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If I use ExCel_AP^® with procedures that involve a great deal of irrigation, and over time, the iodine rinses off, how can I be confident that I'm still maintaining the log reductions indicated in your literature?

While it’s intuitive to think that because the brown color has rinsed away, the efficacy must be rinsing away with it, several key issues need to be considered.

1. Until the site is closed, the procedure is being carried out in a sterile environment. The surgical field is sterile.  The irrigating solution is sterile.  Any blood that may appear is also sterile.  In other words, there should be no source of exogenous bacteria to contaminate the site.
2. Persistence (the ability to suppress the regrowth of bacterial after product application) is a function of…
   • The number of bacteria killed upon application.  The fewer bacteria present, the more time it will take them to achieve densities sufficient to cause an infection.
   • The condition of the surviving bacteria.  Unhealthy organisms will not replicate at the same rate as those who have not been damaged.

Contrary to common understanding, alcohol is actually quite persistent – not because it remains on the skin in contact with whatever bacteria are present, but instead, because…

• It kills more microorganisms than any other antiseptic (including CHG and PVP-I). According to CDC’s Guideline for the Prevention of Surgical Site Infections, it’s the most effective, fast acting single active ingredient.
• It renders those organisms that survive exposure to it extremely limited in their ability to reproduce.  As illustrated in the table below taken from FDA’s Microbiology Review of ChloraPrep’s New Drug Application (see http://www.fda.gov/cder/foi/nda/2000/20-832_CHLORAPREP%20ONE-STEP%20ANTISEPTIC_microbr.pdf), alcohol is as persistent as ChloraPrep for 24 hours.

ExCel_AP^® contains 7.5% Povidone-Iodine and the same amount of Isopropyl Alcohol (70%) as was evaluated in the study above.  Thus, the 70% alcohol component assures persistence for at least 24 hours; the presence of PVP-I and acrylate film left behind, for whatever period of time before being rinsed off, will only add to the product’s persistence.

It’s important to understand that analogous questions can be raised about ChloraPrep^® and DuraPrep™.

• In the case of ChloraPrep, how can one know how much, if any of the CHG present in the formula is being rinsed off by irrigating solution?  Though the product contains a tint, it is only present as a marker of where the product was applied – not where any CHG may or may not be present.
• In the case of DuraPrep, how can one know how much Free Iodine (the only molecular species of iodine molecules with a concentration proven to correlate with bactericidal activity; (Gottardi W. Iodine and iodine compounds. In: Block SS, ed. Disinfection, Sterilization, and Preservation. 4th ed. Philadelphia: Lea & Febiger; 1991:151-66.) is actually coming in contact with whatever bacteria are present vs. trapped in the film? 

Regardless of the antiseptic selected for the initial prep and the amount of irrigation that subsequently occurs, for procedures where surgical site infections are of particular concern (e.g. orthopedic), we would advise prepping the surgical site after closure.

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