The role of the Staphylococcus aureus nasal carriage and type of vascular access in the outcome of high-risk patients on hemodialysis.

BACKGROUND

Populations of elderly and type-II diabetics are increasing worldwide. Therefore elderly diabetics on hemodialysis (HD), known to have higher nasal carriage rates, are also increasing. These patients are more often dialyzed through central venous catheters (CVCs). They represent the high-risk groups for Staphylococcus aureus linked vascular access-related septicemia (VRS) and ensuing mortality. The outcome of VRS in terms of mortality was studied in the three high-risk groups: elderly; type-II diabetics; elderly diabetics, following optimization of arteriovenous fistula (AVF) prevalence to at least 50%.

METHODS

Persistent nasal carriage was defined by two or more positive standardized nasal swab cultures performed on 187 ESRD patients undergoing HD from July 1997 to July 2000. Peripheral blood samples were collected for culture and sensitivity on clinical suspicion of septicemia. Overall, AVF prevalence of over 50% was achieved through joint efforts of nephrology and vascular surgery departments.

RESULTS

A nasal carriage rate of 47.6% was observed in this HD cohort. This included nasal carriage rates of 16.4% in <65 years non-diabetic (reference) group, 55.8% in elderly and 70.7% among type-II diabetics along with that of 75.5% in elderly-diabetic group. We achieved an overall AVF prevalence of 72.7% inclusive of 66.17% in elderly, 65.5% in type-II diabetics and 86.8% in reference group along with 37.7% in elderly-diabetic group. We recorded a mortality due to S. aureus nasal carriage-related VRS of 6.86% in elderly (RR-1.50, p-NS), 10.91% in type-II diabetics (RR-1.52, p<0.02) and 13.20% in the elderly-diabetic group (RR-2.87, p<0.0004) as compared to that of 4.4% per year in the reference group (assigned RR of one) with overall mortality of 7.3% per year.

CONCLUSIONS

AVF prevalence of over 50% is achievable in all the high-risk groups except among elderly-diabetics due to the predominance of peripheral vasculopathy. Optimizing AVF placement is a physiological and safer approach for achieving significant reductions in mortality associated with S. aureus nasal carriage-related VRS among high-risk groups.