The Effect of Increasing the Concentration of Dettol Antiseptic Liquid on the Growth of E.Coli

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Escherichia coli are rod shaped, gram negative bacteria often found in the gut of humans and other warm-blooded mammals (Jacques & Ngo, 2004). It is transmitted primarily through faecal contaminated food and water. Most strains of E. coli are not harmful to humans, however some strains are pathogenic and can cause symptoms including diarrhoea (Unknown, 2012).
The active ingredient in Dettol Antiseptic Liquid is 4.8% chloroxylenol, a chemical that inhibits the growth of a large range of microorganisms including gram negative bacteria. It can be used to cleanse flesh wounds or disinfect surfaces. Chloroxylenol destroys the
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The tweezers were then sterilized by dipping them in methanol and passing them through the flame. They were then held and allowed to cool for 30 seconds. 6. The disks in the 0.00% solution were transferred to an agar plate held next to the blue flame using the sterilized tweezers. Excess disinfectant was removed from the disks by wiping on the side of the well of the spotting tile. When the 5 disks were positioned (refer to Figure 1 below) the lid was replaced and sticky taped down. A label was added indicating the concentration of disinfectant. 7. This process (Step 6) was repeated for each concentration of Dettol. 8. The agar plates were then incubated at 37°C for 48 hours. 9. After the 48 hour time period the inhibition of the Escherichia coli bacteria around the disinfectant disks was measured. A ruler was used to measure the clearing from the edge of the disk to the perimeter of the clearing. Irregularities in the clearing were not included in the area of clearing.
10. Observations including the regularity of the perimeter and signs of contamination were also recorded.


Data Collection and Processing
Table 1: The area of inhibited growth of E.coli at increasing Dettol concentrations shown by the distance of clearing from the soaked disk
|Concentration % ±0.25ml |Distance of Clearing ±1mm |
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