Arcanobacterium phocae infection in mink (Neovison vison), seals (Phoca vitulina, Halichoerus grypus) and otters (Lutra lutra)

Arcanobacterium canis strain DSM 25104 isolated from an English bulldog suffering from otitis externa: complete genome sequence

Many species of the genus Arcanobacterium are known as opportunistic pathogens and have been isolated in association with infectious diseases in humans and animals. Here, we present the complete genome sequence of another opportunistic pathogenic representative, namely Arcanobacterium canis, isolated from the otitis externa of an English bulldog.

Association between Antibiotic Consumption and Resistance in Mink Production

Antibiotic consumption is considered to be a main driver of antibiotic resistant bacteria. Mink breeding follows a distinctive seasonal reproduction cycle, and all of the mink produced in the northern hemisphere are bred, born, and pelted around the same time of year. Some of the diseases are age-related, which is reflected in the seasonal variation of antibiotic consumption. The seasonality makes mink a good model for the investigation of the association between antibiotic consumption and resistance. The objectives of this study were (1) to monitor the farm level of antibiotic resistance during one production cycle and (2) to assess the potential associations between antibiotic consumption and resistance. Twenty-four farms were included in this study (Denmark n = 20, Iceland n = 2, and The Netherlands n = 2), following a cohort of animals born in 2018. Staphylococcus delphini and Escherichia coli were isolated from samples of the carcasses and faeces and were collected randomly. The isolates were susceptibility tested and subsequently divided into the sensitive wildtype (WT) and the resistant non-wildtype (NWT) populations. The antibiotic consumption relative to the sampling periods was assessed as having a short-term or a long-term impact, i.e., in two explanatory factors. For both S. delphini and E. coli, a large between-farm variation of NWT profiles was detected. In the final multivariable, generalized linear mixed models, significant associations between NWT isolates and the consumption of specific antibiotics were found: the short-term use of tetracyclines in the growth period was associated with the occurrence of tetracycline NWT E. coli in the growth period (OR: 11.94 [1.78; 89.28]), and the long-term use of macrolide and tetracyclines was associated with the occurrence of erythromycin NWT S. delphini in the weaning period (OR: 18.2 [2.26; 321.36]) and tetracycline NWT S. delphini in the growth period (OR: 8.2 [1.27; 63.31]), respectively. Farms with zero consumption in the study years prior to sampling also had a substantial proportion of NWT isolates, indicating that NWT isolates are persistent and/or widely spread in the environment. Generally, a high occurrence of tetracycline NWTs was observed. NWT isolates with resistance against the most commonly used antibiotics were found on all the farms, stressing the need for routine surveillance and the prudent use of antibiotics. The results offer a preview of the complex relationship between consumption and resistance, demonstrating some significant associations between use and resistance. Moreover, antibiotic-resistant bacteria are present even on farms with no antibiotic consumption over extended periods, and theoretical explanations supported by the data are offered.

First finding of Streptococcus phocae infections in mink (Neovison vison)

Streptococcus phocae infection has been described in salmon, sea otters, and several families of pinnipeds. The pathology of the infected animals has mainly been located in the respiratory tract and reproductive system, and with indications of septicemia. In this study, we report the finding of S. phocae in diagnostic material from three unrelated cases of farmed mink. Since S. phocae initially has been described in pinnipeds, two isolates from wild harbor seals were included. All isolates originated from Denmark. To our knowledge, this is the first report of S. phocae infection in mink. The animals (three mink, two seals) were necropsied, and samples were collected for bacteriology, virology, and histopathology. Additionally, the S. phocae isolates were whole genome sequenced and compared to sequences of previously reported isolates from other host species. S. phocae was isolated from the lungs of one mink and one seal with bacteremia, and from one seal with pneumonia. The two remaining mink had dermal infections on the paws and S. phocae was isolated from the lesions. The analysis of the sequence data showed that the three mink isolates and one seal isolate were closely related. Further investigation is needed to conclude whether S. phocae is establishing as commensal in farmed mink and to uncover the infection related pathology in mink. Streptococcus phocae has been described as an emerging pathogen in other species, therefore future awareness and surveillance of this pathogen is crucial.

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.

Association between Fur Animal Necrotizing Pyoderma in breeding farm mink (Neovison vison) and reduced fertility

BACKGROUND

The disease Fur Animal Necrotizing Pyoderma (FNP) has since 2000 been reported in many fur producing countries including Canada, Finland and Denmark. Development of FNP is characterised by rapidly forming treatment-resistant wounds on paws and in the head region. Economic losses related to FNP have been associated with mortality and decreased fur quality as well as increased veterinary costs. Also it has been suggested that FNP may be associated with reduced production results for breeding mink. The aim of this study was to evaluate if there is an association between FNP lesions in breeding animals and reduced production results based on a retrospective cohort study.

RESULTS

1465 breeding animals (244 males and 1221 females) were followed during the breeding season 2019 on five Danish mink farms. Two farms were removed from the analysis since no occurrence of FNP appeared in the observation group. After exclusion, 846 breeding animals (148 males and 698 females) remained in the analysis and were divided into two groups: exposed (EXP) or non-exposed (N-EXP) depending on the disease history of the males during mating. Females exposed to FNP positive males during breeding in average produce 14% fewer kits (P = 0.032) and these females were also more than double as likely to produce small litters (N ≥ 3) than N-EXP females. Female's from the EXP group were introduced more times to males than females in the N-EXP group (P = 0.0001, 2.5 more times in average). Females in the EXP group did not have a statistically higher risk of becoming barren (P = 0.138) though the relative risk of becoming barren was 77% higher after encountering a FNP male.

CONCLUSIONS

This study shows that FNP has more economic losses for the farms than direct loss of animals. Females in contact with males with FNP lesion during breeding have a higher risk of becoming barren, and produce significantly fewer kits compared to females whom haven't been in contact with a FNP positive male.

Epidemiological analysis of Arcanobacterium phocae isolated from cases of mink dermatitis of a single farm

The present study was designed to identify nine Arcanobacterium phocae strains isolated from cases of mink dermatitis of a single farm in Finland and characterize the strains for epidemiological relationships. All nine strains and previously described A. phocae used for comparative purposes were identified and further characterized phenotypically, by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), by Fourier Transform Infrared Spectroscopy (FT-IR) and genotypically by detection of phocaelysin encoding gene phl with a previously developed loop-mediated isothermal amplification (LAMP) assay and by sequencing 16S rRNA gene and gene phl, the elongation factor tu encoding gene tuf and the β subunit of bacterial RNA polymerase encoding gene rpoB. Genetic relatedness among isolates was determined using whole-genome single nucleotide polymorphism (wgSNP) analysis. The wgSNP results, partly the MALDI-TOF MS and FT-IR analyses and sequencing of the genes, revealed that the nine A. phocae strains recovered from a single farm showed close sequence similarities among each other and differed from previously investigated A. phocae strains isolated from other farms and animals in Finland and from the A. phocae type strain. This indicated a close epidemiological relationship of the A. phocae strains isolated from a single farm and that the nine A. phocae strains of the present study might have developed from a common ancestor.