This thesis is an investigation of two common skin conditions of pigs: exudative epidermitis (EE) and ear necrosis (EN). The cause of exudative epidermitis and risk factors are well understood, however the study was prompted because of reports of treatment failure. A survey of veterinary practitioners (n=15) and pork producers (n=58) was conducted to determine which treatments are commonly used. Amongst farmer respondents topical treatments were often used and in serious cases injectable penicillin G was administered. Thirty farms with a history of EE were visited and skin samples taken from affected pigs. The antimicrobial resistance pattern for isolates of Staphylococcus hyicus and Staphylococcus aureus revealed that almost all isolates were resistant to penicillin G and ampicillin. In addition, certain isolates of S. hyicus as well as S. aureus were shown to possess the mecA gene which is associated with resistance to methicillin. The presence of widespread resistance to penicillin G among staphylococci isolates suggests a reason for poor treatment response. The presence of the mecA gene in staphylococci other than S. aureus recovered from pigs has not been reported before and is of interest from a public health standpoint. A second study investigated EN. The causative agent(s) and the associated risk factors are not well understood. Eleven case farms were visited and skin biopsies and oral swabs taken from pigs in early, mid and late stages of the disease. Bacteriological culturing was performed for staphylococci and spirochetes as well as histological examination of the biopsy samples. Farm-level risk factors were assessed on 14 case farms and 9 control farms. Staphylococci were generally recovered in abundance from the majority of samples but spirochetes were not cultured and only identified microscopically in a small number of tissue samples. Histology revealed that the disease appeared to occur first as a lesion on the epidermal surface that caused tissue damage and led to subsequent invasion of the dermis. This pathogenesis was consistent with the hypothesis that staphylococci colonize the skin surface and produce exfoliating toxins. Ear biting was noted to be commonly present and may be an important contributing factor. / Ontario Pork Animal Health Strategic Initiative Fund Ontario Ministry of Agriculture, Food and Rural Affairs(OMAFRA) Ontario Veterinary College, University of Guelph

O presente estudo teve o objetivo de avaliar o perfil de sensibilidade in vitro de 171 isolados de Staphylococcus hyicus a nove antimicrobianos utilizados na suinocultura. A coleta das amostras foi realizada através de suabes de pele de leitões das fases de maternidade e creche provenientes de casos de epidermite exsudativa. As amostras foram submetidas ao isolamento e identificação e compreenderam dois grupos, classificadas de acordo com o período em que foram coletadas. O primeiro grupo foi formado por amostras históricas (80 isolados) provenientes de estudos anteriores entre 1975 a 1984 no Rio Grande do Sul, e mantidos liofilizados no laboratório de sanidade do Setor de Suínos (FAVET-UFRGS), e o segundo grupo (91 isolados) coletados no ano de 2012 nos estados do Rio Grande do Sul, Santa Catarina, Paraná e Minas Gerais. A realização do teste de susceptibilidade foi feita utilizando a técnica de diluição em ágar conforme protocolo M31-A3 do CLSI. Através de valores de Concentração Inibitória Mínima (CIM), foi obtido o perfil quantitativo de resistência em relação a nove antimicrobianos utilizados na suinocultura. A análise estatística possibilitou a avaliação de mudanças entre os dois grupos de amostras isoladas em diferentes épocas. Os resultados obtidos nesse estudo revelaram que para todas as cepas obtidas os beta-lactâmicos (ceftiofur e amoxicilina) foram os antimicrobianos mais ativos, com CIM para 90% dos isolados históricos (CIM90) de 0.5 μg/mL e 2.0 μg/mL para isolados recentes. A lincomicina, sulfametoxazol e tilmicosina foram os antimicrobianos menos ativos, com CIM90 variando de 128 a 256 μg/mL. O aumento na resistência entre o grupo de amostras históricas e recentes foi observado em seis dos nove antimicrobianos testados (amoxicilina, enrofloxacina, florfenicol, lincomicina, tilmicosina e tiamulina), em particular para a enrofloxacina e tiamulina. No caso do sulfametoxazole e tetraciclina, não foram observadas diferenças significativas na resistência, entretanto altos valores de CIM foram observados nos dois grupos avaliados (p<0,05). / This study was performed to evaluate the "in vitro" susceptibility profile of 171 Staphylococcus hyicus isolates from cases of exudative epidermitis to nine antibiotics used in pig production. Sample consisted of skin swabs from weanling and nursery piglets from farms suspected of exudative epidermitis. Samples were processed for bacterial isolation and identification and divided in two groups, according to the time of collection. The first group comprised historical samples (80 isolates) from previous studies (1975-1984) conducted in the state of Rio Grande do Sul, and stocked lyophilized in Swine Health Lab (FAVET-UFRGS), and the other group (91 isolates) formed by isolates collected in 2012 in the states of Rio Grande do Sul, Santa Catarina, Paraná and Minas Gerais, Brazil. The test was carried out using agar dilution protocol, according to M31-A3 CLSI. Through Minimal Inhibitory Concentrations (MIC) data, analysis was performed to get a quantitative profile of resistance to antimicrobials. Statistical analysis was performed to evaluate changes in resistance between the groups studied. Results showed that beta-lactam (ceftiofur and amoxicillin) were the most active antimicrobials for all strains tested, with the lowest MIC for inhibition of 90% of isolates (MIC90) of 0.5 μg/ml for historical isolates and of 2.0 μg/ml for recent isolates. Lincomycin, sulfamethoxazole and tilmicosin were the less active antimicrobials, with MIC90 varying from 128 to 256 μg/ml. Significant increase in resistance between historical and recent strains was observed for six out of nine antimicrobials tested (amoxicillin, enrofloxacin, florfenicol, lincomycin, tilmicosin and tiamulin), in particular for enrofloxacin e tiamulin. For sulfamethoxazole and tetracycline there was no significant differences in resistance between strains collected in different periods, however high MIC values were observed for these drugs.

O presente estudo teve o objetivo de avaliar o perfil de sensibilidade in vitro de 171 isolados de Staphylococcus hyicus a nove antimicrobianos utilizados na suinocultura. A coleta das amostras foi realizada através de suabes de pele de leitões das fases de maternidade e creche provenientes de casos de epidermite exsudativa. As amostras foram submetidas ao isolamento e identificação e compreenderam dois grupos, classificadas de acordo com o período em que foram coletadas. O primeiro grupo foi formado por amostras históricas (80 isolados) provenientes de estudos anteriores entre 1975 a 1984 no Rio Grande do Sul, e mantidos liofilizados no laboratório de sanidade do Setor de Suínos (FAVET-UFRGS), e o segundo grupo (91 isolados) coletados no ano de 2012 nos estados do Rio Grande do Sul, Santa Catarina, Paraná e Minas Gerais. A realização do teste de susceptibilidade foi feita utilizando a técnica de diluição em ágar conforme protocolo M31-A3 do CLSI. Através de valores de Concentração Inibitória Mínima (CIM), foi obtido o perfil quantitativo de resistência em relação a nove antimicrobianos utilizados na suinocultura. A análise estatística possibilitou a avaliação de mudanças entre os dois grupos de amostras isoladas em diferentes épocas. Os resultados obtidos nesse estudo revelaram que para todas as cepas obtidas os beta-lactâmicos (ceftiofur e amoxicilina) foram os antimicrobianos mais ativos, com CIM para 90% dos isolados históricos (CIM90) de 0.5 μg/mL e 2.0 μg/mL para isolados recentes. A lincomicina, sulfametoxazol e tilmicosina foram os antimicrobianos menos ativos, com CIM90 variando de 128 a 256 μg/mL. O aumento na resistência entre o grupo de amostras históricas e recentes foi observado em seis dos nove antimicrobianos testados (amoxicilina, enrofloxacina, florfenicol, lincomicina, tilmicosina e tiamulina), em particular para a enrofloxacina e tiamulina. No caso do sulfametoxazole e tetraciclina, não foram observadas diferenças significativas na resistência, entretanto altos valores de CIM foram observados nos dois grupos avaliados (p<0,05). / This study was performed to evaluate the "in vitro" susceptibility profile of 171 Staphylococcus hyicus isolates from cases of exudative epidermitis to nine antibiotics used in pig production. Sample consisted of skin swabs from weanling and nursery piglets from farms suspected of exudative epidermitis. Samples were processed for bacterial isolation and identification and divided in two groups, according to the time of collection. The first group comprised historical samples (80 isolates) from previous studies (1975-1984) conducted in the state of Rio Grande do Sul, and stocked lyophilized in Swine Health Lab (FAVET-UFRGS), and the other group (91 isolates) formed by isolates collected in 2012 in the states of Rio Grande do Sul, Santa Catarina, Paraná and Minas Gerais, Brazil. The test was carried out using agar dilution protocol, according to M31-A3 CLSI. Through Minimal Inhibitory Concentrations (MIC) data, analysis was performed to get a quantitative profile of resistance to antimicrobials. Statistical analysis was performed to evaluate changes in resistance between the groups studied. Results showed that beta-lactam (ceftiofur and amoxicillin) were the most active antimicrobials for all strains tested, with the lowest MIC for inhibition of 90% of isolates (MIC90) of 0.5 μg/ml for historical isolates and of 2.0 μg/ml for recent isolates. Lincomycin, sulfamethoxazole and tilmicosin were the less active antimicrobials, with MIC90 varying from 128 to 256 μg/ml. Significant increase in resistance between historical and recent strains was observed for six out of nine antimicrobials tested (amoxicillin, enrofloxacin, florfenicol, lincomycin, tilmicosin and tiamulin), in particular for enrofloxacin e tiamulin. For sulfamethoxazole and tetracycline there was no significant differences in resistance between strains collected in different periods, however high MIC values were observed for these drugs.

O presente estudo teve o objetivo de avaliar o perfil de sensibilidade in vitro de 171 isolados de Staphylococcus hyicus a nove antimicrobianos utilizados na suinocultura. A coleta das amostras foi realizada através de suabes de pele de leitões das fases de maternidade e creche provenientes de casos de epidermite exsudativa. As amostras foram submetidas ao isolamento e identificação e compreenderam dois grupos, classificadas de acordo com o período em que foram coletadas. O primeiro grupo foi formado por amostras históricas (80 isolados) provenientes de estudos anteriores entre 1975 a 1984 no Rio Grande do Sul, e mantidos liofilizados no laboratório de sanidade do Setor de Suínos (FAVET-UFRGS), e o segundo grupo (91 isolados) coletados no ano de 2012 nos estados do Rio Grande do Sul, Santa Catarina, Paraná e Minas Gerais. A realização do teste de susceptibilidade foi feita utilizando a técnica de diluição em ágar conforme protocolo M31-A3 do CLSI. Através de valores de Concentração Inibitória Mínima (CIM), foi obtido o perfil quantitativo de resistência em relação a nove antimicrobianos utilizados na suinocultura. A análise estatística possibilitou a avaliação de mudanças entre os dois grupos de amostras isoladas em diferentes épocas. Os resultados obtidos nesse estudo revelaram que para todas as cepas obtidas os beta-lactâmicos (ceftiofur e amoxicilina) foram os antimicrobianos mais ativos, com CIM para 90% dos isolados históricos (CIM90) de 0.5 μg/mL e 2.0 μg/mL para isolados recentes. A lincomicina, sulfametoxazol e tilmicosina foram os antimicrobianos menos ativos, com CIM90 variando de 128 a 256 μg/mL. O aumento na resistência entre o grupo de amostras históricas e recentes foi observado em seis dos nove antimicrobianos testados (amoxicilina, enrofloxacina, florfenicol, lincomicina, tilmicosina e tiamulina), em particular para a enrofloxacina e tiamulina. No caso do sulfametoxazole e tetraciclina, não foram observadas diferenças significativas na resistência, entretanto altos valores de CIM foram observados nos dois grupos avaliados (p<0,05). / This study was performed to evaluate the "in vitro" susceptibility profile of 171 Staphylococcus hyicus isolates from cases of exudative epidermitis to nine antibiotics used in pig production. Sample consisted of skin swabs from weanling and nursery piglets from farms suspected of exudative epidermitis. Samples were processed for bacterial isolation and identification and divided in two groups, according to the time of collection. The first group comprised historical samples (80 isolates) from previous studies (1975-1984) conducted in the state of Rio Grande do Sul, and stocked lyophilized in Swine Health Lab (FAVET-UFRGS), and the other group (91 isolates) formed by isolates collected in 2012 in the states of Rio Grande do Sul, Santa Catarina, Paraná and Minas Gerais, Brazil. The test was carried out using agar dilution protocol, according to M31-A3 CLSI. Through Minimal Inhibitory Concentrations (MIC) data, analysis was performed to get a quantitative profile of resistance to antimicrobials. Statistical analysis was performed to evaluate changes in resistance between the groups studied. Results showed that beta-lactam (ceftiofur and amoxicillin) were the most active antimicrobials for all strains tested, with the lowest MIC for inhibition of 90% of isolates (MIC90) of 0.5 μg/ml for historical isolates and of 2.0 μg/ml for recent isolates. Lincomycin, sulfamethoxazole and tilmicosin were the less active antimicrobials, with MIC90 varying from 128 to 256 μg/ml. Significant increase in resistance between historical and recent strains was observed for six out of nine antimicrobials tested (amoxicillin, enrofloxacin, florfenicol, lincomycin, tilmicosin and tiamulin), in particular for enrofloxacin e tiamulin. For sulfamethoxazole and tetracycline there was no significant differences in resistance between strains collected in different periods, however high MIC values were observed for these drugs.