Staphylococcus aureus bacteraemia among patients undergoing dialysis - focus on dialysis catheter-related cases

Background. Central venous catheter-related infections are the most common cause of nosocomial S. aureus bacteraemia in Denmark. Central venous catheters are often used for dialysis, and patients on dialysis often run into staphylococcal infections. The purpose of this study was to investigate S. aureus bacteraemia among dialysis patients, especially those related to dialysis catheters. Methods. This was a retrospective study of 14387 consecutive S. aureus bacteraemia cases during the period 1976-93, of which 793 cases occurred among dialysis patients. By reviewing the case records, 65 dialysis catheter-related cases were described more thoroughly. Results. The number of S. aureus bacteraemia cases among dialysis patients as a proportion of all cases in Denmark has increased from 5.2 to 14.7% during the study period, but the annual incidence among these patients has been almost stable during the period (median 5.7% (3.2-9.0%)). Patients on dialysis had a lower mortality than other patients with S. aureus bacteraemia (18.9 vs 29.0%), but a four times higher mortality from central venous catheter-related S. aureus bacteraemia (5.3 vs 1.3%, P<0.001). The mortality from dialysis catheter-related S. aureus bacteraemia was correlated with greater age (median 71 years (57-73) vs median 56.5 years (15-76), P<0.01) and with septic shock (55.5 vs 7.1%, P<0.05). Patients on dialysis had a lower frequency of S. aureus endocarditis (3.3 vs 5.4%, P<0.01) and of S. aureus bone and joint infections (3.3 vs 8.2%, P<0.001) than other patients. Patients undergoing dialysis had a later onset of catheter-related S. aureus bacteraemia than other patients (median 15 days (1-145) vs 5 days (1-134), P<0.05). Conclusions. Patients on dialysis are at a high risk of S. aureus bacteraemia and they have a four times higher mortality from central venous catheter-related S. aureus bacteraemia than other patients. There is need for prospective studies in which patients as well as catheters are followed more thoroughly to study the pathogenesis of dialysis catheter-related infections.