Stewardship in the pediatrician’s office: Appropriate testing for group A strep

Issue: April 2020

ByAsif Noor, MD, FAAP

ByUlka Kothari, MD

Asif Noor

Ulka Kothari

In this bimonthly column, pediatric infectious disease specialists Asif Noor, MD, FAAP, and Ulka Kothari, MD, share valuable insight on antimicrobial stewardship in pediatric outpatient settings and explain why it is important for your practice. Antimicrobial stewardship programs, or ASPs, have become a crucial intervention to spare patients and facilities from the burden of antibiotic-resistant pathogens, which are responsible for one death every 15 minutes, according to updated estimates from the CDC.

Pharyngitis is a very common reason for pediatric sick office visits, accounting for an estimated 15 million annual outpatient visits. Most cases of pharyngitis in children are due to viral infections. Bacterial infection caused by group A beta-hemolytic Streptococcus accounts for 20% to 30% of cases. A rapid streptococcal antigen test is widely used by pediatricians to diagnose group A strep infection in the outpatient setting and is preferred over culture because of its short turnaround time. It has very high specificity — 98% to 99% — but the sensitivity of rapid streptococcal tests is 70% to 90%. Therefore, a negative rapid strep test needs to be confirmed with streptococcal culture. Molecular assays (PCR) are being frequently used in offices, with sensitivity and specificity of 97% and 93%, respectively, and a short turnaround time.

One of the limitations of streptococcal testing is the inability to differentiate true group A strep infection from colonization in children. The lack of absolute reliable clinical findings to distinguish viral from bacterial pharyngitis, along with fear of suppurative and nonsuppurative complications, particularly acute rheumatic fever, has led pediatricians to commonly test for group A strep and prescribe antibiotics based on testing results even when the signs and symptoms are suggestive of a viral infection and despite published indications of when not to perform a strep test.

Confronting the conundrum of appropriate antibiotic prescription

A sore throat or pharyngitis encounter presents pediatricians with two additional puzzling issues in addition to the daily challenges of time constraints and parental pressure to prescribe antibiotics: differentiating viral and bacterial infections and distinguishing colonization from infection.

1. Differentiating viral from bacterial group A strep pharyngitis

Most pharyngitis cases (70% to 80%) in children are secondary to viruses (such as influenza, parainfluenza, rhinovirus, adenovirus, human coronavirus, respiratory syncytial virus, coxsackie, Epstein-Barr virus, cytomegalovirus, herpes simplex virus, etc.). Group A strep is responsible for 15% to 30% of pharyngitis visits. Rare bacterial causes of pharyngitis that require antibiotics include Fusobacterium (Lemierre’s syndrome), group G and C (similar presentation to group A strep but there is no risk for rheumatic fever), Arcanobacterium (a rare cause of pharyngitis in adolescents) and Neisseria gonorrhea (in sexually active adolescents).

Clinical features of pharyngitis might fit a viral cause and correspond with group A strep infection, but most times there is an overlap of signs and symptoms between viral and bacterial infections. About % to % of pharyngitis cases are from group A strep. However, nationally, 50% to 60% of patients in pharyngitis encounters get an antibiotic prescription. Treatment of viral causes of pharyngitis with antibiotics is of no benefit; therefore, it is of utmost importance for pediatricians to exclude the diagnosis of group A strep infection. Unnecessary antibiotic use in carriers contributes to unwanted side effects such as allergic reaction and diarrheal illness at the patient’s level and increased antibiotic resistance at the community level. Opportunity exists to reduce unnecessary antibiotic use in pharyngitis.

Pediatricians should not test if signs and symptoms are suggestive of a viral infection such as rhinorrhea, cough, hoarseness, conjunctivitis, oral ulcers or a viral exanthem (see Chart 1). In addition, children aged younger than 3 years should not be routinely tested. Not only is the prevalence of infection low, infants and young toddlers are not at risk for acute rheumatic fever.

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A patient with true streptococcal pharyngitis presents with fevers, sore throat (typically rapid onset), tender cervical adenopathy, signs of pharyngeal inflammation (ie, erythema, tonsillar exudates or palatal petechiae or sandpaper (scarlatiniform) rash. Test if signs or symptoms are compatible with group A strep or if there is an overlap.

2. Differentiating group A strep colonization from true infection

The second enigma that pediatricians face is how to separate true group A strep infection from colonization (see Chart 2). Management of colonization can be frustrating to pediatricians as well as parents.

Source: Noor A, Kothari U.

A Streptococcus carrier is a person who is transiently or chronically colonized with group A strep in the pharynx. The bacteria are in a stationary phase and do not result in symptoms of group A streptococcal infection. These children do not mount an immune response, are unlikely to transmit infection to close contacts and are not at higher risk for complications (no risk for acute rheumatic fever, and no suppurative complications such as peritonsillar abscess). About 21% of the general pediatric population are carriers. The prevalence of group A strep carriers in EDs, outpatient clinics and school settings ranges from 3% to 26%, with a pooled prevalence of 12%.

If the child is aged younger than 3 years and has no sore throat or other signs and symptoms of group A strep infection, it is easy to reassure parents that the child is only colonized. However, if the child has a sore throat with few viral features, it poses a challenge. Another way to identify colonized children is from their response to antibiotic therapy. A child should respond to treatment with a penicillin-containing antibiotic within 24 to 48 hours. A failure to respond suggests colonization. When a carrier state is identified, pediatricians should reassure the parents that carrying the bacteria is not associated with acute rheumatic fever and that carriers do not typically transmit infection.

There is often confusion with viral pharyngitis. A common scenario is a child in cold weather presenting with recurrent pharyngitis with viral symptoms and a positive rapid strep test. This implies a carrier state, and repeated antibiotic courses should be avoided.

Consider colonization treatment in the following scenarios: 1) outbreaks of acute rheumatic fever or post-streptococcal glomerulonephritis, 2) the patient has a family history of acute rheumatic fever or 3) there are multiple documented group A strep infections in the patient’s family members for many months despite adequate treatment.

There is no reported antibiotic resistance to penicillin in group A strep pharyngitis. Clinicians should avoid using antibiotics other than penicillin/intramuscular benzathine penicillin or amoxicillin for children without penicillin allergy. In children with mild, non-type I hypersensitivity reactions (ie, mild rash), a first-generation cephalosporin such as cephalexin should be considered, and in children with type I hypersensitivity reaction, clindamycin or azithromycin is recommended.

Practice guidelines for outpatient settings:

The Infectious Diseases Society of America emphasizes accurate diagnosis, followed by appropriate antibiotics.

In compliance with these guidelines, quality improvement projects should be implemented to reduce unnecessary testing. A few easy interventions include:

physician evaluation instead of having triage nurses swab all kids presenting with a sore throat;
educational efforts to reduce testing in children aged younger than 3 years, children without sore throat, children aged 2 years or older or those with viral signs or symptoms; and
use of penicillin/IM benzathine penicillin G or amoxicillin only in children without penicillin allergy.

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Operationalizing an ASP in your office through quality improvement and EHRs

Start with diagnosing reasons for gaps in care — lack of education, standing orders for rapid testing for group A strep when a patient presents with sore throat, etc.
Create a written policy, in addition to education, enabling team members to refer back to the guidance. Although education is an essential intervention, other interventions are required to improve outcomes.
Reduce cognitive load of guideline-based decision-making by incorporating evidence and guidance into standardized templates (eg, history and physical examination for a patient with a chief symptom of sore throat, including special situations such as positive contact with a child aged younger than 3 years). Also, create a clinical decision support (CDS) system on best practices (age, presentation, diagnostic testing and selection of appropriate antibiotics, etc.) and documentation of deliberate and thoughtful decision-making when deviating from guidelines (assessment and plan).
In terms of pharyngitis management, most ASP work focuses on appropriate testing. Embedding evidence-based guidelines for appropriate testing as a CDS will help drive ASP efforts.
A Merit-Based Incentive Payment System quality metric is a percentage of children aged 3 to 18 years who were diagnosed with pharyngitis, dispensed an antibiotic and received a group A strep test for the episode. .
However, miss cases of inappropriate testing. If a CDS does not exist for inappropriate testing, conduct chart reviews to see if clear documentation exists showing the reasons for antibiotic prescriptions.