OXACILLIN AGAR BASE
CAT Nº: 1196
Medium for screening for methicillin resistant
Staphylococcus aureus (MRSA) directly from routine swab samples
FORMULA IN g/l
Peptone
11.8
Manitol
10.00 Sodium Chloride
Lithium Chloride
Yeast extract
Aniline Blue
5.00 Bacteriological Agar
0.2
55.00
12.5
9.00
Final pH 7.2 ± 0.2 at 25ºC
PREPARATION
Suspend 51,75 grams of the medium in 500 ml of distilled water. Dissolve by heating with frequent agitation.
Boil for one minute. Distribute into appropriate containers and sterilize at 121°C for 15 minutes. Allow to cool to 50ºC
and aseptically add one vial of Cat. 6068 Oxacillin Agar Base supplement reconstituted in 5 ml of sterile distilled water.
Mix well and pour into Petri dishes. The prepared medium should be stored at 8-15°C. The colour is blue, slightly
opalescent.
The dehydrated medium should be homogeneous, free-flowing and light grey in color. If there are any physical changes,
discard the medium.
Oxacillin Agar Base supplement (Cat. 6068)
(1 vial for 500 ml of the medium)
Oxacillin ……………………………1.00 mg
Polymixin ……………………….. 25000 UI
USES
OXACILLIN AGAR BASE is a medium intended for screening of methicillin resistant Staphylococcus aureus
(MRSA) directly from routine swab samples.
S.aureus is a pathogen which causes superficial and systemic infections. Due to its prevalence and clinical
implications, its detection is of vital importance.
Oxacillin Agar base with its supplement is based on traditional Mannitol Salt Agar with a reduction in salt
concentration from 75g/l to 55g/l. This lower level of salt is still sufficient to inhibit most bacteria other
than staphylococci whilst optimising growth of low numbers of MRSA.
Oxacillin agar Base, with its supplement is a nutritious and selective medium containing peptones for growth,
a high salt concentration and lithium chloride to suppress non-staphylococcal growth with mannitol and
aniline blue for the detection of mannitol fermentation. The antibiotics contained in Cat. 6068 Oxicillin and
polimyxin B inhibit methicillin sensitive Staphylococcus aureus (MSSA) and polymyxin B for the suppression
of other bacteria able to grow at such a high salt concentration, e.g. Proteus spp.
1
LABORATORIOS CONDA, S.A.
www.condalab.com
MICROBIOLOGICAL TEST
The following results were obtained in the performance of the medium with its supplement from type cultures
after incubation at a temperature of 37 ± 2°C and observed after 24– 48 hours .
Microorganisms
Staphylococcus aureus ATCC 25923
Staphylococcus aureus ATCC 43300
Escherichia coli ATCC 25922
Growth
Colony color
Inhibited (susceptible to
Oxacillin)
Good (presence of colony or haze
of growthshould be read
as resistance)
Inhibited
Blue
-
BIBLIOGRAPHY
Hutchison, M.J., Edwards, G.F.S., Morrison, D. bEvaluation of chromogenic MRSA Reference Laboratory presented at the 2005 Institute
of BioMedical
Jablonski, L.M. and G.A. Bohach. 1997. Staphylococcus aureus. In M. Doyle, L. Beuchat and T. Montville (eds.), Food microbiology
fundamentals and frontiers. ASM, Washington, DC.
U.S. Department of Health and Human Services. 1999. Biosafety in microbiological and biomedical laboratories, HHS Publication (CDC),
4th ed. U.S. Government Printing Office, Washington, DC.
STORAGE
25ºC
Once opened keep powdered medium closed to avoid hydration.
2ºC
2
LABORATORIOS CONDA, S.A.
www.condalab.com