RESUMO
Thirty-five serotypes of Streptococcus suis (serotypes 1-34 and serotype 1/2) have so far been described on the basis of their polysaccharide capsular antigens. However, in the last decade, some serotype reference strains have been reexamined for their taxonomic status, and the reference strains of serotypes 20, 22, 26, 32, 33, and 34 may be different from taxon S. suis. In the present study, we developed a novel PCR method targeting the recombination/repair protein (recN) gene of S. suis, designated recN PCR, which corresponds to the current reclassification of this bacterium. We compared its specificity with other PCR methods for S. suis, and the results obtained confirmed its specificity. In addition, the detection limits of recN PCR were similar among all the reference strains of authentic S. suis, indicating that the recN PCR gave reliable results against bacterial strains and isolates used in this study. Therefore, recN PCR described in the present study will be a useful tool for the identification of authentic S. suis, and can also be used in epidemiological studies on this bacterium.
Assuntos
Reação em Cadeia da Polimerase/métodos , Streptococcus suis/classificação , Streptococcus suis/genética , Animais , DNA Bacteriano , Genes Bacterianos , Sensibilidade e Especificidade , Infecções Estreptocócicas/veterinária , Streptococcus suis/isolamento & purificação , Suínos , Doenças dos Suínos/diagnóstico , Doenças dos Suínos/microbiologiaRESUMO
A long-term study was performed on the prevalence of enterohemorrhagic Escherichia coli (EHEC) O157 in bovine faeces. The present study was conducted on heifers raised on a farm showing a high isolation rate of EHEC O157 in previous years. The prevalence of EHEC O157 isolated from faecal samples was 10.6% (222/2104), 5.6% (181/3225), and 5.6% (153/2744) from 1998 to 2000, respectively. The numbers of EHEC O157-positive heifers for the same 3 years were 46.3% (185/400), 36.8% (147/399), and 31.7% (130/410), respectively. The seasonal prevalence of EHEC O157 varied according to the year. Most positive heifers excreted the EHEC O157 only once during the survey, though it was excreted 2 or 3 times by some heifers. The results obtained in the present study showed that the farm examined was heavily contaminated with EHEC O157. It is assumed that EHEC O157 does not remain in individual cattle long-term, but does exist long-term on farms due to repeated infection.
Assuntos
Doenças dos Bovinos/microbiologia , Infecções por Escherichia coli/veterinária , Escherichia coli O157/isolamento & purificação , Animais , Bovinos , Doenças dos Bovinos/epidemiologia , Estudos Transversais , DNA Bacteriano/análise , Eletroforese em Gel de Ágar/veterinária , Monitoramento Ambiental , Monitoramento Epidemiológico , Infecções por Escherichia coli/epidemiologia , Escherichia coli O157/genética , Fezes/microbiologia , Seguimentos , Testes Genéticos , Japão/epidemiologia , Reação em Cadeia da Polimerase/veterinária , Reto/microbiologia , Toxina Shiga I/genética , Toxina Shiga II/genéticaRESUMO
A PCR identification system targeting 23S rDNA sequences for the identification of eight streptococcal species relevant to animal infections (Streptococcus agalactiae, S. bovis, S. canis, S. dysgalactiae, S. equi, S. porcinus, S. suis and S. uberis) was developed. This system consists of two PCR reactions, A and B, in which seven and eight primers, respectively, are used simultaneously, and was designed so that each amplification product indicates a species by its size. A total of 111 cultures, including the type strain of eight species, could be successfully identified and differentiated as individual species, except for the cross reactivity between S. bovis and S. equinus. The developed PCR system can complete the identification procedure for eight streptococcal species through two tube reactions per isolate, and, therefore, might provide a rapid, simple and accurate diagnostic tool for veterinary laboratories.
Assuntos
DNA Bacteriano/análise , DNA Ribossômico/análise , Reação em Cadeia da Polimerase/métodos , Infecções Estreptocócicas/veterinária , Streptococcus/classificação , Streptococcus/isolamento & purificação , Animais , DNA Bacteriano/química , DNA Ribossômico/química , Eletroforese em Gel de Ágar , Genes de RNAr , Dados de Sequência Molecular , Filogenia , RNA Bacteriano/genética , RNA Ribossômico 23S/genética , Análise de Sequência de DNA , Infecções Estreptocócicas/microbiologia , Streptococcus/genéticaRESUMO
The nucleotide sequences of 16S and 23S rRNA genes (rDNA) were determined for 11 isolates of Streptococcus dysgalactiae subsp. equisimilis from slaughtered pigs with endocarditis, arthritis or lymphadenitis and strain ATCC 35666, designated as a strain of subspecies equisimilis. The sequences of each of the genes were compared phylogenetically with the corresponding sequences of S. dysgalactiae subsp. dysgalactiae ATCC 43078(T) and ATCC 27957, which were also determined in this study. Based on the 16S rDNA analysis, the isolates of S. dysgalactiae subsp. equisimilis were divided into two distinct groups, designated groups 1 and 2. S. dysgalactiae subsp. equisimilis ATCC 35666 was closely related to the group 2 strains. The S. dysgalactiae subsp. dysgalactiae strains seemed to be associated with the group 1 strains, which was not consistent with the conventional subspecific classification of S. dysgalactiae. In contrast, the 23S rDNA analysis distinguished S. dysgalactiae subsp. dysgalactiae strains from subsp. equisimilis strains. This inconsistency between phylogenies based on 16S and 23S rDNA indicates that 23S rDNA is a more rigid marker for determining the phylogenetic relationships and taxonomic position of these organisms than is 16S rDNA.
