Introduction
Linezolid is an oxazolidinone antibiotic against Methicillin resistant Staphylococcus aureus (MRSA), Vancomycin-resistant Enterococcus (VRE) and Drug resistant Streptococcus pneumoniae (DRSP) infections. The structure of linezolid is similar to a selective reversible monoamine oxidase inhibitor (MAO-A) toloxatone that used for depression treatment [1].
Regarding this structure–activity relationship similarities between Linezolid and toloxatone, this antibiotic has non-selective MAO-A inhibition properties [2]. Some drugs including SNRIs, TCAs, SSRIs, stimulants and opioid analgesics such as tramadol, meperidine, methadone and dextromethorphan increase serotonin levels and interact with linezolid [3, 4].The use of linezolid with this drugs increase concentrations of serotonin in the central nervous system and result in serotonin syndrome [1].
Serotonin syndrome (SS) is a rare and potentially fatal condition that was first reported by Mitchell [5] and caused by excessive stimulation of serotonin receptor in nervous system. Features of this syndrome include mental status alteration such as delirium, anxiety and confusion, autonomic stimulation for example hyperthermia, tachycardia, tremor, and neuromuscular abnormalities like myoclonus and rigidity [3]. The main cause of serotonin syndrome is drugs that increase the level of serotonin in CNS [6]. Serotonin syndrome can develop less than 24 hours of ingestion certain medication [6, 7].
In searches, we found only one case report has described serotonin syndrome with linezolid and methadone [8]. We describe a case of SS in 60-year-old drug-addict man who admitted to emergency department.