Hospital use simulation: Which disinfectant test is specifically designed to simulate real, practical conditions of hospital use (organic load, repeated challenges)?

Introduction:
Choosing a disinfectant for hospital practice requires tests that mimic real-world conditions: organic soil, repeated contamination, and realistic contact times. Some laboratory assays are good for comparison or research but do not reflect practical use.

Given Data / Assumptions:

• We compare common assays: phenol coefficient, MIC, capacity (Kelsey–Sykes), and simple suspension tests.
• Goal: identify the assay that simulates practical hospital conditions.
• Hospitals face repeated inoculum challenges and organic load that can neutralize disinfectants.

Concept / Approach:
The Kelsey–Sykes capacity test challenges a disinfectant repeatedly in the presence of organic matter to assess its sustained activity, simulating real hospital conditions (e.g., contaminated surfaces, added soil). In contrast, the phenol coefficient is a historic comparative index against phenol under controlled lab conditions, not a working simulation. MIC measures growth inhibition in broth and is for antibiotics/biocides under standardized conditions, not practical disinfection on surfaces. Simple suspension tests show time–kill but lack repeated challenge.

Step-by-Step Solution:
Identify which test includes repeated inoculation and soil load: capacity (Kelsey–Sykes). Recognize phenol coefficient as comparative, not practical simulation. Exclude MIC and basic suspension tests for lacking real-use features. Choose the capacity test as the best simulation of hospital conditions.

Verification / Alternative check:
Standards texts describe the capacity test as assessing sustained efficacy under repeated contaminations, aligning with hospital practice.

Why Other Options Are Wrong:

• Phenol coefficient: Historic benchmark; does not model repeated challenges.
• MIC: Measures inhibition, not practical surface disinfection capacity.
• Suspension time–kill: Lacks repeated inoculum and soil load.
• None of these: Incorrect because the capacity test exists for this purpose.

Common Pitfalls:
Assuming the oldest or most cited test (phenol coefficient) is automatically the most realistic.

Final Answer:
The capacity test (Kelsey–Sykes) best simulates hospital use.