Deck 31: Haemophilus

Question 1

With one exception, species of the genus Haemophilus require hemin and nicotine adenine dinucleotide (NAD) for in vitro growth.Which is the exception?

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

Answer 1

C
Species of the genus Haemophilus, except for H. aphrophilus, require hemin and nicotine adenine dinucleotide (NAD) for in vitro growth.

Question 2

Actinobacillus actinomycetemcomitans can be distinguished from Haemophilus aphrophilus by

A)its negative test for catalase.
B)its positive test for lactose fermentation.
C)its positive test for catalase.
D)its negative test for oxidase.
E)All of the above are correct.

Answer 2

C
Differentiation of H. aphrophilus from similar organisms (e.g., A. actinomycetemcomitans) is accomplished by performing the catalase test. H. aphrophilus is catalase-negative and ferments lactose or sucrose. A. actinomycetemcomitans yields the opposite reactions in these tests.

Question 3

Isolates from CSF that are gram-negative coccobacilli, grow on chocolate agar in CO₂ but not blood agar, require factor V but not X, and are nonhemolytic on rabbit or horse blood may be identified as

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

Answer 3

A
All characteristics listed are those that describe H. parainfluenzae.

Question 4

Isolates from eye swabs that are gram-negative coccobacilli, grow on chocolate agar in CO₂ but not blood agar, and are porphyrin-negative and nonhemolytic on rabbit or horse blood may be identified as

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

Question 5

Of the following media, which provides the factors necessary for the growth of Haemophilus spp.?

A)5% sheep blood agar
B)Brain heart infusion agar
C)Chocolate agar
D)Nutrient agar
E)All of the above are correct.

Question 6

Isolates from CSF or respiratory tract specimens that are gram-negative coccobacilli, grow on chocolate agar in CO₂ but not blood agar, and are porphyrin-negative and nonhemolytic on rabbit or horse blood may be identified as

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

Question 7

Chancroid is the sexually transmitted disease caused by

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

Question 8

In a phenomenon known as satelliting, tiny colonies of Haemophilus spp.may be seen growing on sheep blood agar very close to colonies of

A)Streptococcus pyogenes.
B)Staphylococcus aureus.
C)Micrococcus species.
D)other Haemophilus species.

Question 9

The major difference between infections caused by type b H.influenzae and those infections caused by nontypeable strains is that

A)infections caused by type b H.influenzae are often systemic and life- threatening.
B)infections caused by other Haemophilus spp.occur much less frequently.
C)the number of type b H.influenzae infections has been greatly reduced.
D)All of the above are correct.
E)None of the above are correct.

Question 10

Growth of H.ducreyi in culture requires

A)incubation at 33° to 35° C.
B)high humidity.
C)increased CO₂.
D)special media.
E)All of the above are correct.

Question 11

Of the following media, which provides the NAD necessary for the growth of Haemophilus spp.?

A)5% sheep blood agar
B)Brain heart infusion agar
C)Chocolate agar
D)Nutrient agar
E)All of the above are correct.

Question 12

The major difference between infections caused by type b H.influenzae and those infections caused by nontypeable strains is that

A)infections caused by type b H.influenzae are often systemic and life-threatening.
B)infections caused by other Haemophilus spp.occur much more frequently.
C)the number of type b H.influenzae infections has been greatly increased.
D)All of the above are correct.
E)None of the above are correct.

Question 13

With one exception, species of the genus Haemophilus require which media ingredients for in vitro growth?

A)Vitamin K and hemin
B)Hemin and nicotine adenine dinucleotide (NAD)
C)Vitamin K and nicotine adenine dinucleotide (NAD)
D)Hemin and cysteine.

Question 14

Compared with nontypable strains of Haemophilus spp., choose the statement that is true about infections caused by type b H.influenzae.

A)Infections caused by type b H.influenzae are often systemic and life-threatening.
B)Infections caused by H.influenzae occur much more frequently.
C)The number of type b H.influenzae infections has been greatly reduced.
D)All of the above are correct.
E)None of the above are correct.

Question 15

Among H.influenzae strains, group designations (e.g., type b) are based on

A)flagellar antigens.
B)capsular characteristics.
C)cell wall antigens.
D)infectious capabilities.

Question 16

H.ducreyi requires what special media to grow?

A)Heart infusion-based agar supplemented with 10% IsoVitaleX and vancomycin
B)Mueller-Hinton-based chocolate agar, supplemented with 1% IsoVitaleX and vancomycin
C)Heart infusion-based chocolate agar, supplemented with 10% fetal bovine serum and vancomycin
D)Mueller-Hinton-based agar, supplemented with 10% IsoVitaleX and vancomycin

Question 17

Performance of the "factor requirement test" for Haemophilus involves

A)inoculation of unsupplemented media with a light suspension of the organism and placement of X and V factor disks on the agar surface.
B)inoculation of liquid media, unsupplemented and supplemented with X and V factors.
C)detecting the presence of enzymes that convert d-aminolevulinic acid (ALA) into porphyrins.
D)growth of the organism in the presence of bacterial species that produce X and V factors as metabolic by-products.

Question 18

Although a useful test in the past, the particle agglutination assay for detection of H.influenzae type b capsular polysaccharide antigen is no longer reliable due to

A)insufficiently high concentration of the organisms in clinical infections.
B)Lack of sensitivity and specificity of the test procedure.
C)Frequent use of antimicrobial therapy before collection of the specimen.
D)Increased use of H.influenzae type b vaccination.

Question 19

Growth of most Haemophilus species in culture is enhanced by

A)incubation at 33° to 35° C.
B)high humidity.
C)5% to 10% carbon dioxide (CO₂).
D)enriched special media.
E)All of the above are correct.

Question 20

In a phenomenon known as satelliting, tiny colonies of Haemophilus spp.may be seen growing on sheep blood agar very close to colonies of bacteria that can produce

A)hemin.
B)nicotine adenine dinucleotide (NAD).
C)vitamin K.
D)cysteine.

Question 21

Match the microscopic morphology with the most likely agent.
a.H. haemolyticus
b.H. influenzae biotype aegypticus
c.H. influenzae
d.H. segnis
e.H. parainfluenzae
Very short bacilli occasionally seen as filamentous forms

Question 22

To increase the sensitivity of direct Gram stain examination of body fluid specimens, the specimens usually are

A)incubated for 18 to 24 hours before staining.
B)centrifuged before staining.
C)examined for at least 1 hour.
D)stained for an additional 5 minutes.

Question 23

Match the microscopic morphology with the most likely agent.
a.H. haemolyticus
b.H. influenzae biotype aegypticus
c.H. influenzae
d.H. segnis
e.H. parainfluenzae
Coccobacilli or small rods

Question 24

Match the microscopic morphology with the most likely agent.
a.H. haemolyticus
b.H. influenzae biotype aegypticus
c.H. influenzae
d.H. segnis
e.H. parainfluenzae
Long, slender rods

Question 25

Match the microscopic morphology with the most likely agent.
a.H. haemolyticus
b.H. influenzae biotype aegypticus
c.H. influenzae
d.H. segnis
e.H. parainfluenzae
Pleomorphic rods

Question 26

Match the microscopic morphology with the most likely agent.
a.H. haemolyticus
b.H. influenzae biotype aegypticus
c.H. influenzae
d.H. segnis
e.H. parainfluenzae
Small coccobacilli or short rods with occasional cells appearing as tangled filaments

Question 27

Match the microscopic morphology with the most likely agent.
a.H. haemolyticus
b.H. influenzae biotype aegypticus
c.H. influenzae
d.H. segnis
e.H. parainfluenzae
Small pleomorphic rods or long filamentous forms

Question 28

Match the microscopic morphology with the most likely agent.
a.H. haemolyticus
b.H. influenzae biotype aegypticus
c.H. influenzae
d.H. segnis
e.H. parainfluenzae
Short to medium-length bacilli

Question 29

Match the microscopic morphology with the most likely agent.
a.H. haemolyticus
b.H. influenzae biotype aegypticus
c.H. influenzae
d.H. segnis
e.H. parainfluenzae
Slender or coccobacillary