Fusobacterium necrophorum - detection and identification on a selective agar

STEFFEN BANK, HANNE MERETE NIELSEN, BORIS HOYER MATHIASEN,DORTE CHRISTIANSEN LETH, LENA HAGELSKJAER KRISTENSEN and JORGEN PRAGDepartment of Clinical Microbiology, Viborg Hospital, Heibergs Alle´4, Viborg, DenmarkBank S, Nielsen HM, Hoyer Mathiasen B, Christiansen Leth D, Hagelskjaer Kristensen L, Prag J.Fusobacterium necrophorum – detection and identification on a selective agar. APMIS 2010; 118: 994–9.Within the last decade, Fusobacterium necrophorum subsp. funduliforme has been considered a clinicallyimportant pathogen causing pharyngitis especially in adolescents and young adults. F. necrophorumpharyngitis can progress into Lemierre’s syndrome, which is a severe and life-threatening infection.However, throat swabs are not cultured anaerobically in the routine and even if cultured anaerobically,it can be difficult to identify F. necrophorum from the normal flora of the throat. F. necrophorum istherefore often overlooked as the cause of pharyngitis. In our laboratory, a F. necrophorum selectiveagar has been developed containing vancomycin and nalidixin, which inhibit the growth of mostGram-positive and many Gram-negative bacteria, respectively. b-haemolysis of horse blood can bedetected, which further facilitates the detection and identification of F. necrophorum. The F. necropho-rum selective agar was evaluated against a quantitative real-time polymerase chain reaction assay andshown to have a significantly higher sensitivity for detecting F. necrophorum than the anaerobic agarcommonly used in Denmark. Furthermore, the F. necrophorum selective agar does not require experi-enced laboratory technicians, require fewer subcultures, is probably less expensive and is faster toperform than other culture methods.Key words: Fusobacterium necrophorum; culture media; pharyngitis; tonsillitis.Steffen Bank, Department of Clinical Microbiology, Viborg Hospital, Heibergs Alle´ 4, DK-8800Viborg, Denmark. e-mail: stb@mb.au.dk