Onset of symptoms, diagnostic confirmation, and occurrence of multiple infective foci in patients with Staphylococcus aureus bloodstream infection: a look into the order of events and potential clinical implications.

Purpose: Data on the systemic dissemination in Staphylococcus aureus bloodstream infection (SAB) remain sparse. We investigated the timing and the sequence of clinical symptoms, diagnostic confirmation, and occurrence of multiple infective foci in relation to three major infective foci.

Methods: From 2006 to 2011, all adult patients with first-time SAB in Cologne and Freiburg, Germany were followed prospectively. The study was restricted to patients with short-term central venous catheter (CVC)-related SAB, vertebral osteomyelitis (VO), and infective endocarditis (IE). The collection date of the first positive blood culture was used as reference point for determining time to onset of clinical symptoms, microbiological findings, imaging results compatible with focal infection, and occurrence of additional infective foci.

Results: We included 266 patients with first-time SAB. Among patients with CVC-related SAB, clinical onset, collection of the first positive blood culture, and microbiological confirmation almost coincided. In contrast, among patients with VO or IE, the onset of clinical symptoms most often preceded the collection of the first positive blood culture, and imaging and microbiological confirmation were most frequently obtained subsequent to the SAB diagnosis. CVC-related SAB was infrequently associated with further foci (n = 15/15.5%). Conversely, more than one infective focus was observed in 44 (56.4%) patient with VO and 68 (64.8%) patients with IE.

Conclusions: The sequence of clinical symptoms, diagnostic confirmation, and occurrence of multiple infective foci varied considerably with different infective foci in SAB. Based on these results, we propose a pragmatic and evidence-based terminology for the clinical course of SAB and suggest the terms "portal of entry", "infective focus", "multiple infective foci", and "dominant infective focus".