RESUMEN
Yersinia enterocolitica comprises six biotypes 1A, 1B, 2, 3, 4, and 5. The virulence of the strains belonging to biotypes 1B and 2-5 depends on the presence of both chromosomal and plasmid-borne genes. Strains belonging to biotype 1A do not carry the virulence plasmid pYV. However, they carry other virulence genes, such as ystB and hreP. The aim of this study was to investigate the distribution of yadA, virF, inv, ystA, ystB, myfA, hreP and ymoA virulence genes in Y. enterocolitica strains in order to select the target genes that could be used for the development of a probe-specific real-time PCR to determine the presence of Y. enterocolitica in food samples. A total of 161 Y. enterocolitica strains isolated in eight countries and grouped into biotypes 1A, 2 (serotypes O3, O5 and O9), 3 (serotypes O3 and O9) and 4 (serotype O3) were examined for virulence genes. The most common virulence-associated gene in pathogenic Y. enterocolitica proved to be ystA, which can therefore be considered the best target gene to be amplified in order to evaluate the presence of pathogenic biotypes. By contrast, to identify Y. enterocolitica 1A strains, ystB, which codes for the enterotoxin YstB, can be proposed. This has been found in all non-pathogenic biotypes studied, but never in pathogenic biotypes.
Asunto(s)
Colorantes Fluorescentes , Genes Bacterianos , Compuestos Orgánicos , Yersinia enterocolitica/genética , Toxinas Bacterianas/genética , Técnicas de Tipificación Bacteriana , Benzotiazoles , Diaminas , Enterotoxinas/genética , Microbiología de Alimentos/métodos , Quinolinas , Reacción en Cadena en Tiempo Real de la Polimerasa , Virulencia/genética , Yersinia enterocolitica/patogenicidadRESUMEN
The present study was aimed at developing a SYBR Green-based real-time polymerase chain reaction (PCR) assay for a rapid differentiation of the genotype G1 from the cluster of genotypes G2/G3 of Echinococcus granulosus, using as marker the 12S mtDNA gene. Eleven hydatid cysts from water buffaloes and 19 from cattle were used. Fourteen samples (identified as G1 using sequencing) showed a mean melting temperature (T (m)) of 76.4 degrees C and 16 samples (identified as G2/G3 using sequencing) showed a mean T (m) of 77.0 degrees C. The detected mean difference of the T (m) of 0.6 degrees C between G1 and G2/G3 genotypes might allow a fast and simple discrimination of these genotypes. In conclusion, the real-time PCR developed in the present study provides a powerful tool for molecular studies on E. granulosus with possibilities for extension to other genotypes using different molecular targets.
Asunto(s)
Echinococcus granulosus/clasificación , Echinococcus granulosus/genética , Reacción en Cadena de la Polimerasa/métodos , Animales , Benzotiazoles , Búfalos/parasitología , Bovinos/parasitología , ADN de Helmintos/genética , ADN Mitocondrial/genética , Diaminas , Genotipo , Compuestos Orgánicos/metabolismo , Quinolinas , Coloración y Etiquetado/métodos , Temperatura de TransiciónRESUMEN
Two newly isolated virulent coliphages (MVBS and MVSS) showed ability to lyse (form plaque on) a high percentage of pathogenic Escherichia coli strains of various serotypes and origins (292/310; 94.2%), whilst displaying low lytic (plaque-forming) capacity on non-pathogenic ECOR strains (MVBS and MVSS lysed 10/72 (13.9%) and 15/72 (20.8%) strains, respectively). In comparison, a higher percentage (196/310, 63.2%) of tested isolates exhibited resistance to a broad range of antibiotics. It was also observed that, in contrast to antibiotics, phage treatment did not induce Shiga toxin production. These findings suggest that the newly isolated bacteriophages have potential for biocontrol and as therapeutic agents for pathogenic E. coli (EHEC and EPEC) strains.
Asunto(s)
Colifagos/genética , Colifagos/aislamiento & purificación , Infecciones por Escherichia coli/terapia , Escherichia coli/fisiología , Escherichia coli/virología , Control Biológico de Vectores , Animales , Antibacterianos/farmacología , Bacteriólisis , Bovinos , Colifagos/fisiología , Farmacorresistencia Bacteriana , Escherichia coli/efectos de los fármacos , Escherichia coli/crecimiento & desarrollo , LisogeniaRESUMEN
In the last two decades, the emergence and spread of antimicrobial-resistant pathogens, among them Salmonella, has become a serious health hazard worldwide, and specifically the high incidence of multidrug resistance has been encountered widely in many European countries. This study examines the antimicrobial susceptibility of Salmonella enterica strains Typhimurium and Enteritidis isolated in Campania and Calabria region (Southern Italy) from animal and food of animal origin. The relationship of antibiotic resistance phenotype and the presence of some resistance genes has been also investigated. As expected, our results show that resistance to ampicillin, chloramphenicol, streptomycin, sulphonamides and tetracycline is common, although resistance to other antibiotics (i.e.: nalidixic acid) and other resistance patterns occur. The genetic resistant patterns have been partially described for this food-borne pathogen but efforts are needed to realize the complete characterization of antimicrobial resistance genes.