For antimicrobial testing, Brilliant Green Agar w/ Sulfapyridine 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 610394 is discussed as a laboratory measurement component; implementation should follow the laboratory SOP and validated reference method.
Analytical scope and method role
Brilliant Green Agar w/ Sulfapyridine is a selective medium used for the isolation of Salmonella spp, other than S. Typhi and S. Paratyphi, from food, animal feed, and other materials.
Method principle
Enzymatic digest of animal tissue and enzymatic digest of casein provide amino acids, nitrogen, carbon, minerals, vitamins and other nutrients for organisms growth. Yeast extract is a source of vitamins, particularly of B-group. Sodium chloride maintains the osmotic balance of the medium. Lactose and sucrose are the fermentable carbohydrates. Brilliant green and sulfapyridine are selective agents, inhibiting Gram-positive bacteria and many Gram-negative organisms, except Salmonella spp. Phenol red is the pH indicator. Agar is the solidifying agent.
Formula and functional interpretation
(g/l)Enzymatic Digest of Animal Tissue 5.0Enzymatic Digest of Casein 5.0Yeast Extract 3.0Sodium Chloride 5.0Lactose10.0Sucrose10.0Brilliant Green 0.0125Phenol Red 0.08Sodium Sulfapyridine 1.0Agar20.0Final pH 6.9 ± 0.2 at 25°C
Review the nutritive, selective, differential, buffering, reducing, and indicator components against the expected target and background flora. Preparation errors can change recovery, inhibition, colour development, or endpoint visibility even when incubation is correct.
Preparation and execution: controlled method points
Preparation: Suspend 59 g of powder in 1 liter of deionized or distilled water. Bring to boil and shake until completely dissolved. Sterilize at 121°C for 15 minutes. Cool up to 45-50°C. Mix well and pour in Petri dishes.
Procedure: Inoculate Brilliant Green Agar w/ Sulfapyridine from a selective enrichment broth, e.g. Tetrathionate Broth (ref. 24451) or Selenite Cystine Broth (ref. 24510), or by direct streaking of the sample onto the plate. Incubate the plates aerobically at 35 ± 2°C for 18-24 h. If growth is not observed, extend the incubation for an additional 24 h. NOTE:For best results in isolating all enteric pathogens, a less selective medium, such as MacConkey Agar (ref. 10029) or Hektoen Enteric Agar (ref. 10043), should be used simultaneously.
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
1.Control of general characteristics, label and print2.Microbiological controlInoculum for productivity: 50-100 CFUInoculum for selectivity: 104-106 CFUIncubation Conditions: 18-24 h / 35 ± 2°CMicroorganismGrowthSpecificationSalmonella TyphimuriumATCC 14028 GoodRed to pink-white colonies with a red haloEscherichia coliATCC 25922Partially inhibitedYellow to yellow-green colonies with a green haloEnterococcus faecalisATCC 29212Inhibited---Proteus mirabilisATCC 12453Inhibited---TABLE OF SYMBOLS Batch code Keep away from Sunlight Manufacturer Use by Fragile, handle withcare Catalogue number
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
Typical Salmonella colonies on Brilliant Green Agar w/ Sulfapyridine appear as red to pink-white with red zones. The red coloration of the medium indicates that lactose or sucrose was not utilized.Lactose or sucrose fermenting microorganisms not completely inhibited will produce yellow to yellow-green colonies with a yellow-greenor green halo.Escherichia coli may be partially inhibited and present as yellow to yellow-green colonies surrounded by a green halo.Shigella spp.
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
The powder is very hygroscopic, store the powder at 10-30°C, in a dry environment, in its original container tightly closed and use it before the expiry date on the label or until signs of deterioration or contamination are evident. Store prepared plates at 2-8°C away from light.WARNING AND
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 contains hazardous substances and is classified as dangerous. It is recommended to consult the safety data sheet for its correct use. The product is designed 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.
FDA BAM Chapter 5: Salmonella
The current FDA BAM Salmonella workflow separates pre-enrichment, selective enrichment, selective plating, and confirmation. That sequence is scientifically important: enrichment increases target representation in a mixed matrix, selective conditions manage competing flora, and confirmation prevents a colour or colony morphology from being treated as identity. A laboratory transferring the method should verify recovery and selectivity on its own matrix classes rather than assuming that a medium performs identically across foods, water, and environmental samples. Review the authoritative source.
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.
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 610394.
- FDA BAM Chapter 5: Salmonella (access checked 2026-07-20).
- EUCAST disk diffusion and quality control (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.