Comparison between patients under hemodialysis with community-onset bacteremia caused by community-associated and healthcare-associated methicillin-resistant Staphylococcus aureus strains

Abstract

Patients receiving hemodialysis infected with methicillin-resistant Staphylococcus aureus (MRSA) have been considered to have healthcare-associated (HA) infections, but strains with community-associated (CA) characteristics have also been identified in this population. The authors compared infections of the two strains among patients with end-stage renal disease. From January 2004 to December 2008 the authors analyzed the demographic and microbiologic data of 57 patients with community-onset (defined as a positive culture obtained ≤ 48 hours after admission) MRSA bacteremia and end-stage renal disease at a 2900-bed tertiary medical center. MRSA isolate with staphylococcal cassette chromosome mec (SCCmec) type II/III was classified as HA strains, and SCCmec type IV/V as CA strains. Forty-seven patients (82%) had HA-MRSA strains and 10 patients (18%) had CA-MRSA strains. The major clones of HA-MRSA were sequence type (ST) 5 with SCCmec type II and staphylococcal protein A (spa) t002 as well as ST239 carrying SCCmec type III and spa t037. The CA-MRSA strains were predominantly ST59, more susceptible to non-β-lactam antimicrobial agents, and had a higher percentage of carrying the Panton-Valentine leukocidin gene in comparision with the HA-MRSA strains. Patients infected with HA-MRSA isolates had a higher overall mortality (57.4%, p = 0.012). In multivariate analysis, male patients were more likely to be infected with HA-MRSA isolates than CA-MRSA strains (p = 0.037), and a history of receiving urinary catheterization within 1 year prior to bacteremia onset (p = 0.047) is an independent risk factor to acquiring HA-MRSA strains. Patients undergoing dialysis and infected with HA-MRSA strains had higher mortality rates and were more commonly associated with urinary catheterization within 1 year before bacteremia.