Arcanobacterium Phocae Research Articles

Comparative Genomics of 42 Arcanobacterium phocae Strains

For the last 13 years, the fur industry in Europe has suffered from epidemic spouts of a severe necrotizing pyoderma. It affects all species currently farmed for fur and causes animal welfare problems and significant losses to the farmers. The causative agent of this disease was identified as Arcanobacterium phocae. Previously, this bacterium has been isolated from seals and other marine mammals, apparently causing wound and lung infections. Attempts at antibiotic treatment have been unsuccessful and the current advice on preventing the disease is to cull all animals with clinical signs. This poses an urgent question regarding possible vaccine development, as well as the need for further understanding of the pathogenicity of this organism. This study compared the whole genomes of 42 A. phocae strains isolated from seals, blue foxes, finnraccoons, mink and otter. The sequences were created using the Illumina technology and annotations were done using the RAST pipeline. A phylogenetic analysis identified a clear separation between the seal strains and the fur-animal-derived isolates, but also indicated that the bacterium readily adapts to new environments and host species with reasonable diversity. A pan- and core-genome was created and analyzed for proteins. A further analysis identified several virulence factors as well as multiple putative and secreted proteins of special interest for vaccine development.

Arcanobacterium wilhelmae sp. nov., isolated from the genital tract of a rhinoceros (Rhinoceros unicornis).

A taxonomic study using a polyphasic approach was performed on an unidentified Arcanobacterium-like Gram-stain-positive bacterium isolated from the genital tract of a rhinoceros. Comparative 16S rRNA gene sequencing showed that the bacterium belonged to the genus Arcanobacterium and was most closely related to the type strains of Arcanobacterium canis (98.8 % 16S rRNA gene sequence similarity), Arcanobacterium phocisimile (97.8 %), Arcanobacterium phocae (97.7 %), Arcanobacterium haemolyticum (97.4 %), Arcanobacterium hippocoleae (96.6 %), Arcanobacterium pinnipediorum (96.4 %) and Arcarnobacterium pluranimalium (95.4 %). DNA-DNA hybridization values between strain 647T and Arcanobacterium canisDSM 25104T were very low, 13.4 % (reciprocal 15.9 %). The genomic DNA G+C content of strain 647T was 58.7 mol%. The presence of the major menaquinone MK-9(H4) supported the affiliation of this strain to the genus Arcanobacterium. The polar lipid profile consisted of the major components diphosphatidylglycerol, phosphatidylcholine and an unidentified phosphoglycolipid. The results of physiological and biochemical testing clearly distinguished the unknown bacterium from other species of the genus Arcanobacterium. Based on these tests, it is proposed that the unknown bacterium should be classified as a representative of a novel species of the genus Arcanobacterium named Arcanobacterium wilhelmaesp. nov. The type strain is 647T (=DSM 102162T=LMG 29418T).

Experimental Infection of Mink Enforces the Role of Arcanobacterium phocae as Causative Agent of Fur Animal Epidemic Necrotic Pyoderma (FENP).

Fur Animal Epidemic Necrotic Pyoderma (FENP) is a severe, often lethal infectious disease affecting all three fur animal species: mink (Neovision vision), foxes (Vulpes lagopus) and finnraccoons (Nyctereutes procyonoides). Previous studies showed an association between Arcanobacterium phocae and FENP. An experimental infection was conducted to confirm the ability of A. phocae to infect mink either alone or concurrently with a novel Streptococcus sp. found together with A. phocae in many cases of FENP. Different inoculation methods were tested to study possible routes of transmission. Typical signs, and gross- and histopathological findings for FENP were detected when naïve mink were infected with the tissue extract of mink with FENP, using a subcutaneous/ intradermal infection route. Edema, hemorrhage, necrosis and pus formation were detected in the infection site. A pure culture preparation of A. phocae alone or concurrently with the novel Streptococcus sp. caused severe acute signs of lethargy, apathy and anorexia and even mortality. The histopathological findings were similar to those found in naturally occurring cases of FENP. In contrast, the perorally infected mink presented no clinical signs nor any gross- or histopathological lesions. This study showed that A. phocae is able to cause FENP. The study also indicated that predisposing factors such as the environment, the general condition of the animals, temperature and skin trauma contribute to the development of the disease.

Otariodibacter oris and Bisgaardia Genomospecies 1 Isolated from Infections in Pinnipeds

We document the first associations of two recently described species of Pasteurellaceae bacteria with lesions in wild pinnipeds in rehabilitation. Samples were collected from nine lesions in four California sea lions (Zalophus californianus) and two Pacific harbor seals (Phoca vitulina) during necropsy or admission examinations at a rehabilitation facility in northern California. Seven Pasteurellaceae isolates were identified using phenotypic tests and partial rpoB gene sequencing. Six strains of Otariodibacter oris were isolated from California sea lions. Otariodibacter oris was isolated in pure culture from four abscesses, an affected lymph node, and a bone lesion consistent with osteomyelitis. Otariodibacter oris was also cultured with Arcanobacterium phocae and β-hemolytic streptococci. A pure culture of Bisgaardia genomospecies 1 was obtained from an abscess in a harbor seal. This is the first time, to our knowledge, that O. oris has been associated with infection. Isolation of these bacteria in pure culture from abscesses and osteomyelitis strongly indicates a pathogenic potential of this organism. Likewise, the isolation of Bisgaardia genomospecies 1 in pure culture from an abscess in a harbor seal implies causality.

Characterization and clinical manifestations of Arcanobacterium phocae infections in marine mammals stranded along the central California coast.

Between 1994 and 2000, 141 Arcanobacterium phocae isolates were recovered from marine mammals that stranded along the central California coast (USA). Arcanobacterium phocae was cultured from tissue sites with abnormal discharge or evidence of inflammation in 66 California sea lions (Zalophus californianus), 50 Pacific harbor seals (Phoca vitulina richardii), 19 northern elephant seals (Mirounga angustirostris), five southern sea otters (Enhydra lutris nereis), and one common dolphin (Delphinus delphis). The overall prevalence of A. phocae among cultured stranded marine mammals was 8%. This is the first report of A. phocae in animals from the Pacific Ocean. Sequence analysis of a portion of the 16S ribosomal RNA gene confirmed recent isolates as A. phocae. Prior to phylogenetic testing and the routine use of the esculin hydrolysis and motility tests, A. phocae isolates may have been misidentified as Listeria ivanovii. Arcanobacterium phocae was commonly isolated from superficial abscesses, was often present in mixed infections, and was susceptible to all antimicrobial agents tested.

Arcanobacterium hippocoleae sp. nov., from the vagina of a horse.

A polyphasic taxonomic study was performed on a previously unidentified gram-positive, facultatively anaerobic, diphtheroid-shaped organism isolated from a vaginal discharge of a horse. Comparative 16S rRNA gene sequencing demonstrated that the strain was a member of the genus Arcanobacterium, but sequence divergence values of >4% with described species of this genus (viz: Arcanobacterium haemolyticum, Arcanobacterium bernardiae, Arcanobacterium phocae, Arcanobacterium pluranimalium and Arcanobacterium pyogenes) demonstrated that the isolate represented a novel species. The unknown bacterium was readily distinguished from other Arcanobacterium species by biochemical tests. Based on phylogenetic and phenotypic evidence, it is proposed that the unknown bacterium be classified as Arcanobacterium hippocoleae sp. nov. The type strain of A. hippocoleae is CCUG 44697T (= CIP 106850T).