SAN DIEGO – Antibiotic prescriptions written by dentists make a substantial but largely unrecognized contribution to the risk of community-acquired Clostridium difficile (CA-CDI) infections, according to results of a public health initiative that was presented at an annual scientific meeting on infectious diseases.

When nearly 1,000 cases of CA-CDI suspected of being the result of antibiotic exposure were evaluated, it was found that 15% of the prescriptions were written by dentists, often for indications that are counter to current guidelines, reported Maria Bye, MPH, an officer in the Infectious Disease Epidemiology, Prevention, and Control Division of the Minnesota Department of Health, St. Paul.

“Everyone plays a role in antibiotic stewardship. Dentists should be following the guidelines for antibiotic prophylaxis and counsel patients about the risk and symptoms of C. diff and other complications,” Ms. Bye said. She said that up until now “dentists have largely been left out of the conversation.”

In another finding from this study relevant to infection control, a substantial proportion of dentist-prescribed antibiotics associated with CA-CDI were not in the medical record. Rather, they were discovered in interviews conducted to isolate risk factors. “This is concerning since clinicians unaware of these exposures will not think about CA-CDI or other complications of antibiotic use, possibly delaying therapy,” Ms. Bye said.

The importance of dental antibiotic prescriptions in CA-CDI was identified in an ongoing infectious disease program managed by the Minnesota Department of Health in collaboration with the Centers for Disease Control and Prevention. In the years 2009-2015, medical records and interviews were conducted to identify risk factors in 1,626 confirmed cases of CA-CDI in five Minnesota counties. All cases were among patients without an overnight stay in a health care facility in the previous 12 weeks, which was an exclusion criterion.

After the review of medical records and patient interviews, 926 (57%) of the CA-CDI cases were deemed likely to be related to antibiotic exposure. Of these antibiotic exposures, 136 (15%) were from prescriptions written by dentists, a figure reached only when patients were interviewed. According to Ms. Bye, 34% of the antibiotics prescribed by dentists were not in the medical record.

There were also notable differences in antibiotic exposures stemming from dentist prescriptions relative to prescriptions from other sources. Perhaps most significantly, dental-related antibiotic prescriptions were far more likely to be for clindamycin (50% vs. 10%; P less than .001), which is commonly associated with increased risk of C. difficile, according to Ms. Bye. Fluoroquinolones (6% vs. 19%; P less than .001) and cephalosporins (7% vs. 30%; P less than .001) were significantly less likely to be prescribed by dentists. Patients who developed CA-CDI associated with antibiotics prescribed by dentists were also significantly older than were those receiving antibiotics from another source (mean age 57 years vs. 45 years; P less than .001).

For the first years of this analysis, information on the indication for dentist-prescribed antibiotics was not collected, but these data were collected beginning in 2015. In the data collected so far, a substantial proportion of prescriptions were written for prophylaxis against systemic infections, including prevention of endocarditis or infection of prosthetic joints. However, few of these prescriptions were indicated.

“The American Dental Association stated that antibiotic prophylaxis is not generally recommended in patients with prosthetic joints,” said Ms. Bye, noting that this is consistent with similar statements issued by the American Academy of Orthopedic Surgery. In 2007, the American Heart Association narrowed its recommendations for prophylactic antibiotics to patients at the highest risk of adverse consequences from endocarditis.

Of the four patients who received prophylactic antibiotics from their dentists for a cardiovascular or orthopedic indication, only one met current criteria, Ms. Bye reported.

The contribution of antibiotic exposures from dentist prescriptions to CA-CDI should not be surprising, according to Ms. Bye. In the United States, dentists prescribe 10% of all outpatient antibiotics. Although there are many valid indications for these prescriptions, Ms. Bye cited a survey that found that the proportion of dentists familiar with current guidelines and the risks of adverse events produced by antibiotics, including CA-CDI, is less than 50%.

“Dentists need to be included in antibiotic stewardship programs,” she advised. This will include educating dentists about the indications for antibiotic prophylaxis for medical conditions. She also suggested that clinicians should routinely ask patients about whether they have received antibiotics from a dentist so that this information gets into the medical record.

The event was the combined annual meetings of the Infectious Diseases Society of America, the Society for Healthcare Epidemiology of America, the HIV Medicine Association, and the Pediatric Infectious Diseases Society.

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Dentist-prescribed antibiotics implicated in community-acquired C. diff