Fusobacterium necrophorum

A New Culprit for Pharyngitis in Adolescents
A gram-negative anaerobe that causes Lemierre syndrome has become a common cause of pharyngitis.

Guideline recommendations for the management of pharyngitis vary from doing nothing, to treating patients with positive test results (rapid or culture), to treating empirically. Current guidelines focus on infections with group A streptococcus, because, although the disease is self-limiting, it can cause substantial complications, most notably rheumatic fever (JW Pediatr Adolesc Med Apr 1 2009).

A recent surge in complicated cases of pharyngitis, particularly in adolescents, prompted more-elaborate microbiological testing. DNA analysis revealed that the gram-negative anaerobe, Fusobacterium necrophorum, is as common as group A strep in this age group. An estimated 1 in 400 cases of F. necrophorum pharyngitis progresses to complications, including abscess, septicemia with septic pulmonary emboli, and Lemierre syndrome, which is a septic thrombophlebitis of the internal jugular vein. In case series of patients with F. necrophorum pharyngitis, death — an almost unknown complication of group A strep pharyngitis — has been reported in 2% to 5% of patients, along with a substantial morbidity rate of 10%.

The organism is not sensitive to macrolides, which are recommended for suspected strep pharyngitis in penicillin-allergic patients. Penicillin or a cephalosporin remains the first treatment choice for adolescents and young adults with pharyngitis, and the addition of clindamycin is indicated for those with evidence of sepsis or neck swelling. Clindamycin should be the primary treatment in penicillin-allergic patients.

Comment:
The differential diagnosis of pharyngitis in adolescents and young adults includes group A strep, mononucleosis, and acute HIV infection and should now also include F. necrophorum, both at initial presentation and in cases that have not resolved in the usual 5-day interval from onset. Any clinical indicator of bacteremia indicates the need for admission (at least to an observation unit), blood cultures, and antibiotic coverage for F. necrophorum pending culture results.

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J. Stephen Bohan, MD, MS, FACP, FACEP
Published in Journal Watch Emergency Medicine January 15, 2010

Citation(s): Centor RM. Expand the pharyngitis paradigm for adolescents and young adults. Ann Intern Med 2009 Dec 1; 151:812.