Samplex notes

Question 1

Enumerate: Gram-positive, aerobic rods:

Answer 1

Listeria

Bacillus

Corynebacterium

Question 2

Enumerate: Gram-positive, anaerobic rods:

Answer 2

Clostridium

Question 3

Tumbling motility:

Answer 3

Listeria

Question 4

narrow zone of Beta-hemolysis:

Answer 4

Listeria

Question 5

cold enhancement:

Answer 5

Listeria

Question 6

Enumerate (2): transmission of Listeria:

Answer 6

• across placenta or contact during delivery
• consumption of unpasteurized milk products, e.g. cheese

Question 7

Virulence factor of Listeria monocytogenes that interacts with E-cadherin on the surface of the cells

Answer 7

Internalin

Question 8

Virulence factor of Listeria monocytogenes that helps the organism escape from phagosomes:

Answer 8

listeriolysin

Question 9

Virulence factor of Listeria monocytogenes that propels the bacteria through the membrane of one human cell and into another

Answer 9

actin rockets

Question 10

granulomatosis infantiseptica

Answer 10

Listeria

Question 11

2 methods of acid-fast staining:

Answer 11

Kinyoun
Ziehl-Neelsen

Question 12

Identify: fatty acids in the cell walls of acid-fast organisms:

Answer 12

mycolic acid

Question 13

Identify: assay that tests for drug resistance of Mycobacterium tuberculosis

Answer 13

luciferase assay

Question 14

• most important virulence factor for Mycobacterium tuberculosis:
• a.k.a.

Answer 14

cord factor
a.k.a. mycolic acid

Question 15

This virulence factor of Mycobacterium tuberculosis triggers cell-mediated immunity leading to granuloma formation, and delayed type hypersensitivity

Answer 15

tuberculin surface protein

Question 16

Enumerate: 2 typess of lesions caused by Mycobacterium tuberculosis infection:

Answer 16

1. Exudative lesions
2. Granulomatous lesions

Question 17

Describe the histopathology of granulomatous lesions:

Answer 17

central area of Langhan giant cells surrounded by a zone of epitheloid cells

Question 18

Enumerate: 3 interpretations of positive PPD skin test result:

Answer 18

• current infection or active disease
• past exposure
• BCG vaccine

Question 19

Enumerate: 2 interpretations of negative PPD skin test result:

Answer 19

• no infection
• anergy (e.g. in immunocompromised, malnutririon, etc.)

Question 20

Most common extrapulmonary TB:

Answer 20

scruffula

Question 21

• Diagnostic test for the detection of Rickettsiae
• explain the mechanism of this reaction

Answer 21

• Weil-Felix reaction
• cross-reaction with antigens of OX strains of Proteus vulgaris

Question 22

DOC for all rickettsial infections:

Drug avoided in rickettsial infection:

Answer 22

• doxycycline
• pwede rin chloramphenicol
• sulfonamides