Overview
ISO 16266:2006 defines a standardized membrane filtration method for the detection and enumeration of Pseudomonas aeruginosa in bottled water and other waters with low background flora (for example, pool waters and waters intended for human consumption). The standard specifies media, incubation conditions, colony selection and confirmatory tests to reliably identify P. aeruginosa for water quality monitoring and regulatory compliance.
Key topics and technical requirements
- Scope: Isolation and enumeration in bottled water (250 ml sample typical) and other low-flora waters (often 100 ml samples).
- Principle: Filter measured sample volumes through a sterile 0.45 µm membrane; place membranes on selective CN agar (Pseudomonas agar base with cetrimide and nalidixic acid); incubate and enumerate characteristic colonies.
- Media and reagents: CN-agar (Pseudomonas agar base/CN-agar), King’s B medium, acetamide broth, nutrient agar, oxidase reagent, Nessler reagent. Use analytical-grade reagents and water meeting ISO 3696 quality.
- Incubation and timing: Incubate at 36 ± 2 °C; examine after 22 ± 2 h and again after 44 ± 4 h. Use the higher count if differences occur.
- Colony identification:
- Blue/green (pyocyanin) colonies = confirmed P. aeruginosa.
- Fluorescing (under UV 360 ± 20 nm) or reddish-brown colonies require confirmatory testing.
- Confirmatory tests: Oxidase reaction, fluorescence on King’s B, and ammonia production from acetamide (acetamide broth).
- Quality and safety: Tests must be performed by trained personnel following laboratory safety practices; avoid prolonged UV exposure to colonies.
Practical applications and users
- Who uses ISO 16266: Water testing laboratories, bottled-water producers, public health authorities, pool operators, regulatory bodies, and quality assurance teams.
- Why it’s used:
- Routine monitoring of bottled water for regulatory compliance and product safety.
- Investigation of suspected contamination events in recreational or drinking water.
- Standardized method for contract testing and inter-laboratory comparability.
- Benefits: Provides reproducible, validated procedures for reliable detection and enumeration of an opportunistic pathogen that can grow in low-nutrient water.
Related standards
Keywords: ISO 16266, Pseudomonas aeruginosa, membrane filtration, water quality, bottled water testing, detection and enumeration.
Open preview (PDF)Water quality — Detection and enumeration of Pseudomonas aeruginosa — Method by membrane filtration