DT: Greg, is it true that after your landmark 2006 New England Journal of Medicine article describing the emergence of MRSA, people started calling you “Mr. SA”?³

GM: That’s one of the nicer things they call me. I prefer that to, “Yo, Pus-Dawg!”

DT: What made this new study so awesome that people will frequently quote you?

GM: There aren’t many studies of commonly used generic antibiotics because pharma only funds trials of newer and more expensive drugs, so props to the NIH. Unlike one previous similar trial by Dr. Dan Pallin, this study was large enough to answer the question with some confidence.⁴ Also, we defined specific failure criteria rather than leaving it to the clinician’s judgment and allowed up to a 25 percent increase in erythema size in the first 48 hours since many successfully treated patients may initially worsen before improving.

DT: How should this trial’s results affect ED practice?

GM: Cephalexin alone for cellulitis! No need to routinely add a second (MRSA) antibiotic. We hope that this study will lead to a reduction in unnecessary antibiotic use.

DT: Finally, what do you make of the MRSA cases among the failures? Are there any exceptions when you might cover for MRSA?

GM: This study does not exclude the possibility that there’s a minority of patients who could benefit from MRSA treatment. About 9 percent of all participants had treatment failure due to MRSA, but this occurred in the same proportion in each treatment group and thus was not prevented with TMP/SMX treatment. We suspect some participants had small abscesses, undetected by ultrasound, which required drainage. While I use cephalexin alone for most cellulitis, I add TMP/SMX for patients with any purulent drainage (excluded from this trial), a history of recurrent abscesses and what looks like folliculitis (commonly caused by MRSA), and patients who are very ill.

DT: Thanks, Pus-Dawg! That means one fewer antibiotic prescription to write and one fewer for my patient to take.

Dr. Talan is professor of medicine in residence (emeritus) at the David Geffen School of Medicine at UCLA, chairman emeritus of the department of emergency medicine, and faculty in the division of infectious diseases at Olive View–UCLA Medical Center in Los Angeles.

Illustration by Adam Talan, Dr. Talan’s son, who obtained his degree in illustration from Academy of Art University in San Francisco and currently works in Los Angeles. See more of his work and contact him at adamtalan.com.

References

1. Crisp JG, Takhar SS, Moran GJ, et al. Inability of polymerase chain reaction, pyrosequencing, and culture of infected and uninfected site skin biopsy specimens to identify the cause of cellulitis. Clin Infect Dis. 2015;61(11):1679-1687.
2. Moran GJ, Krishnadasan A, Mower WR, et al. Effect of cephalexin plus trimethoprim-sulfamethoxazole vs cephalexin alone on clinical cure of uncomplicated cellulitis: a randomized clinical trial. JAMA. 2017;317(20):2088-2096.
3. Moran GJ, Krishnadasan A, Gorwitz RJ, et al. Methicillin-resistant S. aureus infections among patients in the emergency department. N Engl J Med. 2006;355(7):666-674.
4. Pallin DJ, Binder WD, Allen MB, et al. Clinical trial: comparative effectiveness of cephalexin plus trimethoprim-sulfamethoxazole versus cephalexin alone for treatment of uncomplicated cellulitis: a randomized controlled trial. Clin Infect Dis. 2013;56(12):1754-1762.