Quantification of IgY to Erysipelothrix rhusiopathiae in serum from Swedish laying hens.

BACKGROUND: Erysipelas, caused by Erysipelothrix rhusiopathiae (ER), is an important emerging disease in free-range and organic egg-production. The aim of the present study was to assess if quantification of ER specific IgY titers may aid the understanding of erysipelas in commercial laying hens. The methodology was validated with sequentially collected sera from experimentally ER infected SPF-chickens and subsequently applied on sera from Swedish commercial laying hens collected during and after outbreaks of erysipelas or collected at slaughter from healthy hens housed in furnished cages, barn production or in organic production (with outdoor access). RESULTS: In experimentally infected SPF-chickens, titers to ER were significantly increased approximately one week after infection while IgY to ER in uninfected age-matched controls remained low. Also chickens infected with low doses of ER, not displaying clinical signs of disease and with low recovery of ER in blood samples showed high titers of IgY to ER. For laying hens during and after erysipelas outbreaks the majority of samples were considered positive for antibodies to ER with a large variation in levels of IgY titers to ER between individuals. For healthy laying hens at slaughter all samples were deemed positive for antibodies to ER. An influence of flock on levels of IgY titers to ER was observed for both healthy hens and hens during erysipelas outbreaks. For healthy laying hens at slaughter no influence of the housing systems included in the study, history of erysipelas outbreaks at the farm or vaccination on levels of IgY titers to ER was noticed. CONCLUSIONS: Taken together, these results show that high numbers of commercial laying hens showed high IgY titers to ER, comparable to those elicited by experimental ER infection, indicating that ER or bacteria that raises antibodies that cross-react with ER are common in this environment.

Description of Erysipelothrix piscisicarius sp. nov., an emergent fish pathogen, and assessment of virulence using a tiger barb (Puntigrus tetrazona) infection model.

A recently described emergent disease of ornamental fish has been associated with an Erysipelothrix species positive for the surface protective antigen (spa) C gene. Whole genome sequencing was performed on five spaC Erysipelothrix isolates from diseased ornamental fish. In addition, these spaC Erysipelothrix isolates were compared to spaA-, spaB- and other spaC-positive Erysipelothrix species isolated from terrestrial and marine mammals, birds and fish using multi-locus sequence analysis (MLSA). The genomes of fish pathogenic spaC isolates were genetically distinct from Erysipelothrix rhusiopathiae, sharing 86.61-86.94 % average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values of 31.6-32.2 %, but 99.01-99.11 % ANI and 90.8-91.9 % dDDH values with the uncharacterized spaC-positive Erysipelothrix sp. strain 2 isolated from swine. The findings indicate the spaC-positive fish and swine isolates are conspecific and represent a previously unrecognized taxon. While phylogenies inferred from MLSA sequences confirm this conclusion, slight genetic differences between the spaC fish isolates and swine strain 2 were indicated. Bath immersion challenge trials were conducted using tiger barbs (Puntigrus tetrazona) exposed by immersion to 107 c.f.u. ml-1 of three fish pathogenic spaC Erysipelothrix species, and three spaA and two spaB E. rhusiopathiae isolates as a model of infection. Thirty days post-challenge, cumulative mean percentage survival was 37 % for the spaA, 100 % for the spaB and 13 % for the spaC isolates, revealing differences in virulence among the various spa genotypes in fish. Genetic findings and observed differences in virulence demonstrate the fish pathogenic spaC isolates represent a novel species, for which the name Erysipelothrix piscisicarius sp. nov. is proposed. The type strain is E. piscisicarius 15TAL0474T (=NRRL B-65533T=ATCC-TSD-175T=DSM 110099T).

Infective endocarditis due to Erysipelothrix rhusiopathiae in a dog - a case report.

BACKGROUND: Infective endocarditis is a rare but severe condition associated with a high mortality rate in small animal patients. This condition is caused by a microbial (most often bacterial) infection of the valvular portion of the endocardium, from which proliferative and/or erosive lesions on the cardiac valves or immediately adjacent structures develop. The two most commonly affected cardiac valves are the aortic and mitral valves. CASE PRESENTATION: We report the clinical case of a 4-year old male neutered Bull terrier, 27.6 kg, body condition score 4/9, that presented with a 3-months history of pyrexia and general weakness. The patient history also revealed a transient left hind limb lameness (grade 2/4), which coincided with the onset of clinical signs about 3 months before presentation. On physical examination, a left-sided systolic heart murmur (grade 3/6) with the same intensity at the left heart base and apex, and an irregularly irregular heart rhythm were noted. Electrocardiography showed ventricular premature complexes, and echocardiography revealed lesions consistent with endocarditis involving the aortic and mitral valve. Bacterial culture of blood yielded a positive result, and the organism isolated was identified as Erysipelothrix rhusiopathiae. The extended patient history revealed that the dog lived close to a farm housing pigs and other livestock. CONCLUSION: We report a rare case of the premortal diagnosis of infective bacterial endocarditis in a dog due to E. rhusiopathiae infection. Most reports about this condition are from necropsy series. This clinical case report emphasizes that E. rhusiopathiae infection and bacteremia should be considered as a differential diagnosis in dogs with suspected infective endocarditis, especially in dogs living in rural areas with access to livestock and particularly farm pigs. Also, particular emphasis should be placed on the zoonotic potential of this infectious disease.

Wild boars: A potential source of Erysipelothrix rhusiopathiae infection in Japan.

The potential role of wild boars as a source of erysipelas infection was investigated. An ELISA test of wild boar serum samples from 41 prefectures in Japan revealed that proportions of the Erysipelothrix rhusiopathiae-positive samples were very high in all the prefectures, and the mean positive rate was 95.6% (1312/1372). Serovars of E. rhusiopathiae isolates from wild boars were similar to those of previously reported swine isolates, and all serovar isolates tested were found to be pathogenic to mice. These results suggest that wild boars in Japan constitute a reservoir of E. rhusiopathiae and may pose risks to other animals.

Erysipeloid lesions caused by Erysipelothrix rhusiopathiae in a dog: clinical and histopathological findings, molecular diagnosis and treatment.

BACKGROUND: Erysipelothrix rhusiopathiae is a widespread Gram-positive, nonsporulating rod bacterium predominantly associated with skin disease in swine and cetaceans. Cutaneous lesions have yet to be described in dogs. OBJECTIVE: To describe the clinical presentation, molecular and histopathological diagnosis, and treatment of a case of erysipeloid caused by E. rhusiopathiae in a dog. ANIMALS: A 6-month-old spayed female standard poodle dog presented with lethargy, fever, vomiting and diarrhoea. Skin lesions appeared 20 days post first examination. METHODS AND MATERIALS: Complete blood count, serum chemistry profile, urinalysis, urine culture, blood culture, computed topography, forelimb radiography, joint and cerebrospinal fluid aspiration were performed; samples were collected for skin cytological evaluation, culture and histopathological analysis. RESULTS: Blood cultures yielded Gram-positive, catalase-negative bacilli. Histopathological evaluation of skin biopsies revealed lymphoplasmacytic, neutrophilic and histiocytic perivascular and periadnexal dermatitis, and vasculitis. Cutaneous and blood PCR and sequencing of 16S rRNA identified the bacteria as E. rhusiopathiae. Clinical resolution was observed following the use of of amoxicillin/clavulanic acid and ciprofloxacin therapies. CONCLUSIONS AND CLINICAL IMPORTANCE: To the best of the authors' knowledge, this is the first confirmed case of erysipeloid caused by E. rhusiopathiae in a dog. Clinical resolution was attained with the extended use of antibiotics. After 13 months, no clinical signs had returned.

Metabolic Fate of 13C-Labeled Polydextrose and Impact on the Gut Microbiome: A Triple-Phase Study in a Colon Simulator.

The present study introduces a novel triple-phase (liquids, solids, and gases) approach, which employed uniformly labeled [U-13C] polydextrose (PDX) for the selective profiling of metabolites generated from dietary fiber fermentation in an in vitro colon simulator using human fecal inocula. Employing 13C NMR spectroscopy, [U-13C] PDX metabolism was observed from colonic digest samples. The major 13C-labeled metabolites generated were acetate, butyrate, propionate, and valerate. In addition to these short-chain fatty acids (SCFAs), 13C-labeled lactate, formate, succinate, and ethanol were detected in the colon simulator samples. Metabolite formation and PDX substrate degradation were examined comprehensively over time (24 and 48 h). Correlation analysis between 13C NMR spectra and gas production confirmed the anaerobic fermentation of PDX to SCFAs. In addition, 16S rRNA gene analysis showed that the level of Erysipelotrichaceae was influenced by PDX supplementation and Erysipelotrichaceae level was statistically correlated with SCFA formation. Overall, our study demonstrates a novel approach to link substrate fermentation and microbial function directly in a simulated colonic environment.

Characterization of spaC-type Erysipelothrix sp. isolates causing systemic disease in ornamental fish.

Since 2012, low-to-moderate mortality associated with an Erysipelothrix sp. bacterium has been reported in ornamental fish. Histological findings have included facial cellulitis, necrotizing dermatitis and myositis, and disseminated coelomitis with abundant intralesional Gram-positive bacterial colonies. Sixteen Erysipelothrix sp. isolates identified phenotypically as E. rhusiopathiae were recovered from diseased cyprinid and characid fish. Similar clinical and histological changes were also observed in zebrafish, Danio rerio, challenged by intracoelomic injection. The Erysipelothrix sp. isolates from ornamental fish were compared phenotypically and genetically to E. rhusiopathiae and E. tonsillarum isolates recovered from aquatic and terrestrial animals from multiple facilities. Results demonstrated that isolates from diseased fish were largely clonal and divergent from E. rhusiopathiae and E. tonsillarum isolates from normal fish skin, marine mammals and terrestrial animals. All ornamental fish isolates were PCR positive for spaC, with marked genetic divergence (<92% similarity at gyrB, <60% similarity by rep-PCR) between the ornamental fish isolates and other Erysipelothrix spp. isolates. This study supports previous work citing the genetic variability of Erysipelothrix spp. spa types and suggests isolates from diseased ornamental fish may represent a genetically distinct species.

Clonal Lineages of Erysipelothrix rhusiopathiae Responsible for Acute Swine Erysipelas in Japan Identified by Using Genome-Wide Single-Nucleotide Polymorphism Analysis.

Erysipelothrix rhusiopathiae causes swine erysipelas, an important infectious disease in the swine industry. In Japan, the incidence of acute swine erysipelas due to E. rhusiopathiae serovar 1a has recently increased markedly. To study the genetic relatedness of the strains from the recent cases, we analyzed 34 E. rhusiopathiae serovar 1a swine isolates collected between 1990 and 2011 and further investigated the possible association of the live Koganei 65-0.15 vaccine strain (serovar 1a) with the increase in cases. Pulsed-field gel electrophoresis analysis revealed no marked variation among the isolates; however, sequencing analysis of a hypervariable region in the surface-protective antigen A gene (spaA) revealed that the strains isolated after 2007 exhibited the same spaA genotype and could be differentiated from older strains. Phylogenetic analysis based on genome-wide single-nucleotide polymorphisms (SNPs) revealed that the Japanese strains examined were closely related, showing a relatively small number of SNPs among them. The strains were classified into four major lineages, with Koganei 65-0.15 (lineage III) being phylogenetically separated from the other three lineages. The strains isolated after 2007 and the two older strains constituted one major lineage (lineage IV) with a specific spaA genotype (M203/I257-SpaA), while the recent isolates were further divided into two geographic groups. The remaining older isolates belonged to either lineage I, with the I203/L257-SpaA type, or lineage II, with the I203/I257-SpaA type. These results indicate that the recent increased incidence of acute swine erysipelas in Japan is associated with two sublineages of lineage IV, which have independently evolved in two different geographic regions.IMPORTANCE Using large-scale whole-genome sequence data from Erysipelothrix rhusiopathiae isolates from a wide range of hosts and geographic origins, a recent study clarified the existence of three distinct clades (clades 1, 2, and 3) that are found across multiple continents and host species, representing both livestock and wildlife, and an "intermediate" clade between clade 2 and the dominant clade 3 within the species. In this study, we found that the E. rhusiopathiae Japanese strains examined exhibited remarkably low levels of genetic diversity and confirmed that all of the Japanese and Chinese swine isolates examined in this study belong to clonal lineages within the intermediate clade. We report that spaA genotyping of E. rhusiopathiae strains is a practical alternative to whole-genome sequencing analysis of the E. rhusiopathiae isolates from eastern Asian countries.

Infectious tenosynovitis with bloodstream infection caused by Erysipelothrix rhusiopathiae, a case report on an occupational pathogen.

BACKGROUND: Erysipelothrix rhusiopathiae is an established animal pathogen, which may cause infections in humans. It is a gram-positive rod and found in the tonsils or the digestive tracts of animals. The bacterium is occupationally related, as usually only people with frequent animal contacts are infected. We report a case of a patient who was admitted with an infectious tenosynovitis with bloodstream infection due to E. rhusiopathiae, and to our knowledge, this is the first report of a tenosynovitis with systemic manifestation associated with this bacterium. CASE PRESENTATION: A 52-year old Norwegian man, who worked with transportation of swine cadavers, was admitted to the local hospital with sepsis and unknown focus of infection. A few days earlier he had an injury to the skin of one of his fingers that later proved to be infected with E. rhusiopathiae. There were no other causes for his symptoms than the infectious tenosynovitis with systemic manifestation. The infection resolved on treatment with antibiotics and surgery. A transoesophageal echocardiogram was performed to exclude endocarditis, which may be associated with this pathogen. CONCLUSIONS: This case report highlights the importance of clinicians being aware of this bacterium, and we describe risk factors for infection, differences in the clinical manifestations of the disease, challenges with diagnosing the bacterium and adverse effects of immunosuppressive drugs. Recommended treatment is appropriate antibiotic therapy and adequate debridement and surgical drainage of the tendon sheath.

Erysipelothrix rhusiopathiae isolated from gull-inflicted wounds in southern right whale calves.

Southern right whales Eubalaena australis from Peninsula Valdés, Argentina, show wounds produced by kelp gulls Larus dominicanus that feed on the whales' dorsal skin and blubber. During the 2013 whale season, several calves were reported showing kelp gull injuries with a swollen area surrounded by rhomboid-shaped raised edges. Samples from 9 calves were taken in order to establish the etiology of these rhomboid-shaped wounds; 2 calves (one living, one dead) showed gull-inflicted injuries with rhomboid-shaped edges. Samples from the dead calf were histologically characterized by the presence of dermal congestion, suppurative dermatitis and panniculitis, necrotizing vasculitis and vascular thrombosis. Erysipelothrix rhusiopathiae was detected by culture and PCR in samples from both calves. In this study we report, for the first time to our knowledge, the isolation of E. rhusiopathiae from wounds produced by gull attacks on southern right whale calves, supplying evidence that these wounds may act as an entry route for pathogens. This work provides new information about the consequences of gull-inflicted injuries for whale health.

[Identifying immunogenic proteins of Erysipelothrix rhusiopathiae C43065 by MALDI-TOF mass spectrometry and cloning their encoding genes].

OBJECTIVE: To identify immunogenic proteins of Erysipelothrix rhusiopathiae C43065. METHODS: Antigens were extracted from E. rhusiopathiae C43065 by the alkaline extraction method. Proteins in the NaOH-extracted antigen were separated by SDS-PAGE and transferred to nitrocellulose membranes, and then Western blotting was performed with rabbit antiserum against the NaOH-extracted antigens. The immunogenic protein bands were identified by MALDI-TOF mass spectrometry. The genes encoding 5 major immunogenic proteins was amplified by PCR from the genomic DNA of E. rhusiopathiae C43065, and inserted into the pMD18-T vector and then sequenced. RESULTS: A total of 9 immunogenic surface proteins in the NaOH-extracted antigen from E. rhusiopathiae C43065 were successfully identified by MALDI-TOF mass spectrometry. Four of the proteins were putative virulence-associated proteins: enolase, ATP-binding cassette transporter, glyceraldehyde-3 -phosphate dehydrogenase and fructose-bisphosphate aldolase class-II. The genes encoding the chaperone protein GroEL, enolase, ATP-binding cassette transporter, glyceraldehyde-3-phosphate dehydrogenase and fructose-bisphosphate aldolase class-II were 1614, 1296, 1260, 1005 and 867 bp in length, and the nucleotide sequences homologies of the genes between the C43065 strain and the previously reported E. rhusiopathiae Fujisawa strain was more than 98%. CONCLUSION: Several putative virulence-associated proteins in the NaOH-extracted antigen of E. rhusiopathiae C43065 will be useful for elucidating the roles of these proteins in the pathogenesis of the organism.

Erysipelothrix larvae sp. nov., isolated from the larval gut of the rhinoceros beetle, Trypoxylus dichotomus (Coleoptera: Scarabaeidae).

A novel, Gram-stain positive, facultative anaerobic, non-motile and straight to curve rod shaped bacterium, strain LV19(T) was isolated from the larval gut of the rhinoceros beetle, Trypoxylus dichotomus, which was collected from Yeong-dong, Chuncheongbuk-do, South Korea. The colonies of the new isolate were convex, circular, cream white in color and 1-2 mm in diameter after 3 days incubation on Tryptic Soy Agar at 37 °C. Based on the 16S rRNA gene sequence similarity, the new isolate was most closely related to Erysipelothrix inopinata MF-EP02(T), E. rhusiopathiae ATCC 19414 (T) and E. tonsillarum T-305(T) (94.8, 93.8 and 93.7 % similarity, respectively). Strain LV19(T) grew optimally at 37 °C, at pH 8.0 and in the presence of 0.5 % (w/v) NaCl. Oxidase activity and catalase activity were negative. The major cellular fatty acids (>10 %) were C18:2 cis-9,12 (28.9 %), C18:1 cis-9 (22.3 %), C16:0 (22.2 %) and C18:0 (18.5 %). The cell-wall hydrolysates contained ribose as a major sugar. Major polar lipids were phosphatidylglycerol and three unidentified glycolipids. No quinone was detected. The G+C content of the genomic DNA was 36.3 mol%. The levels of DNA-DNA relatedness between strain LV19(T) and all the reference strains were less than 20 %. On the basis of polyphasic evidence from this study, the isolate is considered to represent a novel species of the genus Erysipelothrix, for which the name Erysipelothrix larvae sp. nov. is proposed; the type strain is LV19(T) (=KCTC 33523(T) = DSM 28480(T)).

Acute and Chronic Erysipelothrix rhusiopathiae Infection in Lambs.

Polyarthritis caused by Erysipelothrix rhusiopathiae is a relatively common infection in lambs characterized by low mortality and high morbidity. E. rhusiopathiae is a ubiquitous Gram-positive bacterium that is both a commensal and a pathogen of vertebrates. The disease was studied during an outbreak in a Norwegian Spæl sheep flock. In the acute phase, 48 of 230 (20%) lambs developed clinical signs and 4 died (1.7%). One acute case was necropsied and E. rhusiopathiae was cultured from all major organs investigated and from joints. There was a fibrinous polyarthritis, increased presence of monocytes in vessels, and necrosis of Purkinje cells. Sixteen of the diseased animals (33%) developed a chronic polyarthritis. Eight of these lambs were necropsied; all had lesions in major limb joints, and 3 of 8 also had lesions in the atlanto-occipital joint. At this stage, E. rhusiopathiae was cultured only from the joints in 7 of 8 (87.5%) lambs, but by real-time polymerase chain reaction, we showed persistence of the bacterium in several organs. Pulsed-field gel electrophoresis typing of the bacterial isolates indicated that the same strain caused the acute and chronic disease. Five of 6 (83%) chronically affected animals had amyloidosis of the spleen, and 6 of 8 (75%) had amyloidosis of the liver. All chronically affected animals had a glomerulonephritis, and 6 of 8 (75%) had sparse degeneration in the brain. Ceruloplasmin and haptoglobin were significantly increased in the chronically diseased lambs. These results show that chronic ovine erysipelas is not restricted to joints but is a multisystemic disease.

Fatal Erysipelothrix rhusiopathiae septicemia in two Atlantic dolphins (Stenella frontalis and Tursiops truncatus).

We describe gross, histopathologic, ultrastructural, immunohistochemical, and microbiologic features of acute septicemia by Erysipelothrix rhusiopathiae in an Atlantic spotted dolphin Stenella frontalis and an Atlantic bottlenose dolphin Tursiops truncatus. Generalized lymphadenomegaly and widespread hemorrhages were the most consistent macroscopic findings. Tricavitary effusion and icterus were noted in one individual. Histologically, all organs examined showed numerous variably sized bacillary bacterial emboli (Gram-positive; Ziehl-Neelsen-negative), typically associated with systemic congestion, edema, hemorrhages, and fibrinocellular thrombi. These bacteria were frequently intravascular, either extracellular or intramonocytic/macrophagic, and to a lesser extent, free within the interstitium of parenchymal organs. In both cases, microbiological analysis yielded E. rhusiopathiae. A primary anti-E. rhusiopathiae antibody created in mice from one of the strains isolated allowed positive immunohistochemical detection. Electron microscopy and dual immunohistochemistry with lysozyme and MAC387 antibodies confirmed the intramacrophagic location of the bacilli. E. rhusiopathiae, a known multispecies and zoonotic agent, should be considered as a potential etiologic agent in septicemia cases in free-ranging individuals of these dolphin species.

[Infective endocarditis caused by Erysipelothrix rhusiopathie. Report of one case]. / Endocarditis infecciosa por Erysipelothrix rhusiopathiae.

Erysipelothrix rhusiopathie is an immobile, not sporulated, gram positive bacillus. Man is an accidental host. Infection is acquired through wounds on contact with sick animals or carriers, their products or objects contaminated with their waste. We report a 40 years old tannery male worker, presenting in the emergency room with fever lasting one month. An echocardiogram showed a vegetation and perforation of the aortic valve with severe aortic regurgitation. Blood cultures gave growth to E. rhusiopathiae. The patient was treated with penicillin. After three weeks of treatment an aortic valve replacement with a mechanical valve was performed. At six weeks, he was discharged from the hospital.

Human Erysipelothrix rhusiopathiae Infection: Unsolved Issues and Possible Solutions.

Erysipelothrix rhusiopathiae infection in humans may not be as rare as previously thought. In most cases, the disease is acquired from animals through work-related exposure. Human infection has been reported since the early 1900's up to the present. Unsolved issues associated with this organism include inadequate disease control in animals, difficulty in identification and isolation of the bacteria, diagnostic delay due to unawareness of this uncommon disease or unfamiliarity with the increasingly diverse clinical manifestations, and inappropriate antibiotic use due to misdiagnosis, as well as drug resistance. In this review, we attempt to address the unsolved issues related to human Erysipelothrix infection and suggest possible solutions.

Complete genome assembly and characterization of an outbreak strain of the causative agent of swine erysipelas--Erysipelothrix rhusiopathiae SY1027.

BACKGROUND: Erysipelothrix rhusiopathiae is the causative agent of animal erysipelas and, to a fewer occurrences, human erysipeloid. It is ubiquitous in nature and commensal in diverse species of animals, wild or domestic, from mammals and birds to reptiles and fish. Mechanisms of its virulence and pathogenicity are poorly understood. RESULTS: Making use of the complete genome sequencing of E. rhusiopathiae strain SY1027 and comparative genome analysis between the three highly pathogenic strains (SY1027, Fujisawa and ATCC19414), the genomic structure and putative functional elements, such as pathogenicity island (PAI)-like regions, potential virulence factors and horizontal transferring genes of the bacteria are identified. Strain SY1027 genome is 1,752,910 base pairs long, just 30 kilobases smaller than strain Fujisawa, with the same GC level of 36.36%. It contains 1,845 open reading frames (ORF) predicted by GLIMMER 3.02, of which 1,775 were annotated by PGAAP, 1,757 (~95.23%) were annotated by NCBI nr blast, 1,209 by COG database and 1,076 by KEGG database. 37 potential virulence factors were annotated in strain SY1027 by VFDB, while 19 (~51.35%) of them are common in the 2 strains, 7 of which are potentially related to antibiotic resistance and highly conserved (~98-100% match identity (ID)) amongst the three strains of E. rhusiopathiae and modestly homologous to other gastrointestinal tract-inhabiting Firmicutes (~40% match ID), e.g. Clostridium spp., Enterococcus spp. Genomic island- and pathogenicity island-like regions were also predicted, in which some showed association with tRNA and potential virulence factors. CONCLUSION: Complete genome sequencing of Erysipelothrix rhusiopathiae, the causative agent of animal erysipelas, was performed. Molecular identification of various genomic elements pave the way to the better understanding of mechanisms underlying metabolic capabilities, pathogenicity of swine erysipelas and prospective vaccine targets besides the widely used SpaA antigens.

Erysipelothrix rhusiopathiae contamination in the poultry house environment during erysipelas outbreaks in organic laying hen flocks.

This study investigated organic laying hen farms for the presence of Erysipelothrix rhusiopathiae in the house environment and from potential carriers (i.e. insects and mice) during ongoing erysipelas outbreaks, and compared the obtained isolates with those from laying hens. The samples were investigated by selective culture followed by species-specific polymerase chain reaction on cultures. E. rhusiopathiae was isolated from the spleen, jejunal contents, manure, dust and swabs from water nipples. Three more samples from the house environment tested positive by polymerase chain reaction compared with selective culture alone. Selected isolates were investigated by pulsed-field gel electrophoresis (PFGE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). One farm was represented by isolates from laying hens only, and one of these isolates differed in one PFGE band from the others. Different banding patterns were observed for isolates from laying hens and manure on one farm. On the remaining two farms, the isolates from the house environment and laying hens were identical but differed between farms. Outbreaks reoccurred in the next flock on two of the farms, and different PFGE types were isolated from consecutive flocks. Our results suggest an external source of infection, which would explain the previously reported increased risk of outbreaks in free-range flocks. Contaminated manure and dust may represent sources of transmission. For the isolates, MALDI-TOF MS and biochemical typing results were in agreement but, since the type strain of Erysipelothrix tonsillarum was typed as E. rhusiopathiae using MALDI-TOF MS, further studies into this method are needed.