Management of Staphylococcus aureus Bacteremia: Room for Improvement

Background:  Staphylococcus aureus (SA) bloodstream infections (BSIs) are an important cause of morbidity and mortality worldwide. Strategies aiming at the implementation of standardized guidance to improve patient care are compulsory.   

Methods: Retrospective cohort study of hospitalized adults with SA (methicillin resistant [MRSA] and methicillin susceptible [MSSA]) BSIs, at Jackson Memorial Hospital (1550 beds, Miami, FL) from December 2011 to August  2012. Logistic regression was performed to analyze the main outcomes: length of stay, microbiological cure, relapse, and mortality.

Results: A total of 144 SA BSI episodes (77 [53%] MRSA vs. 67 [47%] MSSA ) were identified in 138 patients.  68/144 (49%) were under the care of Internal Medicine residents and hospitalists’ teams. Infectious diseases (ID) consults were requested in 51/138 (37%). In-hospital mortality was (21% MRSA vs. 28% MSSA). 3/144 (2%) of SA BSIs were not treated with antimicrobials. 39/67(58%) of the MSSA BSI were treated with beta-lactam antimicrobials vs. 26 (39%) with vancomycin; of those, only 7/67 (10%) had a documented penicillin allergy and 2/7 were treated with a beta-lactam. Of the MSSA BSIs treated with vancomycin 8/26 (31%) died vs. 10/39 (26%) of those treated with a beta-lactam (p = .429). Average time from the first to the follow-up blood culture was 2.77 days (+2.14). 7.55 days (+ 9.74) elapsed from admission to ID consult and 4.31 days (+5.2) elapsed from first positive culture to ID consult. Although none of the predictors were significantly associated with mortality or relapse as outcomes, a shorter length of stay was significantly predicted by a shorter elapsed time between first and follow-up blood culture (β = 0.308, p = .001; model R² = 0.108, p = .008) and by a shorter elapsed time between admission and ID consult (β = 0.515, p < .001; model R² = 0.215, p= .004) after adjusting for age and gender.

Conclusion:  Improvement in patient outcomes is related to proper management, notably in selection of antimicrobials, timely blood culture follow-ups and shorter times to obtain an ID consult. These findings suggest that antimicrobial stewardship efforts with streamlined and standardized hospital protocols for treating patients with SA infections can reduce length of stay.