Kirby Bauer Test Lab Report Essay

Introduction

According to an online lab manual, Kirby-Bauer test is a highly standard test used in many labs for antibiotic susceptibility for many years. The use of this test is to determine the sensitivity or resistance of bacteria to antibiotics. It is a highly standardized procedure that makes use of Mueller-Hinton agar. For basic a bacterium is swabbed on the agar surface, and then antibiotic disc containing certain concentrations are placed on the center of a plate, pressed firmly so they don’t move, and then incubated. Presence of zone of inhibition around the disc it means bacteria was sensitive to the drug. Basically zone of inhibition is the area formed around the antibiotic disc, which is the area of no growth and it is a clear zone.

The disinfectants did not have same diffusion rates, whereas some antibiotics did have same diffusion rates, which made it easier to compare their effectiveness in killing the microbes. For example, in case of antibiotics we were able to conclude if bacteria were sensitive, resistant, or stayed intermediate based on their zone of inhibition size. However, in case of disinfectants this could not be specified. In both the methods we did use zone of inhibition method to compare the results. According to an abstract of a journal of infectious disease, Kirby-Bauer test is widely used in clinical medication and has a great application to Carbenicillin, which the zone inhibition with MIC blood levels and urine analysis shows that Carbenicillin has low toxic levels that permits high blood level and has many therapeutic

Also class average is not a very good interpretation of the results because it does contain data from some groups that was slightly deviated. But for the most part, if we look at our results we can say that Strep faecalis is sensitive to all antibiotics except for Erythromycin, so it is resistant to it. However, the class average in this case is a better number to look at which is 14. So in this case there could have been an experimental error or maybe like sterile disc was not completely pressed onto agar that gave us this result. Then Staph aureus is also sensitive to all antibiotics except for Polymeric B, since no zone of inhibition was identified. So Staph aureus was resistant to Polymeric B. Then E.coli, a gram-negative rod bacterium was resistant to most antibiotics like Novobiocin, Bacitracin, Penicillin, and Erythromycin, and sensitive or intermediate to others. With Penicillin and Bacitracin no zone of inhibition was identified which is a very accurate result. Then Pseudo aeruginosa which is resistant to Penicillin but very sensitive to Tetracycline since we saw a inhibition zone of 26mm. Our results were pretty close to class average and turned out accurate except for some. Especially in case of Strep faecalis, where it should have been sensitive to Erythromycin it only covered 6mm. It is possible that maybe the measurement was not taken accurately or antibiotic