An analysis of community and hospital-acquired bacteraemia in a large teaching hospital in the United Kingdom

Abstract

A total of 875 episodes of bacteraemia and fungaemia were analysed in patients admitted to University Hospital, Nottingham, and three smaller hospitals over a four-year period. In 814 episodes (93 per cent) a single organism was isolated, most commonly Escherichia coli (27.4 per cent), other enterobacteria (14.4 per cent), Staphylococcus aureus (11.2 per cent), Streptococcus pneumoniae (9.0 per cent), or Haemophilus influenzae (6.4 per cent). In 61 cases (7.0 per cent) bacteraemia was due to two or more species. In almost 60 per cent of cases, bacteraemia was considered to be community-acquired. The most common sources were the urinary (26.9 per cent), respiratory (14.6 per cent), gastrointestinal (11.6 per cent) and biliary (9.5 per cent) tracts, but in almost 10 per cent of cases the focus of infection was unknown. Polymicrobial bacteraemia was common when the biliary tract was the focus of infection. Shock was recorded in 19.5 per cent of cases, and was commoner in polymicrobial (42.9 per cent) than in monomicrobial (17.4 per cent) episodes. In monomicrobial episodes haemolytic streptococci were associated with the highest incidence of shock (30.0 per cent). Mortality directly related to bacteraemia (19.5 per cent) was higher with Gram-positive (23.5 per cent) than with Gram-negative (15.8 per cent) organisms; in polymicrobial (31.1 per cent) than in monomicrobial episodes (18.7 per cent); and in those who had multiple episodes (34.7 per cent) than in those who had a single episode of bacteraemia (20.3 per cent). Other factors influencing mortality included shock, failure to mount an adequate febrile response, leucopenia or granulocytopenia, and underlying disease. Mortality was markedly reduced by appropriate treatment; a single antimicrobial agent was as effective as combination therapy in bacteraemia caused by Gram-negative bacilli.