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• Many people in hospitals die every year from catheter infections. • A catheter is a perfect breeding ground for infectious bacteria because the immune system cannot reach it to defend the body. • Through all the handling, it is almost impossible to prevent the contamination. • Catheter: a flexible tube inserted into the body for medical uses such as injection or withdrawal of fluids • Ampicillin: this drug has been proved to terminate hazardous germs • DTAB: surfactant with a positive charge (cationic) • Surfactant: a surface active agent • Lysozyme: commercially available protein that exhibits antimicrobial activity at an interface • Nisin: an antimicrobial protein that inhibits the growth of Gram- positive cells and spores • SDS: a surfactant with a negative charge (anionic) • We created two concentrations of DTAB, Beta Lactoglobulin, Lysozyme, SDS, Nisin. • We cut pieces of catheter tubing and then dipped them in the different concentrations of our antibiotics. We held them in the antibiotic for 60 seconds and then rinsed them in sodium phosphate. • Next we placed them in one of two bioassay plates containing either pediococcus or e-coli. • We inserted our plates in the incubator to give the bacteria a chance to grow and be killed. We knew if an antibacterial agent had worked if there was kill zone. • The kill zone is an area that is discolored or is a circle with no living bacteria present. • We noted how our control substances, Ampicillin and water, did as predicted. The Ampicillin was the positive control and the water the negative. • A bioassay plate is a petri dish that often holds agar to grow bacteria. In our project, we used e-coli and pediococcus in the agar to see what would kill bacteria. This would be indicated by a clearer area in the agar. • We were trying to coat the catheter with an antibacterial agent to fend off bacteria that could be harmful. This would prevent infections in people when they have a catheter. Antibiotics Low er Concentration Higher Concentration DTAB .31 mg/ml 31 mg/ml Beta Lactoglobulin .1 mg/ml 1 mg/ml Lysozyme .11 mg/ml 1 mg/ml SDS .285 mg/ml 28.5 mg/ml Nisin .1 mg/ml 1 mg/ml Antibiotics Concentration (mg/ml) Kill Zone (mm) DTAB 0.31 none DTAB 31.00 11 Beta Lactoglobulin 0.10 none Beta Lactoglobulin 1.00 none Lysozyme 0.11 8 Lysozyme 1.00 none SDS 0.29 none SDS 28.50 1 Nisin 0.10 3 Nisin 1.00 4 Ampicillin 1.00 13 Water none Antibiotics Concentration (mg/ml) Kill Zone (mm) DTAB 0.31 none DTAB 31.00 8 Beta Lactoglobulin 0.10 none Beta Lactoglobulin 1.00 none Lysozyme 0.11 none Lysozyme 1.00 none SDS 0.29 none SDS 28.50 none Nisin 0.10 none Nisin 1.00 none Ampicillin 1.00 4.5 mm Water none Since different bacteria have different types of cell walls, certain antibiotics will have more of an affect on one bacteria than another. For this reason our antibiotics were more affective on pediococcus than e-coli. The only antibiotic that killed e-coli, other than our positive control, was the higher concentration of DTAB. Nisin, SDS, lysozyme, and DTAB all had a kill zone in the pediococcus plate. Our control, ampicillin, was by far the most effective antibiotic on that plate. There are a lot of drugs that will do many things to different bacterium. The first question we had was, “What is most effective on both plates?” We found that DTAB worked well in both bacterium, sometimes with better kill zones than our control. In this experiment we have decided that DTAB would do best in the use of coating catheters. A special thanks to our mentor, Clayton Jeffries and Dr. Michelle Bothwell for allowing us to use her lab.
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