Trends in bacteraemia on the haematology and oncology units of a UK tertiary referral hospital

As part of ongoing surveillance of infection in the haematology and oncology units at Belfast City Hospital, microbiologically documented bloodstream infections over three 12-month periods 1994/5, 1998/9 and 1999/00 were reviewed. Gram-positive organisms were the most common cause of blood stream infection in the haematology unit causing 66%, 56% and 64% of episodes of monomicrobial bacteraemia in 1994/5, 1998/9 and 1999/00, respectively. In haematology patients, enterococci have emerged as an important cause of bacteraemia, with increasing levels of glycopeptide resistance, and the `non-fermenting Gram-negative rods other than Pseudomonas aeruginosa' are an increasingly common cause of monomicrobial and polymicrobial bacteraemia. In oncology patients, Gram-negative organisms (predominantly entero-bacteriaceae) were more common than Gram-positive organisms, causing 50% and 54% of monomicrobial bacteraemia in 1998/9 and 1999/00, respectively. Changes in patient population, underlying diseases and chemotherapeutic agents may explain these findings. The spectrum of infection seen in haematology and oncology patients changes as management evolves. Ongoing co-operation between haematologists, oncologists and microbiologists is important to detect trends in epidemiology, which can be used to design empirical antibiotic regimens and guide infection control policies. (C) 2001 The Hospital Infection Society.