ISO 6888-2:2021

Overview

ISO 6888-2:2021 specifies a horizontal microbiological method for the enumeration of coagulase-positive staphylococci (principally Staphylococcus aureus and related species) in the food chain using rabbit plasma fibrinogen agar (RPFA). The method determines counts by plating test portions or dilutions on RPFA, incubating aerobically at 34 °C to 38 °C and examining colonies after 24 h ± 2 h (and, if necessary, after 48 h). The standard is aimed at products for human and animal consumption, environmental samples in food/feed production and primary production samples.

Key topics and technical requirements

• Test principle: Pour-plate technique with RPFA; colonies with typical coagulase-positive morphology are enumerated.
• Incubation: Aerobic, 34–38 °C; primary read at 24 h ± 2 h.
• Sample preparation: Follow ISO 6887 series for test portions, initial suspensions and decimal dilutions.
• Culture media & performance: RPFA composition and performance testing described (Annex B); media production and validation aligned with ISO 11133.
• Equipment & consumables: Standard microbiological apparatus (incubators, water bath 44–47 °C for molten agar, sterile dishes, pipettes, etc.).
• Results & quality: Enumeration and expression of CFU per g, mL, cm² or per sampling device according to ISO 7218 guidance; performance characteristics (interlaboratory study, repeatability and reproducibility) provided in Annex C.
• Limitations: The document notes that the horizontal method may require minimal modifications for some product types and highlights issues where background microbiota or atypical colonies can obscure results. ISO 6888-1 and ISO 6888-2 are given equivalent status for coagulase-positive staphylococci enumeration.
• Safety: Laboratory testing must be carried out in properly equipped facilities under skilled supervision.

Applications and users

Who uses ISO 6888-2?

• Food and feed microbiology laboratories performing routine safety and quality testing.
• Quality assurance teams in food production, processing and primary production (farms, slaughterhouses).
• Regulatory bodies and third‑party auditors assessing compliance with microbiological criteria.
• Manufacturers of culture media and laboratory consumables validating RPFA performance.

Typical applications:

• Enumeration of coagulase-positive staphylococci in raw and processed foods, animal feed and environmental swabs from production/handling areas.
• Investigations where S. aureus contamination is a concern (food poisoning risk or hygiene control).

Related standards

• ISO 6888-1 - Alternative Baird‑Parker agar method (equivalent status).
• ISO 6887 (all parts) - Sample preparation and dilution methods.
• ISO 7218 - General guidance for microbiological examinations.
• ISO 11133 - Preparation and performance testing of culture media.

Keywords: ISO 6888-2, RPFA, rabbit plasma fibrinogen agar, coagulase-positive staphylococci, Staphylococcus aureus, enumeration, food microbiology, ISO 7218, ISO 6887, ISO 11133.