Incidence, aetiology and temporal trend of bloodstream infections in southern Sweden from 2006 to 2019: a population-based study

Background: Bloodstream infections (BSI) are a pub-lic health concern, and infections caused by resistant bacteria further increase the overall BSI burden on healthcare. Aim: To provide a population-based esti-mate of BSI incidence and relate this to the forthcom-ing demographic ageing western population change. Methods: We retrieved positive blood cultures taken from patients in the Skane region, southern Sweden, 2006-2019 from the Clinical Microbiology Department database and estimated incidence rates (IR), stratified by age (0-49, 50-64, 65-79, >= 80 years), sex, year, and species and described antimicrobial susceptibility for Enterobacterales. Results: We identified 944,375 blood culture sets, and 129,274 (13.7%) were posi-tive. After deduplication and removal of contaminants, 54,498 separate BSI episodes remained. In total, 30,003 BSI episodes (55%) occurred in men. The over-all IR of BSI was 307/100,000 person-years, with an average annual increase of 3.0%. Persons >= 80 years had the highest IR, 1781/100,000 person-years, as well as the largest increase. Escherichia coli (27%) and Staphylococcus aureus (13%) were the most frequent findings. The proportion of Enterobacterales isolates resistant to fluoroquinolones and third gen-eration cephalosporins increased from 8.4% to 13.6%, and 4.9% to 7.3%, (p for trend < 0.001), with the larg-est increase in the oldest age group. Conclusion: We report among the highest BSI IRs to date worldwide, with a higher proportion among elderly persons and males, including resistant isolates. Given expected demographic changes, these results indicate a possi-ble substantial future BSI burden, for which preventive measures are needed.