Mannitol Salt Agar – LI 30ml [Pack of 20]

Description

Ten settle plates each with a diameter of 90 mm are single-bagged in transparent, hydrogen peroxide impermeable sleeves (non-irradiated). The sleeves consist of polypropylene with a barrier of PE-EVOHPE.
This medium complies with the specifications given by the harmonized methods of EP, USP, JP for Microbial Examination of Non-sterile Products: Tests for Specified Microorganisms.

Mode of Action
The composition of Mannitol Salt Agar supports the growth of Staphylococcus aureus whereas many other microorganisms are inhibited by the high salt content of 7.5 %. Some halophilic Enteroccci and Vibriones are able to grow on Mannitol Salt Agar.
In contrast to the most other staphylococci S. aureus is able to build acids from mannitol. Therefore, they build up yellow colonies with yellow zones. S. capitis, S. simulans, S. carnosus, S. scuri, S. lentus, S. gallinarum are also mannitol positive.

Typical Composition
Pancreatic Digest of Casein                     5 g/l
Peptic Digest of Animal Tissue                5 g/l
Beef Extract                                             1 g/l
D-Mannitol                                             10 g/l
NaCl                                                      75 g/l
Phenol Red                                           25 mg/l
Agar                                                      15 g/l
The appearance of the medium is clear and pink-red. The pH value is in the range of 7.2-7.6. The medium can be adjusted and/or supplemented according to the performance criteria required.

Application and Interpretation
Each plate is provided with a label including a data matrix code for paperless plate identification. The code consists of a two-dimensional 20-digit serial number, which harbors the following information:
Digits 1-3: here code 797 (corresponds to article 146023); digits 4-9: lot number; digits 10-14: batch specific individual number; digits 15-20: expiration date (YY/MM/DD).
Please check each agar plate before using it on sterility and pay attention to aseptic handling in order to avoid false positive results.
According to the recommendations of the current EP and USP Mannitol Salt Agar is incubated for 18-72 hours at 30-35 °C.
The possible presence of S. aureus is indicated by the growth of yellow/white colonies surrounded by a yellow zone. This is confirmed by identification tests.
The product complies with the test if colonies of the types described are not present or if the confirmatory identification tests are negative.
Possibilities for further identification:
If enterococci have been grown on the medium they can be separated by the detection of catalase and pyrase. Enterococci show a negative reaction for catalase and a positive reaction for pyrase while staphylococci show the opposite results.
Suspect colonies can subcultured on a medium with low salt concentration (e.g. article number 146004) and then be tested for coagulase, e.g. using Rabbit Plasma Fibrinogen Agar (EN ISO 6888-2).
Furthermore the presence of Thermonuclease may be tested with e.g. DNase Test Agar (article number110449). The analysis of the clumping factor may be performed using immunological tests systems like latex tests.

Storage and Shelf Life
The product can be used for sampling until the expiry date if stored upright, protected from light and properly sealed at +15 °C to +25 °C.
Condensation can be prevented by avoiding quick temperature shifts and mechanical stress.
The testing procedures as described on the CoA can be started up to the expiry date printed on the label.

Disposal
Please mind the respective regulations for the disposal of used culture medium (e.g. autoclave for 20 min at 121 °C, disinfect, incinerate etc.).