Organic psychosis induced by ofloxacin and metronidazole
Authors: Koul S , Bhan-Kotwal S , Jenkins HS , Carmaciu CD 
Published: May 2014

An 18-year-old black African woman was referred to the on-call medical team by her GP with a history of confusion and stupor. Three weeks before admission she complained of abdominal pain and was treated for urinary tract infection with co-amoxiclav. After 1 week, as her pain persisted, co-amoxiclav was stopped and she was treated for presumed pelvic inflammatory disease with ofloxacin 400 mg twice daily and metronidazole 400 mg three times daily. After 2 days on this combination she started to develop confusion, so her mother stopped the ofloxacin. The next day her GP advised her to also stop the metronidazole. During the next 5 days she became increasingly confused, frightened, almost mute and at times immobile. She was referred urgently to the accident and emergency department from where she was admitted to the medical ward. On examination, apart from a slight temperature which did not persist, her vital signs were normal. The neurological examination was limited because of poor cooperation, but no gross abnormality was noted except for absent plantar reflexes. No abnormality was seen in the cardiovascular, respiratory or abdominal systems. Her initial investigations were: urinalysis showed trace blood and trace nitrates; urea and electrolytes, liver function tests, chest X-ray and computed tomography of the head were all normal, her C-reactive protein (CRP) was < 1 mg/litre (normal range (NR) = 0.8–2.0 mg/litre); haemoglobin was 14.1 g/dl (NR = 11.5–16.5 g/dl); white blood cell count was 3.6×109/litre (NR = 4.0–11.0×109/litre) and platelets were 131 × 109/litre (NR = 130–400×109/litre).

A comprehensive assessment of her mental state soon after admission revealed a completely mute woman, sitting up in bed and looking very frightened. She shed a few tears and the affect was a mixture of anxiety, sadness and confusion. She was able to turn on command towards her mother and aunt and was able to write, on command, one simple word. However, she did not cooperate with the request to nod her head as an alternative to answering questions with a yes or no. Her motor activities ranged from mostly immobile when the psychiatric assessment took place to periods of agitation later on during the admission. Objectively she appeared low in mood. There was no evidence initially to suggest that she was experiencing hallucinations in any modality. After a few days in hospital, she started improving spontaneously. She started to speak to her mother, asking things that initially made little sense. She also felt paranoid when she heard visitorsspeak in the room adjacent to hers. By day four she started to make significant progress. Subsequent investigations were undertaken, with the following results: magnetic resonance imaging of the brain and electroencephalogram were normal, haemoglobin electrophoresis showed that she had the sickle cell trait, syphilis serology was negative, her CD4 count was 720 cells/μl, antinuclear antibodies was negative, and anti-double-stranded DNA and CRP were normal.

Repeat neurological examination after 1 week of admission revealed moderate hyperreflexia bilaterally but flexor plantar responses. Her CRP remained normal. The neurologist felt that an acute encephalitic infection was unlikely but recommended a lumbar puncture to exclude this. However, neither the patient nor her mother consented to lumbar puncture. A viral serology was also done as viral encephalitis was considered as one of the differential diagnoses, but while the first sample had raised immunoglobulin M, a sample sent to a reference laboratory found no immunoglobulin M, suggesting an original false positive result. After 3 weeks on the medical ward she was discharged home. She had improved greatly by then and her speech and movements were more spontaneous, albeit hesitant.

When she was followed up in the psychiatric outpatient department 2 days after her discharge, she complained of feeling anxious and slowed down. She remembered her admission to the medical ward well and felt guilty for letting her family down. She explained that while on the medical ward she had been hearing voices that were terrifying her. On mental state examination she was very cooperative, initially tense but she relaxed later on and managed to smile. Speech was of normal volume but reduced in rate and quantity. There was no formal thought disorder. Her affect appeared initially to be rather flat. There was no active suicidal intent. She described delusions of reference and was convinced that people on the radio were referring to her. She also gave a vague description of persecutory ideas stating that other people were trying to harm her. There was no thought insertion, broadcast or withdrawal, but she mentioned that she was controlled by an external power. She also had been hearing voices outside her head talking about her in the third person and making threatening remarks. There were no visual hallucinations. Cognition was grossly intact and she had insight into the fact that she had been mentally unwell and appeared happy to accept medication.

She was prescribed risperidone 2 mg at night and citalopram 20 mg in the morning. She missed her next outpatient appointment in 8 weeks time and when she did finally attend 3 months after the initial episode, she said that she had been feeling 100% back to her normal self within 4 days of being discharged from the medical ward, despite not taking any of the prescribed medication. She remembered the psychotic episode quite well, but stated that she wanted to forget it. She could not think of any stress whatsoever before developing the symptoms. She remained well at the time of her next appointment 7 months after the initial episode and was subsequently discharged from psychiatric follow up.