Post-neurosurgical meningitis; gram negative bacilli vs. gram positive cocci

Post-neurosurgical meningitis is a significant cause of mortality and morbidity. In this study we aimed to compare the differences of clinical, laboratory features and outcomes between the post-neurosurgical meningitis caused by gram-negative bacilli (GNB) and gram-positive cocci (GPC).

Cases of post-neurosurgical meningitis (with positive CSF culture) were included. After classifying patients as GNB and GPC groups, clinical and paraclinical data were compared.

Out of 2667 neurosurgical patients, CSF culture was positive in 45 patients. 25 (54.3%) were GNB, 19 (41.3%) GPC. The most common microorganisms were Klebsiella pneumoniae (n=14, 31.1%), Coagulase negative staphylococcus (n=8, 17.8%), Staphylococcus aureus (n=6, 13.3%), Acinetobacter baumannii (n=4, 8.9%), Pseudomonas aeruginosa (n=2, 4.4%), and Escherichia coli (n=2, 4.4%). There were no correlation between CSF Leakage, Surgical site appearance, presence of drain, Age and GCS between two groups (P=0.11, P=0.28, P=0.06, P=0.86, P=0.11 respectively). The only different laboratory indexes were ESR (86.8 mm/h vs. 59.5 mm/h, P=0.01) and PCT (13.1 ng/ml vs. 0.8 ng/ml, P=0.02) which were higher in GNB cases. 20% (n=5) of patients with GNB meningitis received preoperative corticosteroid, while none of GPC cases received (P=0.03). The median length of hospitalization for GNB and GPC cases was 56 and 44.4 days respectively (P=0.3).

The GNB antibiotic coverage should be designed more carefully in post-neurosurgical meningitis especially in patients with recent corticosteroid therapy and elevated ESR and procalcitonin.