Epidemiology of meningitis and bacteraemia due to Streptococcus pneumoniae in The Netherlands.

In The Netherlands, accurate data on the epidemiology of pneumococcal meningitis are available through a clinical microbiology laboratory-based national surveillance of cerebrospinal fluid isolates. The Netherlands Reference Laboratory for Bacterial Meningitis receives isolates of about 80% of all meningitis cases and about 40% of bacteraemic cases. The incidence of pneumococcal meningitis has increased slowly from 1.0/100,000 in 1990 to 1.5/100,000 since 1996. The highest age-specific incidence of meningitis was observed in children < 5 y of age (8.2/100,000 in 1999). Of all isolates, 35% were from children < 5 y of age. The number of isolates from non-meningitis patients with bacteraemia increased considerably since the early 1990s, especially among the elderly. The highest incidence was found in 1996, probably owing to a relatively severe winter. During 1995-1999, pneumococcal meningitis in The Netherlands was caused mainly by serotypes 3, 6B, 7F, 9V, 14, 18C, 19F, and 23F. Of the cases in children < 15 y, almost half were caused by serotypes 6B, 14, 18C, and 19F. The serotypes present in the 23-valent polysaccharide and 7-valent conjugate vaccines accounted for 87% and 47% of all meningitis cases, respectively. Pneumococcal resistance to penicillin in The Netherlands is still low, at about 1%. Genotypically, resistant strains belong to many clones. Horizontal transfer of capsular genes occurs among these isolates. In The Netherlands, 45% of cases of pneumococcal meningitis have severe predisposing factors. The case-fatality rate was significantly higher among patients with impaired immunity than among those with a break in the integrity of the dura.