GATIFLOXACIN‐INDUCED DELIRIUM AND PSYCHOSIS IN AN ELDERLY DEMENTED WOMAN

To the Editor: Fluoroquinolone antibiotics are being used with increasing frequency. We present a case of gatifloxacin-induced delirium and psychosis. Ms. G, an 89-year-old woman, was admitted with increased falls and confusion. She was noted to have pneumonia on chest x-ray and was started on gatifloxacin 400 mg orally every other day for a total of eight doses. (Her baseline creatinine was approximately 130 μmol/L.) Computed tomography of her head revealed no acute processes. Her other medications included nifedipine, enteric-coated acetylsalicylic acid, latanoprost eye drops, and donepezil. She had seen a psychiatrist 1.5 months earlier, who found her to have mild cognitive impairment. (Her Folstein Mini-Mental State Examination (MMSE) score at that time was 26/30.) Two days after initiation of gatifloxacin, her MMSE score was noted to be 17 of 29. She was prescribed risperidone 0.5 mg daily 5 days after gatifloxacin treatment began, which was then titrated up to 2 mg daily. On Day 6 of antibiotic treatment, she was noted to be throwing items at staff and was delusional. Three days after the antibiotic course, she was noted to be concerned and agitated about a fire at a local hotel (which did not occur), and at 4 days after the antibiotic treatment had ended, she was convinced that she was on the street looking for an acquaintance. Throughout these episodes, her laboratory values did not explain her behavior. Psychiatry was consulted when such delusional themes persisted 7 days after the antibiotic treatment had ended. On examination, her MMSE score was 23 of 30, and there was no evidence of delusions. The recommendations were that the risperidone be discontinued and that the patient be observed for lingering effects of the gatifloxacin. Two days later, the patient was noted to no longer speak of delusions to the treating team. Because of change in medical responsibility and recurrence of sepsis, the patient was inadvertently given gatifloxacin. After an initial intravenous dose, she received six daily oral doses of 400 mg and was noted to be hallucinating and paranoid as early as the evening of the first dose. The paranoia resolved with antibiotic cessation. To our knowledge, there is only one previously reported case of gatifloxacin-induced psychosis1 and one case of gatifloxacin-induced delirium.2 Fluoroquinolone antibiotics are known to have significant central nervous system effects, including psychosis.3, 4 With their increased use for urinary and respiratory illness, it is important for physicians to be aware of the potential for antibiotic-related psychosis. Financial Disclosures: None. Author Contributions: Satyendra Satyanarayana and Barry Campbell participated in the clinical work described and participated equally in the preparation of the manuscript. Sponsor's Role: There was no sponsor for this report.

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