SURGICAL SITE INFECTIONS
demonstrated the most effective microbial reduction at each of the time periods after application. After an initial 97.5% reduction in CFU counts, it continues to fall to 99.5% reduction at four hours.
Both the 5th generation SiQuat and 2% CHG, showed a continuous and prolonged drop in CFU counts from the pre-application levels to four hours after application.
Conclusion These results demonstrate that 70% ethyl alcohol on its own has a significantly lower efficacy than either of the other two solutions which both contain alcohol. For surgical procedures of up to two hours in duration, both 2% CHG and the 5th generation SiQuat continued to show good antimicrobial activity on the skin around the surgical wound. At four hours post application it is clear the 2% CHG is losing some of its antimicrobial activity, it may therefore be considered prudent to reapply this solution at around two hours after the original application. The surgical skin preparation that is shown to be most effective at every test point from application over the course of four hours is the 5th generation SiQuat. Reapplication would not be necessary with this type of skin prep solution.
Further investigation into the reasons
why there should be such a significant increase in skin bacterial counts when alcohol is used, has now taken place, the results of which will be published in due course. It is evident that 70% ethyl alcohol needs to be combined with another antimicrobial agent before being considered for use as a surgical skin preparation.
It is an undisputed fact that bacteria at the skin edges during surgery pose a threat to any surgical wound. It is therefore common sense that the most effective surgical skin preparations will not only kill bacteria effectively at the start of an operation but during, and for as long as possible afterwards.
Discussion These results identify the need for studies that use values as well as outcomes to be taken into consideration when determining the most effective products to use as a surgical skin preparation. A much more difficult question to answer is: “What evidence should clinicians be asking for to base decisions about product efficacy in relation to infection rates post surgery?”
It is undeniable that prevention is always better than cure. In the case of surgical site infections, it is also a fact that, due to the continuing rise in the
numbers and type of antibiotic resistant strains of bacteria, attaining a ‘cure’ becomes even more difficult to achieve. It is therefore common sense that any - and all - interventions that can reduce the numbers of bacteria that could potentially cause SSI need to be considered and assessed for efficacy. All surgical procedures differ in duration and the technique for skin preparation differs from clinician to clinician. Further studies may be indicated to be able to determine the most appropriate surgical skin prep based on individual surgical specialities, especially for the highest risk patients and procedures. Current standard tests for all disinfectants including skin sanitisers are based only on short term antimicrobial activity and effect. In Europe, these tests include EN1500, EN12791, and in the US the ASTM E2755-15 is used, amongst others. These standard tests are all complete within one to five minutes of microbial exposure to the surface chemical agents. They were developed many years ago to test the efficacy of short term disinfectants and sanitisers as there were no long acting chemicals available at that time. As it’s clear now that persistent disinfectants have a positive effect on reducing bacterial counts over time, these tests are no longer fit for purpose and new tests methods need to be developed. As the two main bodies referred to for guidance on hand cleaning, is it now time for the USCDC and the WHO – as well as the wider infection prevention community to ask themselves the following questions: Are the current short term standard
tests sufficient to test the true effectiveness of antimicrobial activity on skin, or should there be a longer lasting test standard reflecting the risks over time?
Should the CDC, the regulatory bodies and the numerous organisations whose membership are responsible for surgical outcomes, now include long term disinfection as part of their guidance on prevention of surgical infections?
References for this article are available upon request.
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34 l JULY 2018 l OPERATING THEATRE
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