Overview
ISO 13720:2010 specifies a standardized microbiological method for the enumeration of presumptive Pseudomonas spp. in meat and meat products, including poultry. The method defines sample preparation, use of the selective cephalothin‑sodium fusidate‑cetrimide (CFC) agar, incubation conditions and confirmation by the oxidase test, enabling reproducible counts of presumptive Pseudomonas per gram or millilitre.
Keywords: ISO 13720:2010, Pseudomonas, meat products, enumeration, CFC agar, oxidase test, microbiology of food, meat testing.
Key topics and technical requirements
- Scope: Enumeration of presumptive Pseudomonas spp. in meat and poultry products.
- Sample preparation: Follow ISO 6887-1 and ISO 6887-2 for initial suspension and decimal dilutions.
- Selective medium (CFC agar):
- Basic medium composition and preparation procedures are specified (enzymatic digests, salts, agar, pH adjustment, sterilization).
- Inhibitor solutions: cephalothin, sodium fusidate and cetrimide are prepared and added to the cooled base to create the complete CFC agar.
- Plates: ~15 ml per Petri dish; plates should be dried immediately before use or stored under defined conditions.
- Inoculation and incubation:
- Inoculate 0.1 ml of the initial suspension and decimal dilutions onto CFC plates.
- Incubate at 25 °C for 44 h ± 4 h.
- Use one plate per dilution with at least two successive dilutions (or two plates if a single dilution is used).
- Confirmation:
- Select randomly up to five colonies per retained plate (
