We report a case of serious nosocomial meningitis due to a multidrug-resistant Acinetobacter baumannii in a 23-year-old woman who had a posterior fossa craniotomy with upper cervical laminectomy for excision of a meningioma at the level of foramen magnum. Post-operatively, she had neck pain with continuous fever and deterioration in the level of consciousness and convulsions. The CSF was turbid and had neutrophil pleocytosis. A multidrug-resistant Acinetobacter baumannii was isolated from the blood and CSF. The patient failed high doses of imipenem, ciprofloxacin and systemic colistin but responded well to intraventricular injections of colistin 125,000 units twice daily for 3 weeks. No apparent side effects were noticed. We have reviewed other similar cases reported in the literature.