Study links dental antibiotics to C diff cases

Antibiotics prescribed by dentists could be contributing to rising cases of Clostridium difficile, according to new research released today at IDWeek 2017.

In a study conducted in Minnesota from 2009 through 2015, researchers from the Minnesota Department of Health (MDH) found that 15% of the patients diagnosed with community-associated C difficile infection (CA CDI) had been prescribed antibiotics for a dental procedure. And the authors of the study question how many of the prescriptions were necessary.

"Many of these prescriptions may not be meeting current prescribing guidelines," lead author and MDH epidemiologist Stacy Holzbauer, DVM, MPH, told reporters. "All prescribers, including dentists, should examine prescribing behavior for appropriateness."

CDI causes inflammation of the colon and severe, sometimes deadly diarrhea. The leading cause of healthcare-associated diarrhea and one of the most common healthcare-associated infections in the United States, CDI was responsible for nearly half a million infections and was associated with approximately 29,000 deaths in 2011, according to the Centers for Disease Control and Prevention (CDC). Cases of CDI most frequently occur in older patients who are taking antibiotics for other infections. The antibiotics disrupt the normal gut flora, wiping out both good and bad bacteria and allowing C difficile, a common environmental bacterium, to flourish in the intestinal tract.

Disconnect between medical and dental care

In the study, the MDH researchers, who perform regular surveillance for CDI as part of the CDC's Emerging Infections Program, interviewed 1,626 people from five Minnesota counties who had been diagnosed with CA CDI from 2009 through 2015. The cases were defined as CA CDI if the patients had not had an overnight stay in a hospital in the previous 12 weeks. Holzbauer said the majority of CDI cases in Minnesota occur outside the hospital and are driven by antibiotic use in community or outpatient settings.

Of the 1,626 patients, 926 (57%) had been prescribed an antibiotic, and 136 of those patients (15%) had been prescribed an antibiotic by their dentist. The patients who had received an antibiotic for a dental procedure were older than those prescribed antibiotics for other indications (57 years vs. 45 years) and were more likely to be prescribed clindamycin (50% vs. 10%), an antibiotic that causes diarrhea and has been associated with a higher risk of CDI.

The researchers also noted, however, that among the patients who had taken antibiotics for a dental procedure, more than a third (34%) had no mention of antibiotics in their medical chart. That finding, Holzbauer said, highlights a disconnect between dental care and medical care; many patients aren't telling their doctors about drugs they've been prescribed for dental care, and dentists may not be warning patients about the potential side effects of antibiotic use.

"Better communication is needed between patients, dentists, and medical providers," Holzbauer said. Patients should be sure to tell their primary care provider about any medications they are taking for dental reasons, and doctors should ask patients about dental visits and medication, and dentists should counsel patients about the risks of antibiotics.

Inappropriate antibiotic use in dentistry

According to the most recent estimates, dentists are responsible for roughly 10% of outpatient antibiotic prescriptions, writing more than 24.5 million prescriptions a year. Dentists most often prescribe antibiotics to treat oral infections caused by tooth abscesses, or prescribe them prophylactically to prevent infections in patients with heart conditions and artificial joints. But updated guidelines from the American Heart Association and American Dental Association (ADA) recommend prophylactic antibiotics only in a small number of patients with heart conditions, and not at all in patients with artificial joints.

In their interviews with a subset of the patients and reviews of their medical records, the MDH researchers found that nearly 10% didn't meet current ADA guidelines for receiving prophylactic antibiotics. In addition, Holzbauer added, antibiotics may not be the best treatment for oral infections, either. She noted that under current recommendations, antibiotics aren't warranted for a tooth abscess in healthy individuals unless there are signs of systemic infection. Roughly 43% of the patients had received an antibiotic for an oral infection.

The website of the ADA says the organization supports responsible use of antibiotics to minimize the risk of adverse effects like CDI and the development of drug-resistant bacteria. But when the MDH surveyed Minnesota dentists in 2015, they found that 36% prescribed antibiotics in situations generally not recommended by the ADA. In addition, fewer than half of the respondents said concerns about adverse effects influenced their prescribing.

Holzbauer said she has shared findings of the study with the Minnesota Dental Association, and that they are looking at ways to raise awareness of the issue and work with dentists to discuss barriers to appropriate prescribing. One of the problems is that while dentists are aware that CDI is a risk of antibiotic use, they aren't informed when their patients develop diarrhea and have to go to the doctor.  

"Dentists need to be included in antibiotic stewardship programs," Holzbauer said. "They've often been overlooked, and it's absolutely critical that they are included to improve prescribing."

Ebbing Lautenbach, MD, MPH, a professor of medicine at the University of Pennsylvania Perelman School of Medicine, said the research is an important advance in the field, given the toll and costs of CDI. "The primary driver of Clostridium difficile is antibiotic use, and so the more we understand about how antibiotics are used, in which settings they are used, and how often they are used appropriately versus inappropriately, is incredibly important."

See also:

Oct 6 IDWeek2017 abstract

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