Fifteen years of experience with bacterial meningitis

Background, Introduction of Haemophilus influenzae type b (Hib) vaccines ha s dramatically altered the epidemiology of bacterial meningitis in children . The goal of this study was to describe these changes in a pediatric teach ing hospital. Methods. Patient charts at Children's Hospital and Regional Medical Center, Seattle, were identified by diagnosis codes and reviewed retrospectively. The 1981 to 1995 time period was chosen to incorporate three distinct 5-yea r periods: before the use of unconjugated Hib vaccine; between the unconjug ated and conjugate vaccines; and after the conjugate vaccines were availabl e for routine immunization of infants. Results. Bacterial meningitis was identified in 806 cases. In 13 premature infant cases Escherichia coli was most frequently isolated (6 cases). Group B Streptococcus, E. coli and Listeria monocytogenes were the most common p athogens in 87 neonatal cases. The most common pathogens in 706 cases of ch ildhood meningitis were H. influenzae, Streptococcus pneumoniae and Neisser ia meningitidis. H. influenzae was the most com mon pathogen in the first t wo time periods (73 and 69% of childhood cases, respectively), but not so i n the third period (16%). Conclusions. A changing pattern in childhood meningitis was observed during the study period. H. influenzae cases dramatically declined, altering the relative proportions of other pathogens, S. pneumoniae and N. meningitidis. However, the number of cases caused by these latter pathogens remained ste ady.