Traces of a widely used hospital antiseptic remain on surfaces long enough to help bacteria develop tolerance, according to a study from Northwestern University published in Environmental Science & Technology.
Chlorhexidine has been a cornerstone of hospital infection control since the 1950s, used for patient bathing, surgical skin preparation, equipment sterilisation, and hand washing. However, researchers found the chemical persists in the environment after application.
Laboratory experiments showed chlorhexidine residue remained on common hospital materials, plastic, metal, and laminate, for more than 24 hours after cleaning with standard disinfectants. Whilst these residue levels were too low to kill bacteria, they were sufficient to expose microbes to the chemical, potentially allowing survivors to develop tolerance.
The team conducted an environmental survey in a medical intensive care unit, collecting nearly 200 samples from bed rails, keyboards, door sills, light switches, and sink drains. From these samples, researchers isolated over 1,400 bacteria, with approximately 36% exhibiting some level of chlorhexidine tolerance.
Sink drains emerged as particular hotspots, containing far higher bacterial levels than dry surfaces, including strains tolerating much higher chlorhexidine concentrations. Researchers noted that running water generates aerosols with potential for re-exposure.
Unexpectedly, bacteria with signs of chlorhexidine tolerance were also found on door-sill samples, surfaces people rarely touch, suggesting bacteria may travel on airborne particles such as dead skin cells.
Lead author Professor Erica Hartmann emphasised that chlorhexidine remains necessary and effective in clinical settings but cautioned that homes and offices rarely require disinfection. She recommended using plain soap and water outside healthcare environments to help prevent antimicrobial resistance.
Source: News Medical / Northwestern University (Environmental Science & Technology, 2026)
Chlorhexidine has been a cornerstone of hospital infection control since the 1950s, used for patient bathing, surgical skin preparation, equipment sterilisation, and hand washing. However, researchers found the chemical persists in the environment after application.
Laboratory experiments showed chlorhexidine residue remained on common hospital materials, plastic, metal, and laminate, for more than 24 hours after cleaning with standard disinfectants. Whilst these residue levels were too low to kill bacteria, they were sufficient to expose microbes to the chemical, potentially allowing survivors to develop tolerance.
The team conducted an environmental survey in a medical intensive care unit, collecting nearly 200 samples from bed rails, keyboards, door sills, light switches, and sink drains. From these samples, researchers isolated over 1,400 bacteria, with approximately 36% exhibiting some level of chlorhexidine tolerance.
Sink drains emerged as particular hotspots, containing far higher bacterial levels than dry surfaces, including strains tolerating much higher chlorhexidine concentrations. Researchers noted that running water generates aerosols with potential for re-exposure.
Unexpectedly, bacteria with signs of chlorhexidine tolerance were also found on door-sill samples, surfaces people rarely touch, suggesting bacteria may travel on airborne particles such as dead skin cells.
Lead author Professor Erica Hartmann emphasised that chlorhexidine remains necessary and effective in clinical settings but cautioned that homes and offices rarely require disinfection. She recommended using plain soap and water outside healthcare environments to help prevent antimicrobial resistance.
Source: News Medical / Northwestern University (Environmental Science & Technology, 2026)
