Predictors and clinical outcomes of persistent methicillin-resistant Staphylococcus aureus bacteremia: a prospective observational study

Abstract

Background/aims: The high mortality attributable to persistent methicillin-resistant Staphylococcus aureus (MRSA) bacteremia in spite of glycopeptide treatment has heightened the need for early detection and intervention with alternative agents. The purpose of this study was to determine the clinical characteristics of and risk factors for persistent MRSA bacteremia.

Methods: All first episodes of significant MRSA bacteremia at a 710-bed academic medical center from November 2009 through August 2010 were recorded. Blood cultures were conducted at 3 days and every 2 to 3 days thereafter until clearance. Clinical characteristics and outcomes were compared between persistent MRSA bacteremia (≥ 7 days) and nonpersistent MRSA bacteremia (≤ 3 days).

Results: Of 79 patients with MRSA bacteremia during the study period, 31 (39.2%) had persistent MRSA bacteremia. The persistent MRSA bacteremia group had significantly higher 30-day mortality than the nonpersistent MRSA bacteremia group (58.1% vs. 16.7%, p < 0.001). Multivariate analysis indicated that metastatic infection at presentation (odds ratio [OR], 14.57; 95% confidence interval [CI], 3.52 to 60.34; p < 0.001) and delayed catheter removal in catheter-related infection (OR, 3.80; 95% CI, 1.04 to 13.88; p = 0.004) were independent predictors of persistent MRSA bacteremia. Patients with a time to blood culture positivity (TTP) of < 11.8 hours were at increased risk of persistent MRSA bacteremia (29.0% vs. 8.3%, p = 0.029).

Conclusions: High mortality in patients with persistent MRSA bacteremia was noted. Early detection of metastatic infection and early removal of infected intravascular catheters should be considered to reduce the risk of persistent MRSA bacteremia. Further studies are needed to evaluate the role of TTP for predicting persistent MRSA bacteremia.

Keywords: Methicillin-resistant Staphylococcus aureus; Mortality; Persistent.

Figure 1

Receiver operator characteristic curve of the time to blood culture positivity for predicting persistent methicillin-resistant Staphylococcus aureus bacteremia. The area under the curve was 0.647.

Figure 2

Thirty-day Kaplan-Meier survival curves for patients with methicillin-resistant Staphylococcus aureus (MRSA) bacteremia. The cumulative survival rate of patients with persistent MRSA bacteremia was significantly lower than that of patients with nonpersistent MRSA bacteremia (p < 0.001, log-rank test).