‘Green’ disinfectant shows promise against hospital-acquired infections

By Helen Albert, Senior MedWire Reporter

Research shows that the polyhexamethylene-guanidine hydrochloride (PHMGH)-based disinfectant Akwaton effectively destroys Bacillus subtilis spores even at low concentrations.

The results, published in the Journal of Medical Microbiology, add to previous findings demonstrating that similar concentrations of Akwaton can eliminate Methicillin-resistant Staphylococcus aureus and Escherichia coli.

As well as being fast acting, Akwaton is non-toxic to humans at the tested concentrations and has been shown to be environmentally safe.

"All these properties make it an ideal disinfectant for hospitals and laboratories. It may also have great value in the food industry to tackle spore-forming food pathogens such as Bacillus cereus and Clostridium perfringens," explained study author Mathias Oulé (Université de Saint-Boniface, Winnipeg, Manitoba, Canada) in a press statement.

Oulé and team tested the sporicidal properties of Akwaton against B. subtilis spores suspended in water and attached to surfaces such as stainless steel or glass.

They found that the minimum sporostatic concentration (MSTC), the minimum sporicidal concentration (MSDC), and the time required for sporicidal activity were 0.06% (w/v), 0.08% (w/v), and 8.5 minutes, respectively.

A disinfectant concentration of 0.44% (w/v) killed all spores in a water suspension within 90 seconds and a concentration of 0.24% (w/v) killed all spores within 3 minutes, with equal efficacy seen at concentrations below 0.10% (w/v) if left for longer periods of time.

A higher concentration of Akwaton was needed to kill all spores on glass or stainless steel surfaces within the same time periods, with minimum concentrations of 0.52% (w/v) and 0.36% (w/v) for 90 second and 3-minute exposures, respectively.

The researchers note that there was a significant linear relationship between concentration of disinfectant and exposure time needed for bacterial elimination of the spores suspended in water, but not for those growing on glass or stainless steel surfaces.

"Most disinfectants have to be applied at much higher concentrations - typically between 4-10% - to properly get rid of bacterial spores. Unfortunately such high levels of these compounds may also be harmful to humans and other animals. Akwaton is non-corrosive, non-irritable, odourless and is effective at very low concentrations," said Oulé.

"Bacterial spores demonstrate a remarkable resistance to physical and chemical agents as well as ordinary antiseptics. On top of this micro-organisms are becoming increasingly resistant to disinfectants as well as antibiotics. Our latest study shows Akwaton is effective at destroying these spores as well as bacteria that are known problems in healthcare environments," he concluded.

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