Detection and Impact of Staphylococcus aureus Small Colony Variants in Chronic Wounds: A Pilot Study

Abstract

A unique phenotype of S. aureus called S. aureus small-colony variants (SA-SCVs) are a consequential contributor to multiple infectious processes. SA-SCVs are distinguishable from wild-type S. aureus (WT-SA) by their small size, slowed growth rate, and altered biochemical reactions; these changes make SA-SCV more difficult to detect from clinical specimens using routine diagnostics. While the clinical environment of chronic wound infections has the potential to stimulate the production of SA-SCVs, studies investigating detection of SA-SCVs in chronic wounds have not been previously conducted. Chronic wound specimens found to harbor S. aureus via qPCR screening, and screened for recent aminoglycoside treatment and/or co-infected with Pseudomonas aeruginosa, were collected from a specialty wound care clinic in April 2019. In-house enrichment methods alongside culture-dependent and independent diagnostics were utilized to recover and identify SA-SCVs from these chronic wounds. Our investigation determined difficulties in recovering and identifying SA-SCVs during routine diagnostic procedures, and the potential clinical impact of wounds harboring SA-SCVs related to antimicrobial susceptibility.