Risk factors for methicillin resistance and factors associated with in-hospital mortality during Staphylococcus aureus blood stream infection: an observational study

Abstract number: P1187

Revest M., Tattevin P., Donnio P.Y., Fily F., Cady A., Arvieux C., Le Tulzo Y., Michelet C.

Objective:Staphylococcus aureus is one of the most common aetiologies of bloodstream infection (BSI) and has emerged as the leading cause of infective endocarditis. Previous studies provided conflicting data regarding risk factors for methicillin-resistance and its impact on prognosis during S. aureus BSI.

Methods: The study took place in a 1950-bed tertiary referral medical centre in Rennes, Western France. All adult patients with S. aureus BSI diagnosed from 1/1/2006 to 12/31/2006 were included. Standardised instrument was used for clinical data extraction from medical records. The study was approved by Pontchaillou institutional review board. Statistical analysis was performed using SPSS 15.0 software.

Results: The incidence of S. aureus BSI was 1.5/1000 admissions, which represented 15% of all BSI. Of 122 patients diagnosed with S. aureus BSI over the study period, data were available for 106 (87%). Male/female ratio was 70/36, mean age was 65 years. Seventy-one patients (67%) had been admitted during the previous year, and 24 (23%) had received systemic antibiotics over the last 3 months. Eleven patients (10%) had definite infective endocarditis according to Duke criteria. BSI source was assumed to be an intravenous catheter for 27 patients (25%), skin or soft tissue infection for 19 patients (18%), and was unknown for 23 patients (22%). BSI was classified as nosocomial for 73 patients (69%). Criteria for septic shock and severe sepsis were present for, respectively, 27 (25%) and 25 (24%) patients. On admission, the only significant difference between methicillin-resistant (n = 18) and methicillin-susceptible (n = 88) S. aureus BSI was the presence of foreign device (P < 0.001). In-hospital mortality was 22% for methicillin-susceptible and 33% for methicillin-resistant S. aureus BSI (P=NS). On univariate analysis, Charlson index geqslant R: gt-or-equal, slanted3 (odds ratio 3.24 [1.85–5.66]), septic shock (OR 2.38 [1.26–4.46]), and serum creatinin >120 micromol/L (OR 1.74 [1.12–2.71]) were associated with mortality (P < 0.05). Only Charlson index geqslant R: gt-or-equal, slanted 3 remained predictive of mortality on multivariate analysis (OR 2.07 [1.80–2.85]; P = 0.001).

Conclusion: Co-morbidities, as reflected by Charlson index, and infection severity, as reflected by sepsis stage, are the most potent prognosis factors during S. aureus BSI.

Session Details

Date: 16/05/2009
Time: 00:00-00:00
Session name: 19th European Congress of Clinical Microbiology and Infectious Diseases
Location: Helsinki, Finland, 16 - 19 May 2009
Presentation type:
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