Investigating the effect of varying concentration of chloramphenicol and Kanamycin on Staphylococcus aureus inhibition and inhibition of Staphylococcus aureus, Bacillus subtilis, Salmonella typhimurium by antibiotics
University of KwaZulu-Natal
School of Life Sciences
Discipline of Microbiology
Antibiotics are antimicrobial drugs made from living organisms that are used to treat or prevent bacterial infections by either killing bacteria or slowing down growth rate of bacteria. The aim of this experiment was to investigate the effect of varying concentration of chloramphenicol and kanamycin on S. aureus inhibition and inhibition of S. aureus, B. subtilis, S. typhimurium by antibiotics. To vary concentration liquid Kanamycin (initial concentration 640 pp) and chloramphenicol (initial concentration 1280 ppm) were diluted by pouring 5 ml into 5 ml broth repeatedly until concentration became 0.312 ppm. Circular disc of sterile filter paper was dipped in broth and plated in nutrients agar while broth was inoculated with S. aureus. Both were incubated at 35 OC for 4 days and after incubation diameter of inhibition was measured on plate and turbidity on broth. To detect inhibition by bacteria at the bottom of the provided nutrients agar plate a line was drawn in the middle dividing it into two equal halves. 0.1 ml aliquots of overnight broth culture of S. aureus was pipetted into nutrients agar plate and spread plated evenly covering the whole surface. On the surface of the medium in each half, two antibiotic discs of selected antibiotics were placed. The same was done for S. typhimurium and B. subtilis and plates were incubated at non inverted position at 35 OC for 4 days. After incubation period inhibition diameters were measured. Figure 1, figure 2 and table 1 show S .aureus showed inhibition at higher concentrations for both microorganism and showed more resistance to Kanamycin than to Chloramphenicol. The minimum inhibitory concentration in the agar was 40 ppm but in the broth was 5 ppm. S. typhimurium showed the most resistance to antibiotics, B. subtilis showed moderate resistance and S. aureus showed the least resistance. The aim of this experiment was achieved.
Antibiotics are antimicrobial drugs that are used to treat or prevent bacterial infections by either killing bacteria or slowing down growth rate of bacteria. Antibiotic drugs are made from living organisms such as fungi, molds and soil bacteria that are pathogenic to disease- causing bacteria (Guarlezi et al, 2013)
When bacteria enter the body, the immune system produces white blood cells to fight the infection before multiplication however, when immune system fails due to excessive bacteria antibiotics are used. The most popular industrial uses of antibiotics are in the medicine world where they are used to treat bacterial infections or synthesized to produce semisynthetic antibiotics. These however only work for bacteria related...