Only 50 percent of patients seeking care for common conditions in doctors’ offices, emergency departments, retail clinics, and urgent care centers receive the antibiotics recommended by medical guidelines, or first-line antibiotics, according to a new study by The Pew Charitable Trusts and the Centers for Disease Control and Prevention (CDC) in the journal Antimicrobial Agents and Chemotherapy.

Researchers examined the appropriateness of antibiotic selection for three common conditions: pharyngitis (sore throat), sinus infections, and suppurative middle ear infections identified by the presence of pus. The study relied on data from the 2014 IBM MarketScan Commercial Database, which captures medical and pharmaceutical claims for people under 65 and their dependents who are covered by employer-sponsored health insurance.

Among the four types of outpatient settings studied, patients receiving care in retail clinics for these conditions were most likely to receive first-line antibiotics (70 percent). These walk-in clinics are typically located within retail businesses such as pharmacies, grocery stores, or convenience stores.

By contrast, providers at emergency departments, urgent care centers, and doctors’ offices prescribed first-line antibiotics at significantly lower levels: 57, 49, and 50 percent, respectively. Taken cumulatively across all settings, only half of patients with these conditions received first-line antibiotics. Children were more likely to be prescribed the recommended first-line antibiotic than adults.

Although patients sometimes need to be treated with non-first-line antibiotics—for example, people with drug allergies or with infections that do not respond to initial treatment—experts estimate that first-line antibiotics should be used in at least 80 percent of visits for the ailments studied. Although retail clinics come closest to this target proportion of first-line prescriptions, providers in all outpatient settings have room to improve.

This study underscores the findings of previous research from Pew and CDC, which found that retail clinics were less likely than other outpatient settings to prescribe unnecessary antibiotics. The new work also aligns with earlier findings that pediatric patients are more likely to receive first-line antibiotics than adults.

Because all antibiotic use accelerates the emergence of resistance, these medications should only be prescribed when necessary. Once a medical professional has determined that an antibiotic is needed, choosing the right one helps protect public health by slowing the emergence of resistance and ensures patient safety by using the antibiotic most likely to treat the patient’s infection—with the fewest side effects.

For example, the most commonly prescribed non-first-line antibiotics for pharyngitis, sinus infections, and suppurative middle ear infections are macrolide-class antibiotics, such as azithromycin. But medical guidelines do not recommend these drugs for treatment of sinus infections and suppurative middle ear infections because macrolide antibiotics are less likely to be effective than the first-line treatments. Additionally, azithromycin and other macrolide antibiotics should only be used for treating pharyngitis if patients are allergic to penicillin or amoxicillin (the first-line antibiotics) because macrolides are less likely to be effective.

Because a large proportion of antibiotics in the U.S. are prescribed in outpatient health care settings, establishing and improving antibiotic stewardship in these facilities is key. Health care stakeholders can take lessons learned from retail clinics and pediatric offices to better understand how to improve prescribing across all outpatient settings. Pew looks forward to continued collaboration with CDC and other interested groups to identify effective approaches to drive improved antibiotic stewardship.

David Hyun, M.D., is a senior officer, and Rachel Zetts, M.P.H., is an officer, with The Pew Charitable Trusts’ antibiotic resistance project.