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Published 12 February 2015

Protocol of Antibiogram realisation on a bacterial strain

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Here, you have three files of procedure of antibiogram realisation on a bacterial strain in word, in pdf, and the ppt for the presentation of this experiment.

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Antibiogram realisation on a bacterial strain - Protocol in word
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Antibiogram realisation on a bacterial strain - Protocol in pdf
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Antibiogram realisation on a bacterial strain - Practical training in ppt

Antibiogram realisation on a bacterial strain

1.Preparation of inoculum « I »

1.1 Take a bacterial colony with a sterile inoculation loop.
Warning ! Handling is performed aseptically around the Bunsen burner

1.2 Insert the inoculation loop into the tube of 5 mL physiological water. In water, rub the loop on the wall of the tube, to disperse the bacteria.

1.3 Repeat 4 times, in order to introduce 5 bacterial colonies in the tube.
1.4 Mix the tube by manual rotation and write "I" on the tube.

2. Inoculate Mueller Hinton medium for antibiogram

2.1 In the inoculum tube "I", insert a sterile swab.
Wet the swab and then wring the excess of liquid on the wall of the tube.

2.2 Inoculate Mueller Hinton agar by rubbing the swab on its surface. Achieve tight streaks.

2.3 Reproducing the operation twice by turning 60 ° the box each time in order to ensure an good distribution of the inoculum on the surface of the medium.

3. Filing the antibiotics disks


3.1 Position the Mueller Hinton agar previously sown on the deposit plan provided.

3.2 With sterile forceps, place the antibiotics disks onto the surface of the agar.
Be carefull: when filing antibiotic disk, apply slight pressure to ensure the maintenance of the disk, but not too much to avoid the risk of perforating the agar.

4. Medium incubation

Incubate the box, in the inverted position, 16 h at 37 ° C minimum.

5. Analyse your results

5.1 The second day, after incubation, measure the diameter of the growth inhibition zones around the antibiotics disks.

5.2 Using the reading table below, to conclude on the sensitivity or on the resistance of the strain to different antibiotics tested.

Reading table:

Antibiotic tested Resistance if the diameter of inhibition is less than: Sensitive if the diameter of inhibition is greater than:
Ampicillin 14 mm 19 mm
SXT 10 mm 16 mm
Erythromycin 17 mm 22 mm
Gentamicin 14 mm 16 mm

6. Conclusion

Suggest an antibiotic suitable for the treatment of nosocomial infection caused by your bacteria.