RESUMO
Globally, vibrios represent an important and well-established group of bacterial foodborne pathogens. The European Commission (EC) mandated the Comite de European Normalisation (CEN) to undertake work to provide validation data for 15 methods in microbiology to support EC legislation. As part of this mandated work programme, merging of ISO/TS 21872-1:2007, which specifies a horizontal method for the detection of V. parahaemolyticus and V. cholerae, and ISO/TS 21872-2:2007, a similar horizontal method for the detection of potentially pathogenic vibrios other than V. cholerae and V. parahaemolyticus was proposed. Both parts of ISO/TS 21872 utilized classical culture-based isolation techniques coupled with biochemical confirmation steps. The work also considered simplification of the biochemical confirmation steps. In addition, because of advances in molecular based methods for identification of human pathogenic Vibrio spp. classical and real-time PCR options were also included within the scope of the validation. These considerations formed the basis of a multi-laboratory validation study with the aim of improving the precision of this ISO technical specification and providing a single ISO standard method to enable detection of these important foodborne Vibrio spp.. To achieve this aim, an international validation study involving 13 laboratories from 9 countries in Europe was conducted in 2013. The results of this validation have enabled integration of the two existing technical specifications targeting the detection of the major foodborne Vibrio spp., simplification of the suite of recommended biochemical identification tests and the introduction of molecular procedures that provide both species level identification and discrimination of putatively pathogenic strains of V. parahaemolyticus by the determination of the presence of theromostable direct and direct related haemolysins. The method performance characteristics generated in this have been included in revised international standard, ISO 21872:2017, published in July 2017.
Assuntos
Microbiologia de Alimentos/métodos , Alimentos Marinhos/microbiologia , Vibrio/fisiologia , Animais , Europa (Continente) , União Europeia , Proteínas Hemolisinas/análise , Reação em Cadeia da Polimerase em Tempo Real , Vibrio/genética , Vibrio/isolamento & purificação , Vibrio cholerae/genética , Vibrio cholerae/isolamento & purificação , Vibrio cholerae/fisiologia , Vibrio parahaemolyticus/genética , Vibrio parahaemolyticus/isolamento & purificação , Vibrio parahaemolyticus/fisiologia , Vibrio vulnificus/genética , Vibrio vulnificus/isolamento & purificação , Vibrio vulnificus/fisiologiaRESUMO
The PCR detection of the genes coding for the newly described staphylococcal enterotoxins (SE) G, H, I and J was carried out for 332 foodborne staphylococci, isolated from a variety of foods in France. The frequency of the Staphylococcus aureus strains harboring these genes was found to be very high (57%) and greater than that of the strains harboring "classical" SE genes as previously established. If one takes into account the newly described SE genes, in addition to the classical SE genes, the percentage of foodborne enterotoxigenic S. aureus strains doubles. The S. aureus biovars that were rarely or never enterotoxigenic (i.e., the poultry and bovine biovars) frequently become more potentially toxigenic, if taking into account the seg. seh, sei and sej genes. Furthermore, this work indicated a systematic association between the seg and sei genes and their high incidence among the S. aureus strains, which suggests that these two SE's could be an important phylogenetic link among the staphylococcal enterotoxins.
Assuntos
DNA Bacteriano/isolamento & purificação , Enterotoxinas/genética , Staphylococcus/genética , DNA Bacteriano/classificação , Humanos , Filogenia , Reação em Cadeia da Polimerase , Intoxicação Alimentar Estafilocócica/prevenção & controle , Staphylococcus/patogenicidade , Staphylococcus aureus/genética , Staphylococcus aureus/patogenicidade , Superantígenos/genéticaRESUMO
Two hundred and thirteen Staphylococcus aureus and 51 other staphylococcal strains were isolated from 121 foodstuffs of current consumption and two cutaneous samples. Their ability to produce staphylococcal enterotoxins was tested and S. aureus strains were biotyped. The S. aureus strains (30.5%) produced at least one of the five known staphylococcal enterotoxins whereas coagulase negative staphylococci did not produce any of them. The raw milk cheeses analysed were primarily contaminated by strains belonging to animal or unspecified biovars. Only 15.9% of the S. aureus strains isolated from these products produced enterotoxins whereas 43% were found to be enterotoxigenic amongst the S. aureus strains isolated from the other foodstuffs. The scheme of biotyping used seems to be reliable, allowing the classification of 73.7% of the strains. S. aureus strains of human biovar origin were most often enterotoxigenic and enterotoxin C was the predominant type identified. It was produced by 66% of the enterotoxigenic strains, singly or in combination with other enterotoxins. Approximately 77% of the human strains also produced enterotoxin C, which is an amazing epidemiological distinctive feature of the strains studied. Moreover ELISA tests used in this work exhibit problems of specificity.