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Summary Objectives The rapid diagnosis of bacteremia is crucial for patient management including the choice of antimicrobial therapy, especially in cases of hematological disease, because neutropenia occurs frequently during antineoplastic chemotherapy or disease progression. We describe a rapid detection and identification system that uses universal PCR primers to amplify a variable region of bacterial 16S ribosomal DNA (rDNA), followed by DNA microarray hybridization. Methods Probes for 72 microorganisms including most causal clinical pathogens were spotted onto a microarray plate. The DNA microarray and conventional methods of identification were applied to 335 cultures from patients with hematological diseases. Results Forty-one samples (12.2%) tested positive by conventional blood culture test in a few days, while 40 cases (11.9%) were identified by the new method within 24h. The sensitivity and specificity of this new method were 93% and 99%, respectively, compared with conventional blood culture testing. Conclusions PCR combined with a DNA microarray is useful for the management of febrile patients with hematological diseases.

Background Patients with tsutsugamushi disease sometimes die if they do not receive appropriate chemotherapy. This study measured the concentration of several cytokines both before and after the administration of tetracyclines, and evaluated the changes in cytokine levels in patient serum to investigate the relationship between serum levels of cytokines and disease severity. Methods A total of nine patients were infected with Orientia tsutsugamushi . The diagnosis of tsutsugamushi disease was made using an indirect immunoperoxidase antibody test. The serum concentrations of cytokines were measured using enzyme-linked immunosorbent assays. Results The levels of interleukin (IL)-10 (mean 71.7 pg/ml) and IL-12p40 (mean 588 pg/ml) were elevated in all patients in the acute phase, above the normal upper limits. Tumor necrosis factor-α (TNF-α) levels (mean 9.20 pg/ml) were elevated in 89% and interferon-γ (IFN-γ) levels (mean 41.0 pg/ml) in 44% of patients. The down-regulation of these overproduced cytokines was observed after chemotherapy. There was a significant correlation between the concentrations of TNF-α in the acute phase and the severity of disease ( r =0.918). Conclusion The concentration of TNF-α may predict the severity of tsutsugamushi disease in the acute infectious phase.