agr dysfunction and persistent methicillin-resistant Staphylococcus aureus bacteremia in patients with removed eradicable foci

Persistent Staphylococcus aureus bacteremia (SAB) has been observed in patients with eradicated foci, but there are few studies of the risk factors and clinical outcomes of persistent bacteremia. This study determined the risk factors for persistent methicillin-resistant S. aureus (MRSA) bacteremia in patients without retained eradicable foci, including genotypic characteristics.

All adult SAB patients were investigated between 2008 and 2010. Persistent bacteremia was defined as bacteremia lasting >7 days after treatment and patients were monitored prospectively. The study included patients without retained eradicable foci, e.g., removed prosthetic devices and intravenous catheters removed after diagnosis, and those without metastatic infections.

Persistent bacteremia occurred in 36 % (31/87) SAB patients with eradicated foci. There were no significant differences in successful defervescence (2.0 vs. 2.0 days, P = 0.55) and total length of hospital stay after bacteremia in the persistent bacteremia group and resolved bacteremia group (P = 0.32). The difference in MRSA bacteremia-related 30-day mortality with persistent bacteremia and resolved bacteremia was not significant (P = 0.12). However, agr dysfunction was higher in persistent bacteremia patients (94 %) than those with resolved bacteremia (75 %, P = 0.03). Multivariate analysis using a logistic regression model found that only agr dysfunction [odds ratio (OR) 4.83, 95 % confidence interval (CI) 1.02–22.89, P = 0.04] was an independent risk factor for persistent bacteremia.

This study suggests that persistent bacteremia with eradicated foci might not adversely affect the outcome for MRSA bacteremia patients. agr dysfunction in S. aureus was significantly associated with persistent bacteremia.