RP 6 - Aseptic Technique

• Aseptic techniques are used to avoid contamination of the sample from external substances such as microorganisms.
• Aseptic techniques include wiping down surfaces with antibacterial cleaner, using a Bunsen burner in the work space, flaming the wire hoop before using it to transfer bacteria, flaming the neck of any bottles before using them, keeping all vessels containing bacteria open for the minimum amount of time, and closing windows and doors to limit air currents.
• The equipment list for this practical includes a bacteria sample, disinfectant, Bunsen burner, heatproof mat, ethanol, inoculating loop, pipette, forceps, plastic spreader, prepared agar plate, multidisc antibiotic ring, and ruler.
• The bacteria sample is transferred from broth to agar plate using a sterile pipette or wire hoop.
• The bacteria are spread evenly over the plate using a sterile plastic spreader.
• A multi disc antibiotic ring is placed on the plate using sterile forceps.
• The agar plate is incubated at 25°C for 48 hours.
• After incubation, the diameter of the inhibition zone is measured and the area of the inhibition zone is worked out using the formula: pi X d ,where d= diameter.
• In the risk assessment, disinfectant is classified as flammable and should be kept away from naked flame.
• Biohazard contamination; infection risk is associated with this practical and it involves using disinfectant, washing hands with soap after dissection, not incubating at human body temperature, and not opening the agar plate post incubation.
• The conclusion of this practical is that if there is a larger inhibition zone around the antibiotic, it has killed more bacteria and therefore, the larger the inhibition zone, the more efficient the antibiotic.
• Some antibiotics will have no/very little inhibition zone, indicating that the bacteria are resistant to this antibiotic and are not killed by it.