Surgical Scrub Evaluation and antimicrobial efficacy test method (ASTM E1115)

The Highest Standard for Operating Theatre Antimicrobial Efficacy

Surgical hand scrub formulations are subject to the most rigorous efficacy requirements because they are used in high-risk clinical settings such as operating theatres, where the prevention of surgical site infections is critical. The ASTM E1115 antimicrobial efficacy test method is a globally recognised standard for assessing the effectiveness of these high-performance products. It evaluates both their immediate and residual antimicrobial activity to ensure comprehensive protection for healthcare professionals.

Purpose

The ASTM E1115 standard measures a product’s ability to deliver two key outcomes:

• Immediate Reduction: To achieve a rapid and significant decrease in the natural microbial flora on the skin following application.
• Persistent (Residual) Effect: To maintain antimicrobial protection for up to six hours under surgical gloves, preventing microbial regrowth.

This dual focus makes ASTM E1115 the benchmark standard for assessing surgical scrub products intended for critical healthcare environments.

Methodology

The ASTM E1115 procedure is an advanced in vivo test method designed to replicate real-world surgical scrub conditions. Unlike artificial contamination tests, it assesses the product’s effect on the natural resident microbial flora of the skin, offering a true representation of clinical use.

Key Steps of the ASTM E1115 Test

1. Subject Selection: Volunteers are chosen with a high baseline bacterial count (≥ 1×10⁵ CFU per hand) who have avoided antimicrobial products for a week.
2. Baseline Measurement: Initial bacterial counts are recorded using the standardised ‘glove juice’ sampling method.
3. Simulated Surgical Scrub: Participants perform a timed, supervised scrub using the test formulation in accordance with manufacturer instructions or a standardised protocol.
4. Dual-Time Sampling: One hand is sampled immediately after scrubbing to measure instant reduction; the other is gloved and sampled after 3–6 hours to measure residual effect.
5. Cumulative Effect (Optional): A five-day protocol can be conducted to assess whether repeated use improves long-term antimicrobial protection.

This robust method provides comprehensive data on both immediate and sustained antimicrobial performance, ensuring that surgical scrubs meet the highest infection-control standards.

Significance

Conducting ASTM E1115 testing demonstrates a laboratory’s commitment to scientific excellence and quality assurance. The method is widely recognised for its complexity and clinical relevance and is essential for manufacturers developing surgical hand scrubs and other antiseptic products for critical care use. Passing ASTM E1115 testing provides authoritative evidence of both immediate and persistent efficacy— strengthening regulatory compliance and brand credibility.

FAQs

Q1: What is the ASTM E1115 antimicrobial efficacy test method?

It is an in vivo procedure that evaluates surgical scrub formulations for both immediate and long-lasting antimicrobial activity, ensuring compliance with international healthcare standards.

Q2: Why is ASTM E1115 important for surgical scrubs?

It confirms that a surgical scrub reduces microbial flora effectively and maintains prolonged protection during surgery, reducing the risk of infection.

Q3: What does the test measure?

It measures both the immediate microbial reduction after scrubbing and the persistent antimicrobial activity beneath gloves for up to six hours.

Q4: How does ASTM E1115 differ from other test methods?

Unlike laboratory-based microbial assays, ASTM E1115 is performed on human skin with natural flora, delivering results that mirror real clinical conditions.

Q5: Who requires ASTM E1115 testing?

Manufacturers of surgical hand scrubs and antiseptic products intended for critical care and operating theatre use require ASTM E1115 data to validate their claims and achieve regulatory approval.

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