For antimicrobial testing, Baird Parker Agar + RPF Suppl. 90 mL Culture Media sits at the point where organism growth becomes a quantitative or categorical measurement. The discussion below connects its documented role with preparation variables, controls, interpretation, and the limits of inference. Catalogue 420010 is discussed as a laboratory measurement component; implementation should follow the laboratory SOP and validated reference method.
Analytical scope and method role
Baird Parker Agar Base + RPF Supplement is a kit used for preparing a selective and differential medium intended for the isolation and enumeration of coagulase-positive staphylococci from food and other materials, according to ISO 6888-2.KIT CONTENTSEach kit contains:•6 bottles of Baird Parker Agar Base•6 vials of lyophilized RPF Supplement•1 instruction sheet
Method principle
OF THE METHODPancreatic digest of casein, yeast extract and meat extract provide carbon, nitrogen, amino acids, vitamins and minerals for organisms growth. Sodium pyruvate and glycine stimulate growth of staphylococci. Agar is the solidifying agent. Lithium chloride and potassium tellurite make the medium selective for staphylococci by suppressing the accompanying flora. Fibrinogen and rabbit plasma allow the coagulase reaction. Trypsin inhibitor is added to prevent fibrinolysis. COMPOSITIONBaird Parker Agar BaseContent / liter of mediumRPF SupplementContent / vialPancreatic Digest of CaseinYeast ExtractMeat ExtractSodium PyruvateL-GlycineLithium ChlorideAgarFinal pH 7.2 ± 0.2 10.0 g 1.0 g 5.0 g10.0 g12.0 g 5.0 g17.0 gPotassium TelluriteBovine FibrinogenRabbit Plasma – EDTATrypsin Inhibitor2.5 mg0.5 g2.5 ml2.5 mg
Preparation and execution: controlled method points
Procedure: FOR USEMelt the content of 1 bottle of Baird Parker Agar Base in a boiling water bath at 100°C (loosing the caps partially unscrewed) until completely dissolved. Cool down to 48 ± 1°C. Aseptically, add the content of 1 vial of RPF Supplement reconstituted with 10 ml of sterile distilled water. Mix well avoiding foam formation.
Translate the method into controlled worksheet fields: catalogue and lot, preparation mass or volume, water quality, pH where applicable, heating or sterilization, supplements, dispense volume, preparation date, expiry assignment, incubation atmosphere and temperature, reading window, equipment, and analyst. Record departures as deviations instead of silently normalizing them.
Quality control: what the control result protects
Challenge both sides of performance. Include a target reaction demonstrating recovery and, when relevant, a non-target or alternate reaction challenging inhibition or differentiation. Record expected and observed responses, acceptance criteria, strain and passage, lot, incubation, and disposition. A failed control blocks result interpretation until the cause is resolved.
Interpretation and confirmation pathway
OF THE RESULTSISO 6888-2 recommends to inoculate the medium by using the Pour Plate Method. Incubate plates at 37± 1°C for 24 ± 2 hours. If necessary, re-incubatefor 24 ± 2 hours. Staphylococci form black or grey or even white, small colonies surrounded by halo of precipitation, indicating coagulase activity.
Record the raw observation before the conclusion: morphology or colour, growth pattern, endpoint, reaction intensity, reading time, and control response. Presumptive reactions remain presumptive. Route atypical, weak, mixed, or delayed reactions through the confirmation step in the current method.
Storage, stability, and pre-use inspection
2-8°C in its original packaging. Keep away from sources of heat and avoid excessive changes of temperature. Use until the expiry date indicated on the label. Eliminate without using if there are signs of deterioration. Once reconstituted , the product can be stored for a maximum duration of 30 days at -20°C,shielded from light.
Receipt and storage records should reconstruct temperature exposure, lot rotation, expiry, container integrity, and time outside controlled storage. Inspect colour, clarity, fill volume, gel integrity, contamination, dehydration, and precipitate before use.
Limitations and boundaries of use
The product does not contain hazardous substances in concentrations exceeding the limits set by current legislation and therefore is not classified as dangerous. it is nevertheless recommended to consult the safety data sheet for its correct use. The product is intended for professional use only and must be used by properly trained operators.
Applicability depends on matrix, target organism, interfering flora, inoculum, validated method, and regulatory setting. Do not transfer conditions or acceptance criteria from a different matrix without verification.
Troubleshooting from evidence, not guesswork
- Poor recovery: check preparation, pH, overheating, supplement addition, inoculum, atmosphere, storage, and control performance.
- Loss of selectivity: review formulation, sterilization, expiry, inoculum burden, enrichment sequence, and incubation time.
- Weak or atypical reaction: confirm reading time and atmosphere, compare controls, document mixed growth, and follow confirmation requirements.
- Run-to-run drift: trend lot, analyst, equipment, water, preparation batch, controls, and environmental conditions.
External method context
The product should be understood as one measurement component in an antimicrobial susceptibility method. The analytical chain includes isolate purity, standardized inoculum, medium composition, antimicrobial concentration, incubation atmosphere and time, endpoint reading, and the interpretive table selected by the laboratory. A shift in any upstream variable can move an MIC or zone without a change in organism biology, which is why QC distributions and trend review are more informative than a single pass/fail control.
External laboratory-quality guidance also supports a lifecycle view: verify the method when introduced, bridge new lots against an accepted lot, trend control results, investigate nonconformities, and retain enough raw observations to reconstruct the decision. This is the practical difference between reproducing a preparation instruction and demonstrating that the resulting measurement is fit for its intended use.
EUCAST disk diffusion and quality control
EUCAST requires standardized methodology, current breakpoint tables, and routine quality control; the laboratory remains responsible for the final susceptibility report. For broth dilution, inoculum density, cation content, pH, incubation atmosphere, endpoint definition, and two-fold dilution design influence MIC reproducibility. Breakpoints are interpretive rules applied after a technically valid MIC or zone measurement; they are not properties of the product alone. Review the authoritative source.
FDA Bacteriological Analytical Manual
FDA BAM methods organize food microbiology around validated sampling, preparation, enrichment, isolation, and confirmation steps, with method applicability tied to the matrix and target organism. Sampling uncertainty, homogenization efficiency, inhibitory ingredients, dilution design, and countable range can dominate the result before the culture medium is ever inoculated; those variables belong in method verification and uncertainty review. Review the authoritative source.
WHO Laboratory Quality Management System handbook
WHO laboratory quality guidance treats document control, equipment, purchasing and inventory, process control, records, occurrence management, and continual improvement as connected parts of reliable testing. Review the authoritative source.
Technical references
- Manufacturer product documentation for catalogue 420010.
- EUCAST disk diffusion and quality control (access checked 2026-07-20).
- FDA Bacteriological Analytical Manual (access checked 2026-07-20).
- WHO Laboratory Quality Management System handbook (access checked 2026-07-20).
Bench-use checklist
- Verify product identity, catalogue number, lot, expiry, and storage history.
- Document preparation and incubation exactly as controlled in the SOP.
- Define controls and acceptance criteria before testing.
- Record raw observations, control response, reading time, and confirmation decision.
- Escalate failed controls, atypical reactions, and departures through the quality system.