- Petriplate containing microbial culture(For example, Escherichia coli)
- Inoculation loop
- Bunsen burner
- Saline solution
- McFarland solution
- MHA plate
- Cotton swab
- Antibiotic disks(Streptomycin (S), Ciprofloxacin (CIP), Chloramphenicol (C), Doxycycline (D), Penicillin G (P), Gentamycin (G)
- Tooth pick
- Select a pure culture plate of one of the organisms to be tested.
- Aseptically emulsify a colony from the plate in the sterile saline solution. Mix it thoroughly to ensure that no solid material from the colony is visible in the saline solution.
- Repeat until the turbidity of the saline solution visually match that of the standard turbidity.
- Take a sterile swab and dip it into the broth culture of organism.
- Gently squeeze the swab against the inside of the tube in order to remove excess fluid in the swab.
- Take a sterile Mueller-Hinton agar (MHA) plate or a nutrient agar (NA) plate.
- Use the swab with the test organism to streak a MHA plate or a NA plate for a lawn of growth.
- After the streaking is complete, allow the plate to dry for 5 minutes.
- Antibiotic discs can be placed on the surface of the agar using sterilized forceps.
- Gently press the discs onto the surface of the agar using flame sterilized forceps or inoculation loop.
- Carefully invert the inoculated plates and incubate for 24 hours at 37° C.
- After incubation, use a metric ruler to measure the diameter of the zone of inhibition for each antibiotic used.
- Compare the measurement obtained from the individual antibiotics with the standard table to determine the sensitivity zone.
- Compare the measurement obtained from the individual antibiotics to the standard table to determine whether the tested bacterial species is sensitive or resistant to the tested antibiotic.
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