Linezolid-Induced Near-Fatal Serotonin Syndrome During Escitalopram Therapy: Case Report and Review of Literature
A 65-year-old elderly female, from urban and middle socioeconomic background, presented with history suggestive of depressed mood, middle and late insomnia, anorexia, lethargy, reduced interest in pleasurable activities since 1 year. She was diagnosed as depressive disorder as per ICD-10 diagnostic criteria.[] She had no prior medical history of hypertension, diabetes, or any drug intake. Escitalopram (5 mg/day) and clonazepam (0.25 mg/day) therapy showed partial improvement, fortnight later. Escitalopram was increased to 10 mg/day, while clonazepam was discontinued due to drowsiness, a month later. Patient had full remission of depressive symptoms with escitalopram (10 mg/day), 2 months later. Compliance with medications was ensured and supervised by her apprehensive spouse.\nPatient presented with acute onset high-grade fever, cough with greenish-yellow expectoration, breathlessness, and asthenia of a week's duration following recent travel. She had received antipyretics, mucolytics, expectorants, antibiotics (amoxicillin and clavulanate) for 5 days from medical practitioner but found no respite. Later, she was referred to physician and hospitalized. On admission, she had 101°F temperature, pulse rate of 126/min, and blood pressure (BP) of 136/88 mm Hg. Her general physical and systemic examination revealed no other abnormal findings, except for bilateral scattered fine crepitations and reduced bilateral air entry in lower respiratory areas. A complete blood count revealed leukocytosis (15640/cmm) and neutrophilia (80%). Her blood glucose (105 mg/dL), blood urea (25 mg/dL), and serum creatinine (1.0 mg/dL) were within normal limits. Electrocardiograph revealed no abnormalities. Her chest roentgenogram showed bilateral patchy consolidation suggestive of pneumonitis. Patient was treated with intravenous linezolid (600 mg twice daily), antipyretics, bronchodilators (etophylline), expectorants (guaiphenesin), mucolytics (ambroxol), and chest physiotherapy.\nWithin the first 24 hours of antibiotic treatment, the patient had a rapid clinical deterioration with restlessness, diaphoresis, tremor, shivering, myoclonus, diarrhoea, exaggerated deep tendon reflexes, hypoxia (SPO2-80% with 6-8 L of oxygen) and high fever (103°F), along with mental status changes such as disorientation, confusion, and hallucinatory behavior. However, in view of neurological symptoms, cranial computerized tomography and lumbar puncture for the exclusion of central nervous system (CNS) infection were performed but were unremarkable. The patient was intubated due to severe respiratory difficulties and transferred to the intensive care unit. Psychiatrist consultation was sought for delirium. Detailed history and sequence of emergence of events (including history of depression and escitalopram treatment from caregivers) were observed and SS was suspected. Linezolid and escitalopram were discontinued, and cyproheptadine (4 mg thrice daily) via the nasogastric tube was initiated. Pneumonitis was treated with intravenous cephalosporin (cefotaxime; 2 g twice daily) and aminoglycoside (amikacin; 500 mg twice daily) antibiotics. Patient showed the first signs of improvement few hours later. Withdrawal of sedation and ventilator weaning took place 48 hours later. Patient gradually regained consciousness and orientation to person, location, and time. At discharge, vital parameters were stable with pulse of 86 bpm and BP of 130/80 mm Hg. Patient was discharged with escitalopram 10 mg/day.