negative bacteria

A

Proteus and H. Pylori

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18
Q

Zoonotic bacteria

A
  1. Borrelia burdorferi
  2. Francisella tularensis
  3. Yersinia pestis
  4. Pasteurella multocida
  5. Brucella spp. (Undulant fever from dairy/contact with animals)

Mnemonic: Bugs From Your Pet Undulate and Unpasteurized dairy gives you Undulant fever

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19
Q

Borrelia burgdorferi: Disease states

A

Lyme disease

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20
Q

Brucella: Disease states

A

Undulant fever/Brucellosis. Temperature slowly rises during day, peaks in the evening, and slowly declines to normal by morning.

Accompanied by other systemic symptoms.

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21
Q

Brucella: Transmission

A

from animal contact (meat worker, farmer, veterinarian) or unpasteurized milk

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22
Q

Gross mechanism of brucellosis

A
  1. Penetration of skin (but no buboes or primary skin ulcer), conjunctiva, lungs, GI tract
  2. Lymphatic spread
  3. Facultative intracellular growth in macrophages, and blood and organ invasion
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23
Q

Francisella Tularensis: Disease states (list)

A

Tularemia, either:

  1. Pneumonic
  2. Oculoglandular
  3. Ulceroglandular
  4. Typhoidal

(Don’t POUT when you’ve got tularemia.)

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24
Q

Describe Ulceroglandular tularemia

A

a. Well-demarcated hole in the skin with a black base
b. Fever and systemic symptoms
c. Swollen/red/painful purulent lymph nodes

Similar to plague, but with skin ulcer, and low mortality.

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25
Q

Francisella tularensis: Transmission

A

Most common: Handling of infected rabbits or from bites of ticks and deer flies

Hundred creatures in total all over US.

Mnemonic: Francis the rabbit is playing in the TULips, with a deerfly on one ear and a tick on the other.

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26
Q

Virulence of Francisella tularensis

A

Very. (10 organisms cause disease.)

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27
Q

Diagnosis of Francisella tularensis

A

Clinical picture, PPD-like skin test, and titers of Francisella Ig

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28
Q

Yersinia pestis: Transmission

A

PESTS like rats harbor the disease and fleas are the vector, biting the skin of humans. Found in campers, hunters, and hikers.

Mnemonic: A rat driving a fuel-injected (F1) VW bug (V and W antigens) fleeing (flea-ing) from a macrophage.

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29
Q

Fraction 1 (F1) antigen

A

Enables Yersinia pesitis to resist destruction after phagocytosis (facultative intracellular)

Mnemonic: A rat driving a fuel-injected (F1) VW bug (V and W antigens) fleeing (flea-ing) from a macrophage.

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30
Q

V antigen

A

Enables Yersinia pesitis to resist destruction after phagocytosis (facultative intracellular)

Mnemonic: A rat driving a fuel-injected (F1) VW bug (V and W antigens) fleeing (flea-ing) from a macrophage.

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31
Q

W antigen

A

Enables Yersinia pesitis to resist destruction after phagocytosis (facultative intracellular)

Mnemonic: A rat driving a fuel-injected (F1) VW bug (V and W antigens) fleeing (flea-ing) from a macrophage.

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32
Q

Yersinia pestis: Presentation in humans

A
  1. Lymph node (usually inguinal [boubon is Greek for groin]) becomes inflamed (all four signs).
  2. Fever, and headache.
  3. Blackish discoloration under skin (“Black death”)
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33
Q

Disease states caused by Yersinia pestis

A

Bubonic plague/pneumonic plague

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34
Q

Pasteurella Multocida: Transmission

A

Cat, dog, and animal bites. Also infects birds.

Mnemonic: Cat and dog chasing a bird in a “Pasteur”.

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35
Q

T/F: All Zoonotic Gram negative bugs are facultative intracellular.

A

False. Pasteurella is not.

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36
Q

Pasteurella: Treatment

A

Do not suture wound after dog or cat bite/scratch. (Best breeding ground for Pasteurella)

Treat with penicillin or doxycycline.

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37
Q

Gardnerella: Characterization

A

Pleomorphic, gram-variable rod.

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38
Q

What disease states does Gardnernella cause?

A

Vaginosis

  1. Greenish vaginal discharge with fishy smell
  2. Noninflammatory (nonpainful)
  3. Mobiluncus (anaerobe) is also seen
  4. Clue cells are visible (vaginal epithelium covered with bacteria)
  5. Positive Whiff test
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39
Q

Clue cell, indicative of Gardnerella vaginosis

A

What is this?

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40
Q

What does a positive PPD indicate?

A
  1. Current infection
  2. Past exposure
  3. BCG vaccination
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41
Q

What does a negative PPD indicate?

A
  1. No infection
  2. Anergy (due to: steroids, immunocompromise, malnutrition), inject candida/mumps vaccine into other arm. If still negative, anergic.
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42
Q

Fast-fermenting lactose bacteria

A

Fast fermenters: (EEK! Too fast!)

  1. E.coli
  2. Enterobacter sp.
  3. Klebsiella
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43
Q

Slow fermenting lactose bacteria

A

Slow fermenters:

  1. Serratia
  2. Citrobacter
  3. “Others”
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44
Q

Tuberculosis infection: Gross mechanism

A
  1. Inhaled aerosols from infected adults
  2. Land in middle or lower lobes of lung (highest airflow) leading to small area of pneumonitis.
  3. Bacteria enter macrophages, multiply, and spread hematogenously.
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45
Q

Mechanism of asymptomatic primary TB

A
  1. Cell-mediated defense walls off foci of bacteria in caseous granulomas
  2. Granulomas heal with fibrosis, calcification and scar formation
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46
Q

Difference between Ghon focus and Ghon complex

A

Ghon focus: Calcified tubercle in the middle or lower lung

Ghon complex: Ghon focus accompanied by perihilar or lobar lymph node calcified granulomas

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47
Q

What is a Ranke complex?

A

Same as a Ghon complex: Ghon focus accompanied by perihilar or lobar lymph node calcified granulomas

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48
Q

Mechanism of symptomatic primary TB

A
  1. Large caseous granulomas develop in the lungs/other organs.
  2. In the lungs, caseous material liquifies, is extruded out the bronchi and leaves cavitary lesions behind.
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49
Q

Mechanism of secondary Pulmonary TB

A
  1. Infection occurs at apical areas of lung around the clavicles due to highest oxygen tension caused by decreased pulmonary circulation.
  2. Infected areas grow, caseate, liquify and cavitate.
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50
Q

TB reactivation sites

A
  1. Pulmonary (Lung parenchyma)
  2. Pleura
  3. Pericardium
  4. Scrofula (Cervical lymph nodes: most common extrapulmonary site worldwide)
  5. Kidney (Sterile pyuria)
  6. Thoracic and lumbar spine (Pott’s disease)
  7. Chronic monoarthritis
  8. CNS (subacute meningitis or parenchymal tuberculoma)
  9. Miliary TB (Millet sized tubercles all over the body)
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51
Q

Tuberculosis rule of 5s

A
  1. Droplet nuclei are 5 micrometers and contain 5 mycobacteria
  2. 5% risk of reactivation in first 2 years and then 5% lifetime risk
  3. Patients with HIV (“High five”) have 5+5% yearly reactivation risk.
  4. Induration measurements
    a. HIV: >5 mm
    b. High risk: >5+5 mm
    c. Everyone else: >5+5+5 mm
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52
Q

Cause of Miliary tuberculosis

A

Severe bacteremia

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53
Q

Types of Mycobacteria and what they cause

A

Mnemonic: Identifying mycobacteria is no Light TASK

Mycobacterium

  1. Leprae
  2. Tuberculosis
  3. Avium-intracellulare
  4. Scrofulaceum
  5. Kansasii
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54
Q

What disease state does Mycobacterium Avium-intracellulare cause?

A

bugs are multiple drug resistant and cause disseminated disease in AIDS

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55
Q

Symptoms of tuberculosis

A
  1. Fever
  2. Night sweats
  3. Weight loss
  4. Hemoptysis
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56
Q

Two Langhans type giant cells in which the nuclei are lined up around the periphery of the cell in a horseshoe pattern.

Seen in granulomatous conditions like TB

A

What is this?

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57
Q

What is Hansen’s disease?

A

leprosy

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58
Q

What is leprosy caused by?

A

Mycobacterium leprae

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59
Q

Characterization and reservoir of Mycobacterium Leprae

A
  1. Acid fast bacillus
  2. Likes cool temperatures
  3. Infects skin and superficial nerves
  4. Cannot be grown invitro
  5. Reservoir: Armadillos
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60
Q

Presentation of lepromatous leprosy

A

“Leonine facies”

  1. Loss of eyebrows
  2. Nasal collapse
  3. Lumpy earlobe
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61
Q

Treatment for leprosy

A

Long-term oral dapsone

Alternative: Rifampin, clofazimine, and dapsone

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62
Q

Toxicity of longterm oral dapsone

A
  1. Hemolysis

2. Methemoglobinemia

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63
Q

2 forms of leprosy

A
  1. Lepromatous (Due to failed cell-mediated immunity. Lep. is Lethal)
  2. Tuberculoid (self=limiting)
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64
Q

Rickettsiae: Characterization

A

Obligate intracellular parasites. Need CoA and NAD.

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65
Q

Rickettsiae: Transmission and presentation

A

Coxiella: Atypical. Transmitted by aerosol and causes pneumonia

All others: Arthropod vector causes classic triad of headache, fever and rash (vasculitis)

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66
Q

Treatment of Rickettsiae

A

Tetracycline

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67
Q

Difference between spread of rash in typhus and spotted fever

A

tyPHus is centriPHugal (moves outwards)

sPotted fever is centriPetal (moves inwards)

Both are caused by Rickettsiae

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68
Q

Which bug causes Rocky Mountain spotted fever?

A

Rickettsia rickettsii, transmitted by tick

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69
Q

Which bug causes endemic typhus?

A

Rickettsia typhi, transmitted by fleas

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70
Q

Which bug causes epidemic typhus?

A

Rickettsia prowazekii, transmitted by human body louse

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71
Q

Which bug causes typhus?

A

Endemic: Rickettsia typhi, transmitted by fleas

Epidemic: Rickettsia prowazekii, transmitted by human body louse

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72
Q

Which bug causes Q fever?

A

Coxiella burnetii, by inhaled aerosols from cowhide and placentas.

Remember: Carol Burnett coughing “Q” after inhaling spores from cowhide.

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73
Q

What separates Q fever from other rickettsial diseases?

A

Q fever is Queer. Rickettsial, but has an endospore, thus:

  1. Caused by Coxiella burnetii (not called Rickettsia)
  2. No rash
  3. No vector (inhaled aerosols)
  4. Negative Weil-Felix
  5. Causative organism can survive outside for a long time.
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74
Q

Difference in tropism between Chlamydia and Rickettsia

A

Rickettsia: Endothelial cells of blood vessels

Chlamydia: Columnar epithelium

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75
Q

Where is the rash in Rocky Mountain spotted fever found?

A

Palms and soles, migrating to wrists, ankles, then trunk.

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76
Q

Where can rashes on the palms and soles of feet be seen?

A
  1. Rocky mountain spotted fever
  2. Syphilis
  3. Coxsackie virus A infection (hand, foot, and mouth disease)
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77
Q

Weil-Felix reaction

A

Assays for antirickettsial antibodies, which cross-react with Proteus antigen

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78
Q

Typhus: positive or negative Weil-Felix

A

positive

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79
Q

Rocky mountain spotted fever: positive or negative Weil-Felix

A

positive

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80
Q

Q fever: positive or negative Weil-Felix

A

negative

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81
Q

What bug: Atypical walking pneumonia in prisoner or military recruit younger than 30

A

Mycoplasma pneumoniae

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82
Q

Describe mycoplasma pneumoniae pneumonia

A
  1. Atypical walking pneumonia (insidious onset, headache, non productive cough, diffuse interstitial infiltrate)
  2. X-ray looks worse than patient
  3. High titer of cold agglutinins (IgM)
83
Q

Special culture requirements for: Mycoplasma pneumoniae

A

Eaton’s agar

84
Q

Treatment for mycoplasma pneumoniae

A

Tetracycline or erythromycin.

Pencillin resistant because they have no cell wall.

85
Q

Characterization of Mycoplasma pneumoniae

A
  1. Facultative anaerobe with no cell wall (hence no gram stain)
  2. Only bacterial membrane with cholesterol
  3. High titer of cold agglutinins
  4. Grown on Eaton’s agar
86
Q

True or False: No Gram-positive bugs have endotoxin.

A

False. Listeria monocytogenes has it.

87
Q

Characterize Chlamydia

A

Obligate intracellular parasites

88
Q

2 forms of chlamydia

A
  1. Elementary body (small, dense) which Enters cell via endocytosis
  2. Initial or Reticulate body, which Replicates In cell by fission
89
Q

Disease states caused by Chlamydia trachomatis

A
  1. Reactive arthritis (aka Reiter’s syndrome)
  2. Conjunctivitis
  3. Non-gonococcal urethritis, cervicitis, and PID
90
Q

Disease states caused by Chlamydia pneumoniae

A

Atypical pneumonia

91
Q

Disease states caused by Chlamydia psittaci

A

Atypical pneumonia

92
Q

Chlamydia species

A
  1. Trachomatis
  2. Pneumoniae
  3. Psittaci
93
Q

What is unusual about the chlamydial wall?

A

It lacks muramic acid.

94
Q

Treatment of Chlamydia

A

Erythromycin or tetracycline

95
Q

Reservoir for Chlamydia psittaci

A

Avian

96
Q

Which chlamydia has an animal reservoir?

A

Psittaci: Avian

97
Q

Lab diagnosis of chlamydia

A

Cytoplasmic inclusions seen on Giemsa or fluorescent-antibody stained smear

98
Q

What disease is caused by Chlamydia Trachomatis serotypes A-C

A
  1. Chronic infection
  2. Blindness in Africa

Mnemonic: ABC: Africa, Blindness, Chronic infection

99
Q

What disease is caused by Chlamydia Trachomatis serotypes D-K

A
  1. Urethritis/PID
  2. Ectopic pregnancy
  3. Neonatal pneumonia
  4. Neonatal conjunctivitis
100
Q

What disease is caused by Chlamydia Trachomatis serotypes L1-L3

A

Lymphogranuloma venereum

  1. acute lymphadenitis with a positive Frei test
  2. ulcers
  3. rectal strictures

Mnemonic: L1-3: Lymphogranuloma

101
Q

Positive Frei test

A

Chlamydia Trachomatis serotypes L1-L3

102
Q

Acquisition and treatment of neonatal conjunctivitis

A

Chlamydia trachomatis serotypes D-K acquired by passage through infected birth canal. Treat with erythromycin eye drops.

103
Q

Characterization of spirochetes

A

Spiral-shaped bacteria with axial filaments

104
Q

List of spirochetes

A

Mnemonic: BLT with spiral bacon

  1. Borrelia (Big!)
  2. Leptospira
  3. Treponema
105
Q

Visualization of Borrelia

A

Light microscopy with choice of aniline dye:

  1. Wright’s stain
  2. Giemsa’s stain
106
Q

Stages of Lyme disease

A
  1. Erythema chronicum migrans and flu-like symptoms
  2. Neurologic and cardiac manifestations
  3. Autoimmune migratory polyarthritis
107
Q

Signs and symptoms of Lyme disease

A

Mnemonic: BAKE a Key Lime pie

  1. Bell’s palsy (and other CNS manifestations in Stage 2)
  2. Arthritis (Autoimmune migratory in Stage 3)
  3. Kardiac block (Stage 2)
  4. Erythema chronicum migrans (Stage 1)
108
Q

What species transmits Borrelia burgdorferi to humans?

A

Ixodes tick. Live o

109
Q

Classic symptom of Lyme disease and which stage is it in?

A

Erythema chronicum migrans, an expanding “bull’s eye” red rash with central clearing. Stage 1.

110
Q

Animal reservoirs for borrelia burgdorferi

A

White-footed mouse and other small rodens, and the white-tailed deer. Ixodes tick picks up bugs from these animals and transmits them.

111
Q

Most common setting for Borrelia burgdorferi infection

A

In the summer months in northeastern US (Lyme, CT)

112
Q

What disease states does Treponema cause?

A

Treponema Pallidum causes syphilis.

Treponema Pertenue causes yaws (a non-STD tropical infection with positive VDRL)

113
Q

What is yaws?

A

Treponema Pertenue causes yaws (a non-STD tropical infection with positive VDRL)

114
Q

Presentation of primary syphilis

A

Painless chancre (localized disease)

115
Q

What stage of syphilis: Painless chancre (localized disease)

A

Primary

116
Q

Presentation of secondary syphilis

A

Disseminated disease with:

  1. constitutional symptoms (fever, lymphadenopathy)
  2. maculopapular rash (palms and soles)
  3. condylomata lata

Mnemonic: Secondary means Systemic

117
Q

What stage of syphilis: Disseminated disease with constitutional symptoms

A

Secondary syphilis

118
Q

Presentation of tertiary syphilis

A
  1. Gummas
  2. Aortitis
  3. Neurosyphilis (tabes dorsalis, general paresis)
  4. Argyll Robertson pupil
119
Q

What stage of syphilis: Gummas

A

tertiary syphilis

120
Q

What stage of syphilis: Aortitis

A

tertiary syphilis

121
Q

What stage of syphilis: Neurosyphilis (tabes dorsalis)

A

tertiary syphilis

122
Q

What stage of syphilis: Argyll Robertson pupil

A

tertiary syphilis

123
Q

What stage of syphilis: maculopapular rash (palms and soles)

A

Secondary syphilis

124
Q

What stage of syphilis: condylomata lata

A

Secondary syphilis

125
Q

Presentation of Congenital syphilis

A
  1. Saber shins
  2. Saddle nose
  3. Deafness
126
Q

What stage of syphilis: Saber shins

A

Congenital syphilis (not a stage)

127
Q

What stage of syphilis: Saddle nose

A

Congenital syphilis (not a stage)

128
Q

What stage of syphilis: Deafness

A

Congenital syphilis (not a stage)

129
Q

Treatment for Syphilis

A

Penicillin G

130
Q

Signs and symptoms of tertiary syphilis

A
  1. Broad-based ataxia
  2. Positive Romberg sign
  3. Charcot joints
  4. Stroke without hypertension
131
Q

What is an Argyll-Robertson pupil?

A

Same as prostitute’s pupil. Constricts with accommodation but is not reactive to light. Pathognomonic for tertiary syphilis.

132
Q

What is the prostitute’s pupil.

A

Same as Argyll-Robertson pupil. Constricts with accommodation but is not reactive to light. Pathognomonic for tertiary syphilis.

133
Q

What is FTA-ABS used for?

A

FTA-ABS: Find the Antibody-Absolutely

  1. Most specific for treponemes
  2. Positive the earliest
  3. Remains positive the longest
134
Q

Interpret: Positive VDRL, Positive FTA

A

Active treponemal infection

135
Q

Interpret: Positive VDRL, Negative FTA

A

Probably false positive

VDRL

  1. Viruses (mono, hepatitis)
  2. Drugs
  3. Rheumatic fever and rheumatoid arthritis
  4. Lupus and leprosy
136
Q

Interpret: Negative VDRL, Positive FTA

A

Successfully treated treponemal infection

137
Q

Sexuality of fungal spores

A

Asexual (mostly)

138
Q

Which fungal infections are transmitted by inhalation of asexual spores?

A
  1. Coccidioidomycosis

2. Histoplasmosis

139
Q

What are conidia?

A

Asexual fungal spores

140
Q

What disease states does Candida albicans cause?

A
  1. Thrush esophagitis in immunocompromised patients (neonates, steroids, diabetes, AIDS)
  2. endocarditis in IV drug users
  3. vaginitis post-antibiotic use
  4. diaper rash
  5. Disseminated candidiasis to any organ
  6. Chronic mucocutaneous candidiasis
141
Q

Treatment for Candida Albicans infection

A

Superficial: Nystatin

Serious systemic: Amphotericin B

142
Q

Histologic appearance of Candida Albicans

A

Budding yeast with pseudohyphae in culture at 20 degrees celsius

Germ tube formation at 37 degrees celsius

143
Q

Candida albicans: Germ tube formation at 37 degrees celsius

A

What is this?

144
Q

Candida albicans: Budding yeast with pseudohyphae in culture at 20 degrees celsius

A

What is this?

145
Q

Which fungus causes thrush in immunocompromised

A

Candida albicans

146
Q

Which fungus causes vulvovaginitis?

A

Candida albicans (high pH, diabetes, use of antibiotics)

147
Q

Which fungus is endemic to Southwestern US?

A

Coccidioidomycosis

148
Q

Which fungus is endemic to Mississippi and Ohio river valleys

A

Histoplasmosis

149
Q

What fungus is this area known for: Southern Ohio

A

Histoplasmosis

150
Q

What fungus is this area known for: Southern Illinois

A

Histoplasmosis

151
Q

What fungus is this area known for: Missouri

A

Histoplasmosis

152
Q

What fungus is this area known for: Kentucky

A

Histoplasmosis

153
Q

What fungus is this area known for: Tennessee

A

Histoplasmosis

154
Q

What fungus is this area known for: Arkansas

A

Histoplasmosis

155
Q

What fungus is this area known for: Southern California

A

Coccidiomycosis

156
Q

What fungus is this area known for: Southern Arizona

A

Coccidiomycosis

157
Q

What fungus is this area known for: Mississippi river valley

A

Histoplasmosis (also Blastomycosis)

158
Q

What fungus is this area known for: Ohio river valley

A

Histoplasmosis (also Blastomycosis)

159
Q

What fungus is this area known for: Southwestern US

A

Coccidiomycosis

160
Q

What fungus is this area known for: Rural Latin America

A

Paracoccidioidomycosis

161
Q

What fungus is this area known for: Wisconsin

A

Blastomycosis

162
Q

What fungus is this area known for: Minnesota

A

Blastomycosis

163
Q

Spherule filled with endospores in coccidioidomycosis

A

What is this?

164
Q

Characterize histoplasmosis histologically

A

Tiny yeast inside macrophages. Thin cell wall with no true capsule.

165
Q

What is the vector for histoplasmosis?

A

Bird or bat droppings

166
Q

What do bird and bat droppings carry?

A

Histoplasmosis

167
Q

histoplasmosis showing intracellular organisms in bone marrow macrophages

A

What is this?

168
Q

Paracoccidioidomycosis (captain’s wheel appearance)

A

What is this?

169
Q

Blastomycosis (Big, Broad-Based Budding)

A

What is this?

170
Q

What characterizes dimorphic fungi?

A

Mold in soil (lower temperature) and yeast in tissue (body temperature)

Mnemonic: Cold is mold, heat is yeast

171
Q

List the dimorphic fungi

A

Histoplasmosis, Blastomycosis, and Paracoccidioidomycosis (but not coccidioidomycosis which is a spherule in tissue)

172
Q

Treatment for coccidiomycosis

A

Local: Fluconazole or ketoconazole

Systemic: Amphotericin B

173
Q

Treatment for paracoccidiomycosis

A

Local: Fluconazole or ketoconazole

Systemic: Amphotericin B

174
Q

Treatment for Histoplasmosis

A

Local: Fluconazole or ketoconazole

Systemic: Amphotericin B

175
Q

Treatment for Blastomycosis

A

Local: Fluconazole or ketoconazole

Systemic: Amphotericin B

176
Q

What is cultured on Sabouraud’s agar?

A

Fungi (specifically dimorphic fungi)

177
Q

What disease state does Malassezia furfur cause?

A

Tinea versicolor: Hypopigmented skin lesions which occur in hot humid weather.

178
Q

Treatment for Tinea versicolor

A

Topical miconazole or selenium sulfide (Selsun)

179
Q

What resembles spaghetti and meatballs histologically?

A

combination of mycelium strands and numerous spores of Malassezia furfur in KOH prep

180
Q

What disease state does Cladosporium werneckii cause?

A

Tinea nigra: Infection of keratinized layer of skin. Appears as brownish spot.

181
Q

What causes Tinea versicolor?

A

Malassezia furfur

182
Q

What causes Tinea nigra?

A

Cladosporium werneckii

183
Q

Treatment for Tinea nigra

A

topical salicylic acid

184
Q

What are the common dermatophytes and what do they cause?

A

Microsporum, Trichophyton, and Epidermophyton

cause all the tineas except for versicolor and nigra

185
Q

What causes Tinea corporis?

A

Dermatophytes (such as Microsporum, Trichophyton, and Epidermophyton)

186
Q

What causes Tinea cruris?

A

Dermatophytes (such as Microsporum, Trichophyton, and Epidermophyton)

187
Q

What causes Tinea pedis?

A

Dermatophytes (such as Microsporum, Trichophyton, and Epidermophyton)

188
Q

What causes Tinea capitis?

A

Dermatophytes (such as Microsporum, Trichophyton, and Epidermophyton)

189
Q

What causes Tinea unguium?

A

AKA Tinea onychomycosis.

Dermatophytes (such as Microsporum, Trichophyton, and Epidermophyton)

190
Q

What causes Tinea onychomycosis?

A

AKA Tinea unguium.

Dermatophytes (such as Microsporum, Trichophyton, and Epidermophyton)

191
Q

How does Tinea corporis present?

A

Ring shape with a red raised border

192
Q

How does Tinea cruris present?

A

AKA jock itch

Itchy red patches on groin and scrotum

193
Q

How does Tinea capitis present?

A

Scaling on the scalp

194
Q

How does Tinea unguium/onychomycosis present?

A

Nails are thickened discolored and brittle

195
Q

Lab diagnosis of dermatophyte infection

A
  1. Dissolve skin scrapings in KOH, which digests the keratin. Microscopic examination reveals branched hyphae.
  2. Direct examination of skin with Wood’s light (UV light at 365 nm wavelength) will fuoresce green if Microsporum.
196
Q

Treatment for dermatophyte infection

A
  1. Topical imidazoles

2. Oral griseofulvin (Tinea capitus and tinea unguium)

197
Q

What causes a fungus ball?

A

Aspergillus

198
Q

What disease states does Aspergillus cause?

A
  1. Allergic bronchopulmonary aspergillosis
  2. Lung cavity aspergilloma
  3. Invasive aspergillosis
199
Q

Histologic appearance of aspergillus

A

Mold (not dimorphic) with septate hyphae that branch at a V-shaped (45 degree) angle). Rare fruiting bodies.

200
Q

Aspergillus (septate hyphae branching at 45 degrees with fruiting bodies)

A

What is this?

201
Q

What disease states does cryptococcus neoformans cause?

A
  1. Cryptococcal meningitis

2. Cryptococcosis

202
Q

Histologic appearance of cryptococcus neoformans

A

5-10 micrometer yeasts with wide capsular halo. Narrow based unequal budding.

203
Q

How is cryptococcus neoformans stained?

A
  1. India ink

2. Latex agglutination test for polysaccharide capsular antigen

204
Q

Where is cryptococcus neoformans found?

A

Soil and pigeon droppings.

USMLE (13 decks)

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