Susceptibility of Antibacterial Chemicals on Pseudomonas aeruginosa Research performed by: Clayton Brady Health Science Biology Major Tennessee Technological University

Introduction Many diseases arise from bacteria that grow resistant to the agents that are made to combat them. Through new research, scientists can develop new antimicrobial agents and antibiotics to ensure the elimination of a bacterium for a limited period of time. Pseudomonas aeruginosa is responsible for 16% of nosocomial pneumonia cases, 12% of hospital-acquired urinary tract infections, 8% of surgical wound infections, and 10% of bloodstream infections.

Objective/Hypothesis The objective of my research is to determine if chemicals commonly found in the antibacterial sprays we use so abundantly today can in fact render potentially hazardous bacteria, such as Pseudomonas aeruginosa, non-viable. I believe that the chemicals will have no effect on Pseudomonas aeruginosa.

Materials This experiment required Petri dishes, a synthetic stock of Pseudomonas aeruginosa, an inoculation loop, and a sterilizer (incinerator) for streaking the plates. For my chemicals I used Isopropyl Alcohol, 1 M Hydrochloric Acid, 5 % Hypochlorite Bleach, and Vesphene. In order to have the bacteria to grow we needed an incubation device. A ruler was needed to measure the zone of inhibition around the discs. Finally an autoclave was required to sterilize the tools after use.

Methods Using aseptic techniques, the experiment began with taking an inoculating loop, sterilizing it by way of heating it, and obtaining a sample of the bacteria being used. The bacteria were then exposed to discs dipped in each of the four chemicals. The dishes were separated into quadrants for each of the four chemicals tested. The bacteria were given a day to grow and on the third day the zone of inhibition was observed and measured for results.

Results After careful aseptic experimentation, I was able to kill Pseudomonas aeruginosa with the antibacterial chemicals used in the experimental process. Vesphene, Isopropyl Alcohol and the 1 M Hydrochloric Acid were unable to kill the bacteria.

Results Cont. Pseudomonas aeruginosa Disk Diffusion Chart Disc Diffusion Assays SusceptibleResistant Zone of Inhibition Isopropyl Alcohol + 1 M HCl + 5 % hypochlorite bleach+ 21 millimeters Vesphene +

Discussion The other chemicals, perhaps effective on other types of bacteria, were ineffective against Pseudomonas aeruginosa. I originally wanted to test household sprays against this bacteria, but after closer examination I realized that the same chemicals are in most of the sprays. In order to continue my research I changed the sprays to specific chemicals commonly used to “sterilize” equipment and tools in hospitals.

Project Summary Pseudomonas aeruginosa is an opportunistic pathogen that engages in a plasmid exchange with other bacteria making it very hard to kill because of its ability to build resistance to many cleaners and medicines. By subjecting Pseudomonas aeruginosa to chemicals found in many hospitals and often used to sterilize equipment, I learned that many chemicals claiming to kill bacteria do not work on Pseudomonas aeruginosa.

Conclusions Bleach (5% hypochlorite solution) was found to be an effective antibacterial agent proving my hypothesis wrong. Although Isopropyl alcohol, vesphene, and HCL (1M) may disinfect some bacteria it is not effective as an antibacterial agent against Pseudomonas aeruginosa.

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