Experimental Infection of Pigs with a ST 245 Brachyspira hyodysenteriae Isolated from an Asymptomatic Pig in a Herd with No History of Swine Dysentery.

Swine dysentery (SD) is characterized by a severe mucohemorrhagic colitis caused by infection with Brachyspira species. In infected herds the disease causes considerable financial loss due to mortality, slow growth rates, poor feed conversion, and costs of treatment. B. hyodysenteriae is the most common etiological agent of SD and infection is usually associated with disease. However, isolated reports have described low pathogenic strains of B. hyodysenteriae. The aim of this study was to describe an experimental infection trial using a subclinical B. hyodysenteriae isolated from an animal without clinical signs and from a disease-free herd, to evaluate the pathogenicity and clinical pathological characteristics compared to a highly clinical isolate. Forty-eight 5-week-old pigs were divided into three groups: control, clinical and the subclinical isolates. The first detection/isolation of B. hyodysenteriae in samples of the animals challenged with a known clinical B. hyodysenteriae strain (clinical group) occurred 5th day post inoculation. Considering the whole period of the study, 11/16 animals from this group were qPCR positive in fecal samples, and diarrhea was observed in 10/16 pigs. In the subclinical isolate group, one animal had diarrhea. There were SD large intestine lesions in 3 animals at necropsy and positive B. hyodysenteriae isolation in 7/15 samples of the subclinical group. In the control group, no diarrhea, gross/microscopic lesions, or qPCR positivity were observed. Clinical signs, bacterial isolation, macroscopic and histologic lesions were significantly difference among groups, demonstrating low pathogenicity of the subclinical isolate in susceptible pigs.

Diversity and potential genetic relationships amongst Brazilian Brachyspira hyodysenteriae isolates from cases of swine dysentery.

The aim of this study was to evaluate genetic diversity, distribution, evolution and population structure of Brazilian Brachyspira hyodysenteriae strains isolated from swine. Multilocus Sequence Typing (MLST) analysis using seven housekeeping genes was applied to 46 isolates obtained from outbreaks of swine dysentery that occurred between 2011 and 2015 in the states of Minas Gerais, São Paulo, Mato Grosso, Rio Grande do Sul and Santa Catarina. Historical isolates from Rio Grande do Sul obtained in 1998 were also included in the study. An independent international profile of the global sequences deposited in the B. hyodysenteriae database was used for comparisons with the Brazilian strains. All isolates from 2011 to 2015 were classified into nine sequence type (STs) and divided into four clonal complexes. These findings indicated genetic relationships among the B. hyodysenteriae from different Brazilian states, among historical strains isolated in 1998 and from recent outbreaks, and relatedness with global isolates. Seven STs were unique and, to date, only reported in Brazil.

Use of oral fluids to detect anti Lawsonia intracellularis antibodies in experimentally infected pigs / Utilização de fluidos orais para detecção de anticorpos anti Lawsonia intracellularis em suínos experimentalmente infectados

Several pathogens and antibodies derived from serum or produced in tissues associated with the oral cavity are present in the oral fluid (OF). Considering the applicability of this alternative sample, recent studies in veterinary medicine have tested OF as a replacement for serum in diagnostic assays. The aim of this study was to standardize the immunoperoxidase monolayer assay (IPMA) to detect anti-Lawsonia intracellularis immunoglobulin A (IgA) and immunoglobulin G (IgG) in OF samples from experimentally infected pigs. Sixty-two pigs were divided into two groups: control (T1, n=30) and inoculated with L. intracellularis (T2, n=32). Blood, OF and fecal samples were collected at 0, 7, 14, 21, 28 and 42 days post-inoculation (dpi). Some adaptations of the standard technique for serum were made to IPMA for the detection of IgA and IgG in OF. The IPMA showed high specificity and sensitivity for serum samples and high specificity and moderate sensitivity for the detection of IgA and IgG in OF. There was high agreement between the results of serum IgG and OF IgA and IgG. Based on our results, oral fluid samples may be used for the evaluation and determination of anti-L. intracellularis antibodies in pigs, but not for individual diagnosis of swine proliferative enteropathy.(AU)

Vários patógenos e anticorpos derivados do soro ou produzidos em tecidos associados a cavidade oral estão presentes no fluido oral (FO). Considerando a aplicabilidade dessa amostra alternativa, estudos recentes em medicina veterinária têm testado o FO como substituto do soro para testes diagnósticos. O objetivo desse estudo foi padronizar a imunoperoxidase em monocamada de célula (IPMC) para a detecção de imunoglobulina A e imunoglobulina G anti-Lawsonia intracellularis em amostras de FO de suínos experimentalmente infectados. Um total de 62 suínos foram divididos em dois grupos: controle (T1, n=30) e inoculados com L. intracellularis (T2, n=32). Sangue, FO e amostras de fezes foram coletados aos 0, 7,14, 21, 28 e 42 dias após a inoculação (dpi). Algumas adaptações da técnica foram realizadas na técnica padrão da IPMC para a detecção de IgA e IgG. A IPMC demostrou alta especificidade e sensibilidade para amostras de soro e alta especificidade de moderada sensibilidade para a detecção de IgA e IgG em FO. Houve alta concordância entre resultados de detecção de IgG em soro com a IgA e IgG em amostras de FO. Baseado em nossos resultados, amostras de fluido oral podem ser usadas em avaliações e detecção de anticorpos anti-L. intracellularis em suínos, porém não de forma individual.(AU)

Evaluation of the involvement of mice (Mus musculus) in the epidemiology of porcine proliferative enteropathy.

The aim of this study was to evaluate the fecal-oral transmission of L. intracellularis between mice and pigs. The study was divided into two parts. The first part aimed to determine whether mice could be infected by feces from pigs that are experimentally infected with L. intracellularis. Thirty-four Swiss mice received L. intracellularis PCR-positive feces from experimentally infected pigs (M1) for four consecutive days. Twelve other mice received swine negative feces (M2). Pools of mice feces were collected on alternating days post-exposure (dpe). The second part of the study aimed to test whether pigs could be infected when exposed to L. intracellularis PCR-positive feces from experimentally infected mice. Twelve 5-week-old pigs received feed mixed with L. intracellularis PCR-positive mice feces (P1), while the other two pigs received PCR-negative mice feces (P2) for four consecutive days. In the first study, the amount of L. intracellularis provided to M1 boxes per day was between 106 and 108. Mice shed, an average of 104 bacterial units every collection day. Three mice from M1 were positive for L. intracellularis by immunohistochemistry (IHC) at the end of the study. In the second part of the study, pigs in P1 received an average of 105 bacterial units per day. Ten pigs were infected by L. intracellularis based on positive qPCR and/or immunohistochemistry and serology results. These pigs shed an average of 104L. intracellularis/g of feces. Mice and pigs experimentally infected with L. intracellularis can infect each other, therefore, rodents should be considered players in the epidemiology of this disease in pig farms.

Virulence profiles of enterotoxigenic Escherichia coli isolated from piglets with post-weaning diarrhea and classification according to fecal consistency / Perfis de virulência de Escherichia coli enterotoxigênica isoladas de leitões desmamados com diarreia do Sul do Brasil e classificação das amostras de acordo com a consistência fecal

The aim of this study was to assess the frequency and association of virulence factors of Escherichia (E.) coli isolated from weaned piglets with diarrhea and to correlate it with fecal consistency. A total of 152 rectal swabs were collected from 25-40 day-old piglets with diarrhea, in farms of Southern Brazil. Phenotypical and molecular techniques were used for bacterial isolation, characterization and classification of enterotoxigenic E. coli (ETEC) pathotypes. Statistical analysis was carried out to determine the frequency of virulence factors and virotypes, of fimbriae F4, F5, F6, F18, F41 and toxins LT, STa, STb and STx2e. Out of 456 E. coli isolates, 287 (62.9%) samples showed significant growth of E. coli. Among them, 194 (67.6%) samples showed at least one virulence factor, indicating that ETEC is an important etiological agent of diarrhea in weaned piglets. Higher frequencies were found of fimbria F4 and F18 and enterotoxins LT, STa and STb. Significant association was found to F4, LT, STa and STb; between F18 and STa and STx2e; between F5 and LT, STa and STb. The most frequent virotypes were F18-STa, F4-LT-STa-STb, F4-STa, F4-LT-STb and F18-STa-STx2e. Beta-hemolysis was observed in 47.4% of samples and there was significant association between hemolytic samples and virulence factors F4, F18, STa and STx2e. Regarding fecal consistency, there was significant association of liquid feces and F4 fimbria, STa toxin and virotypes F4-STa and F4-F5-LT-STa-STb. Since there was significant association of ETEC and liquid feces in nursery piglets, it is important to prioritize the sampling of liquid feces for the diagnosis etiologic cause of diarrhea.

O objetivo deste estudo foi avaliar a frequência e associação de fatores de virulência de Escherichia (E.) coli isoladas de leitões desmamados com diarreia e correlacioná-la com consistência fecal. Suabes retais foram coletados em leitões com 25-40 dias de idade com sinal clínico de diarreia, em granjas do Sul do Brasil, totalizando 456 amostras. Foram utilizadas técnicas fenotípicas e moleculares para isolamento bacteriano, caracterização e classificação de patotipos de E. coli enterotoxigênica (ETEC). A análise estatística foi realizada para determinar a frequência de fatores de virulência e virotipos, de fímbrias F4, F5, F6, F18, F41 e toxinas LT, STa, STB e STx2e. Duzentas e oitenta e sete (62,9%) amostras apresentaram crescimento significativo de E. coli. Entre os quais, 194 (67,6%) amostras apresentaram pelo menos um fator de virulência, indicando que ETEC é um importante agente etiológico de diarreia em leitões desmamados. As frequências mais elevadas foram encontradas para as fímbrias F4 e F18 e enterotoxinas LT, STa e STb. Associação significativa foi encontrada para F4, LT, STa e STb; entre F18 e STa e STx2e; entre F5 e LT, STa e STb. Os virotipos mais frequentes foram F18-STa, F4-LT-STa-STb, F4-STa, F4-LT-STb e F18-STa-STx2e. Beta-hemólise foi observada em 47,4% das amostras e houve associação significativa entre amostras hemolíticas e fatores de virulência F4, F18, STa e STx2e. Quanto consistência fecal, houve associação significativa de fezes líquidas e fímbria F4, toxina STa e virotipos F4-STa e F4-F5-LT-STa-STb. A associação significativa da ETEC e fezes líquidas em leitões de creche, é importante para priorizar a amostragem de fezes com essa consistência para no diagnóstico etiológico da diarreia.