Community versus Hospital Acquired Staphylococcus aureus Bacteremia in A Canadian Tertiary Care Center: A Retrospective Chart Review, 2010-2012
Staphylococcus aureus (SA) bloodstream infections (BSI) are a significant cause of morbidity and mortality. The objective of this study is to compare rates of MRSA and MSSA bacteremia in our hospital over time and to describe the characteristics of community-acquired (CA) and healthcare associated (HA) BSI admitted to hospital over a two year period.
This study took place at a 739-bed inpatient tertiary care center in Edmonton, Canada. All patients who had a blood culture positive for SA between January 1, 2010 and Dec 31, 2012 and were admitted to the University of Alberta Hospital were included. Information was extracted from paper charts. Data analysis was performed using IBM SPSS 22.
A total of 342 separate episodes of SA BSI were reviewed. Of the 342 episodes, 198 were admitted to medical services (57.8%) and 149 (43.5%) required ICU admission. The mean age was 60.6 years (+/- 17.6 years, range 18-99 years). More men than women were affected (237, 69.3%). Fifty four percent (54.3%, 186) of SA BSI were CA. Rates of BSI did not change over time, except in the last quarter of 2012, HA-MRSA rates fell. Thirty-day mortality was similar (CA 24.2%, 45; HA 19.2%, 30). Greater 120-day mortality was seen in the CA group (60, 32.3% vs 41, 26.2%). In 305 (89.1%) cases, infection source was identified. Main sources of CA BSI were skin and soft tissue infections (37, 12%), endocarditis (26, 8.5%), and pneumonia/aspiration (29, 9.5%). Main sources of HA BSI were central access (47, 15.4%), pneumonia/aspiration (20, 6.6%) and post-operative infections (30, 9.8%). Age and sex distributions, mean duration of bacteremia and the mean vancomycin mean inhibitory concentration were the same in both groups. On average, patients with HA bacteremia stayed one day longer in the ICU (5.9 vs 6.8, range 0-72) and 1.6 days longer in hospital overall (35.1 days vs 33.5 days, range 1-745 days).
To our knowledge very few studies have examined differences in CA and HA SA BSI. Our study suggests the geographical place of onset is not determined by age, sex or resistance pattern and does not affect mortality. The main difference between the two entities is the source of infection. Soft tissue infections are the predominant source in community acquired SA bacteremia whereas central catheters are the predominant source in hospital acquired SA BSI.
J. Fuller, None
S. Smith, None