Research unveils troubling facts about disinfectants

Monday, July 17, 2017

Sealed Air’s Diversey Care division released the first series of studies conducted with Purdue University, which focus on how well disinfectants kill bacteria.

The research, expected to be published in the August 2017 issue of the American Journal of Infection Control (AJIC), determined that the three tested disinfectants were significantly less effective and bactericidal at lower than label use contact times and concentrations.

“In busy healthcare facilities, disinfectants are often applied once and left to dry, regardless of the unique label instructions,” said Peter Teska, infection prevention application expert, Diversey Care. “As this study shows, disinfectants don’t live up to their claims if they get over diluted or are not reapplied as directed.”

“Choosing an Environmental Protection Agency-registered disinfectant and following label directions are key elements of effective disinfection and preventing the spread of healthcare-associated infections,” he adds.

The study

Accelerated hydrogen peroxide (AHP), quaternary ammonium compounds (Quats) and sodium hypochlorite were each tested on stainless steel surfaces at room temperature 25 degrees Celsius using EPA procedure MB-25-02. For each treatment, bacterial reduction was calculated, compared and analyzed to find key results, also related to Staphylococcus aureus bacteria, more commonly known as S. aureus.

This gram-negative bacteria is one of the five most common causes of infections after injury or surgery. The World Health Organization ranked it one of the world’s 12 most dangerous pathogens in need of R&D for new antibiotics.

The findings

  • All disinfectants were significantly less bactericidal against S aureus when applied for times shorter than label contact times.
  • All disinfectants were significantly less bactericidal against S aureus at lower than label concentrations.
  • AHP at 25 per cent and 50 per cent label concentrations resulted in 40.9 per cent and 75.7 per cent reductions. Quats at 25 per cent and 50 per cent label concentrations resulted in 62.5 per cent and 67.5 per cent reductions and Sodium hypochlorite at 25 per cent label concentration resulted in 50.7 per cent reduction.
  • The bactericidal efficacy of the sodium hypochlorite disinfectant was most tolerant to decreases in concentration and contact time. AHP followed close behind while the Quat disinfectant was the least tolerant and most affected by contact time and concentration.

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