High occurrence of shiga-like toxin-producing strains among diarrheagenic Escherichia coli isolated from raw beef products in Rio de Janeiro City, Brazil

Raw beef samples (n=105) were examined for diarrheagenic Escherichia coli (DEC) using standard methods. The isolates obtained (n=1,066) were screened for Shiga-like toxins (SLT-I and SLT-II), cytolethal distending toxin (CLDT), enterotoxins (LT-I and STa), and classical enteropathogenic (EPEC) and enteroinvasive (EIEC) serogroups. Seventy-three (6.8%) DEC isolates representing 42 strains isolated from 34 (32.4%) beef samples were detected. SLT-producing E. coli (SLTEC) was the most frequent DEC category found and corresponded to 21 (50%) of the 42 DEC strains. Several serotypes were detected among the SLTEC and some of them have been found previously in animal and human isolates, but E. coli O157:H7 was not isolated. Other virulence markers found in DEC strains included enterotoxin production (38.1%), CLDT (7.1%), and EPEC serogroups (4.3%). This is the first report of CLDT-producing E. coli (CLDTEC) isolated from food samples in Brazil. Production of both SLT-I and LT-I was found in one E. coli isolate, and 3 beef samples harbored both SLTEC and ETEC strains. Although a high frequency of DEC groups was found in commercial beef samples in Rio de Janeiro City, Brazil, the significance of these strains as agents of human diarrhea remains to be established.FED UNIV RIO DE JANEIRO,INST MICROBIOL,RIO JANEIRO,BRAZILUNIV FED SAO PAULO,ESCOLA PAULISTA MED,DISCIPLINA MICROBIOL,SAO PAULO,BRAZILUNIV FED SAO PAULO,ESCOLA PAULISTA MED,DISCIPLINA MICROBIOL,SAO PAULO,BRAZILWeb of Scienc

Padrão de susceptibilidade a antimicrobianos e perfil plasmidial em Salmonella Muenster isoladas de suínos e do ambiente de abatedouros

Foram analisadas para a presença de plasmídios 38 amostras de Salmonella Muenster isoladas de suínos e do ambiente de abatedouros localizados no Estado do Rio de Janeiro, no período de março de 1991 a fevereiro de 1992. A seleção das amostras teve como orientação o perfil apresentado frente aos antimicrobianos estreptomicina, tetraciclina, sulfonamida e sulfametoxazol-trimetoprim, sendo analisadas 13 cepas resistentes a um ou mais antimicrobianos, 18 com grau intermediário e sete sensíveis. Plasmidios variando em tamanho de 1,2 Kb a 42 Kb foram detectados em 37 (97,36%) das 38 amostras, correspondendo a 11 perfis distintos (P1 a P11), variando em número de 1 a 6 plasmidios por modelo. O número e diversidade de plasmidios foi maior que os marcos de resistência por cepa. O plasmidio de 2,85 Kb foi o mais freqüente, estando presente em 83,78% das 37 cepas; somente o de 7,95 Kb foi detectado nos dois abatedouros. Não houve paralelismo entre padrão de resistência e perfil plasmidial, onde um mesmo antibiotipo foi encontrado em vários perfis plasmidiais. Os resultados na presente investigação permitiram concluir que a caracterização de plasmidios constituiu-se uma ferramenta útil e simples no rastreamento epidemiológico deste sorovar

Antimicrobial resistance and R-plasmid in Salmonella spp from swine and abattoir environments

Salmonella serovars isolated from swine are of particular interest not only because of the pathogenic potential for this animal species, but also due to its relevance with regard to public health. On basis of the profile of resistance to antimicrobials, 13 Salmonella strains were selected which belonged to the serovars Muenster (7), Derby (4), Typhimurium (1), and Braenderup (1). They were isolated from healthy swine as well as from the abattoir environment in the state of Rio de Janeiro. All strains of Salmonella were subjected to bacterial conjugation, and the E. coli K12 Nal r Lac+ F standard strain was used as receptor, with the purpose to verify the ability to transfer the resistance marks. Gene transfer phenomenon was detected in seven strains, and except SalmonellaTyphimurium which transconjugated to Sm, Tc and Su, the remaining ones were characterized by transferring mark Su only. By plasmidial analysis of strains used and their respective transconjugants, 63 Kb plasmid was found, which was probably related to S. Typhimurium resistance