To increase the sensitivity of direct Gram-stain examination of body fluid specimens, the specimens are usually:
a. incubated for 18 to 24 hours before stain-ing.
b. centrifuged before staining.
c. examined for at least 1 hour.
d. stained for an additional 5 minutes.
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. H. parainfluenzae.
b. H. influenzae.
c. H. aphrophilus.
d. H. ducreyi.
Isolates from an ear swab that are gram-negative coccobacilli grow on chocolate agar in CO2 but not blood agar, require both X and V factors for growth, and are nonhemolytic on rabbit or horse blood may be identified as:
a. H. parainfluenzae.
b. H. ducreyi.
c. H. aphrophilus.
d. H. influenzae.
Although a useful test in the past, the particle agglutination assay for the detection of H. influenzae, type b, capsular polysaccharide antigen is no longer reliable because of:
a. insufficiently high concentration of the organisms in clinical infections.
b. a lack of sensitivity and specificity of the test procedure.
c. the frequent use of antimicrobial therapy before collecting the specimen.
d. the increased use of H. influenzae, type b, vaccination.
A 6-year-old boy was diagnosed with purulent conjunctivitis caused by a species of Haemophilus. What would the biochemical profile of the organism be?
a. Growth requirements require both X and V factors; the organism is hemolytic on rabbit blood.
b. Growth requirements require both X and V factors; the organism is nonhemolytic on rabbit blood.
c. Growth requirements require V factor; the organism is hemolytic on rabbit blood.
d. Growth requirements require X factor; the organism is nonhemolytic on rabbit blood.
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