EXPERT ANALYSIS FROM AAP 2017
CHICAGO (FRONTLINE MEDICAL NEWS) – When a child is sitting in your exam room with recurrent strep pharyngitis, the first question to ask yourself is “Is it real?”
According to pediatric infectious disease specialist John Bradley, MD, the answer to that question comes with careful attention to the history and clinical presentation, but titers and viral polymerase chain reaction tests can also help clarify the diagnosis.
Although that involves some detective work and perhaps some legwork by the provider or the office staff, it’s worth the effort, especially in an era of increased concerns about antimicrobial stewardship, said Dr. Bradley during an antimicrobial update session at the annual meeting of the American Academy of Pediatrics.
“Are the episodes really documented by you in your office?” asked Dr. Bradley. If so, the job is easier. If not, it’s important to differentiate whether documentation of the strep infection was done by culture, whether it was done by an extremely sensitive rapid test, or whether any testing has been done at all, said Dr. Bradley , chief of the division of infectious diseases at the University of California, San Diego.
Somehow, said Dr. Bradley, it’s still true that all group A streptococci are susceptible to penicillin, but penicillin does not always work. There’s about a 10% failure rate for reasons that are not completely understood. Perhaps some individuals have other oropharyngeal flora that produce beta-lactamases, thereby negating penicillin’s efficacy against the strep, he added.
One very good clue as to whether the child has recurrent strep is the appearance of the throat, said Dr. Bradley. A viral illness also can produce a very red posterior oropharynx, so – unless there’s frank pus – it’s unlikely to be strep pharyngitis.
Some patients will, in fact, have recurrent strep, but some patients who might even have positive rapid strep tests may actually be carriers.
So, “what the heck is the carrier state?” asked Dr. Bradley. Although a rapid strep test will occasionally be positive, he explained, the culture is only weakly positive, with growth that’s usually less than 1+. The child who’s a carrier is not symptomatic, will not have an elevated antistreptolysin O titer, and is not contagious. Also, the child will not respond to penicillin treatment.
How can clinicians differentiate recurrent strep from a child with frequent viral illnesses who’s a carrier?
“For the standard case of ‘recurrent strep,’ please get cultures and document the density of group A strep to rule out the carrier state,” said Dr. Bradley. Having parents text pictures of the throat during an episode – for which his facility has a secure portal – can save families an office visit. A negative antistreptolysin O titer can help rule out a recurrent infection, he added.
When a child is having recurrent bouts of pharyngitis, but the clinical picture isn’t clearly consistent with strep, physicians can consider submitting multiplex viral polymerase chain reaction tests. “This can give the family an alternative diagnosis” and reassure parents that it’s safe to hold off on antibiotics, noted Dr. Bradley.
Culturing between episodes of pharyngitis, when the patient is asymptomatic, can also help determine whether a child is a carrier. Sometimes, it makes sense to culture the whole family, and there have also been reports of family pets being Group A strep reservoirs, said Dr. Bradley.
For recurrent infection, choose a broad spectrum agent that will knock back both Group A strep and the oral flora that may be producing beta-lactamases or adhesion molecules that negate penicillin’s efficacy. One logical choice is clindamycin for 10 days, although some strains are resistant. Another good choice is amoxicillin/clavulanate for 10 days or 10 days of a cephalosporin. Penicillin can still be used if it’s augmented by oral rifampin during the last 4 days of the 10-day course.
Long-term prophylaxis can also be considered for stubborn recurrences, he noted.
Dr. Bradley reported no relevant conflicts of interest.