Mixed Infection in Adult Post-neurosurgical Bacterial Meningitis: a Hospital-based Study

Background: Post-neurosurgical (post-NS) adult bacterial meningitis (ABM) with mixed infection is rarely examined solely in the literature.

Methods: The clinical features and laboratory data of post-NS ABM patients with mixed infection were included for analysis.

Results: Totally 170 post-NS ABM cases were identified and 18 (11 men and 7 women, aged 20-77 years, median = 57.5) of them had a mixed infection. A total of 45 bacterial strains including 34 Gram-negative [Gm(-)] strains and 11 Gram-positive [Gm(+)] strains were isolated. Of the implicated pathogens, Escherichia coli, Acinetobacter, Pseudomonas, and Klebsiella spp. were the common Gm(-) strains, while staphylococcal, streptococcal, and enterococcal strains were the common Gm(+) strains. Compared with the post-NS ABM cases with monomicrobial infection, those with mixed infection had a lower cerebrospinal fluid (CSF) white blood cell count. The mortality rate of post-NS ABM cases was 33.3% (6/18) without significant clinical and laboratory difference between the fatal and non-fatal groups.

Conclusion: Mixed infection is not uncommon in post-NS ABM (10.6%, 18/170), and its mortality rate is high. Seventy-six percent of the implicated bacterial pathogens belonged to Gm(-) strains, while the other 24% were Gm(+) strains. The clinical and laboratory features of ABM with mixed infection are not unique; its diagnosis can only be confirmed by a positive CSF culture.