Reference no: EM132735013

Three-year-old Molly was brought to the emergency department crying. She had a stiff neck and high fever (40°C, or 104°F). Gram stain of her cerebrospinal fluid revealed Gram-positive cocci, generally in pairs. The attending physician diagnosed Molly with meningitis and immediately prescribed intravenous ampicillin. Unfortunately, the child's condition worsened, so antibiotic treatment was changed to a third-generation cephalosporin (ceftriaxone). Molly began to improve within hours and was released after two days. A report from the clinical microbiology laboratory two days later identified the organism as Streptococcus pneumoniae. The report also included antibiotic susceptibility results, which revealed that this strain of S. pneumoniae was resistant to ampicillin but remained susceptible to cephalosporin.

The clinical laboratory performed a Kirby-Bauer assay to determine the antibiotic susceptibility of S. pneumoniae. Which of the following is true about this assay?

Select one:

a. It requires the organism to be autoclaved
b. It uses serial dilutions to determine the MIC.
c. It can tell you which antibiotic is bactericidal.
d. It is performed on an agar plate and the antibiotic diffuses throughout the media.
e. It is performed on a mannitol salt agar plate.