Download WARNING! The sample is realized in asepsis around the Bunsen

Antibiogram realisation
on a bacterial strain
Materials avalaible
Sterile physiological water tube
Agar with
bacteria
Mueller
Hinton
culture
medium
Swab
Deposit
plan
Antibiotics disks
1. Preparation of
inoculum
1.1. With a sterile inoculation loop, take a
bacterial colony on agar Petri dish.
WARNING! The sample is realized in asepsis
around the Bunsen burner.
1.2. Make a suspension with
this bacterial colony in a
steril tube of physiological
water (5mL).
In the water, rub inoculation
loop on the tube side to
disperse all the bacteria.
1.3. Repeat 4 times, in order
to introduce 5 bacterial
colonies in the tube
WARNING! The sample is realized in asepsis
around the Bunsen burner.
I
1.4
Homogenize your
tube by manual rotations
and write « I » on this
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.
WARNING! The sample is realized in asepsis
around the Bunsen burner.
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 :
60°
Streaks in 3
passes
60°
=
2. Filing the antibiotics
disks
3.1. Position the Mueller Hinton agar
previously sown on the deposit plan provided
3.2. With a sterile
forceps, place the
antibiotics disks on
the surface of the
agar
When filing disks, apply slight pressure ton 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. After incubation, measure the diameter
of the growth inhibition zones around the
antibiotics disks
5.2. Use the reading table, to conclude on the
sensitivity or on the resistance of the strain
to different antibiotics tested
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