ISO 22718:2015

Overview

ISO 22718:2015 - Cosmetics - Microbiology - Detection of Staphylococcus aureus provides standardized guidance for detecting and identifying Staphylococcus aureus in cosmetic products. The standard defines a two-step approach: enrichment in a non‑selective liquid medium (enrichment broth) followed by isolation on a selective agar medium. It also stresses the need for a microbiological risk analysis to determine applicability across varied cosmetic formulations.

Key topics and technical requirements

• Scope and intent: Detection/identification of S. aureus as a specified microorganism in cosmetics; applicability may vary by national regulation.
• Two-step method: enrichment in a non‑selective broth to recover viable cells, then isolation on selective/differential agar for identification.
• Neutralization of antimicrobial properties: Products with preservative or antimicrobial activity require validated neutralizers and demonstration of effectiveness (Clause 11).
• Media and diluents: Standard includes formulations and options - e.g., tryptone sodium chloride diluent, soybean‑casein digest agar (SCDA) or tryptic soy agar (TSA) for suitability testing, and enrichment broths such as Eugon LT 100 that contain lecithin, polysorbate 80 and dispersants.
• Sample handling and definitions: A “sample” is at least 1 g or 1 ml for preparation of the initial suspension; procedures address water‑miscible, water‑immiscible and filterable products.
• Suitability testing: The method and any substituted/automated alternatives must have demonstrated equivalence and suitability for the product matrix.
• Identification cues: Typical traits of S. aureus (gram‑positive cocci in clusters, catalase and coagulase positive) are referenced as part of identification workflows.

Practical applications and who uses this standard

• Cosmetic manufacturers - routine microbiological quality control, batch release screening, and product safety assurance.
• Contract and in‑house QC laboratories - validated analytical method for detecting S. aureus across diverse cosmetic matrices.
• Regulatory agencies and auditors - a benchmark for assessing microbial safety practices and test method adequacy.
• Formulation and R&D teams - risk analysis to determine when S. aureus testing is required (e.g., aqueous products, products for sensitive sites).
• Supply chain and CAPA investigations - investigative testing following contamination events or process failures.

Related standards

• ISO 29621 - Guidance on microbiological risk (low‑risk product categories)
• ISO 18415 - Microbiology of cosmetics for certain product types (alternative methods for some matrices)
• ISO 21148 - General instructions for microbiological examination of cosmetics
• EN 12353 - Preservation of test organisms for activity testing

ISO 22718:2015 is essential for organizations managing cosmetic microbiological quality, providing a clear, validated framework for Staphylococcus aureus detection and ensuring consumer safety through demonstrable, matrix‑appropriate testing.