This study described a group of strains obtained from a slaughter house in Mendoza, in terms of their pathogenic factors, serotype, antibiotype and molecular profile. Ninety one rectal swabs and one hundred eight plating samples taken from carcasses of healthy cattle intended for meat consumption were analyzed. Both the swab and the plate samples were processed to analyze the samples for the presence of virulence genes by PCR: stx1, stx2, eae and astA. The Stx positive strains were confirmed by citotoxicity assay in Vero cells. The isolates were subsequently investigated for their O:H serotype, antimicrobial susceptibility and molecular profile by Random Amplification of Polymorphic DNA (RAPD). Twelve E.coli strains were identified by their pathogenicity. Nine were from fecal origin and three from carcasses. Three strains carried the stx1 gene, three the stx2 gene, two carried eae and four the astA gene. The detected serotypes were: O172:H-; O150:H8; O91:H21; O178:H19 and O2:H5. The strains showed a similarity around 70% by RAPD. Some of the E.coli strains belonged to serogroups known for certain life-threatening diseases in humans. Their presence in carcasses indicates the high probability of bacterial spread during slaughter and processing.

Infant botulism is the most common form of human botulism in some countries including Argentina. However, its transmission has not been completely elucidated. In Argentina, 366 laboratory-confirmed infant botulism cases were reported between March 1982 and December 2005. The average annual incidence was 2.2 per 100,000 live births. All 108 cases diagnosed in our laboratory had botulinum toxin producing organisms in their feces, 96.3% also had botulinum toxin in feces, and 69% had detectable botulinum toxin in their serum. Biochemical tests showed uniformity among the botulinum toxin-producing clostridia isolated from infant botulism cases and soil samples. A positive relationship between presence of botulinum spores in soil and illness incidence was observed in the Northeast and West regions but not in the Central, South and Northwest regions. In the Northwest and Central regions, there was a relatively high occurrence of botulinum spores in the soil but low incidence of the disease. Type A botulinum toxin was detected in all infant botulism cases and also it was the toxin type most prevalent in the soil. Despite the presence of B and F types in the soil, there were no reports of infant botulism cases by these types in Argentina between 1982 and 2005.

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The Escherichia coli Shiga toxin (Stx) producing strains may cause medical conditions that range from diarrhea to hemolytic uremic syndrome; life-threatening conditions worldwide. Shiga toxin-producing E. coli (STEC) strains isolated from patients who usually possess, in addition to one or more stx genes, the eae gene, encoding adhesin intimin. However, a subset of STEC strains associated with human disease lack eae. One of the most common among these is the serogroup O91. This paper reports on the isolation and description of the genophenotypic characteristics from a bovine-derived E. coli O91:H21 strain in a slaughterhouse dependent from Cattle Direction of Mendoza Province, during 2007.