Fastidious GNR

Question 1

Which of the following organisms require specific screening cultures to be ordered due to their fastidious nature?

a) Bordetella pertussis
b) Haemophilus influenza
c) Legionella sp.
d) A and C
e) All of the above

Answer 1

D) A and C

Question 2

T/F: The Hib vaccine protects against all type of H. flu infections?

Answer 2

False- Type B (causes most human disease)

Question 3

T/F: Legionella sp. are spread via respiratory droplets from person-to-person?

Answer 3

False: Water

Question 4

What disease does the CDC recommend women in the 3rd trimester of pregnancy be vaccinated for?

Answer 4

Pertussis

Question 5

If an individual is confirmed to have pertussis, should prophylaxis for household or close contacts be prescribed? If so, with what treatment?

Answer 5

Yes- a macrolide. See Sanford p. 37

Question 6

How are sputum specimens screened for quality prior to culture?

Answer 6

Gram stain to detect squamous epithelial cells

Question 7

Haemophilus sp, Bordetella sp. and legionella sp.: What would the gram stain look like for these organisms?

Answer 7

Gram negative coccobacilli (very small gram-negative rods)

Question 8

What clinical presentation can Haemophilus influenzae cause?

Answer 8

Respiratory tract infections (often secondary to viral infections), Meningitis, Otitis media, Conjunctivitis

Question 9

What virulence factor of H. influenzae has the most significant role and what type causes most human disease?

Answer 9

Capsule. Type B

Question 10

How would you treat meningitis caused by H. influenzae? Both life threatening and non-life threatening

Answer 10

Life threatening: Cefotaxime or ceftriaxone (alt: ampicillin if susceptible, FQ).
Non-Life Threatening: Amoxicillin-clavulanate, oral 2nd/3rd gen cephalosporins

Question 11

H. Influenzae will grow on what medium and when would you expect growth?

Answer 11

Will grow on chocolate agar, which is part of routine cultures. Growth within 24-48 hours.

Question 12

Direct specimen testing for B. pertussis is done how and about how long does it take to get results?

Answer 12

Nucleic acid testing (molecular methods such as PCR), and results usually within 24 hours.

Question 13

Describe specific culture for B. pertussis

Answer 13

• Plate specimen at bedside to appropriate agar (Regan-lowe, or swab in Regan-lowe transport medium).
• Submit immediately (w/i 24 in transport medium.
• Organism must remain viable
• Growth visible at 3-4 days

Question 14

Specimen of choice for all tests for Bordetella pertussis

Answer 14

Nasopharyngeal aspirate or swab. Press swab through nares until resistance is met

Question 15

Legionella sp. is the etiologic agent for (2)

Answer 15

Pontiac fever, legionnaires pneumonia

Question 16

Specimen of choice for legionella sp.

Answer 16

Bronchial alveolar lavage (BAL) fluid- sputum often not produced

Question 17

Culture medium for legionella sp. and how long until growth detected?

Answer 17

buffered charcoal yeast extract agar and organism growth at 3-5 days

Question 18

Drug of choice for legionella sp.

Answer 18

FQ (moxifloxicin, levofloxacin) and macrolides (azithromycin)

Question 19

Most common gram-negative coccobacilli isolated

Answer 19

H. influenzae

Question 20

Due to their fastidious nature, standardized susceptibility methods are not available for isolates of:

Answer 20

Bordetella pertussis and Legionella sp.

Question 21

An adequate sputum specimen will contain _________ cells with few ___________cells.

Answer 21

White blood cells, squamous epithelial cells

Question 22

A direct specimen Gram stain of a 5-year-old’s eye exudate is reported as:
Moderate WBCs
Moderate gram-negative coccobacilli
This is most consistent with:

Answer 22

-Haemophilus influenzae
*NOTE: Bordetella and Legionella are not known to cause eye infections.
Neisseria gonorrhoeae is a gram-negative diplococci and is usually seen in newborns.
Haemophilus influenzae, a gram-negative coccobacilli, is known to cause suppurative conjunctivitis.