ISO 6888-1:2021

Overview

ISO 6888-1:2021 specifies a horizontal method for the enumeration of coagulase-positive staphylococci (principally Staphylococcus aureus) using Baird‑Parker agar (BPA). The standard describes inoculation, aerobic incubation, colony counting and coagulase confirmation to report counts per gram, millilitre, sampled area or device. It is intended for products and environments across the food chain including foods for human consumption, animal feed, environmental monitoring in food/feed production, handling and primary production samples.

Keywords: ISO 6888-1:2021, Baird‑Parker agar, coagulase-positive staphylococci, Staphylococcus aureus, food microbiology standard, enumeration method.

Key topics and technical requirements

• Culture medium: Baird‑Parker agar medium is the selective medium specified; composition and preparation details are provided in Annex B.
• Incubation: aerobic incubation at 34 °C to 38 °C with examination after 24 h ± 2 h and at 48 h as needed.
• Plating and enumeration: surface inoculation of test sample or dilutions, selection of plates within counting limits and calculation of results per appropriate unit (g, mL, cm², device).
• Confirmation: colonies typical or atypical on BPA must be confirmed by a coagulase test (tube test) or by rabbit plasma fibrinogen agar (RPFA) as an alternative.
• Scope and limitations: applicable across the food chain but not fully suited for some fermented products or products with technological Staphylococcus flora (e.g., S. xylosus in some raw‑milk cheeses or raw meat), where atypical colonies or background flora may obscure results.
• Quality & performance: includes requirements for media performance testing (Annex B), referencing ISO 11133 for culture media production/storage and interlaboratory study results (Annex C).
• Laboratory practice: aligned with general microbiology guidance in ISO 7218 and sampling/dilution procedures in the ISO 6887 series.

Applications and users

Who uses ISO 6888-1:2021:

• Food and feed microbiology laboratories performing routine testing and QC
• Food manufacturers and processors monitoring product safety and hygiene
• Regulatory and inspection authorities validating compliance with microbial limits
• Primary producers and environmental hygiene teams in food/feed facilities Practical applications include routine enumeration of S. aureus in raw ingredients, finished products, environmental swabs and investigating contamination sources.

Related standards

• ISO 6888-2, ISO 6888-3 (other horizontal methods for coagulase‑positive staphylococci)
• ISO 7218 - General requirements for microbiological examinations
• ISO 11133 - Preparation and performance testing of culture media
• ISO 6887 (all parts) - Preparation of test samples, initial suspension and dilutions

Using ISO 6888-1 helps ensure consistent, validated enumeration of coagulase‑positive staphylococci across the food chain and supports food safety, quality control and regulatory testing programs.