Answers to a reader’s question on: Throat cultures for pharyngitis

When is throat culture indicated for an adult with pharyngitis?

I have seen conflicting recommendations concerning the use of throat cultures and empirical antibiotic therapy in patients with pharyngitis. When do you consider throat cultures to be indicated? Are your recommendations different for children than for adults?

The management of pharyngitis in adults has attracted much attention over the past decade. A recent article in the Annals of Family Medicine compared 11 guidelines, finding dramatic disagreements in approach. ¹ I suspect that the reason for the conflicting recommendations stems from different experts and expert panels emphasizing different values.

I personally subscribe to the aggressive treatment school. I base this strategy on the observation that early treatment of patients with significant symptoms shortens disease duration.² Since I highly value clinical improvement, I favor early empirical antibiotic therapy for severe pharyngitis, defined as a pharyngitis score of 3 or 4. The pharyngitis score assigns 1 point each for tonsillar exudates, tender anterior cervical adenopathy, fever, and lack of cough.

This strategy supports rapid testing in patients with a score of 2 and bases treatment on that result. All experts recommend reassurance and no antibiotics for patients with scores of 0 or 1. Some guidelines recommend rapid testing for patients with scores of 3 or 4. Some European guidelines eschew antibiotictreatment for any patient with pharyngitis, arguing that pharyngitis is a self-limited disease (usually lasting 3 to 5 days). Although antibiotic therapy for group A streptococcal pharyngitis can decrease symptoms by 1 or 2 days, many of the European experts do not believe that this is a good use of antibiotic therapy.

Why do we treat pharyngitis? As an internist, I seek to decrease the duration of symptoms, decrease the probability of suppurative complications, and decrease the risk of spreading infection to contacts. The risks of nonsuppurative complications, such as acute rheumatic fever and glomerulonephritis, are so low that their prevention is no longer an important consideration in pharyngitis management.

Traditionally, we have focused only on group A streptococcal pharyngitis. Recent data suggest that group C and, to a lesser extent, group G streptococci can cause pharyngitis. We have data showing that treating group C streptococcal pharyngitis decreases the duration of symptoms. Group C streptococcal infections can cause epidemics and suppurative complications.

The most recent consideration in adults with pharyngitis is Fusobacterium necrophorum. This anaerobic organism can cause Lemierre syndrome, peritonsillar abscess, and persistent sore throat syndrome. Emerging data suggest that this organism may cause as much as 10% of pharyngitis in adolescents and young adults. In adults, I treat severe pharyngitis empirically with penicillin or a macrolide if they are allergic to penicillin. If their condition does not improve or if it worsens, I advise them to return for further evaluation. I cannot make recommendations about preadolescents with sore throats, but I suspect that they have a different spectrum of infectious agents.

I reserve cultures for patients who either do not improve or have worsening symptoms. If you decide to use rapid testing for group A streptococcal pharyngitis, I would recommend antibiotics for patients with positive results. Patients with negative test results should be told to return if they do not improve, or if they worsen, in 2 or 3 days.

References:

REFERENCES

1. Matthys J, De Meyere M, van Driel ML, De Sutter A. Differences among international pharyngitis guidelines: not just academic. Ann Fam Med. 2007;5:436-443.

2. Zwart S, Sachs AP, Ruijs GJ, et al. Penicillin for acute sore throat: randomized double blind trial of seven days versus three days treatment or placebo in adults. BMJ. 2000;320:150-154.