Identifying hospital-onset Escherichia coli bacteraemia cases from English mandatory surveillance: the case for applying a two-day post-admission rule

Background A national voluntary surveillance programme has shown year-on-year increases in the number of bacteraemias caused by Escherichia coli. Mandatory surveillance of E. coli bacteraemia was introduced in 2011 with the aim of improving the quantity and quality of data collected. In contrast to the other national mandatory surveillance programmes, cases are not currently categorized based upon time of onset in relation to hospital admission. Aim To assess the case for applying time-of-onset categorization to cases of E. coli bacteraemia in England. Methods Data for all cases of E. coli bacteraemia reported to Public Health England between April 2012 and March 2016 were extracted from the national mandatory surveillance database. Cases were categorized as hospital-onset if positive blood cultures were obtained two or more days after admission. Results Approximately 21% of cases were categorized as hospital-onset. However, the proportion of hospital-onset cases decreased by 1% in each successive 12-month period, from 23% in 2012/13 to 20% in 2015/16 (P<0.001). Conclusions Approximately one-fifth of E. coli bacteraemia cases reported via mandatory surveillance were identified as hospital-onset. Given that prevention and control strategies will vary by setting, the routine feedback of this information will prove important in informing infection prevention and control efforts. The categorization of this subset of cases represents an important step towards better understanding of the epidemiology of E. coli bacteraemia.