Post neurosurgery Gram-negative bacillary meningitis

The findings of a retrospective analysis of 20 patients who developed Gram-negative bacillary meningitis (GNBM) following neurosurgery are reported. The predisposing causes included surgery for skull fracture or cerebral contusion (9 patients), neoplasm (6) and vascular disease (2). Nine of the patients (45 per cent) had a cerebrospinal fluid (CSF) leak from a fistula. The organisms isolated, which included Pseudomonas aeruginosa (6), Klebsiella spp. (5) and Escherichia coli (4), had, in 75 per cent of cases, been isolated from other sites prior to the onset of GNBM. Initial diagnosis was achieved by Gram-stain of CSF in 15 of 19 cases (78 per cent). Culture of lumbar CSF was positive in 19 of the patients (95 per cent) and concommittant ventriculitis was confirmed by positive culture of ventricular CSF in 10 of 11 cases (91 per cent) from whom it was obtained. The overall mortality was 80 per cent, 11 patients dying of causes directly related to GNBM. Eradication of the infecting organism from CSF was achieved in 79 per cent of patients receiving intraventricular aminoglycoside therapy, but in only 40 per cent of those receiving intralumbar therapy. Deaths in the latter group were associated with ventriculitis whereas those in patients receiving intraventricular therapy resulted from intracranial abscess formation. These findings, plus the observation of chloramphenicol resistance in 80 per cent of the isolates, suggest that systemic and intraventricular aminoglycoside administration is indicated in patients with post-neurosurgical GNBM.