Bacteraemia in hospitalised patients with malignant blood disorders: a retrospective study of causative agents and their resistance profiles during a 14-year period without antibacterial prophylaxis.

Bacteraemia is a major cause of morbidity and mortality in patients with haematological disorders during chemotherapy-induced neutropenia. The generally reported trend during the last two decades has been a gradual replacement of Gram-negative bacilli by Gram-positive cocci as the major causes of bacteraemia in neutropenic hosts. However, data that are unaffected by the use of antibacterial prophylaxis are scarce. Our objective therefore was to study the incidence of bacteraemia with different microorganisms in a haematology centre where antibacterial prophylaxis has not been used during the years 1988-2001. A total of 1402 episodes of clinically significant bacteraemia in 927 patients were identified. All patients were treated in the haematology wards and had an underlying haematological disorder, with lymphoma, leukaemia, and myeloma dominating. There were 536 (58%) male, and 391 (42%) female patients, with a median age of 58 years. The dominating pathogens were coagulase-negative staphylococci (CNS) 17%, Escherichia coli 16%, alpha-haemolytic streptococci 12%, Staphylococcus aureus 9%, Klebsiella spp 9%, Enterococcus spp 7%, and Pseudomonas spp 5%. The only significant incidence change was an increase of E. faecium bacteraemia. The balance between Gram-negative and Gram-positive microorganisms was essentially stable over the 14-year period. The rates of antibiotic resistance were generally low and stable. Gram-negative bacteria exhibited resistance to fluoroquinolones after 1998. The 7- and 30-day mortality rates were 6.3 and 15.6%, respectively, being significantly higher in patients with bacteraemia caused by Pseudomonas aeruginosa, Stenotrophomonas maltophilia, or E. faecium.