BETHESDA, MD—Military trainees are at high risk for skin and soft-tissue infections (SSTIs) but, while Staphylococcus aureus is associated with purulent SSTI, it is unclear to what degree this pathogen causes nonpurulent cellulitis.

A study published online by PLOS One sought to inform effective prevention strategies and provide novel insights into SSTI pathogenesis. To do that, Uniformed Services University of the Health Sciences researchers and colleagues studied the etiology of SSTI in the military training population.1

A prospective observational study in Army infantry trainees with SSTI—cutaneous abscesses and cellulitis—was performed from July 2012 through December 2014. Researchers employed standard microbiology, serology and high-throughput sequencing to determine the etiology of SSTI. In addition, they compared purported risk factors, as well as anatomic site colonization for S. aureus.

Results indicate that, among 201 SSTI cases evaluated for risk factors, cellulitis was associated with lower extremity blisters, while abscess was associated with methicillin-resistant S. aureus (MRSA) colonization.

Among the 22 tested cellulitis cases that were part of the microbiome analysis, only one leading edge aspirate was culturable (Coagulase-negative Staphylococcus), according to the researchers, who add that microbiome evaluation of aspirate specimens demonstrated that Rhodanobacter terrae was the most abundant species (66.8% average abundance), while abscesses were dominated by S. aureus (92.9% average abundance).

“Although abscesses and cellulitis share the spectrum of clinical SSTI, the bacterial etiologies as determined by current technology appear distinct,” study authors concluded. “Furthermore, the presence of atypical bacteria within cellulitis aspirates may indicate novel mechanisms of cellulitis pathogenesis.”

1 Johnson RC, Ellis MW, Schlett CD, Millar EV, LaBreck PT, Mor D, Elassal EM, Lanier JB, Redden CL, Cui T, Teneza-Mora N, Bishop DK, Hall ER, Bishop-Lilly KA, Merrell DS. Bacterial Etiology and Risk Factors Associated with Cellulitis and Purulent Skin Abscesses in Military Trainees. PLoS One. 2016 Oct 25;11(10):e0165491. doi: 10.1371/journal.pone.0165491. PubMed PMID: 27780238; PubMed Central PMCID: PMC5079656.