ABSTRACT
<b>Background: </b>Blood culture is an essential examination for diagnosis of causative microorganisms and determination of optimal antimicrobials in serious cases of infectious diseases. We examined temporal trends in the number and multiplicities of blood culture submission, two pre-analytic parameters indicating quality of the examination, in the Minami Ibaraki Area.<br><b>Methods: </b>We reviewed all computerized and available paper-based laboratory records of microbiological examination in five hospitals in the area between 2002 and 2011.<br><b>Results: </b>Blood culture submissions, estimated to be 2.4–7.3 (median: 5.1) sets per hospital bed, 8.6–23 (17) per 1,000 inpatient-days, and 0.13–0.41 (0.25) per newly admission in 2011, almost constantly increased during the study period in all hospitals. Proportions of blood specimens to all materials for microbiological cultures also increased up to 15–30% (20%) in 2011. In contrast, it was not until the latter half of the study period that solitary submission, accounting for 26–56% (35%) in 2011, decreased. Positive blood cultures were between 11 and 28% through the study period. Coagulase-negative staphylococci accounted for approximately one fourth of recovered organisms in 2006 and 2011.<br><b>Conclusion: </b>Frequency and multiplicity of blood culture submission markedly increased in hospitals in the Minami-Ibaraki Area of Japan.