Research Paper Title

Bacterial Aetiology and Risk Factors Associated with Cellulitis and Purulent Skin Abscesses in Military Trainees.

Background

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

Methods

To inform effective prevention strategies and to provide novel insights into SSTI pathogenesis, the researchers aimed to determine the aetiology of SSTI in this population. They conducted a prospective observational study in US Army Infantry trainees with SSTI (cutaneous abscesses and cellulitis) from July 2012 through December 2014. The researchers used standard microbiology, serology, and high-throughput sequencing to determine the etiology of SSTI. Furthermore, they compared purported risk factors as well as anatomic site colonisation for S. aureus.

Results

Among 201 SSTI cases evaluated for SSTI risk factors, cellulitis was associated with lower extremity blisters (P = 0.01) and abscess was associated with methicillin-resistant S. aureus (MRSA) colonization (P<0.001). Among the 22 tested cellulitis cases that were part of the microbiome analysis, only 1 leading edge aspirate was culturable (Coagulase-negative Staphylococcus). 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).

Conclusions

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

Reference

Johnson, R.C., Ellis, M.W., Schlett, C.D., Millar, E.V., LaBreck, P.T., Mor, D., Elassal, E.M., Lanier, J.B., Redden, C.L., Cui, T., Teneza-Mora, N., Bishop, D.K., Hall, E.R., Bishop-Lilly, K.A. & Merrell, D.S. (2016) Bacterial Etiology and Risk Factors Associated with Cellulitis and Purulent Skin Abscesses in Military Trainees. PLoS One. 11(10):e0165491. doi: 10.1371/journal.pone.0165491. eCollection 2016.