Baird-Parker Agar ISO

Description

The presence of tellurite and egg yolk allows the differentiation of presumptive pathogenic staphylococcal colonies. There is a high correlation between the coagulase test and the presence of clear zones of lipolysis in this medium, which is due to the staphylococcal lecithinase. Studies show that almost 100% of coagulase-positive staphylococci are capable of reducing tellurite, which produces black colonies, whereas other staphylococci cannot always do so.

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. After 24-48 hours of incubation at 37 ± 1 °C, select the colonies which are black, shiny and convex with regular margins surrounded by a clear zone. These can be presumptively identified as coagulase-positive Staphylococcus aureus.

Colonial appearance after 24-48 hours at 37 ± 1 °C (± 2.0):

• Staphylococcus aureus: Black, shiny, convex, regular margins, 1.0-1.5 mm diameter, surrounded by a clear zone of lipolysis (egg yolk clearing reaction) 2-5 mm in width. Wide opaque zones of precipitate extending into the cleared medium may occur after 48 hours.
• Other species of Staphylococcus: Black, usually dull, with regular margins. Sometimes brown with zones of clearing but these present as wide opaque zones.
• Micrococcus spp.: Brown, very small and without clearing zones.
• Bacillus spp.: Various shades of brown, big. May produce clearing zones after 48 hours.
• Yeasts: White, big and smooth.

Precautions

Do not reuse. For professional use only.

Do not use the product if it shows evidence of microbial contamination, discoloration, drying, cracking or other signs of deterioration.

LC-4530, contact plates

Solid selective culture medium for the screening of staphylococci from a variety of samples, according to pharmacopoeias and ISO standards.

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).

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. Clean the surface where the sample was collected in order to remove any traces of agar.

The inoculated plates are incubated at 37 ± 1 °C for 24-48 ± 2 h and examined daily.

Note: Contact plates are used for monitoring the microbiological contamination of surface and air inside cleanrooms, isolators, RABS, food industries and hospitals.

Physical/chemical control

Microbiological control

Inoculate: practical range 100 ± 20 CFU, min. 50 CFU (productivity) / 10⁴-10⁶ (selectivity) and < 100 CFU (specificity, Ph. Eur.) and ≥ 10³ CFU (specificity, ISO).

Microbiological control according to ISO 11133:2014/Amd 1:2018.

Analytical methodology according to ISO 11133:2014/Amd 1:2018; A2:2020.

Aerobiosis. Incubation at 37 ± 1 °C, reading after 24-48 ± 2 h.

S. aureus and E. coli: double incubation temperature 30-35 °C / 37 °C.

LC-4530, contact plates: microbiological control

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

Aerobiosis. Incubation at 37 ± 1 °C, reading after 24/44 ± 4 h.

Sterility control

Incubation 48 h at 30-35 °C and 48 h 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. London.
• BAIRD-PARKER, A.C. (1962) An improved diagnostic and selective medium for isolating coagulase-positive staphylococci. J. Appl. Bact. 25:12.
• COLIPA (1997) Guidelines on Microbial Quality Management (MQM). Brussels.
• DOWNES, F.P. & K. ITO (2001) Compendium of Methods for the Microbiological Examination of Foods. 4th ed. APHA. Washington. USA.
• EUROPEAN PHARMACOPOEIA (2007) 5th ed. Suppl. 5.6 § 2.6.13 Microbiological examination of non-sterile products. EDQM. Council of Europe. Strasbourg.
• FIL-IDF 60:2001 Standard. Lait et produits à base de lait - Detection des staphylocoques à coagulase positive - Technique du nombre le plus probable. Brussels.
• ISO 5944:2001 Standard. Milk and Milk based products - Detection of coagulase positive staphylococci - MPN Technique. Geneva.
• ISO 6888-1:2021. Standard. Microbiology of food and animal feeding stuffs - Horizontal method for the enumeration of coagulase-positive staphylococci (Staphylococcus aureus and other species) - Part 1 Technique using Baird-Parker Agar medium. Amendment 2: Inclusion of an alternative confirmation test using RPFA stab method.
• ISO 6888-2:2021 Standard. Microbiology of food and animal feeding stuffs - Horizontal method for the enumeration of coagulase-positive staphylococci - Part 1 Technique using rabbit plasma fibrinogen agar medium. Geneva.
• ISO 11133:2014/Amd 1:2018. Microbiology of food, animal feed and water. Preparation, production, storage and performance testing of culture media.
• ISO 22718 Standard (2015). Cosmetics - Microbiology - Detection of Staphylococcus aureus.
• USP 31 - NF 26 (2008) <61> Microbial Limit Tests. US Pharmacopeial Conv. Inc. Rockville. MD. USA.
• ZANGERL, P. & H. ASPERGER (2003) Media used in the detection and enumeration of Staphylococcus aureus. In Handbook.