Brachyspira hyodysenteriae isolate multilocus sequence type dashboard.

This focus article has been prepared by Susanna Williamson, Emma Stubberfield and Anna Brzozowska of the APHA and Jill Thomson of SRUC - Veterinary Consulting Services, Edinburgh.

Treatment of clinical Brachyspira hyodysenteriae with zinc chelate in pigs: a blinded, randomised controlled trial.

BACKGROUND: Brachyspira hyodysenteriae infection in pigs ('swine dysentery') leads to decreased feed conversion, growth losses and mortality. Current countermeasures have the downside of antibiotic resistance (antibiotics) and ecotoxicity (zinc oxide). The aim of this study was to evaluate the effect of a novel zinc chelate (Intra Dysovinol (ID)) on clinical signs of swine dysentery and shedding of B hyodysenteriae under field conditions. METHODS: In a randomised, double-blinded, controlled trial under Good Clinical Practice on two commercial farms, 58 B hyodysenteriae positive pigs from 16 pens received drinking water containing ID, or placebo, during six consecutive days. Faecal quality (consistency, colour, additions) was scored and faeces were analysed for presence of B hyodysenteriae by PCR. ID treatment positively affected faecal quality (consistency) and daily growth rates. RESULTS: At the last treatment day, B hyodysenteriae was not detectable in the faeces of any of the ID-treated animals, while all placebo animals remained B hyodysenteriae positive by PCR. All ID-treated animals recovered, while 5 placebo-treated animals died and 12 placebo pigs required additional treatment before the end of the study (up to 14 days after treatment start). CONCLUSION: This non-antibiotic treatment stopped the clinical signs and shedding of B hyodysenteriae in naturally infected pigs.

Diagnosis of Brachyspira pilosicoli, Brachyspira hyodysenteriae and Brachyspira intermedia in hens and laying hens in the western region of Paraná through bacterial isolation and identification in qPCR / Diagnóstico de Brachyspira pilosicoli, Brachyspira hyodysenteriae e Brachyspira intermedia em aves de postura e matrizes de corte na região oeste do Paraná através do isolamento bacteriano e identificação na qPCR

Bacteria of the genus Brachyspira can cause enteric diseases in poultry causing a decrease in productivity. The occurrence of this disease in chickens has already been verified in countries such as Australia, Italy, and the United States, but in Brazil, until now, epidemiological studies about Brachyspira sp. frequency were only carried out on pig farms. The objective of this study was to evaluate the presence of bacteria of the genus Brachyspira sp. through isolation and confirmation of the species Brachyspira pilosicoli, Brachyspira hyodysenteriae and Brachyspira intermedia using the qPCR technique. Samples from 110 hens aged from 35 to 82 weeks were collected, 40 were from commercial egg farms and 70 were from laying hens matrices. For the first evaluation, bacterial isolation was performed from the feces. Positive samples were submitted to qPCR to identify the three species proposed. Cecum fragments of the birds were collected and fixed in formaldehyde for histological evaluation and counting of goblet cells. Of the 110 samples, 48 characteristic isolates of Brachyspira (43.6%) were obtained and of these in qPCR 13 identified as B. hyodysenteriae (11.8%) and 5 all from the same farm as Brachyspira intermedia (4.5%), 2 samples were positive for both agents (1.8%) and 28 were not characterized by qPCR (25.5%). None histopathological lesions were observed in the chicken cecum and no significant statistical difference was noticed in the count of goblet cells of the positive hens. It can be evidenced by the occurrence of Brachyspira sp. in laying farms and hens in Brazil, with special relevance to Brachyspira intermedia that can be potentially pathogenic for these animals.(AU)

Bactérias do gênero Brachyspira podem ocasionar enfermidades entéricas em aves acarretando a queda de produtividade. A ocorrência desta enfermidade em galinhas já foi verificada em países como a Austrália, Itália e Estados Unidos, porém no Brasil, até o momento, trabalhos epidemiológicos sobre a frequencia de Brachyspira sp. só foram realizados em granjas de suínos. O objetivo deste estudo foi avaliar a presença de bactérias do gênero Brachyspira sp. através do isolamento e confirmação das espécies Brachyspira pilosicoli, Brachyspira hyodysenteriae e Brachyspira intermedia utilizando a técnica de qPCR. Foram coletadas amostras de 110 aves com idade entre 35 e 82 semanas, sendo 40 de granjas de postura comercial e 70 de granjas de matrizes de corte. Para avaliação primeiramente procedeu-se o isolamento bacteriano a partir das fezes. As amostras positivas foram submetidas a qPCR para identificação das três espécies propostas. Fragmentos de ceco das aves foram coletados e fixados em formol para avaliação histológica e contagem de células caliciformes. Das 110 amostras foram obtidos 48 isolamentos característicos de Brachyspira (43,6%) e destes na qPCR 13 identificadas como B. hyodysenteriae (11,8%) e 5 sendo todas da mesma granja (4,5%) como B. intermedia, 2 amostras foram positivas para ambos os agentes (1,8%) e 28 não foram caracterizadas através da qPCR (25,5%). Não foram observadas alterações histopatológicas no ceco e diferença estatística significativa na contagem de células caliciformes das aves positivas. Conclui-se que a Brachyspira sp. é frequente em granjas de poedeiras e matrizes de corte no Brasil, com especial relevância para a B. intermedia que possui potência patogênico para estas aves.(AU)

Coinfection with Entamoeba polecki and Brachyspira hyodysenteriae in a pig with severe diarrhea.

Enteric disease in pigs is usually of multifactorial etiology, including infectious and non-infectious factors. In many cases of endemic diarrhea in weaner-to-finisher pigs, the combination of 2 or more microorganisms leads to aggravation of intestinal lesions and, consequently, clinical signs. We autopsied a 4-mo-old fattening pig with diarrhea and diagnosed severe fibrinonecrotizing typhlocolitis. Numerous spiral-shaped bacteria and amoeba-like PAS-positive protozoa were observed in the cecal and colonic mucosa and submucosa. Brachyspira hyodysenteriae was detected by PCR from colonic content. By in situ hybridization, large numbers of Entamoeba polecki were found within the lamina propria and submucosa; moderate numbers of Blastocystis sp. and scattered trichomonads were present in intestinal content. In addition, Entamoeba polecki, Balantidium spp., Blastocystis sp., and Trichomonas sp. were also detected by PCR.

Predominance of a macrolide-lincosamide-resistant Brachyspira hyodysenteriae of sequence type 196 in Swiss pig herds.

Worldwide emergence of antimicrobial-resistant Brachyspira (B.) hyodysenteriae led us question whether specific clones are present in Switzerland. Fifty-one B. hyodysenteriae isolates originating from 27 different Swiss pig herds sampled between 2010 and 2017 were characterised. Multilocus sequence typing revealed the presence of four different sequence types (STs) ST6, ST66, ST196 and ST197 with ST196 being predominant. Antimicrobial susceptibility to six different antimicrobial agents was determined by measurement of the minimal inhibitory concentration by broth dilution. Isolates were examined for the presence of point mutations and genes known to be associated with antimicrobial resistance in B. hyodysenteriae by PCR and sequence analysis. Forty-one isolates belonging to ST6 (n = 1), ST66 (n = 4) and ST196 (n = 36) exhibited decreased susceptibility to macrolides and lincomycin associated with an A2058 T/G mutation in the 23S rRNA gene. One isolate of ST66 and five isolates of ST196 exhibited decreased susceptibility to doxycycline associated with a G1058C mutation in the 16S rRNA gene. The Swiss B. hyodysenteriae population is characterised by a low genetic diversity, with macrolide-lincosamide-resistant isolates of ST196 being predominant.

Isolation of Brachyspira hyodysenteriae from a crow (Corvus corone) in close proximity to commercial pigs.

The aim of this study was to determine whether crows (Corvus corone) can harbour Brachyspira hyodysenteriae, the cause of swine dysentery, and whether the organism carried by crows is related to strains infecting pigs. B. hyodysenteriae was isolated from one crow in close proximity to two pig farms in Switzerland. This isolate, along with five isolates of B. hyodysenteriae from one of the farms, belonged to sequence type (ST) 66 using multilocus sequence typing. This finding suggests that crows are potential vectors of B. hyodysenteriae, but further studies will be necessary to clarify the role of crows in the epidemiology of this organism.

Phylogenetic diversity, antimicrobial susceptibility and virulence gene profiles of Brachyspira hyodysenteriae isolates from pigs in Germany.

Swine dysentery (SD) is an economically important diarrheal disease in pigs caused by different strongly hemolytic Brachyspira (B.) species, such as B. hyodysenteriae, B. suanatina and B. hampsonii. Possible associations of epidemiologic data, such as multilocus sequence types (STs) to virulence gene profiles and antimicrobial susceptibility are rather scarce, particularly for B. hyodysenteriae isolates from Germany. In this study, B. hyodysenteriae (n = 116) isolated from diarrheic pigs between 1990 and 2016 in Germany were investigated for their STs, susceptibility to the major drugs used for treatment of SD (tiamulin and valnemulin) and genes that were previously linked with virulence and encode for hemolysins (tlyA, tlyB, tlyC, hlyA, BHWA1_RS02885, BHWA1_RS09085, BHWA1_RS04705, and BHWA1_RS02195), outer membrane proteins (OMPs) (bhlp16, bhlp17.6, bhlp29.7, bhmp39f, and bhmp39h) as well as iron acquisition factors (ftnA and bitC). Multilocus sequence typing (MLST) revealed that 79.4% of the isolates belonged to only three STs, namely ST52 (41.4%), ST8 (12.1%), and ST112 (25.9%) which have been observed in other European countries before. Another 24 isolates belonged to twelve new STs (ST113-118, ST120-123, ST131, and ST193). The temporal distribution of STs revealed the presence of new STs as well as the regular presence of ST52 over three decades (1990s-2000s). The proportion of strains that showed resistance to both tiamulin und valnemulin (39.1%) varied considerably among the most frequent STs ranging from 0% (0/14 isolates resistant) in ST8 isolates to 46.7% (14/30), 52.1% (25/48), and 85.7% (6/7) in isolates belonging to ST112, ST52, and ST114, respectively. All hemolysin genes as well as the iron-related gene ftnA and the OMP gene bhlp29.7 were regularly present in the isolates, while the OMP genes bhlp17.6 and bhmp39h could not be detected. Sequence analysis of hemolysin genes of selected isolates revealed co-evolution of tlyB, BHWA1_RS02885, BHWA1_RS09085, and BHWA1_RS02195 with the core genome and suggested independent evolution of tlyA, tlyC, and hlyA. Our data indicate that in Germany, swine dysentery might be caused by a limited number of B. hyodysenteriae clonal groups. Major STs (ST8, ST52, and ST112) are shared with other countries in Europe suggesting a possible role of the European intra-Community trade of pigs in the dissemination of certain clones. The identification of several novel STs, some of which are single or double locus variants of ST52, may on the other hand hint towards an ongoing diversification of the pathogen in the studied area. The linkage of pleuromutilin susceptibility and sequence type of an isolate might reflect a clonal expansion of the underlying resistance mechanism, namely mutations in the ribosomal RNA genes. A linkage between single virulence-associated genes (VAGs) or even VAG patterns and the phylogenetic background of the isolates could not be established, since almost all VAGs were regularly present in the isolates.

The role of transportation in the spread of Brachyspira hyodysenteriae in fattening farms.

BACKGROUND: Direct and indirect contact among animals and holdings are important in the spread of Brachyspira hyodysenteriae. The objective of this study was to investigate the role of slaughterhouse vehicles in spreading B. hyodysenteriae between unconnected farms. RESULTS: Multilocus sequence typing (MLST) and Multiple Locus Variable number tandem repeat Analysis (MLVA) were used to characterize B. hyodysenteriae strains isolated from trucks. Before cleaning, 976 batches of finishing pigs transported by 174 trucks from 540 herds were sampled. After cleaning, 763 of the 976 batches were also sampled. Sixty-one of 976 and 4 of 763 environmental swabs collected from trucks before and after cleaning and disinfection operations, respectively, were positive for B. hyodysenteriae. The 65 isolates in this study originated from 48 farms. Trucks were classified into five categories based on the number of visited farms as follows: category 1: 1-5 farms, category 2: 6-10 farms, category 3: 11-15 farms, category 4: 16-20 farms, category 5: >21 farms. Although the largest number of vehicles examined belonged to category 1, the highest percentage of vehicles positive for B. hyodysenteriae was observed in categories 3, 4 and 5. Specifically, 90.9% of trucks belonging to category 5 were positive for B. hyodysenteriae, followed by categories 4 and 3 with 85.7% and 83.3%, respectively. The results of MLST and MLVA suggest that trucks transporting pigs from a high number of farms also play a critical role in spreading different B. hyodysenteriae genetic profiles. STVT 83-3, which seems to be the current dominant type in Italy, was identified in 56.25% of genotyped isolates. The genetic diversity of isolated strains from trucks was high, particularly, in truck categories 3, 4 and 5. This result confirmed that MLST and MLVA can support the study of epidemiological links between different B. hyodysenteriae farm strains. CONCLUSIONS: This study highlights the potential role of shipments in B. hyodysenteriae spread. Moreover, it emphasizes the importance of strict vehicle hygiene practices for biosecurity programmes.

Brachyspira hyodysenteriae detection in the large intestine of slaughtered pigs.

Detection of subclinical Brachyspira hyodysenteriae infection in pig herds using feces is challenging. However, the ability to detect the pathogen in intestinal samples of slaughtered pigs has not been investigated, to our knowledge. Therefore, we determined the detection of B. hyodysenteriae in the colon, cecum, and rectum from slaughtered pigs. We analyzed the correlation between detection rates and intestinal lesions, ingesta or fecal consistency, and time from sample collection until processing. A total of 400 ingesta-mucosal (colon, cecum) and 200 fecal (rectum) samples from 200 pigs originating from 20 different herds were bacteriologically examined using selective culture followed by Brachyspira spp. identification by PCR and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Ingesta or fecal consistency and intestinal lesions were scored. Brachyspira hyodysenteriae was detected in 23 samples from 16 intestines originating from 7 herds. Brachyspira spp. were detected in 96 samples. More intestinal (16) than fecal (7) samples tested positive for B. hyodysenteriae. For Brachyspira spp., this difference was significant (69 vs. 27; p < 0.01). In particular, colon samples tested positive ( n = 42, p = 0.06). Most (91%) of the intestines showed no lesions typical for clinical B. hyodysenteriae infection, and median ingesta or fecal consistency was "soft and formed," indicating subclinical infection, colonization, or absence of infection. Ingesta from slaughtered pigs, in particular from the colon and sites with lesions, is useful material for detection of B. hyodysenteriae.

Characterization of Brachyspira hyodysenteriae isolates from Italy by multilocus sequence typing and multiple locus variable number tandem repeat analysis.

AIMS: To evaluate and compare the capabilities of multilocus sequence typing (MLST) and multiple locus variable number tandem repeat analysis (MLVA) techniques to characterize Brachyspira hyodysenteriae isolates and to investigate the relationship between pleuromutilin resistance and genetic variability. METHODS AND RESULTS: MLST genotyping was performed on 180 B. hyodysenteriae isolates, and the results were evaluated considering profiles from 108 other strains previously reported in the database. In total, 37 sequence types were obtained. The MLVA approach completely characterized 172 strains and grouped the isolates into 22 different profiles. The combination of MLST and MLVA showed a slight increase in the discriminatory power, identifying 33 joint profiles. An antibiotic resistance analysis showed a reduction in the susceptibility to pleuromutilins over time, and a weak association between susceptibility to valnemulin and inclusion in clonal complex 4. CONCLUSION: MLST and MLVA are reliable methods for characterizing B. hyodysenteriae strains and they have comparable discriminatory power. SIGNIFICANCE AND IMPACT OF THE STUDY: The genotyping of B. hyodysenteriae isolates and a database of all the genetic profiles collected during the diagnostic activities could support traditional epidemiological investigations in identifying infection sources and routes of transmission among herds, and in developing more effective control measures.

Minimum inhibitory concentration of Brazilian Brachyspira hyodysenteriae strains / Concentração inibitória mínima de cepas Brachyspira hyodysenteriae brasileiras

The objectives of this study were to characterize Brachyspira hyodysenteriae isolates and to evaluate the antimicrobial susceptibility patterns of strains obtained from pigs in Brazil based on the minimal inhibitory concentration test (MIC). The MIC was performed for 22 B. hyodysenteriae isolates obtained from 2011 to 2013 using the following antimicrobial drugs: tylosin, tiamulin, valnemulin, doxycycline, lincomycin and tylvalosin. Outbreaks of swine dysentery were diagnosed based on clinical presentation, bacterial isolation, gross and microscopic lesions, duplex PCR for B. hyodysenteriae and B. pilosicoli and nox gene sequencing. All obtained MIC values were consistently higher or equal to the microbiological cut-off described in the literature. The MIC 90 values for the tested drugs were 8µg/ml for doxycycline, >4µg/ml for valnemulin, 8µg/ml for tiamulin, 32µg/ml for tylvalosin, >64µg/ml for lincomycin and >128µg/ml for tylosin. These results largely corroborate those reported in the literature. Tiamulin, doxycycline and tylvalosin showed the lowest MIC results. All of the samples subjected to phylogenetic analysis based on the nox gene sequence exhibited similar results, showing 100% identity to B. hyodysenteriae. This is the first study describing the MIC pattern of B. hyodysenteriae isolated in Brazil.(AU)

Os objetivos deste trabalho foram a caracterização de isolados de Brachyspira hyodysenteriae e avaliar os padrões de sensibilidade antimicrobiana de isolados obtidos a partir de suínos no Brasil com base no teste de concentração inibitória mínima (MIC). A MIC foi realizada em 22 isolados de B. hyodysenteriae obtidos entre 2011 a 2013 usando os seguintes antimicrobianos: tilosina, tiamulina, valnemulina, doxiciclina, lincomicina e tilvalosina. Surtos de disenteria suína foram diagnosticados com base na apresentação clínica, isolamento bacteriano, lesões macroscópicas e microscópicas, PCR duplex para B. hyodysenteriae e B. pilosicoli e sequenciamento do gene nox. Todos os valores de MIC obtidos foram consistentemente mais elevados ou igual ao ponto de corte microbiológica descrito na literatura. Os valores de MIC 90 para os fármacos testados foram de 8 µg / mL para a doxiciclina, > 4 µg/ml de valnemulina, 8 µg / mL para a tiamulina, 32 µg / ml para tilvalosina, > 64 µg / ml para a lincomicina e > 128 µg / ml de tilosina. Estes resultados corroboram em grande parte com os relatados na literatura. Tiamulina, doxiciclina e tilvalosina apresentaram os menores resultados de MIC. Todas as amostras submetidas à análise filogenética com base na sequência do gene nox exibiram resultados semelhantes, indicando 100% de identidade com B. hyodysenteriae. Este é o primeiro estudo que descreve o padrão MIC de B. hyodysenteriae isoladas no Brasil.(AU)

An update of Brachyspira hyodysenteriae serotyping.

Brachyspira (B.) hyodysenteriae the causative agent of swine dysentery (SD) has been divided into 9 serotypes on basis of its lipooligosaccharide (LOS). Knowledge on circulating serotypes in Europe, however, is rare. Regarding that immunity to SD is serotype specific an update of B. hyodysenteriae serotyping was undertaken. A LOS band of 10 to 25kDa was identified being appropriate for this purpose. Isolates from Germany, Spain, Denmark, USA and Japan were characterized in the immunoblot by sera raised to serotypes 1 through 7, serogroups H and I (reference strains) and to eight German strains. In total, 57 (51%) isolates responded to at least one of the antisera. Regarding German isolates (n=75) only 35 (46.7%) were identified but mainly by antisera to German strains. Positive Spanish isolates (12 of 17) yielded similar results. In contrast, positively reacting Danish isolates (9 of 12) were mainly identified by antisera to the reference strains as it was the case for recent U.S. (1 of 8) and Japanese isolates (3 of 5). Results indicate that B. hyodysenteriae has a high degree of serological heterogeneity that has probably differently developed in diverse geographical areas over time. This situation represents a challenge for vaccine development.

Antimicrobial susceptibility of Brachyspira hyodysenteriae in Switzerland.

INTRODUCTION: Brachyspira (B.) hyodysenteriae is the causative agent of swine dysentery (SD), a severe mucohaemorrhagic diarrheal disease in pigs worldwide. So far, the antimicrobial susceptibility patterns of B. hyodysenteriae in Switzerland have not been investigated. Therefore, a panel of 30 porcine B. hyodysenteriae isolates were tested against 6 antimicrobial agents by using the VetMIC Brachy panel, a broth microdilution test. Tiamulin and valnemulin showed high antimicrobial activity inhibiting all isolates at low concentrations. The susceptibility testing of doxycycline revealed values from ≤0.25 µg/ ml (47%) to 2 µg/ml (10%). The MIC values of lincomycin ranged between ≤0.5 µg/ml (30%) and 32 µg/ml (43%). For tylosin, 57% of the isolates could not be inhibited at the highest concentration of ≥128 µg/ml. The MIC values for tylvalosin were between ≤0.25 µg/ml (10%) and 8 µg/ml (20%). These findings reveal Switzerland's favourable situation compared to other European countries. Above all, tiamulin and valnemulin are still effective antimicrobial agents and can be further used for the treatment of SD.

INTRODUCTION: Brachyspira (B.) hyodysenteriae est l'agent de la dysenterie porcine, une affection diarrhéique muco-hémorragique grave des porcs connue dans le monde entier. Jusqu'à ce jour, la sensibilité aux antibiotiques B. hyodysenteriae n'avait pas été étudiée en Suisse. C'est pour cela qu'on a examiné, au moyen du test de micro dilution VetMIC Brachy panel, un choix de 30 isolats porcins de B. hyodysenteriae quant à leur sensibilité face à 6 substances antimicrobiennes. La Tiamuline et la Valnémuline ont montré une activité antimicrobienne élevée, bloquant tous les isolats à de faibles concentrations. Les tests de sensibilité vis-à-vis de la Doxycilline ont donné des valeurs comprises entre ≤0.25 µg/ml (47%) et 2 µg/ml (10%). Les valeurs de CMI de la Lincomycine variaient entre ≤0.5 µg/ml (30%) et 32 µg/ml (43%). Avec la Tylosine, 57% des isolats n'ont pas pu être bloqués avec la concentration la plus élevée de ≥128 µg/ml. Les valeurs de CMI pour la Tylvalosine se situaient entre ≤0.25 µg/ml (10%) et 8 µg/ml (20%). Ces résultats montrent que la situation suisse est favorable en regard d'autres pays européens. La Tiamuline et la Valnémuline en particulier restent des substances antimicrobiennes efficaces qui peuvent continuer à être utiliser pour lutter contre la dysenterie porcine.

Comparison of Brachyspira hyodysenteriae Isolates Recovered from Pigs in Apparently Healthy Multiplier Herds with Isolates from Herds with Swine Dysentery.

Swine dysentery (SD) is a mucohaemorrhagic colitis of grower/finisher pigs classically resulting from infection by the anaerobic intestinal spirochaete Brachyspira hyodysenteriae. This study aimed to determine whether B. hyodysenteriae isolates from pigs in three healthy German multiplier herds supplying gilts to other farms differed from isolates from nine German production herds with SD. Isolates were subjected to whole genomic sequencing, and in silico multilocus sequence typing showed that those from the three multiplier herds were of previously undescribed sequence types (ST132, ST133 and ST134), with all isolates from the same herd having the same ST. All isolates were examined for the presence of 332 genes encoding predicted virulence or virulence lifestyle associated factors, and these were well conserved. Isolates from one multiplier herd were atypical in being weakly haemolytic: they had 10 amino acid substitutions in the haemolysin III protein and five in the haemolysin activation protein compared to reference strain WA1, and had a disruption in the promoter site of the hlyA gene. These changes likely contribute to the weakly haemolytic phenotype and putative lack of virulence. These same isolates also had nine base pair insertions in the iron metabolism genes bitB and bitC and lacked five of six plasmid genes that previously have been associated with colonisation. Other overall differences between isolates from the different herds were in genes from three of five outer membrane proteins, which were not found in all the isolates, and in members of a block of six plasmid genes. Isolates from three herds with SD had all six plasmid genes, while isolates lacking some of these genes were found in the three healthy herds-but also in isolates from six herds with SD. Other differences in genes of unknown function or in gene expression may contribute to variation in virulence; alternatively, superior husbandry and better general health may have made pigs in the two multiplier herds colonised by "typical" strongly haemolytic isolates less susceptible to disease expression.

Brachyspira hyodysenteriae isolated from apparently healthy pig herds following an evaluation of a prototype commercial serological ELISA.

Swine dysentery (SD) is a disease mainly of grower/finisher pigs characterised by severe mucohaemorrhagic colitis. The classical aetiological agent is the anaerobic intestinal spirochaete Brachyspira hyodysenteriae, although "Brachyspira hampsonii" and Brachyspira suanatina also cause SD. This study reports on the unexpected isolation of B. hyodysenteriae from pigs in apparently healthy herds that gave positive reactions when tested with a prototype commercial serological ELISA for detecting herds infected with B. hyodysenteriae (Priocheck(®)Brachyspira porcine Ab ELISA). The ELISA was tested with sera collected at abattoirs from 1770 slaughtered pigs from 30 Australian herds, including 12 with a history of SD and18 that were considered by their consulting veterinarians to be healthy. The latter herds had no history of SD and did not routinely use antimicrobials that may have masked the disease. Based on the recommended ELISA cut-off value, 25 herds were recorded as showing evidence of infection, including 11 of 12 herds that were considered infected by the submitters and 14 of the 18 "healthy" herds. When faecal or colonic wall samples from 11 of the 14 "false positive" herds subsequently were culturing 6-24 months after the original ELISA testing was completed, different strains of B. hyodysenteriae were isolated from six herds, including a high-health status breeding herd. The existence of apparently healthy herds that are colonised by B. hyodysenteriae has major implications for the control of SD. Had the ELISA not been trialled it is unlikely that colonic samples from these herds would have been cultured and the colonisation identified.

Occurrence of Brachyspira hyodysenteriae in multiplier pig herds in Switzerland.

OBJECTIVE: This research was aimed to determine the occurrence of Brachyspira (B.) hyodysenteriae in Swiss multiplier pig herds. MATERIALS AND METHODS: In a pilot study a direct real-time polymerase chain reaction (PCR) method for B. hyodysenteriae was compared to culture followed by PCR on 106 samples from three herds. Subsequently 40 multiplier herds were epidemiologically characterized and analysed for the presence of B. hyodysenteriae using direct PCR on 1412 rectal swabs. For external validation 20 swabs obtained from two positive conventional herds were analysed. RESULTS: The comparison of direct PCR with culture followed by PCR resulted in a moderate agreement (kappa index: 0.58). In the two conventional herds, 35% of the samples (7/20) tested positive. Samples from 39 multipliers tested negative. In one multiplier herd, 25% (9/36) of the samples tested PCR positive. Risk factors in the multiplier herd may have been rodents or birds, but not pig purchase. CONCLUSION AND CLINICAL RELEVANCE: B. hyodysenteriae have been detected in a Swiss multiplier herd, which underlines the threat of potential spread by replacement pigs. Consequently, a Brachyspira monitoring programme was established for Swiss multiplier herds.

Drug-susceptibility of isolates of Brachyspira hyodysenteriae isolated from colonic mucosal specimens of pigs collected from slaughter houses in Japan in 2009.

Twenty nine isolates identified as Brachyspira hyodysenteriae were most susceptible to carbadox and metronidazole, whereas they were resistant to macrolides. The isolates showed intermediate susceptibility to tiamulin, lincomycin, penicillin G, ampicillin, chloramphenicol, tetracycline, enrofloxacin and valnemulin, with MIC50 values ranging from 0.39 to 3.13.

Comparison of culture, polymerase chain reaction, and fluorescent in situ hybridization for detection of Brachyspira hyodysenteriae and "Brachyspira hampsonii" in pig feces.

Swine dysentery is characterized by mucohemorrhagic diarrhea and can occur following infection by Brachyspira hyodysenteriae or "Brachyspira hampsonii ". A definitive diagnosis is often based on the isolation of strongly beta-hemolytic spirochetes from selective culture or by the application of species-specific polymerase chain reaction (PCR) assays directly to feces. While culture is highly sensitive, it typically requires 6 or more days to complete, and PCR, although rapid, can be limited by fecal inhibition. Fluorescent in situ hybridization (FISH) has been described in formalin-fixed tissues; however, completion requires approximately 2 days. Because of the time constraints of available assays, a same-day FISH assay was developed to detect B. hyodysenteriae and "B. hampsonii " in pig feces using previously described oligonucleotide probes Hyo1210 and Hamp1210 for B. hyodysenteriae and "B. hampsonii", respectively. In situ hybridization was simultaneously compared with culture and PCR on feces spiked with progressive dilutions of spirochetes to determine the threshold of detection for each assay at 0 and 48 hr. The PCR assay on fresh feces and FISH on formalin-fixed feces had similar levels of detection. Culture was the most sensitive method, detecting the target spirochetes at least 2 log-dilutions less when compared to other assays 48 hr after sample preparation. Fluorescent in situ hybridization also effectively detected both target species in formalin-fixed feces from inoculated pigs as part of a previous experiment. Accordingly, FISH on formalin-fixed feces from clinically affected pigs can provide same-day identification and preliminary speciation of spirochetes associated with swine dysentery in North America.