At ACDASM 2017

SYDNEY (FRONTLINE MEDICAL NEWS) – All patients undergoing Mohs surgery should be treated with intranasal mupirocin and a chlorhexidine body wash for 5 days before surgery, without any requirement for a nasal swab positive for Staphylococcus aureus, according to Dr. Harvey Smith.

He presented data from a randomized, controlled trial investigating the prevention of surgical-site infection in 1,002 patients undergoing Mohs surgery who had a negative nasal swab result for S. aureus. Patients were randomized to intranasal mupirocin ointment twice daily and chlorhexidine body wash daily for the 5 days before surgery, or no intervention, said Dr. Smith , a dermatologist in group practice in Perth, Australia.

Researchers saw a significant 50% reduction in the relative risk of surgical-site infection among patients in the intervention arm, compared with the control arm (2% vs. 5%, P = .04), despite the fact that none of the patients had positive nasal swabs for S. aureus, Dr. Smith said at the annual meeting of the Australasian College of Dermatologists.

The results add to earlier studies by the same group. The first study – Staph 1 – showed that swab-positive nasal carriage of S. aureus was a greater risk factor for surgical-site infections in Mohs surgery than the Wright criteria, and that decolonization with intranasal mupirocin and chlorhexidine body wash for a few days before surgery reduced the risk of infection in these patients from 12% to 4%.

The second previous study – Staph 2 – showed that using mupirocin and chlorhexidine before surgery was actually superior to the recommended treatment of stat oral cephalexin in reducing the risk of surgical-site infection.

“So, our third paper has been wondering what to do about the silent majority: These are the two-thirds of patients on whom we operate who have a negative swab for S. aureus,” Dr. Harvey said.

A negative nasal swab was not significant, he said, because skin microbiome studies had already demonstrated that humans carry S. aureus in several places, particularly the feet and buttocks.

“What we’re basically saying is we don’t think you need to swab people, because they’ve got it somewhere,” Dr. Harvey said in an interview. “We don’t think risk stratification is useful anymore, because we’ve shown it’s a benefit to everybody.”

The strategy of treating all patients with mupirocin and chlorhexidine, regardless of nasal carriage, rather than using the broad-spectrum cephalexin, fits with the World Health Organization’s global action plan on antimicrobial resistance, Dr. Harvey explained.

While there had been cases of mupirocin resistance in the past, Dr. Harvey said these had been seen in places where the drug had previously been available over the counter, such as New Zealand. However, there was no evidence of resistance developing for such a short course of use as employed in this setting, he said.

An audience member asked about whether there were any side effects from the mupirocin or chlorhexidine. Dr. Harvey said the main potential adverse event from the treatment was the risk of chlorhexidine toxicity to the cornea. However, he said that patients were told not to get the wash near their eyes.

Apart from one or two patients with eczema who could not tolerate the full 5 days of the chlorhexidine, Dr. Harvey said they had now treated more than 4,000 patients with no other side effects observed.

The study was supported by the Australasian College of Dermatologists. No conflicts of interest were declared.

dermnews@frontlinemedcom.com

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