Pediatric bacterial meningitis in Japan, 2013–2015 – 3–5 years after the wide use of Haemophilus influenzae type b and Streptococcus pneumoniae conjugated vaccines

Background Haemophilus influenzae type b (Hib) vaccine and pneumococcal conjugated vaccine (PCV) have been widely used since 2010 in Japan when both vaccines were supported by the regional governments, and they were covered as routine recommended vaccines in 2013. The incidence of bacterial meningitis due to these organisms decreased in 2011 and 2012, but meningitis due to Streptococcus agalactiae and Escherichia coli remained unchanged. Objectives We planned to confirm whether the incidence also decreased in subsequent years. Methods We analyzed the epidemiological and clinical data for 2013–2015, and compared the information obtained in the previous nationwide survey database and our previous reports. We also investigated the risk factors for disease outcome. Results In the 2013–2015 surveys, 407 patients from 366 hospitals from all prefectures were evaluated. S. agalactiae (33%), Streptococcus pneumoniae (25%), and E. coli (10%) were the main organisms. The total number of patients hospitalized with bacterial meningitis per 1000 admissions decreased from 1.19 in 2009–2010 to 0.37 in 2013–2015 (p < 0.001). The incidence of H. influenzae and S. pneumoniae meningitis significantly decreased from 0.66 in 2009–2010 to 0.01 in 2013–2015, and from 0.30 to 0.09, respectively (p < 0.001). Only 0–2 cases with Neisseria meningitidis were reported each year throughout 2001–2015. The fatality rates for H. influenzae, S. pneumoniae, S. agalactiae, and E. coli in 2013–2015 were 0.0, 4.1, 3.1, and 2.6%, respectively. Risk factors for death and sequelae were consciousness disturbance, convulsion, low CSF glucose, and Staphylococcus sp. as a causative organism (p < 0.01). Conclusions Hib vaccine and PCV have decreased the rate of bacterial meningitis. S. agalactiae has subsequently become the most common cause of bacterial meningitis in Japan.