Characterization ofFusobacterium necrophorumisolated from llama and alpaca

Abstract

Fusobacterium necrophorum, a Gram-negative, anaerobic bacterium, is an opportunistic animal and human pathogen that causes a variety of infections termed necrobacillosis. There are 2 subspecies of F. necrophorum (subsp. necrophorum and subsp. funduliforme) that differ morphologically and biochemically and in virulence. Leukotoxin, a secreted protein, is considered to be the major virulence factor. In camelids, F. necrophorum causes a variety of infections, generally involving the lips, tongue, pharynx, interdigital spaces, foot pad, larynx, mandible, or maxillary bones. The objective of the current study was to characterize the presumptive Fusobacterium isolates from a variety of necrotic infections in llama ( Lama glama) and alpaca ( Vicugna pacos) and determine whether the strains possess leukotoxin activities. A total of 7 isolates from alpaca and 2 isolates from llama were characterized. Based on growth characteristics in broth culture, and biochemical and polymerase chain reaction analyses, all 9 isolates belonged to subsp. necrophorum and possessed the putative hemagglutinin gene. Western blot analysis with antileukotoxin antibodies raised in rabbit showed the presence of leukotoxin protein in the culture supernatant of all isolates. Furthermore, flow cytometry of the culture supernatants demonstrated cytotoxicity to bovine and alpaca polymorphonuclear leukocytes (PMNs). The extent of cytotoxicity to either alpaca or bovine PMNs differed among camelid strains. The cytotoxicity of many of the camelid strains was higher ( P < 0.05) toward alpaca PMNs compared to bovine PMNs. Fusobacterium necrophorum isolates from llama and alpaca are similar to bovine isolates, and leukotoxin may be a major virulence factor.

Characterization of Fusobacterium isolates from the respiratory tract of white-tailed deer (Odocoileus virginianus)

“…27 Amplification by PCR of the lkt promoter and the hemagglutinin gene differentiated F. necrophorum subspecies from other Fusobacterium spp. 10 In the current study, the inconsistency in the band produced by F. n. subsp. funduliforme with fund primers may represent polymorphisms in the sequence of this virulence gene.…”

Alimentary necrobacillosis in alpacas

“…F. necrophorum is considered a normal inhabitant of the alimentary tract of alpacas. 8,11 Two subspecies of this microorganism have been identified: F. necrophorum ssp. necrophorum (biotype A) and F. necrophorum ssp.…”

“…12,13 In a study performed with F. necrophorum isolates obtained from different necrotic lesions in alpacas and llamas, leukotoxin was demonstrated in the culture supernatant in all isolates, suggesting that this toxin may play a role in the pathogenesis of necrotic lesions in these animal species. 11…”

“…T. pyogenes and F. necrophorum are normally present on mucous membranes of the alimentary tract of camelids. 8,11 Pseudomonas spp. have been implicated in opportunistic infections and linked to environmental sources, particularly aqueous systems.…”

“…12,13 In a study performed with F. necrophorum isolates obtained from different necrotic lesions in alpacas and llamas, leukotoxin was demonstrated in the culture supernatant in all isolates, suggesting that this toxin may play a role in the pathogenesis of necrotic lesions in these animal species. 11 In ruminants, most of the ulcerative lesions in the upper digestive system that are associated with F. necrophorum occur after physical damage to tissues (e.g., trauma, ischemia, and parasitic or viral infections), which provides an anaerobic environment. 12,23,25 Once established in the tissue, F. necrophorum proliferates, causing extensive foci of coagulative necrosis.…”