PCR detection of Fusobacterium necrophorum subsp. funduliforme in tonsils in different patient populations

Background: Fusobacterium necrophorum has recently been suggested to be associated with tonsillopharyngitis, peritonsillar abscess, and recurrent tonsillitis. Among the 2 subspecies of F. necrophorum, subsp. funduliforme is known to be a major human pathogen. To better understand the epidemiology of F. necrophorum subsp. funduliforme (FNSF), we studied the prevalence of FNSF in the tonsils of patients undergoing elective tonsillectomy for different indications.

Methods: Adult patients who underwent elective tonsillectomy from October 2014 to November 2015 were included. The tonsils were sent for aerobic and anaerobic tissue culture within 30 minutes of excision; species identification was performed using standard methods and PCR assay based on the gyrB subunit gene to detect the presence of FNSF DNA was also performed.

Results: A total of 32 patients (14 men [43.8%], median [IQR] age = 38 [26–44] years) were enrolled. The prevalence of F. necrophorum in the tonsils excised for different indications is shown in the Table. The prevalence of FNSF identified by either culture or gyrB PCR did not significantly differ by indication for tonsillectomy (recurrent tonsillitis vs non-infectious diseases). Among patients with non-infectious diseases, FNSF was identified by culture and PCR in 1 patient with periodic fever with aphthous stomatitis, pharyngitis, and adenitis (PFAPA syndrome); and only by PCR in 1 patient with IgA nephropathy. Only 1 (3.8%) each of the recurrent tonsillitis patients was positive for Group A Streptococcus (GAS) or Group C/G Streptococcus (GCS/GGS), respectively.

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Conclusion: The prevalence of FNSF did not differ between patients with recurrent tonsillitis or non-infectious diseases. The presence of F. necrophorum might not be an essential factor in causing recurrent tonsillitis.

Table. Prevalence of F. necrophorum among excised tonsils
	Total (N = 32)	Indications for tonsillectomy
		Recurrent tonsillitisA (n = 26)	Non-infectious diseasesB (n = 6)
F. necrophorum culture positive	6 (18.8%)	5 (19.2%)	1 (16.7%)
FNSF gyrB positive	7 (21.9%)	5 (19.2%)	2 (33.3%)
GAS	1 (3.1%)	1 (3.8%)	0
GCS/GGS	1 (3.1%)	1 (3.8%)	0
A.     Including 2 cases of recurrent peritonsillar abscess. B.     3 IgA nephropathy, 1 PFAPA syndrome, 1 sleeping apnea syndrome, 1 chronic urticaria