Hasan M Alshami, Fatemah Alzaghabi, Abdullah Al-Garni, Ibrahim Asiri, Tariq M Alshami
Background Contemporary multicenter data describing adult community-acquired pyogenic bacterial meningitis in Saudi Arabia remain limited. This study characterized the demographic, clinical, microbiological, and in-hospital outcome profile of cases identified across five hospitals in Jeddah. Methods We conducted a multicenter retrospective cohort study using surveillance and hospital records from January 1, 2020, to December 31, 2025. Adults with confirmed or probable community-acquired pyogenic bacterial meningitis were included. Microbiological confirmation was established by culture or cerebrospinal fluid (CSF) polymerase chain reaction (PCR), with PCR applied to culture-negative specimens. Descriptive analyses used variable-specific denominators. Exploratory group comparisons were performed using the Mann-Whitney U test and Fisher exact test. Because of the limited sample, multivariable analyses were conducted using Firth penalized logistic regression with adjustment for age and admission Glasgow Coma Scale (GCS) score as covariates. Results Among 39 candidate records, five pediatric records and five records with a non-community-acquired source were excluded, leaving 29 adults. No eligible adult cases were identified during 2020-2022. The median age was 41 years, and 13 patients (44.8%) were male. All 29 cases (100.0%) were microbiologically confirmed after including cerebrospinal fluid (CSF) polymerase chain reaction (PCR) results, and PCR alone established the etiology in nine culture-negative cases (31.0%). Streptococcus pneumoniae was found in 11 cases (37.9%), Neisseria meningitidis in 10 (34.5%), gram-negative bacilli in six (20.7%), and other confirmed pyogenic bacteria in two (6.9%). Intensive care unit (ICU) admission occurred in 19 of 28 patients (67.9%), and nine of 29 patients died in the hospital (31.0%). The median length of stay was 15 days. Patients who died were older than survivors, and a GCS score of eight or lower was associated with mortality in unadjusted analysis. In the limited mortality model, age and GCS did not independently reach statistical significance. Older age remained associated with ICU admission in the exploratory adjusted model. Conclusions In this cohort, community-acquired pyogenic bacterial meningitis in adults was associated with high critical care requirements and substantial in-hospital mortality. The combined use of CSF culture and PCR identified an etiology in all patients and provided microbiological confirmation for nine culture-negative episodes. These findings support early assessment of clinical severity, routine use of molecular diagnostics in culture-negative specimens, and surveillance strategies that reflect local etiologic patterns.