559. Two Different Beasts: Comparing Epidemiology of Healthcare-Associated vs. Community-Acquired Methicillin-Resistant Staphylococcus aureus Bacteremia

Abstract

Background. Methicillin-resistant staphylococcus aureus (MRSA) bloodstream infection (BSI) is associated with significant morbidity and mortality. Healthcareassociated (HCA) MRSA infection (occurring >48 hours after hospitalization or in those with prior healthcare exposure) has traditionally been associated with severe invasive disease, while community-associated (CA) MRSA infection (occurring within 48 hours of hospitalization and without prior healthcare exposure) has been observed in otherwise healthy individuals. We characterized the epidemiology, resistance patterns, and clinical outcomes associated with MRSA BSI over a 5 year period comparing patients with community-onset bacteremia to those with hospital onset bacteremia. Methods. We performed a retrospective chart review of 151 MRSA bloodstream infections from 2013-2018 at the University of Alberta Hospital (Edmonton, Canada). We assessed each BSI by: classification (CA vs. HCA), presence of MRSA risk factors, source of infection, MRSA resistance, rate of ICU admission, and 30-day mortality. Results. The median age of all patients with MRSA BSI was 53 years (range 23-94). MRSA BSI occurred more commonly in males for both CA and HCA infection (53% and 62%). HCA-MRSA infections had a higher rate of previous MRSA colonization (64.8%) compared with CA-MRSA patients (41.7%). Injection drug use was higher in CA-MRSA infections (47% vs. 11%). The most common source of CA-BSI was bone/joint (30%) while line-associated infections were the most common in HCABSI. Clindamycin resistance was common (46-53% susceptible) while resistance to tetracyclines (91-97% susceptible) and trimethoprim/sulfamethoxazole (98-100% susceptible) was uncommon. HCA-MRSA BSI was associated with a higher rate of ICU admission (44% vs. 33%) and 30-day mortality (18.7% vs. 11.7%). Conclusion. Invasive MRSA infection continues to be associated with significant morbidity and mortality. We found that healthcare-associated MRSA BSI was associated with a high rate of prior MRSA colonization as well as a higher rate of ICU admission and 30-day mortality. There are significant differences in the demographics of patients with CA BSI compared with HCA BSI. Interventions to prevent these infections need to be targeted to the geographic location of acquisition.