OGYE Agar ISO

Description

It has a high oxytetracycline concentration that will provide almost total inhibition of bacteria. According to ISO 13681 (1995), the combination with gentamicin increases the inhibition of bacterial growth in the medium.

Technique

Collect, dilute and prepare samples and volumes as required according to specifications, directives, official standard regulations and/or expected results.

Spread the plates by streaking methodology or by spiral method.

Incubate the plates right side up aerobically at 20-25 °C for up to 5 days.

(Incubation times longer than those mentioned above or different incubation temperatures may be required depending on the sample, on the specifications, etc. This medium can be inoculated directly or after enrichment with broth.)

After incubation, enumerate all the colonies that have appeared onto the surface of the agar.

Each laboratory must evaluate the results according to their specifications.

LC-4664 and LC-4665, bottles

ISO 7954 recommends chloramphenicol or oxytetracycline as antibiotic.

These antibiotics do not, however, sufficiently inhibit Gram-negative microorganisms occurring in meat, especially raw material. The addition of gentamicin is necessary in cases of heavy contamination to obtain inhibition.

The combination of chloramphenicol and gentamicin inhibits certain types of yeasts. The alternatively specified antibiotic, oxytetracycline, is the antibiotic of choice.

To use, the contents of the bottle should be poured into plates. The melting of the culture medium should be carried out according to the manufacturer's instructions, either in a water bath or microwave oven. Never apply direct heat to melt a medium. The melting temperatures and times depend on the shape of the container, the volume of medium and the heat source. Before melting any medium, loosen the screw cap of the container to avoid breaking the container. The medium should be melted only once and used. Media with agar should not be melted repeatedly as their characteristics change with each remelting. Overheating should be avoided as much as prolonged heating, especially with regard to media with an acidic or alkaline pH. Once melted, pour the plates using aseptic techniques.

To inoculate, follow standard laboratory methods or the applicable norms: spiral plate method, streak plating, ecometric methods, dilution banks or spread plating.

Physical/chemical control

Microbiological control

LC-851: spiral spreading: practical range 100 ± 20 CFU; min. 50 CFU (productivity) / 10⁴-10⁶ CFU (selectivity).

LC-4664 and LC-4665: melting - pour plates - inoculation: practical range 100 ± 20 CFU; min. 50 CFU (productivity) / 10⁴-10⁶ CFU (selectivity).

LC-851 and LC-4665: microbiological control according to ISO 11133:2014/Amd 1:2018.

Aerobiosis. Incubation at 22.5 ± 2.5 °C. Reading at 24-72 h for bacteria and 3-5 days for yeasts and moulds.

Sterility control

Incubation 48 hours at 30-35 °C and 48 hours at 20-25 °C: NO GROWTH.

Check at 7 days after incubation in same conditions.

• DOWNES, F.P. & K. ITO (2001) Compendium of methods for the microbiological examination of foods. APHA. Washington DC. USA.
• ISO 11133:2014/Amd 1:2018. Microbiology of food, animal feed and water. Preparation, production, storage and performance testing of culture media.
• ISO 13681 Standard (1995) Enumeration of Yeasts and Moulds. Colony Count Technique.
• MacFADDIN, J.F. (1985) Media for isolation-cultivation-identification-maintenance of medical bacteria. William & Wilkins. Baltimore. MD. USA.
• MARSHALL, R.T. (1992) Standard methods for the examination of dairy products 16th ed. APHA. Washington DC, USA.
• MOSSEL, D.A.A., A.M.C. KLEYNEN-SEMMELING, H.M. VINCENTIE, H. BEERENS & M. CATSARAS (1970) Oxytetracycline-Glucose-Yeast Extract Agar for selective enumeration of moulds and yeasts in foods and clinical material. J. Appl. Bacteriol. 33:454-457.
• SABOURAUD, R. (1910) Les Teignes. Masson, Paris.