473. Staphylococcus aureus Bloodstream Infection: A Two-year Study of Outcomes
Session: Poster Session: Hospital-acquired and Transplant Infections
Friday, October 30, 2009: 12:00 AM
Room: Poster Hall A
Background: Staphylococcus aureus bloodstream infections (SA-BSI) especially Methicillin Resistant Staphylococcus aureus (MRSA) have high rate of mortality and health care cost. Emergence of resistant to commonly used antibiotics for SA-BSI is an imminent threat. This study was designed to evaluate SA-BSI in a county hospital over a period of two-year and the impact of Infectious Diseases (ID) consultation on the outcome.
Methods: This was an IRB approved retrospective chart review study of SA-BSI in adult population at Kern Medical Center from December 1, 2006 to December 31, 2008. The microbiology data base was utilized and cases were evaluated for demographics, risk factors and outcomes. Minimum Inhibitory Concentrations (MIC) were obtained from Automated Microbiology System Vitec-1.
Results: 97 cases of SA-BSI were identified. The average age was 48.8 years (19-93). Of these, 49% were Latino, 36% Caucasian and 15% others. 75% were male. The average length of hospitalization was 21.9 days with average use of interavenous antibiotics of 17.9 days (1-50). Source of SA-BSI was attributed to Skin and Soft Tissue in 47% and diagnosis of Infective Endocarditis (IE) were made in 44% of cases. ID consultations were performed on 43% of the SA-BSI with average length of stay of 22.3 days.
Overall ratio of MRSA was 63% which was significantly higher in Caucasians (OR 3.7; 95%CI: 1.2-11.6; P = 0.008) and more common in Injecting Drug Users. (P = 0.06). Vancomycin MIC for MRSA was 2 in 68% of the isolates and less than 2 in all others.
The overall mortality rate for SA-BSI was 20%. Of those who deceased 75% had IE (OR 5.2; 95%CI: 1.5-18.7; P = 0.002). Mortality was higher in cases with more than one positive set of blood culture (OR 6.0; 95%CI: 1.2-40.0; P = 0.01). 70% of fatalities had MRSA. Consultation with ID service was correlated with significant reduction in mortality of MRSA BSI. (OR: 0.1; 95%CI 0.02-0.6; P = 0.003).
Conclusion: Diagnosis of Infective Endocarditis was associated with a high mortality rate of MRSA BSI. ID consultation had a notable reduction in the mortality of BSI with MRSA. ID consultation had no impact on the length of hospitalization. Increased MIC of Vancomycin for MRSA is emerging.
Sevag Balikian, MD1, Bahareh Ghafarizadeh, M.D., Arash Heidari, M.D., Royce Johnson, MD1 and  A. Heidari,
Ortho- McNeil Role(s): Grant Investigator, Received: Research Grant.
Pfizer Role(s): Grant Investigator, Received: Research Grant.
S. Balikian, None..
B. Ghafarizadeh, None. 
R. H. Johnson,
Ortho-McNeil Role(s): Grant Investigator, Received: Research Grant.
Pfizer Role(s): Grant Investigator, Received: Research Grant.
Enzon Role(s): Speaker's Bureau, Received: Speaker Honorarium.
Bio-K Plus International Inc. Role(s): Consultant, Received: Consulting Fee., (1)Kern Medical Center, Bakersfield, CA