A new study has reaffirmed that, as methicillin‐sensitive Staphylococcus aureus (MSSA) remains the most common skin infection in pediatric atopic dermatitis (AD) patients, first‐generation cephalosporins remain the appropriate empiric therapy.

“Clindamycin, tetracyclines, or TMP‐SMX can be considered in patients suspected to have, or with a history of, MRSA [methicillin‐resistant S. aureus] infection,” wrote Cristopher C. Briscoe, MD, of the Washington University School of Medicine in St. Louis, Missouri, and his coauthors. The study was published in Pediatric Dermatology.

To determine the optimal empiric antibiotic for pediatric AD patients with skin infections, the researchers analyzed skin cultures from 106 patients seen at Saint Louis Children’s Hospital (SLCH). The results were also compared to cultures from pediatric patients who presented at the SLCH emergency department (ED) with S. aureus skin abscesses.

Of the 170 cultures that grew S. aureus, 130 (77.8%) grew MSSA, and 37 (22.2%) grew MRSA. Three of the cultures grew both. The prevalence of MRSA in the cohort differed from the prevalence in the ED patients (44%). The prevalence of either infection did not differ significantly by age, sex or race, though the average number of cultures in African American patients topped the average for Caucasian patients (1.8 vs. 1.2, P less than .003).

All patients with MSSA – in both the cohort and the ED – proved 100% susceptible to cefazolin. Cohort patients with MSSA saw lower susceptibility to doxycycline compared to the ED patients (89.4% vs. 97%), as did MRSA cohort patients to trimethoprim‐sulfamethoxazole (92% vs. 98%).

“When a patient with AD walks into your office and looks like they have an infection of their eczema, your go-to antibiotic is going to be one that targets MSSA,” said coauthor Carrie Coughlin, MD, of the Washington University School of Medicine in an interview. “You’ll still do a culture to prove or disprove that assumption, but it gives you a guide to help make that patient better in the short term while you work things up.”

“Also, remember that MSSA is not ‘better’ to have than MRSA,” she added. “You can now see some of the virulence factors from MRSA strains in MSSA strains, so treating both of them is important.”

The authors acknowledged their study’s limitations, including the limited generalizability of a single-center design and a lack of information as to the body sites from which the cultures were obtained. They were also unable to reliably determine prior antibiotic exposure, noting that “future work could examine whether prior exposure differed significantly in the MRSA and MSSA groups.”

The study was funded by grants from the Agency for Healthcare Research and Quality. The authors reported no conflicts of interest.

SOURCE: Briscoe CC et al. Pediatr Dermatol. 2019 May 24. doi: 10.1111/pde.13867.