Blood stream infections during chemotherapy-induced neutropenia in adult patients with acute myeloid leukemia: treatment cycle matters

The purpose of this study was to assess the frequency of blood stream infections (BSIs) during neutropenia in different cycles of intensive chemotherapy treatment in acute myeloid leukemia (AML). The register data of 327 consecutive patients aged 16-66 years having de novo AML between September 1992 and December 2001 were prospectively gathered in five Finnish tertiary care leukemia centers. The patients had not received fluoroquinolone prophylaxis. Reported BSI rates were compared during neutropenia in four chemotherapy treatment cycles (C). There were 956 treatment episodes, with 456 (47.7%) positive blood cultures. BSI was monomicrobial in 327 episodes (71.7%) and polymicrobial in 129 (28.3%). The overall incidence rate (per 1,000 hospital days) for BSI was 13.2, varying from 6.8 in CI after idarubicin, conventional-dose cytarabine, and thioguanine to 15.6 in CII, 15.8 in CIII, and 17.6 in CIV. The distribution of monomicrobial gram-positive BSIs was as follows: CI, 71.7%; CII, 62.8%; CIII, 53.3%; CIV, 36.6%; and CI-IV together, 43.2%. The most common finding in the four different cycles was coagulase-negative staphylococci (38.3 to 30.6%). Viridans group streptococci were most commonly observed (in 20.4% of positive blood cultures) during CII after high-dose cytarabine and idarubicin treatments. The distribution of monomicrobial gram-negative BSIs was as follows: CI, 21.7%; CII, 36.3%; CIII, 45.7%; CIV, 46.9%; and CI-IV together, 37.9%. A great variation of incidence and types of microorganisms between AML chemotherapy cycles was found. It would be more reasonable to analyze chemotherapy cycle-based BSI results rather than the overall results.