DIT review - Micro 3

Question 1

What is the Ziehl Neelson stain

Answer 1

Acid-fast stain

Question 2

What agar shoul dbe used to culture TB

Answer 2

Lowenstein-Jenson

Question 3

What virulence factor is responsible for clumping of TB into a serpentine form in order to cause virulence

And how does it work

Answer 3

Cord factor

• Cord factor will increases granuloma formation by increasing TNF-a, activating other macrophages, and walling itself off in a granuloma – this will protect the bacteria but also stop it from spreading

Question 4

What is the MOA of Sulfatide virulence factor of TB?

Answer 4

Inhibits the fusion of lysosome and phagosome

Question 5

Which part of the lung is affect in primary and secondary TB

Answer 5

Primary = lower lung

Secondary = upper lung

Question 6

How does immunosuppression lead to reactivation of latent TB

Answer 6

• Immunosuppresion leads to down-regulation of TNF-alpha release
  
  • TNF is a pro-inflammatory cytokine that causes infection to be contained
  • If TNF is neutralized, infection can be spread again

Question 7

MOA of Isoniazid

Answer 7

Inhibition of mycolic acid production (component of cell wall)

Bacterial catalase-peroxidase (encoded by KatG) needed to convert INH to active metabolite

Question 8

MOA of Rifampin

Answer 8

Inducer of CYP450

Binds to bacterial RNA polymerase, inhibiting it

Question 9

MOA of Ethambutol

Answer 9

o Ethambutol blocks the enzyme arabinosyl transferase, inhibiting carbohydrate formation at the cell wall

Question 10

Drug used for prophylaxis of M. tuberculosis

Answer 10

Isoniazid

Question 11

Prophylaxis of M. avium

Answer 11

Azithromycin

Question 12

Describe presenation of Tuberculoid leprosy

Answer 12

Hypoesthetic, hairless skin plaques

Question 13

Primary immune cell in tuberculoid leprosy

Answer 13

Th1 immune response

• Sketchy: Helper TH1 cells stimulate macrophages to engulf the bacteria in cell mediated immunity
  
  • = Jail Cell 1
  • = prisoner behind bars (macrophages)

Question 14

Primary immune response of lepromatous leprosy

Answer 14

• Sketchy: TH2 cells promote humoral (humorous) response
  
  • = Jail Cell 2 with laughing prisoner

Question 15

Treatment of tuberculoid leprosy

Answer 15

Dapsone and Rifampin

Question 16

Treatment of lepromatous leprosy

Answer 16

Dapsone, Rifampin, and Clofazimine

Question 17

Stain used to visualize Bartonella

Answer 17

Wartharin-Starry silver stain

Question 18

Presentation of Bartonella in immunocompetent

Answer 18

Cat scratch fever - fever + axillary lymphadenitis

Question 19

Presentation of Bartonella in immunocompromised

Answer 19

Bacillary angiomatosis - red vascular lesions (similar to Kaposi sarcoma)

Question 20

Treatment for Bartonella

Answer 20

Doxycycline

Macrolides

Question 21

Source for Brucella

Answer 21

Unpasteurized milk

Or direct contact with farm animals

Question 22

Symptoms of Brucella

Answer 22

Undulant fever, chills, anorexia, hepatosplenomegaly, osteomyelitis

Question 23

Treatment of Brucella

Answer 23

Doxycycline and Rifampin

Question 24

Mode of transmission of Tularemia

Answer 24

Caused by Francisella

Direct contact with rabbits or dermacentor tick

Question 25

Presentation of Tularemia

Answer 25

Painful ulcer at site of tick bite

Lymphadenopathy

Granulomas with caseating necrosis

Question 26

Treatment of Tularemia

Answer 26

Streptomycin (aminoglycoside)

Question 27

Presentatino of pasteurella

Answer 27

Cellulitis and osteomyelitis

Question 28

Characteristics of pasteurella

Answer 28

Catalase +

Oxidase +

Encapsulated

Grows on 5% sheep’s blood agar

Bipolar / safety pin staining

Question 29

Treatment of pasteurella

Answer 29

Penicillin

Question 31

Stain used to visualize Borrelia

Answer 31

Lyme diseaes

Write stain or Giemsa stain

Question 32

Presentation of Stage I lyme disease

Answer 32

Flu-like symptoms

Erythema migrans (bulls eye)

Question 33

Presentation of stage II lyme disease

Answer 33

Heart block

Bilateral Bell’s Palsy

Question 34

Presentation of stage III lyme disease

Answer 34

Encephalopathy

Arthritis

Question 35

Treatment of early vs. late stage lyme disease

Answer 35

Early = doxycycline

Late = ceftriaxone

Question 36

Presenation of milder form of leptospirosis

Answer 36

Fever, myalgias (clasically of the calves), conjunctival suffusion (redness without exudate)

Question 37

Presentation of Weil’s disease

Answer 37

More severe form of leptospirosis

Kidney damage = azotemia

Liver damage = jaundice

Question 38

Screening tests for syphilis

Answer 38

VDRL (Venereal disease) - not specific

RPR (rapid plasmin reagent) - detects nonspecific antibody that reacts with cardiolipin

Question 39

Confirmatory test of syphilis

Answer 39

FTA-Abs (FTA antibody test)

Question 40

What causes VDRL false positives?

Answer 40

THINK: VDRL

Viral infection (EBV, hepatitis)

Drugs

Rheumatic fever

Lupus and leprosy

Question 41

Presentation of primary syphilis

Answer 41

Painless genital chancre

Question 42

Presenation of secondary syphilis

Answer 42

Constitutional symptoms

Maculopapular rash including hands and soles

Condyloma latum

Patchy hair loss

Question 43

Presentation of tertiary syphilis

Answer 43

Gummas

Aortitis (tree barking) - can lead to aneurysm

Tabes dorsalis (damage to posterior colum of spinal cord)

Argyll Robertson pupil

Ataxia

Question 44

Presenation of congenital syphilis

Answer 44

Saber shins (anterior bowing)

Saddle nose

Hutchinson teeth (notched)

Deafness

Snuffles (blood-tinged nasal discharge)

Question 45

Treatment of Syphilis

Answer 45

Penicillin

Question 46

What is Jarisch Herxheimer reaction

Answer 46

Flu-like symptoms following antibiotic tx of Syphilis due to killed bacteria releasing toxins