National database study of trends in bacteraemia aetiology among children and adults in Japan: a longitudinal observational study.

Abstract

Domestic epidemiological studies are needed to ascertain the disease burden of bacteraemia in individual countries. This study aimed to evaluate the domestic trends in paediatric and adult bacteraemia in Japan. Laboratory-based surveillance was used to obtain data from 592 hospitals located throughout Japan. The study was conducted using the results of 827 780 and 3 512 524 blood culture tests obtained from children and adults, respectively, between January 2010 and December 2016. We analysed the temporal trends in specific bacterial species (<i>Staphylococcus aureus</i>, <i>Streptococcus pneumoniae</i>, <i>Streptococcus pyogenes</i>, <i>Streptococcus agalactiae</i>, <i>Escherichia coli</i>, <i>Klebsiella pneumoniae</i>, <i>Salmonella enterica</i>, <i>Haemophilus influenzae</i>, <i>Listeria monocytogenes</i> and <i>Neisseria meningitidis</i>) detected from the blood cultures of children and adults. For children aged ≤2 years, the data were analysed for each year of age. The proportions of bacteraemia-positive results among the patients were also evaluated. The number of bacteraemia-positive samples over the study period was 47,125/827,855 (5.7%) in children and 959,765/3,513,885 (27.3%) in adults. <i>S. pneumoniae</i> was the most frequent cause of bacteraemia in children in 2010. However, after 2011, <i>S. aureus</i> bacteraemia was the most frequent, followed by <i>S. pneumoniae</i> and <i>E. coli. E. coli</i> bacteraemia showed significant increases in both children and adults. In children, <i>S. pneumoniae</i> and <i>H. influenzae</i> bacteraemia decreased from 2010 to 2013. However, <i>S. pneumoniae</i> bacteraemia case numbers stabilised from 2013, whereas <i>H. influenzae</i> bacteraemia cases continued to decrease until 2016. The results suggest that the introduction of the 13-valent pneumococcal conjugate vaccine did not substantially affect disease occurrence. In contrast to the decreasing trends in <i>H. influenzae</i> and <i>S. pneumoniae</i> bacteraemia, <i>S. aureus</i>, <i>E. coli</i> and <i>S. agalactiae</i> bacteraemia showed increasing trends. These findings shed light on recent temporal trends in bacteraemia in both children and adults in Japan.