Background: Hemodialysis patients with tunneled catheters are at increased risk of bacteremic Staphylococcus aureus infections. In vitro and in vivo studies showed that aspirin has direct antistaphylococcal effects by inhibiting expression of alpha-toxin and matrix adhesion genes through activation of sigma factor B stress-induced operon. We hypothesized that long-term treatment with aspirin may decrease the frequency of S aureus bacteremia in such patients.
Methods: We retrospectively analyzed electronic medical records for a variety of clinical parameters, including catheter dwell times, blood culture results, and aspirin use in our dialysis population.
Results: A total of 4,722 blood cultures were performed in 872 patients during more than 476 patient-catheter-years. There was a lower rate of catheter-associated S aureus bacteremia in patients treated with aspirin versus those not treated with aspirin (0.17 versus 0.34 events/patient-catheter-year, P = 0.003), whereas no such difference was observed for other bacteria. This association was dose dependent, seen mostly with the 325-mg aspirin dose. Using the Cox proportional hazard method, risk to develop a first episode of S aureus bacteremia decreased by 54% in patients using aspirin (confidence interval, 24 to 72; P = 0.002). Aspirin was associated with decreased risk of: (1) a first episode of methicillin-resistant S aureus bacteremia and (2) metastatic complications during the first episode of catheter-related S aureus bacteremia.
Conclusion: These data are consistent with our clinical hypothesis that aspirin has a clinically useful antistaphylococcal effect in the dialysis population.