Written by Record Pilot Staff Thursday, 27 March 2014 00:00
North Shore Middle School students in Maryalice Kelly’s eighth grade “Disease” class recently conducted a lab using the Kirby-Bauer method to determine which antibiotic is most effective on E. coli and B. cereus bacteria.
Kelly said, “This technique is used in hospitals and medical labs to help doctors prescribe the most effective antibiotic to their patients with bacterial infections.” She added, “The antibiotics that we examined were: Gentamicin, Penicillin, Streptomycin and Ampicillin.”
Under Kelly’s direction, her students learned that Antibiotic Susceptibility Testing (AST) is carried out to determine which antibiotic will be most successful in treating a bacterial infection. Small wafers containing antibiotics were placed onto an agar plate where bacteria were growing.
She said, “If the bacteria are sensitive to the antibiotic, a clear ring, or zone of inhibition, is seen around the wafer indicating poor growth. The size of the ring is measured.”
The disc that has the largest “inhibition ring” will be declared as the most effective in killing the bacteria.
“My students discovered that Streptomycin worked best on inhibiting the growth of B. cereus and Ampicillin worked best in inhibiting the E. coli,” said Kelly.