Strain, Disinfectant, Concentration and Contact Time Impact Disinfectant Efficacy


Transmission of healthcare-associated infections caused by antibiotic- and multi-drug resistant (MDR) pathogens (e.g. Methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa) are a major concern in patient care facilities. Disinfectant usage is critical to control and prevent pathogen transmission, yet the relationships among strain, disinfectant type, contact time, and concentration are not well-characterized. West, et al. (2018) hypothesized that there would be significant differences in disinfectant efficacy among clinically relevant strains under off-label disinfectant conditions, but there would be less no differences among at registered label use concentrations and contact times. The purpose of this study was to quantify the effect of disinfectant concentration and contact time on the bactericidal efficacy of clinically relevant strains of S. aureus and P. aeruginosa.

Accelerated hydrogen peroxide (AHP), quaternary ammonium compounds (Quat), and sodium hypochlorite were tested at label and reduced contact times and concentrations against four MDR P. aeruginosa strains and four MRSA strains. Quantitative EPA method MB-25-02 was used to measure disinfectant efficacy reported as log10 reduction.

Both off-label disinfectant concentrations and contact times significantly affected efficacy of all disinfectants tested. Bactericidal efficacy varied among MRSA and P. aeruginosa strains.

The researchers conclude that the quantitative disinfectant efficacy method used highlights the inter-strain variability that exists within a bacterial species. It also underscores the need for a disinfectant validation method that takes these variances into account.

Reference: West AM, Teska PJ, Lineback CB and Oliver HF. Strain, disinfectant, concentration, and contact time quantitatively impact disinfectant efficacy. Antimicrobial Resistance & Infection Control. 2018;7:49

Related Videos
Infection Control Today Topic of the Month: Mental Health
Infection Control Today Topic of the Month: Mental Health
Cleaning and sanitizing surfaces in hospitals  (Adobe Stock 339297096 by Melinda Nagy)
Set of white bottles with cleaning liquids on the white background. (Adobe Stock 6338071172112 by zolnierek)
Association for the Health Care Environment (Logo used with permission)
Woman lying in hospital bed (Adobe Stock, unknown)
Photo of a model operating room. (Photo courtesy of Indigo-Clean and Kenall Manufacturing)
Mona Shah, MPH, CIC, FAPIC, Construction infection preventionist  (Photo courtesy of Mona Shah)
UV-C Robots by OhmniLabs.  (Photo from OhmniLabs website.)
CDC  (Adobe Stock, unknown)
Related Content