Typing of Fusobacterium necrophorum Strains Using Polymerase Chain Reaction (PCR) Based Methods

Fusobacterium necrophorum as a non-spore-forming Gram-negative anaerobic bacillus is an important human and animal pathogen. It may cause severe systemic infections (Lemierre's syndrome) and some other infections. The aim of this study was to subtype Fusobacterium necrophorum by using PCR methods.
Twenty five strains of Fusobacterium necrophorum subspecies funduliformis were used. Extraction of DNA and typing of the strains using REP-PCR, ERIC-PCR and BOX-PCR were done.
Molecular typing of Fusobacterium necrophorum using REP1-R-I and REP-2-I primers generated 2 to 5 amplicons ranging in size from 1500bp to 2000bp. GelCompar comparison of banding patterns revealed seven distinct ribotype strains from 25 strains tested of which most were 2 and 4 with 8 and 7 strains respectively. BOX-PCR subtyping generated 2 to 7 comparable amplicons ranging in size from approximately 600bp to more than 2000bp. ERIC-PCR subtyping generated 6 to 11 amplicons ranging in size from approximately 100bp to 1500bp.
F. necrophorum strains have genomic variations that suggest they are never truly clonal in nature, or they may have undergone localized genetic variation across worldwide. This study also showed subtypes existing in Fusobacterium necrophorum species. We have demonstrated that Fusobacterium necrophorum REP-PCR types can be divided into seven, three subtypes by BOX-PCR and six subtypes by ERIC-PCR. BOX-PCR typing proved to be the most discriminatory method, yielding two-seven major bands. The sample size was too small to interpret statistically.