Comparative effect on skin bacterial counts of three surgical skin preparations. Chlorhexidine Gluconate 2% v 70% alcohol v a 5th generation SiQuat.

Dr Andrew Kemp1,2,3, Dr Vanessa Hodgkinson4, Ms Alexander Bugg5

1Q Biotechnologies, Lincoln, United Kingdom,

2University of Lincoln, Lincoln, United Kingdom,

3University of Baltimore, Baltimore, USA,

4Nottingham University Hospitals Trust, Nottingham, United Kindom,

5Leicester University, Leicester, United Kingdom


The significance of skin flora around surgical wounds and its direct/ indirect effect as a cause of Surgical site infections (SSI’s) have therefore been well documented and recommendations made by agencies such as the US CDC and NICE in the UK.  This study of bacterial colony counts on surgical sites includes, Chlorhexidine 2% in alcohol (ChloraPrep), a 5th generation long acting Silane Quaternary compound (SiQuat) and a 70% alcohol solution with no other active ingredient.


A total of 300 samples were taken from areas of abdominal skin 2 cm x 1 cm along the mid line. These areas were marked to ensure that further samples were taken from the same areas.   A sample from each area was taken prior to any skin prep being used and tested using a rapid metabolic live bacteria specific assay.  All areas were prepared for surgery using one of the chosen skin antimicrobial preparations.


The results showed that the long acting SiQuat killed more quickly than the Chlorhexidine Gluconate 2%, and continued to do so more effectively for each of the time periods up to and including 4 hours after application.  Alcohol although effective initially had a negative impact compared to the chlorhexidine solution over time.


These results demonstrate that 70% alcohol on its own should now be considered an inadequate surgical skin preparation.  For operative procedures of 2 hours or more in duration, 2% CHG in alcohol may now also be considered to be inadequate as a surgical skin preparation.


Dr Andrew Kemp holds a PhD in surface disinfection and decontamination.  He has spent more than 35 years working as a specialist in infection control and prevention within the healthcare industry. Based in the research labs at the University of Lincoln UK, and working with researchers in Baltimore USA, he continues to research into surface microbial testing methods and the effects of disinfectant chemicals on surfaces and the skin. Dr Kemp lectures across the world on the subjects of infectious disease prevention and infection control.

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