Delayed etiologic diagnosis of meningitis in an extremely low birth weight newborn

Bacteroides fragilis meningitis in a Saudi infant: case report and literature review

Background

Anaerobic meningitis is mainly caused by Bacteroides fragilis and it is rarely detected in children. Few cases have been reported and there is usually an underlying cause. The timing of early recognition is crucial because any delay in the diagnosis and initiation of appropriate antimicrobial therapy has a devastating outcome. Only 14 cases have been reported in 50 years. To the best of our knowledge, the present case is the first to be reported in Saudi Arabia with no underlying etiology.

Case presentation

We describe a 35-day-old male infant with culture-negative pyogenic meningitis who did not show satisfactory response to the empirical antibiotics, consequently, he developed severe subdural/epidural empyema and ventriculitis. When the drained empyema was cultured anaerobically, B. fragilis was detected and the patient improved after treatment with metronidazole combined with adjuvant surgical drainage of the empyema, and he finally had hydrocephalus. No underlying etiology was found to explain his infection.

Conclusion

B. fragilis is an uncommon cause of meningitis that requires a high index of clinical suspicion. Any pyogenic cerebrospinal fluid with negative culture should draw the attention of physicians to an unusual organisms such as anaerobes because early identification and initiation of appropriate antimicrobials can prevent long-term morbidity and mortality.

Routine testing for anaerobic bacteria in cerebrospinal fluid cultures improves recovery of clinically significant pathogens

In North America, the widespread use of vaccines targeting Haemophilus influenzae type b and Streptococcus pneumoniae have dramatically altered the epidemiology of bacterial meningitis, while the methodology for culturing cerebrospinal fluid (CSF) specimens has remained largely unchanged. The aims of this study were 2-fold: to document the current epidemiology of bacterial meningitis at a tertiary care medical center and to assess the clinical utility of routinely querying for anaerobes in CSF cultures. To that end, we assessed CSF cultures submitted over a 2-year period. A brucella blood agar (BBA) plate, incubated anaerobically for 5 days, was included in the culture procedure for all CSF specimens during the second year of evaluation. In the pre- and postimplementation years, 2,353 and 2,302 CSF specimens were cultured, with 49 and 99 patients having positive culture results, respectively. The clinical and laboratory data for patients with positive cultures were reviewed. Anaerobic bacteria were isolated in the CSF samples from 33 patients post-BBA compared to two patients pre-BBA (P = 0.01). The anaerobic isolates included Bacteroides thetaiotaomicron (n = 1), Propionibacterium species (n = 15), and Propionibacterium acnes (n = 19) isolates; all of these isolates were recovered on the BBA. Eight of the 35 patients from whom anaerobic organisms were isolated received antimicrobial therapy. Although six of these patients had central nervous system hardware, two patients did not have a history of a neurosurgical procedure and had community-acquired anaerobic bacterial meningitis. This study demonstrates that the simple addition of an anaerobically incubated BBA to the culture of CSF specimens enhances the recovery of clinically significant anaerobic pathogens.