Elevated urinary glycosaminoglycans in Staphylococcus aureus bacteraemia with endovascular source

The differentiation of endovascular sources of Staphylococcus aureus bacteraemia from non-endovascular infection carries significant prognostic information that can be used to therapeutically stratify patients. The endovascular glycocalyx is a protective barrier composed of glycosaminoglycans (GAGs) that can be degraded and excreted in the urine from endothelial injury occurring in endovascular infections, but not in non-endovascular infections. To determine whether patients who had S. aureus endovascular infections, including endocarditis, had increased urinary glycocalyx shedding suggestive of endothelial damage, urine samples from 55 patients with bacteraemia caused by S. aureus were assessed for GAG content. Patients with endovascular source bacteraemia were compared to those from non-vascular source bacteraemia (e.g. prosthetic joint infections, pyomyositis and cellulitis) for GAG content. As expected, patients with S. aureus bacteraemia stemming from endovascular foci of infection showed increased GAG content in the urine (24.11±4.9 g GAG/mol creatinine, n =22) compared to those with non-vascular infections (13.65±1.6 g GAG/mol creatinine, n =33, P =0.024). Further analysis of GAG composition in urine revealed differential presence of GAGs between these two groups. In the first pilot study of its kind, we found that the measurement of GAG in the urine of patients with S. aureus bacteraemia shows promise for clinical risk stratification to identify high-risk endovascular infections in order to guide clinical diagnostic and therapeutic decision-making. Larger studies will be needed to determine relevant quantitative cut-off values.