A sore throat in persons aged 15 to 30 years who test negative for strep may indicate a serious infection with Fusobacterium necrophorum, according to findings of a study published in the February 17 issue of the Annals of Internal Medicine.
In this age group, F necrophorum pharyngitis was more common than group A beta-hemolytic streptococcal (GAS) pharyngitis.
Morbidity and mortality may be higher because of complications of peritonsillar abscess and potentially fatal internal jugular thrombophlebitis.
"Recent European studies have estimated that Fusobacterium necrophorum, an obligate anaerobic gram-negative bacillus, causes approximately 10% of endemic pharyngitis in adolescents and young adults," write Robert M. Centor, MD, from the University of Alabama at Birmingham, and colleagues. "F. necrophorum is also the most common cause of peritonsillar abscess in this age group and the primary cause of the Lemierre syndrome...[which] starts a few days after the onset of a sore throat [and] includes suppurative internal jugular thrombophlebitis with subsequent metastatic infections (most commonly lung, brain, or joints)."
To date, however, pharyngitis guidelines have only covered GAS infection. Therefore, the authors aimed to estimate the prevalence of F necrophorum, Mycoplasma pneumoniae, and group A, C, or G beta-hemolytic streptococcal pharyngitis, as well as to assess clinical similarities between pharyngitis caused by F necrophorum and GAS.
The investigators studied 312 students aged 15 to 30 years who presented to a university student health clinic with acute sore throat and 180 asymptomatic students.
According to polymerase chain reaction testing from throat swabs, 20.5% of patients and 9.4% of asymptomatic students were positive for F. necrophorum. GAS was present in 10.3% of patients and 1.1% of asymptomatic students; group C or G beta-hemolytic streptococcus was present in 9.0% and 3.9%, respectively; and M. pneumoniae was present in 1.9% and 0%, respectively.
Higher Centor scores, calculated from the presence of fever history, lack of cough, and swollen, tender lymph nodes and tonsils, were linked to higher infection rates with F. necrophorum, GAS, and group C or G streptococcus (P < .001). Patients with scores of 2 to 4 were nearly twice as likely as patients with scores of 0 or 1 to have bacterial pathogens.
"These data show that the occurrence of F. necrophorum pharyngitis in university students aged 15 to 30 years exceeds [GAS] pharyngitis," the study authors conclude. "The clinical presentation for this bacterial pharyngitis resembles the clinical presentation of [GAS] pharyngitis."
The authors note several limitations, including a sample that was limited to a narrow age range from a single institution, the use of a convenience sample, and the use of asymptomatic students rather than seasonal control participants.
In an accompanying editorial, Jeffrey A. Linder, MD, MPH, from Brigham and Women's Hospital and Harvard Medical School in Boston, Massachusetts, cautions against changing pharyngitis guidelines on the basis of these study findings, some of which were notably different from previous studies.
He noted additional study limitations including the use of polymerase chain reaction instead of paired acute and convalescent serologies, lack of a commercially available test for F necrophorum, and lack of a direct correlation between F necrophorum pharyngitis and Lemierre's syndrome.
He does support the use of Centor scoring criteria to avoid overcomplicating the diagnosis and treatment of pharyngitis. Patients with scores of 0 to 1 have a low likelihood of bacterial pharyngitis requiring antibiotic treatment, and therefore do not need antigen testing or antibiotic prescription.
"[F]rom an empiric standpoint, there is no evidence that treating F. necrophorum pharyngitis with antibiotics decreases symptoms or prevents Lemierre's disease," Dr Linder concludes.
"[T] he major quality problem in sore throat management remains that physicians overcomplicate uncomplicated pharyngitis.
Physicians and practices should remember the prevalence of GAS in adults with sore throat is about 10%, use the Centor Criteria, selectively use rapid antigen detection testing, limit antibiotic treatment to patients most likely to have GAS, and, most of the time when prescribing antibiotics, use penicillin."
The University of Alabama at Birmingham and the Justin E. Rodgers Foundation funded this study. The study authors have disclosed no relevant financial relationships. Dr Linder has been supported by grants from the National Institutes of Health, the National Institute of Allergy and Infectious Diseases, and the Agency for Healthcare Research and Quality. He receives funding from Astellas Pharma, Inc. for research unrelated to antibiotic prescribing or acute respiratory infections.
Laurie Barclay, MD