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Background A new 23S ribosomal RNA genes-targeted in situ hybridization (ISH) probe to detect global bacterial genomic DNA (59 species from 35 genera; referred to as the GB probe) phagocytized in leukocytes was recently developed. This method provided early and direct evidence of bacterial infection with high sensitivity and specificity in spontaneous bacterial peritonitis ascites. However, the utility of this method in febrile neutropenia (FN) is unknown. Methods We prospectively evaluated the utility of the ISH approach using the GB probe and previously reported probes in patients with neutropenia and fever undergoing chemotherapy at our institution between June 2011 and July 2013. Blood samples for culture analysis and ISH tests were collected simultaneously at the onset of fever; the latter were performed repeatedly. Results Fifty febrile episodes were evaluated. In 24 episodes of fever of unknown origin and 15 episodes of local infection (all negative for blood cultures), ISH tests identified causal bacteria in 21% and 13% of cases, respectively, at the onset of fever. In seven sepsis cases (all positive for blood culture), positive ISH test results at fever onset were achieved in 71%; for two patients with neutrophil counts of 0/μl and 171/μl, respectively, negative results were obtained. Conclusions This new ISH approach could prove useful for early detection of bacteria in patients with neutropenia and blood culture-negative, with fever of unknown etiology after chemotherapy. Using this method in combination with blood culture, even in cases with extremely low neutrophil counts, might contribute to better management of FN.

Background Whether presepsin (soluble CD14-subtype) is better than other markers including procalcitonin (PCT), has not been adequately investigated in febrile neutropenia (FN). Methods We prospectively examined the utility of presepsin in FN in Cohort 1 (C1) and 2 (C2), between November 2010 and February 2012, and between November 2013 and January 2014, respectively. The purpose of this study was to investigate 1) the relative value of serum presepsin over serum PCT in C1, and 2) the relative value of plasma presepsin as compared with serum PCT, C-reactive protein, interleukin-6 and interleukin-8 with frequent, repeated sampling in C2. Results Seventy-nine FN episodes (C1, 75; C2, 4) were evaluable. In C1, when compared with control values, presepsin was significantly higher at onset of FN (P = 0.004), while PCT was not significantly higher (P = 0.54). The median value of serum presepsin within 72 h of onset of FN in subjects with fever of unknown origin, local infection, bacteremia and septic shock was 680 (reference 314) pg/ml, 763, 782 and 1359, respectively. In C2, the mean levels of plasma presepsin from onset of FN to 72 h were classified as negative in the two patients with no suspected site of infection, and those of the remaining two patients with clinically probable infections were positive (175, 131, 346 and 329 pg/ml, respectively). In contrast, the other markers did not discriminate between this two groups. Conclusions In FN, presepsin may be an earlier and more sensitive indicator of bacterial infection than PCT.