The Effect of Antibacterial Disinfectants¬ on Killing the E-coli Bacteria

چکیده مقاله

The aim of this experiment was to investigate to what extent E-coli bacteria would become resistant after repeated use of same type of antibacterial. Antibacterial are agents used to disinfect surfaces and decrease the harmful bacteria.  In our everyday life, we use different antibacterial such Bleach, alcohol, hydrogen peroxide, acetic acid and Dettol for cleaning our home. However, various biological and molecular responses of bacteria may be developed in the presence of antimicrobial agents. It has been claimed that ethyl alcohol is the least effective antibacterial agent and hydrogen peroxide is the most effective antibacterial on killing the E-coli bacteria.

The experiment was done by cultivating E-coli bacteria from the previously treated plate into a new plate and treating it with the same active ingredient, from which it originated. Then the kill zone was measured by ruler for the E-coli bacteria that was treated for three times with the desired antibacterial. Ethyl created the smallest kill zone. After repeated treatment for three more times, the E-coli bacteria got more resistant since the size of kill zone dropped from 1.7 cm to 0.7 cm. Dettol created a kill zone with the size of 3.0 cm but after several treatments, its kill zone dropped to 1.6 cm. Hydrogen peroxide with silver created smaller kill zone compared to Dettol. After repeated treatment bacteria got resistant and its kill zone dropped from 2.5 cm to 1.9 cm. Bleach was less effective than Dettol as it created a kill zone with the size of 1.9 cm and after repeated treatment its kill zone dropped to 0.9 cm.  Acetic acid created the largest kill zone with the size of 3.4 cm, after repeated treatment, its kill zone dropped to 2.4 cm.

The results obtained showed that ethyl 90% was the least effective antibacterial as it created the smallest kill zone and E-coli became resistant to it by repeated treatments. Hydrogen peroxide with silver didn’t create the greatest kill zone yet E-coli became less resistant to it. Acetic acid created the greatest kill zone, however, E-coli was resistant to it.

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