What indicates that disinfection has not been effective and may require re-cleaning?

• A. Soil remaining on the surface.
• B. Surface looks clean.
• C. Disinfectant is still wet after application.
• D. Client reports no issues.

Answer: (A)

The key idea is that disinfection only works if the surface is clean first. When soil or debris remains on a surface, the disinfectant can’t fully contact the microorganisms hiding in that soil, so the disinfection may not be effective and you should re-clean before reapplying the disinfectant with the proper contact time. A surface that looks clean can still harbor hidden residues, so appearance isn’t a reliable sign of full disinfection. If the disinfectant stays wet for the required contact time or dries too quickly, that points to proper application or drying issues, but the direct indicator that disinfection is likely ineffective is the presence of soil left on the surface.