When evaluating the antibacterial performance of materials used in urban outdoor furniture, selecting appropriate bacterial strains is critical for accurate and meaningful results. The test should simulate real-world microbial challenges these surfaces face from environmental exposure and public use.
The most commonly used and internationally recognized bacterial strains for this purpose are:
1. Escherichia coli (E. coli) (ATCC 25922): This Gram-negative bacterium is a standard indicator for fecal contamination and hygiene testing. Its presence on public furniture is a significant concern, making it a primary strain for assessing a material's ability to inhibit Gram-negative bacteria.
2. Staphylococcus aureus (S. aureus) (ATCC 6538): This Gram-positive bacterium is commonly found on human skin and in the environment. It is a frequent cause of skin infections and is used to test a material's efficacy against resilient Gram-positive pathogens.
3. Pseudomonas aeruginosa (P. aeruginosa) (ATCC 15442): This environmentally robust Gram-negative bacterium is known for forming biofilms and resisting disinfectants. Including this strain tests the material's performance against a more challenging, ubiquitous environmental contaminant.
4. Klebsiella pneumoniae (K. pneumoniae): Another Gram-negative bacterium relevant for public health, often associated with healthcare settings but increasingly found in communities. It tests efficacy against a capsule-forming bacterium.
These strains are recommended by standard testing protocols such as ASTM E2149 (Standard Test Method for Determining the Antimicrobial Activity of Immobilized Antimicrobial Agents Under Dynamic Contact Conditions) and ISO 22196 (Measurement of antibacterial activity on plastics and other non-porous surfaces). Using a combination of Gram-positive and Gram-negative bacteria provides a comprehensive assessment of a material's broad-spectrum antibacterial properties, ensuring the outdoor furniture is hygienic, durable, and safe for public use.