Infections in patients with hematological diseases: recent advances in serological diagnosis and empiric therapy

Recent advances in the diagnosis and therapy of infections in patients with hematological diseases are reviewed. In general, 40-60% of febrile episodes lack clinical or microbiological evidence of infection and are thus treated empirically. Among the cases of microbiologically documented bacteremia treated in our department, the incidence of Gram-negative bacteria was high (47.1%) and the incidence of Gram-positive bacteremia is increasing. To improve the diagnostic rate of Gram-negative sepsis, the measurement of plasma endotoxin was performed. Of 147 febrile neutropenic episodes, endotoxemia was observed in 58 (39.5%) and the causative microorganisms of these infections were deemed Gram-negative bacteria. The measurement of plasma (1-->3)-beta-D-glucan, a ubiquitous component of fungi, was also performed for making early diagnosis of deep mycosis; the sensitivity of this assay was 90% and the specificity was 100%. The detection of (1-->3)-beta-D-glucan appears to be useful as a screening test of deep mycosis. The effects of the concomitant use of granulocyte-colony stimulating factor (G-CSF) and empiric antibiotic therapy for febrile neutropenia were studied in a randomized fashion. G-CSF did not affect the rate of the response to the empiric antibiotic therapy, although a significant effect of G-CSF on neutrophil recovery was observed. Guidelines for empiric antibiotic and antifungal therapy combined with serological diagnosis are proposed.