P1318EPIDEMIOLOGY OF BLOODSTREAM INFECTIONS IN A SCOTTISH HAEMODIALYSIS POPULATION WITH FOCUS ON VASCULAR ACCESS METHOD

Abstract

Abstract Background and Aims Haemodialysis (HD) vascular access infections account for approximately 28% of infection-associated hospitalisations in patients with end-stage renal disease1. Traditionally there has been focus on Staphylococcus aureus (S. aureus) infections, however there is increasing recognition of the burden of Gram-negative bloodstream infection (BSI) in the HD population2,3. Epidemiological analysis has enabled surveillance of the impact of antimicrobial protocols on BSI rate and outcome2. Scottish Registry data reflects that access methods are changing alongside the HD population phenotype, with increasing use of arterio-venous graft (AVG) and central venous catheters for incident and prevalent HD access3. In this study, the rate of BSI in a contemporary Scottish HD cohort is reported by microbial species and vascular access type: arterio-venous fistula (AVF), AVG, tunnelled central venous catheter (TCVC) or non-tunnelled central venous catheter (NTCVC). Method The Strathclyde Electronic Renal Patient Record (SERPR) database for the West of Scotland was utilised to obtain retrospective observational data all adult patients attending inpatient and outpatient renal services across seven dialysis units between 1st January 2017 and 31st December 2017. All BSIs were analysed as separate episodes if more than 14 days apart, regardless of the suspected source of infection, and expressed as events per 1000 HD days. The number of days each patient was exposed to each vascular access subtype was calculated utilising the prospectively recorded HD access observations. Prevalent HD vascular access type was noted for each BSI. Results There were 786 patients who underwent HD with 217 503 total HD days over the study period. A total of 147 separate BSIs occurred, involving 115 patients. A total of 168 organisms were encountered in these BSIs. There were 49 BSIs during 126, 674 HD days using AVF access, 14 BSIs during 25, 511 AVG HD days, 81 BSIs during 64, 353 TCVC HD days and 3 BSIs during 965 NTCVC HD days. Table 1 outlines the BSI rates by vascular access and organisms identified Staphylococci-related BSI comprised the majority of events (51.7%), with S. aureus implicated in 47% of these BSIs. Coagulase-negative staphylococci were the most commonly identified organisms in the AVF, TCVC and NTCVC groups, with S. aureus the leading organism in the AVG group. Gram-negative organisms accounted for the next largest proportion of BSIs (27%) and were more prevalent in the TCVC and NTCVC groups. Conclusion AVF access subtype was associated with the lowest BSI rate, and NTCVC the highest which is in keeping with previous studies and one of the drivers for AVF as the preferred HD access type internationally. Staphylococci continue to represent a large proportion of BSIs in this cohort, however other organisms are prevalent. BSIs caused by Gram-negative organisms and Candida species were represented more heavily in the TCVC and NTCVC population, perhaps representing co-morbidity of these groups.