Determining the Minimum Inhibitory Concentration (MIC) of Different Antibiotics Against a Drug-Resistant Bacteria

Antibiotics are molecules that assist against bacterial infections by destroying the bacteria or preventing their reproduction. This experiment examined the effect of three different antibiotics, Chloramphenicol, Kanamycin, and Erythromycin, on the growth of a Tetracycline-resistant laboratory strain, E. coli AR3110. By monitoring bacterial growth inhibition in the presence of increasing antibiotic concentration, the minimum inhibitory concentration (MIC) of each drug against E. coli AR3110 was obtained. The MIC of Chloramphenicol and Kanamycin was calculated as 4.87 ± 1.39 µg/mL and 55.33 ± 15.18 µg/mL respectively, while the MIC of Erythromycin was undetermined. The observed MIC for both Chloramphenicol and Kanamycin agree very well with the literature, results of Erythromycin’s MIC suggest that E. coli strain AR3110 could also be resistant towards this antibiotic. Knowing these values is imperative as they indicate the minimum concentration required to prevent bacterial growth. Keywords: minimum inhibitory concentration, MIC, antibiotic resistance, chloramphenicol, kanamycin, erythromycin, E. coli AR311