Question

An antibiotic sensitivity test was performed for S. aureas, B. cereus, E coli and S. typhimurim. The antibiotics used are Gentamycin (GM), Chloramphenicol (C), Streptomycin (S), Ampicillin (AM), Tetracycline (TE) and Erythromycin (E). The diameters of the zones of inhibition were measured for each antibiotic and recorded. S = susceptible. R = resistant. I = intermediate. Do the results align with the expected results for each organism?

Answer 1

Antibiotic Sensitivity or Susceptibility Test (AST) is usually carried out to determine which antibiotic will be most successful in treating a bacterial infection. If the bacteria are sensitive to the antibiotic a clear ring or zone of inhibition is seen around the wafer (wafer containing antibiotic are placed on a plate in which bacteria are growing) indicating poor growth.

• In the given data we can analyse that Chloramphenicol antibiotic is more effective for a bacterial infection (Zone of inhibition diameter is 30 and above in all bacteria)
• In most case Chloramphenicol, Tetracycline and Gentamycine are made large clear ring indicating these are good medicine for S.aureas,B.cereus,E.coli and S.typhimurim infection.
• The diameter of clear ring formed in E.coli and S.typhimurim is small (when compare to other) indicating they are little danger than other two.
• Streptomycine and Erythromycine are less effective for these bacterial infection. Which shows intermediate and resistant response in  S.aureas,E.coli and S.typhimurim.