Bacterial Resistance to Antibiotics Names:
A. Objectives *Study the effects of various antibiotics on the growth of bacteria, Escherichia coli (E. coli) *Learn how to culture bacteria in vitro (in the laboratory) *Connect genetics to evolution to the resistance of bacteria to antibiotics
B. Materials *Agar dextrose growth medium; bacterial starter colony plate; 18 culture plates with growth medium; disposable sterile inoculating loops; disposable sterile microtainers, disposable sterile pipets; culture fluid, forceps, ampicillin disks, bacitracin disks, novobiacin disk, and tetracycline disks
C. Procedure 1) Obtain one culture plate, with growth medium, per group of two. Divide the bottom plate into 3 pie-shapes. Mark which areas will contain which two of the four antibiotics. One area is the control or no antibiotic. 2) Add 0.25 ml of culture fluid to a microtainer 3) Using a sterile inoculating loop, obtain a small colony of bacteria from the starter plate and swirl the loop in the culture fluid to remove bacteria from the loop 4) Transfer the bacteria suspended in fluid to the culture plate and using a clean inoculating loop, gentle spread the bacteria across the agar growth medium. 5) Using forceps, add the antibiotic disk to the appropriate section of the plate. 6) Cover and incubate at 37 degrees Celsius.
D. Results: Attached to back.
E. Discussion: Antibiotic resistance in bacteria has increased over time because of genetics and evolution. When a genetic change allows bacteria to tolerate antibiotics, usually from beneficial mutations or transfer of genetic material, the bacteria can withstand different levels of antibiotics. This bacterium is a less susceptible bacterium. When humans take antibiotics these only less susceptible bacterium survive. The antibiotic does not create the resistant; it provides the environment