RESUMO Escherichia coli é reconhecida como causa freqüente de diarréia em suínos em todo o mundo. O objetivo do presente estudo foi caracterizar fenotipicamente os tipos fimbriais de 349 linhagens de E. coli isoladas de suínos com diarréia, em diferentes faixas etárias, utilizando os testes de microhemaglutinação e soroaglutinação, bem como determinar o perfil de suscetibilidade frente aos principais antimicrobianos utilizados em granjas de suínos. Do total de 159 linhagens de E. coli que não aglutinaram eritrócitos no teste de hemaglutinação manose-resistente (HAMR), 57 (35%) foram positivas para a expressão do antígeno fimbrial F6 no teste de soroaglutinação rápida em placa. Considerando a faixa etária e o fenótipo fimbrial, os sorotipos de E. coli, potencialmente patogênicos mais prevalentes até a terceira semana de idade, foram F5 (K99), F6 (987P), F42 e F41 em, respectivamente, 29%, 23%, 11% e 10% das linhagens. Em leitões com mais de 25 dias, predominaram fimbrias F4 (K88) em 44,6% (58) das linhagens. Os animais foram suscetíveis às cepas contendo F4, durante todas as faixas etárias, mas com maior predominância em idades mais avançadas, acima de 76 dias. Os maiores índices de resistência das linhagens foram observados para oxitetraciclina (84,0%), gentamicina (76,0 %) e amoxicilina (72,0%). Os menores valores de Concentração Inibitória Mínima (CIM) 50 e 90 foram observados para o ceftiofur.

ABSTRACT Escherichia coli is recognized as a frequent cause of diarrhea in swine. The objective of this study was to phenotypically characterize the fimbrial types of 349 E. coli strains isolated from swine with diarrhea, in different age groups, through the microhemagglutination and seroagglutination tests and to determine the susceptibility profile in regard to the more common antimicrobials used on pig farms. Of the 159 strains that not agglutinate eritrocytes in the manose-resistant hemagglutination test (HAMR), 57 (35%) were positive for the expression of the fimbrial antigen F6, in the fast seroagglutination test carried out in plates. Considering the age group and the fimbrial phenotype, the potentially pathogenic serotypes of E. coli more prevalent until the third week of age were: F5 (K99), F6 (987P), F42 and F41 in, respectively, 29%, 23%, 11% and 10% of the strains. In piglets over 21 days old, fimbriae F4 (K88) predominated in 44.6% (58) of the strains. The animals were susceptible to strains containing F4, in all of the age groups, but with more frequency at more advanced ages, above 76 days. The largest resistance indexes were observed for oxytetracycline (84.0%), gentamicin (76.0%) and amoxicilin (72.0%). The smallest CIM 50 and 90 values were observed for ceftiofur.

The prevalence and profile of resistance to antimicrobials of Salmonella serovars isolated from raw pork sausage were studied in Lages county, Santa Catarina, Brazil. A total of 125 samples of 12 trademarks were collected in different commercial establishments. Salmonella sp. was present in 12.8% (16/125) of the samples and Typhimurium serovar was the most prevalent. Fourteen different antimicrobials were tested and most of the samples showed resistance to sulfonamide and tetracycline (81.2%). Eight positive samples (50%) were resistant at least to four antimicrobials, being considered as multi-resistant Salmonella. Seven (58.3%) trademarks were disagreement with the Brazilian law, representing a risk to the public health. The high level of resistance to the antimicrobials should produce a concern by the pig industry and veterinarians in order to prevent the transmission of resistant strains through the food chain.