ABSTRACT
Shiga toxin producing-Escherichia coli (STEC), an important emerging foodborne pathogen, has been associated with bloody and non-bloody diarrhea, hemorrhagic colitis, hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura. The cattle have been shown to be a major reservoir of STEC and raw foods such as ground beef and milk are the most common vehicles of infection. In the present study, the prevalence of STEC in 95 samples of frozen hamburgers and in 114 samples of soft cheese was established in 8.4% and 0.9%, respectively. The genotypic and phenotypic characteristics of the strains were determined. The virulence genes stx1, stx2, eaeA and EHEC-hlyA were identified by PCR and by colony blot hybridization assays. Serotyping, antimicrobial susceptibility and production of Stx using specific cytotoxicity assays on Vero cells were also determined. All STEC strains were characterized as eaeA-/EHEC-hlyA+. The stx2 genotype was prevalent (77.8%), and four different O:H serotypes were found, comprising: O8:H19 (5 strains), O113:H21 (1), O8:H16 (1), and O39:H49 (1). One STEC strain was nontypable. Although soft cheese complimented the microbiological quality controls for the coliform counts, the detection of STEC in one sample raises doubts concerning the effectiveness of the current quality controls. These data contribute to the implementation of strategies for the prevention and control of HUS.
Subject(s)
Cheese/microbiology , Escherichia coli/isolation & purification , Food Contamination , Food Microbiology , Meat/microbiology , Shiga Toxin 1/biosynthesis , Shiga Toxin 2/biosynthesis , Adhesins, Bacterial/biosynthesis , Adhesins, Bacterial/genetics , Animals , Argentina , Bacterial Toxins/biosynthesis , Bacterial Toxins/genetics , Carrier Proteins/biosynthesis , Carrier Proteins/genetics , Cattle , Chlorocebus aethiops , Cryopreservation , Drug Resistance/genetics , Escherichia coli/classification , Escherichia coli/genetics , Escherichia coli/metabolism , Escherichia coli/pathogenicity , Escherichia coli Proteins/biosynthesis , Food Inspection , Food Preservation , Genotype , Hemolysin Proteins/biosynthesis , Phenotype , Shiga Toxin 1/genetics , Shiga Toxin 2/genetics , Vero Cells , Virulence/geneticsABSTRACT
Shiga toxin producing-Escherichia coli (STEC), an important emerging foodborne pathogen, has been associated with bloody and non-bloody diarrhea, hemorrhagic colitis, hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura. The cattle have been shown to be a major reservoir of STEC and raw foods such as ground beef and milk are the most common vehicles of infection. In the present study, the prevalence of STEC in 95 samples of frozen hamburgers and in 114 samples of soft cheese was established in 8.4
and 0.9
, respectively. The genotypic and phenotypic characteristics of the strains were determined. The virulence genes stx1, stx2, eaeA and EHEC-hlyA were identified by PCR and by colony blot hybridization assays. Serotyping, antimicrobial susceptibility and production of Stx using specific cytotoxicity assays on Vero cells were also determined. All STEC strains were characterized as eaeA-/EHEC-hlyA+. The stx2 genotype was prevalent (77.8
), and four different O:H serotypes were found, comprising: O8:H19 (5 strains), O113:H21 (1), O8:H16 (1), and O39:H49 (1). One STEC strain was nontypable. Although soft cheese complimented the microbiological quality controls for the coliform counts, the detection of STEC in one sample raises doubts concerning the effectiveness of the current quality controls. These data contribute to the implementation of strategies for the prevention and control of HUS.
ABSTRACT
Leishmania (Viannia) braziliensis and its variants were implicated in the epidemic outbreak of mucocutaneous leishmaniasis that occurred in Salta, northwestern Argentina, in 1985. A total of 24 suspected, untreated cases were evaluated clinically and parasitologically. Four of five stable isolates were consistent with the reference strain of L. (V.) braziliensis as determined by monoclonal antibodies and indirect immunofluorescence or radioimmunobinding assays. Zymodeme analysis in agarose gels showed a close relationship with L. (V.) guyanensis and L. (V.) panamensis. All zymograms obtained with polyacrylamide gels belonged to the subgenus Viannia; the patterns were different from, but very closely related to, the reference strains of L. (V.) braziliensis as determined by dendrogram analysis. Hamsters infected with two isolates showed a pattern consistent with L. (V.) braziliensis. The pattern of development in the gut of Lutzomyia longipalpis was consistent with members of Viannia.
