Wednesday, January 6, 2010

Everybody loves chlorhexidine!

There are two randomized controlled trials* about surgical site infection (SSI) prevention published in the New England Journal of Medicine this week. In one multicenter study, investigators randomized 849 patients undergoing clean-contaminated surgery to preoperative skin preparation with chlorhexidine (CHG)-alcohol or povodone-iodine (P-I), using a primary outcome of SSI at 30 days postoperatively. By intent-to-treat analysis, CHG-alcohol use resulted in lower overall SSI rates (9.5% vs. 16.1% for P-I; p=0.004), and lower rates of superficial (4.2% vs. 8.6%) and deep (1% vs. 3%) incisional SSI.

So CHG, which is already preferred for skin prep prior to intravascular catheter placement, and which is being used increasingly to bathe ICU patients, in catheter dressings, and in oral care, should probably also be preferred for preoperative skin prep. CHG for everyone, everywhere!

In a second multicenter study, Dutch investigators screened 6771 newly admitted patients for S. aureus nasal carriage, using real-time PCR. Of the 1251 S. aureus carriers, 918 were randomized to receive 5 days of either nasal mupirocin (2% ointment twice daily) and CHG soap (daily), or placebo. The rate of healthcare-associated S. aureus infections was almost 60% lower in the mupirocin-CHG group (3.4%, versus 7.7% for placebo; relative risk 0.42 [0.23-0.75]. Most enrolled patients were surgical (88%), and most S. aureus infections were SSI (82%). Among surgical patients, the rate of deep SSI was lower in the mupirocin-CHG group (0.9 vs. 4.4%; RR 0.2 [0.07-0.62]).

The implications of this study are less clear, since the relative importance of the two topical therapies (nasal mupirocin and CHG soap) is unknown. Many centers now routinely use pre-operative CHG bathing for elective procedures. Until we know whether screening and targeted decolonization is superior to the preoperative bathing of all patients with CHG soap, this approach should be reserved for high risk procedures (e.g. cardiac surgery, orthopedic implants).

Dick Wenzel wrote a nice editorial about both pieces, and uses the opportunity to make a point we’ve made several times before in this blog: interventions that can be applied to all patients and that reduce all infections are preferred to organism-specific approaches that carry the added expense and logistical difficulty associated with identifying all carriers of an organism.

*COI alert: Both studies were industry supported—one by Cardinal Health, and one by grants from GlaxoSmithKline, Roche, bioMerieux, and 3M.


  1. I read these studies quickly tonight, skipping the Discussion sections and editorial, but have a couple of initial comments. The first is that in the Dutch study all isolates were methicillin and mupirocin sensitive, which may or may not make a difference. Presumably the peri-op antibiotics would cover MSSA, though not MRSA and since most HAIs in the study were SSIs this may be important. At least it might hinder generalizability to places with higher (>0%!) MRSA prevalence.

    The second is a silly epi/stats point, but in both studies' Table 1's p-values were provided. In an RCT, I was always taught differences between each group were do to chance (random), so what does the p-value mean and why does NEJM want p-values in Table 1 now?

    In any case, I will read the Discussion sections and Dr. Wenzel's editorial in a few minutes; right after I take my CHG bath.

  2. There are these research studies and these testing periods that are trying to deal with infections but not all are very successful.

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