Rose Bengal Agar with Chloramphenicol

Description

The chloramphenicol included in the formulation inhibits bacterial growth, but does not interfere with the growth of fungi.

Technique

For plate inoculation, follow the laboratory's standard methods or the applicable norms (spiral plating method, ecometric methods, streak plating, dilution banks, spread plating with Drigalski rod, etc.).

After making a dilution bank, take 0.1 mL from each dilution and inoculate on Rose Bengal Agar plates with a Drigalski loop or glass spreader. Incubate at 25 ± 1 °C for 5 days and enumerate the fungi.

Limitations

• Due to the low concentration of antibiotic contained in the culture medium, it can be expected that the growth of certain strains of bacteria is inhibited only partially.
• This medium is photosensitive. Do not expose this medium to light, since photodegradation of Rose Bengal produces compounds toxic to fungi.

LC-4529, contact plates

Solid and selective medium for the isolation of yeasts and moulds from the environment and food products.

Contact plates are used in the microbiological control of disinfection and cleaning of surfaces. They act simultaneously as a sampler and incubation culture medium without the need for any other intermediate steps.

The plates come in a form appropriate for this function and can be used with different culture media depending on the type of microbe that needs to be controlled. On average the plates provide a contact surface of approximately 25 cm².

To use, remove the cover and gently press the culture medium on the surface to be controlled, ensuring contact between the two surfaces. The contact plate is removed and covered with the lid to prevent air contamination. It is advisable that the lid is secured with adhesive tape and the bottom labelled with the sampling data (place, date and time). The inoculated plates are incubated at 25 ± 1 °C for 5 days and examined daily.

If the sample surfaces are rough, the contact plates will not make good contact, even when the pressure is increased. In these cases it is advisable to delineate a sample surface area of 25 cm² and rub this area vigorously with a wet sterile swab and then rub the swab over the contact plate.

If verifying the effectiveness of a cleaning or disinfection process, contact plates should be used within two hours after the end of the process, ensuring that the sample surface is dry. It is advisable to always include positive controls, sampling the area before disinfection or dirty areas beside the disinfected area.

The technician will determine the frequency of sampling and disinfection according to performance criteria.

Apply the agar directly onto the surface to be monitored ensuring that the pressure is distributed over the whole plate for 10 seconds.

Note: Contact plates are used for monitoring the microbiological contamination of surface and air inside cleanrooms, isolators, RABS, food industries and hospitals. The double/triple irradiated wrapping ensures that the package itself doesn't contaminate the environment as the first wrapper is removed just before entering the clean area.

Physical/chemical control

Microbiological control

LC-950: spiral spreading: practical range 100 ± 20 CFU; min. 50 CFU (productivity) / 10⁴-10⁶ CFU (selectivity).

LC-4529: inoculate: practical range 100 ± 20 CFU; min. 50 CFU (productivity) / 10⁴-10⁶ (selectivity).

Aerobiosis. Incubation at 25 ± 1 °C, reading at 24-48-72 h to 5 days.

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.

• ATLAS, R.M., L.C. PARKS (1993) Handbook of Microbiological Media. CRC Press, Inc. London.
• CLESCERI, L.S., A.E. GREENBERG & A.D. EATON (1998) Standard Methods for the examination of water and wastewater. 20th ed. APHA. Washington DC.
• DOWNES, F.P. & K. ITO (2001) Compendium of Methods for the Microbiological Examination of Foods. 4th ed. APHA. Washington DC.
• ISO 11133:2014/Amd 1:2018. Microbiology of food, animal feed and water. Preparation, production, storage and performance testing of culture media.
• MARSHALL, R.T. (1993) Standard methods for the examination of dairy products. 16th ed. APHA, Washington DC.