New research indicates that antibiotics used to treat patients with infections could be linked to a disruption in brain function, called delirium, and to other brain problems.
Delirium causes temporary confusion that may be accompanied by hallucinations and agitation. Although medications are often the culprit, antibiotics are not necessarily the first medications doctors suspect.
Because people who have delirium are more likely to suffer complications, such as falls, and to be discharged to recover at nursing homes, rather than their own homes, it is important to understand its underlying causes, says lead author Dr. Shamik Bhattacharyya, a neurologist at Brigham and Women’s Hospital in Boston and an instructor at Harvard Medical School.
The research, published in a recent online issue of Neurology, reviewed case reports of 391 patients from a 70 year period who were given antibiotics and later developed delirium and other brain problems. A total of 54 different antibiotics from 12 different classes were involved including commonly used antibiotics, such as sulfonamides and ciprofloxacin (Cipro), and intravenous antibiotics such as cefepime and penicillin.
Patients exhibited a wide variety of symptoms. About 47 percent suffered delusions or hallucinations, 14 percent had seizures, 15 percent had involuntary muscle twitching and 5 percent had loss of control of body movements. In addition, EEG tests, which detect electrical activity in the brain, were abnormal in 70 percent of the cases. Twenty-five percent of the patients suffered kidney failure.
The researchers identified three types of delirium and other brain problems:
- Type 1 was characterized by seizures and most often associated with penicillin and cephalosporins.
- Type 2 was marked by symptoms of psychosis and associated with procaine penicillin, sulfonamides, fluoroquinolones and macrolides. Symptoms associated with both Type 1 and Type 2 issues appeared within days of treatment with the antibiotics and likewise subsided within days after the treatment was stopped.
- Type 3 was characterized by abnormal brain scans, impaired muscle coordination and other signs of brain dysfunction and was only associated with the drug metronidazole. Symptoms did not appear for weeks and took longer to go away once the antibiotic was stopped.
Researchers noted that all the patients whose cases were reviewed were being treated for an active infection, and the infection itself could possibly have been the cause of their brain problems.
“This study is very helpful in identifying another potential etiology for encephalopathy in the hospitalized patient,” says Dr. John Webb, a neurologist with St. Elizabeth Physicians. “Obviously, given the small scope of the underlying study, additional research needs to continue. However, since delirium affects such a large number of hospitalized patients, research into this area will remain significant.”
More than 262 million courses of antibiotics are prescribed each year in the United States, according to the U.S. Centers for Disease Control and Prevention. This equates to more than five antibiotic prescriptions written each year for every six people in the United States.
