Gram-negative coccobacilli

Question 1

How is Haempohilus ducreyi transmitted?

Answer 1

sexual contact

Question 2

What are the clinical manifestations of Haemophilus ducreyi? (1)

Answer 2

chancroid-penile lesion that becomes a nonindurated painful ulcer with sharp margins (Compare with hard chancre of syphilus). May progress to infect lymph nodes, forming bubo.

Question 3

How does Haemophilus vaginalis (Gardnerella) gram stain?

Answer 3

variable

Question 4

What part of the world is most associated with Haemophilus ducreyi?

Answer 4

common in tropical countries

Question 5

How does Haemophilus influenzae gram stain?

Answer 5

negative

Question 6

What is the morphology of Haemophilus vaginalis (Gardnerella)?

Answer 6

coccobacilli

Question 7

What lab findings are useful to help diagnose Haemophilus vaginalis (Garnerella)? (2)

Answer 7

positive whiff test (fishy odor after application of 10% KOH); clue cells

Question 8

When is the H. influenzae vaccine given?

Answer 8

between 2 and 18 months of age

Question 9

Name four diseases caused by H. influenzae.

Answer 9

epiglottitis, meningitis, otitis media, pneumonia

Question 10

How does Haemophilus ducreyi gram stain?

Answer 10

negative

Question 11

How is Bordetella pertussis transmitted?

Answer 11

human to human, repiratory droplets.

Question 12

What lab findings are useful to help diagnose Bordetella pertussis? (3)

Answer 12

nasopharyngeal swab will give colonies that grow on Bordet-Gengou medium; small colonies glisten “like pearls”; PCR can make rapid identification.

Question 13

What are the clinical manifestations of Haemophilus influenzae? (5)

Answer 13

otitis media-pain, fever, ruptured tympanic membrane (pus, blood). Also meningitis, sinusitis, pneumonia, acute epiglottitis.

Question 14

What symptoms are associated with G. vaginalis infection? (3)

Answer 14

vaginosis-greenish vaginal discharge, fishy odour, not painful

Question 15

What are the laboratory characteristics of G. vaginalis? (2)

Answer 15

pleiomorphic, gram-variable rods; clue cells-vaginal epithelial cells covered with bacteria are visible under a microscope

Question 16

What is the morphology of Bordetella pertussis?

Answer 16

coccobacilli, encapsulated

Question 17

Identify relevant epidemiology and risk factors associated with Bordetella pertussis. (2)

Answer 17

very contagious, mostly affecting young children.

Question 18

How does Bordetella pertussis gram stain?

Answer 18

negative

Question 19

What lab findings are useful to help diagnose Haemophilus influenzae? (2)

Answer 19

requires chocolate agar (lysed RBC’s that provide heme and NAD) to grow; Colonies grow as satellites next to S. aureus.

Question 20

Which mechanism do pertussis toxin and choleratoxin have in common?

Answer 20

act via ADP ribosylation to permanently activate adenyl cyclase, resulting in increased cAMP.

Question 21

T/F: H. influenzae causes the flu

Answer 21

false-influenza virus causes the flu

Question 22

Identify the major virulence/toxicity factors associated with Bordetella perussis. (2)

Answer 22

filamentous hemagglutinin on pili help organism to stick to epithelium. Pertussis toxin stimulates G protein to raise [cAMP] in epithelial cells and also causes lymphocytosis by inhibition of chemokine receptors.

Question 23

What is the morphology of Haemophilus influenzae?

Answer 23

coccobacilli

Question 24

Identify the major virulence/toxicity factors associated with Haemophilus influenzae. (2)

Answer 24

secretes a protease that digests secretory IgA. Encapsulated strains can reach the meninges.

Question 25

What is the morphology of Haemophilus ducreyi?

Answer 25

coccobacilli

Question 26

Describe the clinical picture of Bordetella pertussis infection. (3)

Answer 26

pertussis (whooping cough)-7-10 days incubation followed by mild URT infection for 1 or 2 weeks and then a “whooping” cough that produces copious mucus. May be followed by vomiting.