Blood culture findings during neutropenia in adult patients with acute myeloid leukaemia:the influence of the phase of the disease, chemotherapy and the blood culture systems

In Oulu University Hospital Haematological Ward during the years 1990–1991, a manual blood culture system was able to detect bloodstream infection (BSI) in 23% of febrile episodes of patients with acute myeloid leukaemia (AML), whereas during the years 1992–1993 an automated continuous-monitoring blood culture system (CMBCS) BacT/Alert® detected BSI in 40% of febrile episodes (p = 0.043). During the years 1997–2003, regimens containing high-dose cytarabine predisposed patients to laboratory-confirmed BSI (LCBI) with an odds ratio (OR) of 2.3 (with 95% confidence interval (CI) from 1.2 to 4.2). The LCBI risk was lowest after thioguanine-containing regimens (OR 0.26, 95% CI; 0.12–0.58). In the register data (years 1992–2006) from the prospective multi-centre AML -92 trial, when compared to cycle I, the OR for LCBI was significantly higher (from 4.8 to 5.8) in subsequent cycles (p < 0.001). In all, 67% of mortality due to BSI occurred in patients with active leukaemia. An inoculum of microorganisms to produce 10 colony-forming units (cfu)/ml of 10 gram-positive coccal strains, 10 gram-negative bacillar strains and 8 Candida yeast strains was cultured in BacT/Alert® blood culture bottles in the presence of several chemotherapeutic drugs. Of the chemotherapeutic drugs tested, the anthracyclines exhibited inhibitory effects on the growth of microorganisms in concentrations corresponding to the therapeutic levels. In the standard bottles, doxorubicin increased the incubation time of gram-positive cocci and idarubicin increased the incubation time of Candida glabrata. However, no increase in the incubation time of any microbes was detected in the antimicrobial-neutralizing FAN bottles. In conclusion, the use of CMBCSs has resulted in an increased LCBI rate in neutropenic AML patients. In general, chemotherapeutic agents have no significant inhibitory effects on the growth of common microbial pathogens in blood culture. The detection of some difficult-to-culture