Deck 18: Haemophilus and Other Fastidious Gram-Negative Bacilli

Question 1

All of the following are characteristics of Haemophilus spp.except:

A)gram-positive cocci.
B)small coccobacilli.
C)oxidase positive.
D)catalase positive.

Answer 1

A
The genus Haemophilus consists of gram-negative, pleomorphic coccobacilli or rods that may vary microscopically from small coccobacilli in direct smears of clinical material to long filaments occasionally seen in stained smears of colony growth.They are nonmotile, facultatively anaerobic, ferment carbohydrates, are generally oxidase and catalase positive, reduce nitrates to nitrites, and are obligate parasites on the mucous membranes of humans and animals.

Question 2

Which one of the virulence factors associated with Haemophilus spp.plays the most significant role in the invasiveness of the organism?

A)IgA protease
B)Pili
C)Capsule
D)Enterotoxin

Answer 2

C
Of all the potential virulence factors, the capsule, if present, plays the most significant role.Before widespread use of a vaccine, most invasive infections were caused by encapsulated strains of H.influenzae belonging to capsular serotype b and occurred primarily in young children.

Question 3

A microbiologist is reading a sputum culture and notices tiny, translucent colonies growing closely around a b-hemolytic colony on sheep blood agar (SBA).In fact, the colonies are growing in the area where the blood has been hemolyzed.What is the probable identity of the organism that is growing closely to the b-hemolytic organism, and why are they growing in the hemolyzed area?

A)Neisseria spp., because they need the factor X in this area
B)Haemophilus spp., because they need the factor V in this area
C)Acinetobacter spp., because they need the factors X and V
D)Alcaligenes spp., because they require antibiotics be added to the media

Answer 3

B
A phenomenon that helps in the recognition of Haemophilus spp., which require V factor, is satellitism.Satellitism occurs when an organism such as Staphylococcus aureus, Streptococcus pneumoniae, or Neisseria spp.produces V factor as a by-product of its metabolism.On SBA plates, tiny colonies of Haemophilus may be seen growing or engaging in satellitism around the V factor-producing organism.

Question 4

What Haemophilus species is called the Koch-Weeks bacillus?

A)H.influenzae
B)H.parainfluenzae
C)H.aegyptius
D)H.aphrophilus

Question 5

Which species are associated with infections in humans?

A)Haemophilus influenzae
B)H.aegyptius
C)H.ducreyi
D)All of the above

Question 6

What are the names of the two diseases caused by Legionella species?

A)Rabbit fever and Pontiac fever
B)Scalded skin syndrome and Legionnaires disease
C)Malta fever and undulating fever
D)Legionnaires disease and Pontiac fever

Question 7

Which species of Haemophilus requires both X and V factors?

A)H.parainfluenzae
B)H.aphrophilus
C)H.influenzae
D)H.paraphrophilus

Question 8

What medium will sustain the growth of most Haemophilus spp.?

A)Chocolate agar
B)SBA
C)PEA
D)Thayer-Martin

Question 9

What organism causes Brazilian purpuric fever (BPF)?

A)Haemophilus parainfluenzae
B)H.aphrophilus
C)H.aegyptius
D)H.influenzae biogroup aegyptius

Question 10

What is the name of the organism that causes tularemia, which can be contracted from rabbits?

A)Brucella tularensis
B)B.hareis
C)Francisella tularensis
D)F.philomiragia

Question 11

A mother brings her lethargic, feverish baby into the emergency department.The baby is diagnosed with meningitis and the doctor does a spinal tap.The cerebrospinal fluid (CSF) Gram stain shows many tiny gram-negative rods.What is the most probable identification of this organism?

A)Haemophilus influenzae serotype b
B)H.parainfluenzae
C)H.aegyptius
D)H.aphrophilus

Question 12

What organisms often are involved in septicemia in the granulocytopenic patient?

A)Capnocytophaga spp.
B)Eikenella corrodens
C)Kingella spp.
D)Fusobacterium spp.

Question 13

What is the drug of choice for treating a life-threatening illness caused by H.influenzae?

A)Penicillin
B)Macrolides
C)Aminoglycosides
D)Ceftriaxone

Question 14

What is the most frequently isolated Pasteurella species?

A)P.multocida
B)P.septica
C)P.gallicida
D)P.canis

Question 15

All of the following are normal inhabitants of the human oral cavity except Capnocytophaga:

A)fusofurium.
B)gingivalis.
C)ochracea.
D)haemolyticus.

Question 16

What is the name of the disease that is characterized by rapid onset, acute inflammation, and intense edema that may cause complete airway obstruction in 2- to 4-year-olds?

A)Cellulitis
B)Epiglottitis
C)Meningitis
D)Conjunctivitis

Question 17

All the following organisms are associated with human illness except:

A)Brucella melitensis.
B)B.ovis.
C)B.suis.
D)B.canis.

Question 18

The HACEK group includes all of the following except:

A)Haemophilus spp.
B)Aggregatibacter actinomycetemcomitans.
C)Cardiobacterium hominis.
D)Clostridium difficile.

Question 19

A microbiologist is reading a sputum culture and notices that there is no growth on the sheep blood and MacConkey agars, but there is growth on the chocolate plate.The colonies on the plate are translucent, moist, smooth, and convex, with a mousy odor.What is the most likely identification of the organism?

A)Haemophilus parainfluenzae
B)H.influenzae
C)H.aegyptius
D)H.ducreyi

Question 20

What organism is likely to cause an infection after a cat bite?

A)Campylobacter spp.
B)Dysgonomonas capnocytophagoides
C)Francisella tularensis
D)Pasteurella spp.

Question 21

What medium is used to isolate Legionella?

A)MacConkey
B)BCYE
C)Chocolate
D)Bordet-Gengou

Question 22

What agar is used to isolate the Bordetella species?

A)BCYE
B)Bordet-Gengou
C)Chocolate
D)Martin-Lewis

Question 23

What is the drug of choice for treating Bordetella infections?

A)Erythromycin
B)Penicillin
C)Aminoglycosides
D)Quinolones

Question 24

What is the specimen of choice for Bordetella species?

A)Throat cultures
B)Sputum specimens
C)Bronchial aspirations
D)Nasopharyngeal swabs

Question 25

All of the following are rapid methods used to definitively identify Legionella species except:

A)direct fluorescent antibody (DFA).
B)DNA detection.
C)indirect immunofluorescence.
D)urine antigen testing.

Question 26

What organism produces a community-acquired pneumonia, with symptoms different than a Streptococcus pneumonia infection, leading to the designation of atypical pneumonia?

A)Legionella pneumophila
B)Mycoplasma
C)Chlamydophila asteroides
D)C.trachomatis

Question 27

How is Bordetella disease spread?

A)Fomites
B)Contaminated food
C)Respiratory droplet
D)Airborne

Question 28

What organism causes the disease called whooping cough?

A)Bordetella pertussis
B)Legionella pneumoniae
C)Mycoplasma pneumoniae
D)Chlamydophila pneumoniae

Question 29

What is the drug of choice for treating a Legionella infection?

A)Aminoglycosides
B)Penicillin
C)Vancomycin
D)Azithromycin