Successful treatment of Acinetobacter meningitis with intrathecal polymyxin E

linezolid 600 mg twice daily. At that time the patient was also receiving venlafaxine 150 mg nocte for depression. Twenty days after commencing the oral antibiotic regimen the patient was noted to be confused and disorientated, with disturbance of his sleep–wake cycle, and was intermittently aggressive. A computed tomography scan of the brain did not reveal any significant abnormality, serum biochemistry was normal, full blood examination (FBE) showed normal white cell count and there was no clinical evidence of sepsis. His vital signs were within the normal range and clinical examination did not reveal a specific reason for his altered mental status. Four days later the patient became drowsy and was transferred from the rehabilitation centre to an acute hospital. There he was found to have a reduced level of consciousness and fever of 37.68C. He had widespread increased tone, generalized myoclonic jerks and down-going plantar reflexes. FBE and electrolytes did not show any significant abnormality and creatinine kinase was within the normal range. A drug reaction was suspected; linezolid and ven-lafaxine were stopped. Within 2 days the patient had recovered to his usual level of mental functioning. The most likely diagnosis was serotonin syndrome due to the interaction between line-zolid and venlafaxine. Serotonin syndrome is caused by excessive central nervous system and peripheral serotonergic activity, predominantly 5HT-1a (5-hydroxytryptamine). 1 This is usually due to drug interactions between agents that promote release of serotonin, or inhibit the reuptake or metabolism of serotonin in the intersynap-tic space. Onset may be acute or delayed after instigation of offending agents. The syndrome manifests as altered mental status , including agitation, confusion and coma, neuromuscular hyperactivity (restlessness, myoclonus, hyperreflexia, tremors), and autonomic dysfunction. 1 It may be clinically confused with neuroleptic malignant syndrome (NMS), although resolution is generally faster, creatinine kinase levels are only minimally raised in proportion to the degree of rigidity and the 'lead-pipe' rigidity seen in NMS is absent. The diagnosis is based on clinical signs and symptoms and an appropriate drug history. 1 Treatment is symptomatic, although the use of serotonin-receptor antagonists may speed resolution. Cyproheptadine is a drug with 5HT-1a and 5HT-2 receptor blocking activity, and may be used. 1 Linezolid is the first member of the synthetic oxazolidinone family of antimicrobials to be used in clinical practice. This group of drugs was originally developed as monoamine-oxidase inhibitors for the treatment of depression, but was subsequently noted to have …