Baseline and seasonal trends of and from clinical samples in Japan.

BACKGROUND

Outbreaks of bloodstream infections (BSIs) are a concern in Japanese medical settings.

AIM

This study determined baseline values for detection in clinical samples that are useful as reference values for hospitals when assessing the need for intervention.

METHOD

A retrospective analysis of detection in the Japan Nosocomial Infections Surveillance data from 2008 to 2014 was performed; it included 950 individual hospitals across the country.

FINDINGS

spp. were detected in 0.54% of the clinical specimens submitted for bacteriological testing. Specimens positive for spp. were mainly blood (24.6%), stool (26.5%), and respiratory specimens (23.3%). Identification of spp. at the species level (i.e., or ) was reported in 55.3%, 14.7%, and 15.4% of cases, of which 88.9%, 48.3%, and 33.1% were in blood, stool, and respiratory specimens, respectively. Of the 4105 hospital-years, 75.7% had blood specimens with spp., with a median of 0.85 blood specimens/100 beds annually (interquartile range, 0.17-2.10). The detection showed significant summer seasonality, regardless of specimen type or geographic distribution. The detection did not show seasonality, and its detection remained constant throughout the year. The seasonality of spp. reflects the high proportion of .

CONCLUSIONS

The increased detection rate of spp. during summer should be interpreted as a risk factor for BSIs. A post-summer decrease in spp. should not be interpreted as an effect of interventions.