Clinical Implications of the Skip Phenomenon in Patients with Persistent Staphylococcus aureus Bacteremia.

Abstract

Intermittent negative blood cultures, known as the skip phenomenon (SP), frequently occur in patients with Staphylococcus aureus bacteremia (SAB), yet the clinical implications of SP in persistent SAB are not well understood. In this retrospective cohort study conducted at four university hospitals, SP was observed in 25 (11.3%) of 221 patients with persistent SAB. Infections involving methicillin-resistant S. aureus (MRSA) were more prevalent in patients with SP, who also experienced longer durations of bacteremia and delayed active antibiotic therapy compared with those without SP. The 30-day in-hospital mortality was lower in patients with SP than in those without SP (12.0% vs. 30.6%, respectively, p = 0.052). The median time from the initiation of active antibiotic therapy to the occurrence of SP was 6 days, and from SP to the last positive blood culture was 7 days. The duration of bacteremia and MRSA were independent predictors of SP. These findings suggest that SP can cause the duration of bacteremia to be underestimated by more than 1 week, indicating that confirmation of serial negative blood cultures might be necessary to reliably rule out SP in patients with prolonged MRSA bacteremia.