The incidence of postoperative meningitis in neurosurgery: An institutional experience

Introduction : Meningitis is the most dreaded cause of morbidity and mortality in neurosurgical patients. The reported incidence of postoperative meningitis is quite varied 0.5-8%. Material and Methods : The study cohort included all the patients who underwent neurosurgery at the department of neurosurgery, National Institute of Mental Health and Neurological Sciences, Bangalore, India over a period of seven years (2001 - 2007). Patients with culture positive meningitis were included for analysis. The incidence of postoperative meningitis was analyzed depending on the type of surgery performed and the microbiological profile of the organisms, and their sensitivity pattern. Results : Of the 18,092 patients who underwent neurosurgical procedures during the study period, 415 patients developed infection. The overall incidence of meningitis was 2.2%. The incidence of meningitis was high (7.7%) in patients who had a pre-existing infection like post-pyogenic meningitis or tuberculosis hydrocephalus. The procedure mainly performed in this subgroup was shunt. The most common organisms causing meningitis were non-lactose fermenting Gram-negative bacillus followed by Pseudomonas and Klebsiella species. The methicillin-resistant Staphylococcus aureus strains were isolated in 2.6% of the patients. Ninety-one strains were multi-drug resistant, among which four strains were resistant to all antibiotics tested. The overall mortality in patients with meningitis was 5%. Conclusion : Meningitis remains one of the most dreaded complications of neurosurgical procedures and is common in patients with preexisting infection. Gram-negative organisms are the most common causative pathogens of postoperative meningitis.