Optimizing antibiotic use and infectious diagnostic testing

In their “New bugs, new drugs” session from the virtual 2020 American Academy of Pediatrics National Conference & Exhibition, Rana El Feghaly, MD, and Jennifer Goldman, MD, associate professors of Pediatrics at UMKC School of Medicine and Children’s Mercy Hospital in Kansas City, Missouri, used a case-based format to highlight several important clinical pearls relating to optimizing antimicrobial use in the outpatient and inpatient pediatrics settings.

Community-based quality improvement initiatives should focus on decreasing inappropriate testing for Group A Streptococcus (GAS) pharyngitis.

El Feghaly provided key points from the Centers for Disease Control and Prevention (CDC) 2019 report on Antibiotic Threats in the United States: More than 2.8 million antibiotic-resistant infections occur each year in the United States,¹ and many of those resistant infections considered to be serious threats are acquired in the community setting, like methicillin-resistant Staphylococcus aureus (MRSA), resistant Streptococcus pneumoniae, and diarrhea-causing bacteria like Salmonella, Shigella, and Campylobacter. Studies from nationally representative databases have found that at least one-third of all antibiotics prescribed nationally in the outpatient setting are unnecessary, and an additional 20% may be inappropriate. Two of the top 8 diagnoses leading to antibiotic prescriptions include viral upper respiratory tract infections and bronchitis, conditions for which antibiotics should never be prescribed.²

Focusing on appropriate testing for Group A Streptococcus (GAS) pharyngitis is one high-impact target in the ambulatory pediatrics setting that can lead to significant decrease in inappropriate antibiotic prescriptions. The GAS carrier rate among asymptomatic children in the United States is approximately 20%. Group A Streptococcus pharyngitis does not present with cough, congestion, rhinorrhea, or conjunctivitis, but viral upper respiratory tract infections do. For this reason, any patient presenting with these viral symptoms should not undergo throat swab for GAS testing, because a positive test is more likely to represent a GAS carrier status in a patient with a viral illness than true GAS pharyngitis. Consensus guidelines also recommend against GAS testing in children aged younger than 3 years unless there is a clear exposure in a household contact, because acute rheumatic fever is rare, and the incidence of GAS pharyngitis is uncommon in this age group.

Clinical criteria alone (such as the Centor Score criteria) are not reliable for identifying a child with GAS pharyngitis, so treating presumptively for GAS pharyngitis in children without obtaining a throat swab for GAS testing is never recommended.

Despite these consensus guideline recommendations, El Feghaly highlights results from a retrospective cohort study she and colleagues performed at Children’s Mercy Hospital showing that 53% of GAS pharyngitis tests ordered were inappropriate (9% were in children aged < 3 years old and 44% in patients with viral symptoms).³ The good news, El Feghaly notes, is that quality improvement initiatives focusing on reducing inappropriate testing for GAS pharyngitis have been successful in reducing inappropriate testing in both the primary care and emergency department settings by implementing algorithms to guide clinicians on when testing is indicated.^4,5 Given how common this condition is, reduction of inappropriate testing for GAS pharyngitis is an important antibiotic stewardship target in the ambulatory pediatric setting.

Documented penicillin allergy results in suboptimal therapy and should always be clarified

Goldman presented national antibiotic resistance data from the CDC highlighting substantial increases over the past twelve years in clindamycin and macrolide resistance among isolates from invasive GAS infections. Group A Streptococcus resistance to clindamycin has increased from <5% in 2006 to 25% in 2018, and GAS resistance to macrolide antibiotics (ie, erythromycin and azithromycin) has increased from 12% in 2006 to 25% in 2018. These data showing that non-penicillin antibiotics provide suboptimal empiric therapy for invasive GAS infections are one example highlighting the importance of clarifying penicillin allergies with patients and their families.

Although documented penicillin allergies are prevalent among 10% of children, true Immunoglobulin E-mediated allergies for which the drug would be contraindicated are present in <1% of children. Understanding the local antibiotic resistance patterns in your patient population is essential to making the best antibiotic choices for empiric and definitive therapy.

COMMENTARY

El Feghaly and Goldman highlighted here the importance of evaluating both diagnostic testing and antibiotic prescribing practices to address opportunities to improve, knowing the susceptibility patterns of your patient population, and developing facility-specific clinical algorithms to guide diagnostic and treatment of infectious conditions.

References

1. Centers for Disease Control and Prevention. Antibiotic resistance threats in the United States, 2019. CDC.gov. Updated December 1, 2019. Accessed November 17, 2020. https://www.cdc.gov/drugresistance/pdf/threats-report/2019-ar-threats-report-508.pdf.

2. Fleming-Dutra K, Hersh A, Shapiro D, et al. Prevalence of inappropriate antibiotic prescriptions among US ambulatory care visits, 2010-2011. JAMA. 2016;315(17):1864. doi:10.1001/jama.2016.4151

3. Linafelter A, Burns A, Lee B, et al. Group A streptococcal pharyngitis testing appropriateness in pediatric acute care settings. Pediatr Emerg Care. September 4, 2020. Epub ahead of print. doi:10.1097/pec.0000000000002223

4. Norton L, Lee B, Harte L, et al. Improving guideline-based streptococcal pharyngitis testing: a quality improvement initiative. Pediatrics. 2018;142(1):e20172033. doi:10.1542/peds.2017-2033

5. Ahluwalia T, Jain S, Norton L, Meade J, Etherton-Still J, Myers A. Reducing streptococcal testing in patients <3 years old in an emergency department. Pediatrics. 2019;144(4):e20190174. doi:10.1542/peds.2019-0174