Clinical significance of Staphylococcus aureus bacteriuria in a nationwide study of adults with S. aureus bacteraemia.

Summary Objectives To evaluate the clinical significance of Staphylococcus aureus bacteriuria (SABU) in adults with S. aureus bacteraemia (SAB). Methods All individuals ≥18 years old diagnosed with SAB in Iceland between December 1st 2003 and November 30th 2008 were retrospectively identified. Data was collected from medical records. Concomitant SABU was defined as growth of S. aureus in a urine sample taken within 24 h of the index blood culture. Results SABU was seen in 27 of 166 (16.3%) SAB patients having urine cultured before administration of antibiotics, but after excluding those with SAB of urinary tract origin SABU was seen in 16 of 152 (10.5%). In this latter cohort SABU was independently associated with having endocarditis (RR 6.68; 95% CI 1.53–17.3) and admission to intensive-care unit (RR 2.84; 95% CI 1.25–4.44), while for having complicated SAB the RR was 1.56 (95% CI 0.96–1.80). No correlation was seen with mortality or relapse rates. Conclusions SABU appears to be secondary to SAB in some cases while it is the primary infection causing SAB in others. In patients with SAB of non-urinary tract origin SABU should probably be regarded as distant haematogenous seeding and a marker of deep tissue dissemination, thus affecting general management and treatment duration.