Background
In the Middle East, some evidence suggests marked declines in cases of H. influenzae type b infection where conjugate vaccines were introduced. This study examined the causative agents of bacterial meningitis in Saudi Arabia over time in both children and adults.
Material and Method
From January 1993 to December 2005 there was a total 179 cases of meningitis, of which 63 (35.2%) were bacterial meningitis, 37 (20.7%) partially treated, and 79 (44.1%) which were considered viral in origin.
Results
The annual incidence rates of bacterial meningitis were 0.48-2.8 per 100,000 population, with an overall insignificant decline over the study period (P=0.8). There were 37 males and 26 females (ratio: 1.4:1) with an age range of <1 month to 72 years and a median age of 2 years. Of the total number of patients, 22.2% (n=14) were 1-23 months and 39.7% (n=25) were 2-18 years of age. The causative organisms were Streptococcus pneumoniae (35%, n=22), Haemophilus influenzae type b (22.2%, n=14), Neisseria meningitides (15.9%, n=10), Group B streptococci (7.9%, n=5), and 19% (n=12) were other organisms. Of H. influenzae type b cases, 57% (n=8) were in children one year of age and 78.6% (n=11) were in the years 1993-1999. The rates of H. influenzae meningitis cases in the periods of 1993-1999 and 2000-2005 were 4.2 and 1.2 per 100,000 population, respectively.
Conclusions
There was a drop in the number of cases of H. influenzae type b, but it was not statistically significant, and might be related to the small sample size.

Keywords: Saudi Arabia - epidemiology, Streptococcus pneumoniae - isolation & purification, Neisseria meningitidis - isolation & purification, Meningitis, Bacterial - etiology, Incidence, Hospitals, Haemophilus influenzae - isolation & purification, Community-Acquired Infections - microbiology, Child, Preschool, Child, Age Distribution, Adolescent