Better Antibiotic Prescribing Means Less Community-Associated Clostridium difficile

The Division of Healthcare Quality Promotion at the Centers for Disease Control and Prevention (CDC) recently published a study based on 2011 active population data, along with laboratory-based surveillance data, to determine the impact of outpatient antibiotic use on community-associated Clostridium difficile infection (CA-CDI).¹ The results are a wakeup call for primary care providers.

Healthcare providers prescribed more than 5.5 million courses of oral antibiotics to a population that included adults from 33 counties in 9 states. Laboratory-based surveillance identified 4682 adults with CA-CDI. Using regression modeling, the CDC researchers estimate that reducing antibiotic prescription by 10% would reduce CA-CDI by 17%.¹

“This is a good study from a good group at the CDC. The strength of the study is its pharmacoepidemiologic data, prescription data along with laboratory testing data, not just clinical diagnosis,” says Steven Gordon, MD, chairman of infectious diseases at the Cleveland Clinic.

Key Findings of the Study

The key findings of the study should be considered against previous studies that show continued inappropriate use of antibiotics, which is the main cause of CA-CDI and pseudomembranous colitis outside the hospital setting. For example, although only 10% of cases of acute pharyngitis respond to antibiotics, approximately 60% of patients receive a prescription for an antibiotic.¹

“We can’t tell from this study which antibiotics were [appropriately prescribed], but we know that 75% of antibiotic prescriptions for upper respiratory infections and sinusitis are not needed,” says Dr Gordon.

Some of the key findings of the study include:

• 39% of the subjects identified with CA-CDI were age 65 and older; Female patients and older adults were more likely to get a prescription for an antibiotic than male patients and younger adults; and
• Reducing use of oral penicillin and amoxicillin/clavulanic acid would result in the greatest decline in cases of CA-CDI.¹

“This was a very valid study that gives us a much-needed big-picture view,” says Stuart Johnson, MD, professor of infectious disease at the Stritch School of Medicine of Loyola University. “In the hospital setting, we worry about CDI from fluoroquinolones and clindamycin. In fact, pseudomembranous colitis used to be called clindamycin colitis. It is interesting that penicillin and Augmentin are the big players out in the community setting.”

About CA-CDI

“There may be up to 500,000 cases of CDI every year, and it causes about 29,000 deaths, so it is not an insignificant disease,” says Dr Johnson.  According to the CDC, approximately 32% of CDI is CA-CDI.¹

Most cases of pseudomembranous colitis caused by CDI occur in the hospital, and the infection may be passed from person to person. In the community setting, pseudomembranous colitis is almost always due directly to antibiotic use. “Patient-to-patient transmission in the community is very rare,” says Dr Johnson.

“Symptoms of pseudomembranous colitis include watery stool, cramps, and fever. There is usually not any blood in the stool. Patients describe it as the ‘worst diarrhea ever,’” says Dr Johnson.

Mild cases of pseudomembranous colitis are treated by discontinuing use of the antibiotic and managing the diarrhea with supportive care. Moderate to severe cases require treatment with medication. “According to the latest Infectious Disease[s] Society guidelines, oral vancomycin for 10 to 14 days is probably the best treatment. It is important to know that treatment may not be a ‘one and done.’ CDI has about a 25% recurrence rate,” says Dr Johnson.

“Oral vancomycin, metronidazole, and probiotics may all play a role in treatment. A new drug called fidaxomicin may reduce recurrence. In the future, there may be a place for a vaccine and for fecal transplant therapy. The good news is that we have not run into any significant drug resistance yet,” says Dr Gordon.

CDI can be diagnosed with immunoassay of toxins in a stool sample, but the best test is probably polymerase chain reaction (PCR) assay. “The upside and the downside of PCR is that it is very sensitive. You can detect more [cases of] C diff, but they may not be pathogenic,” says Dr Johnson.

Bottom Line for Primary Care

In the community setting, common antibiotics are the main cause of CDI. Pseudomembranous colitis caused by CDI is associated with significant morbidity and mortality. A modest reduction in antibiotics can have a substantial impact on CA-CDI prevention.  “Clinicians need to be more mindful of appropriate diagnosis and treatment. Patient expectations also need to change. You don’t need a prescription for every cold and fever,” says Dr Gordon.

Medically reviewed by Pat F. Bass III, MD, MS, MPH.

References

1.     Dantes R, Mu Y, Hicks LA, et  al. Association between outpatient antibiotic prescribing practices and community-associated Clostridium difficile infection. Forum Infect Dis. 2015; 11 Aug [Epub ahead of print].