Bacterial Load in Spinal Fluid Could Predict Pneumococcal Meningitis Outcomes


High bacterial load in cerebrospinal fluid was associated with unfavorable outcomes and death for adults with pneumococcal meningitis.

High bacterial load in cerebrospinal fluid (CSF) can help predict complications and unfavorable outcomes for adults with pneumococcal meningitis, according to results of a study published in Clinical Microbiology and Infection. In the study, investigators aimed to determine the association between CSF pneumococcal load and the outcomes for adults with community-acquired meningitis.

According to the study authors, community-acquired pneumococcal (CAP) meningitis causes high morbidity and mortality rates, despite the implementation of the conjugate vaccines. Further, they stated that experimental models showed Toll-like receptor-deficiency has been “associated with an increased bacterial load, higher levels of TNF-α, and increase disease severity.” Investigators of the study hoped to determine the prognostic accuracy of CSF bacterial load and the interaction between CSF pneumococcal load and C5a concentrations for patients with CAP meningitis in a nationwide study in the Netherlands.

Patients aged 16 years and older with community-acquired bacterial meningitis are included in an ongoing nationwide prospective cohort study called MeninGene, which is being conducted to identify host and pathogen factors that are associated with the risk and outcomes of bacterial meningitis, according to the study authors. Data on baseline characteristics, clinical course, treatment, and neurological outcomes are collected, with neurological examinations being done at discharge using the Glasgow Outcome Scale (GOS) with scores ranging from 1 (death) to 5 (mild or no disability). CSF samples were collected between August 2020 and November 2022, and patients were included if the culture was positive for Streptococcus pneumoniae or if the CSF had 1 finding predictive of bacterial meningitis, according to the study authors.

In the study, investigators included 221 adult episodes with pneumococcal meningitis, with 152 episodes having leftover CSF in 152 patients being included. According to the authors, the median age of the patients was 61 years old and 45% were female. Approximately 49% presented with otitis or sinusitis and 9% received antibiotics pre-admission to the hospital. Approximately 39% were immunocompromised, defined as history of diabetes, active cancer, splenectomy, HIV, alcoholism, or use of immunosuppressive drugs, according to the study authors. Headache occurred in 84% of patients, neck stiffness in 69%, fever in 69%, and altered mental state in 76%.

Key Takeaways

  1. Adults with high bacterial load in their cerebrospinal fluid (CSF) were more likely to experience complications, death, and other unfavorable outcomes from pneumococcal meningitis compared to those with lower bacterial load.
  2. This study highlights the high rate of complications in adults with pneumococcal meningitis, with nearly 40% experiencing issues like circulatory shock, respiratory failure, and neurological deficits.
  3. Even when considering other factors like age and immune function, CSF bacterial load emerged as the strongest predictor of unfavorable outcomes in this study.

The study authors reported unfavorable outcomes in 37% of patients and 15% died. Of the survivors (129 patients), 35% had focal neurological defects upon discharge. Complications occurred in a high number of individuals, according to the study authors, which included circulatory shock, respiratory failure, cerebrovascular complications, and focal neurological deficits.

Investigators found that high bacterial load was associated with the development of circulatory shock and cerebrovascular complications. It was also associated with unfavorable outcomes and death. The study results showed that those with unfavorable outcomes had a 14-fold higher bacterial load compared to those with favorable outcomes, according to the study authors. Additionally, they found that non-survivors had a 45-fold higher bacterial load when compared with survivors.

Furthermore, in a logistic regression model that included age, immunocompromised state, presence of extrameningeal infection focus, admission GOS score, and CSF C5a concentration, the results were still robust, according to the study authors. Investigators also said that CSF bacterial load was the strongest predictor for unfavorable outcomes in the multivariate analysis.


Chekrouni N, van Soest TM, da Cruz Campos AC, Brouwer MC, Beek DV. Bacterial load in cerebrospinal fluid predicts unfavourable outcome in pneumococcal meningitis: a prospective nationwide cohort study. Clin Microbiol Infect. 2024. doi:10.1016/j.cmi.2024.03.012

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