engleski

Monitoring of Escherichia coli O157:H7 in Croatia

The main virulent factor of EHEC strains is a verotoxin or Shiga-like toxin, after which the entire group has been named verotoxigenic E. coli (VTEC) or Shiga-like producing E. coli (SLTEC). Some fifty VTEC serogroups cause enterohemorrhagic disease. In humans, the infection manifests with bloody diarrhea, hemorrhagic colitis, and hemolytic-uremic syndrome (HUS), and trombic-trombocitopenic purpura (TTP). In cattle, the disease manifestations include hemorrhagic colitis and diarrhea, whereas in pigs the symptoms of systemic disease prevail. The disease has not yet been thoroughly investigated in other animal species. VTEC strains may also be isolated from healthy animals. As differentiated from other strains of the E. coli species, the O157:H7 serogroup does not ferment sorbitol, thus making identification on a selective medium possible. The present study on the presence of sorbitol-negative E. coli strains included a total of 677 strains isolated during 1997 from the organs of various animal species (pigs, n=573 ; cattle, n=29 ; sheep, n=17 ; goat, n=10 ; and poultry, n=48). Apart from the organs, the presence of sorbitol-negative strains was also determined in washouts of the swabs obtained from beef (n=75) and pork (n=43) sides in slaughterhouses. Several nutrient media were used for isolation and identification, while the CT SMAC (Merck) was used as a selective medium. Biochemical features of the isolated strains were assessed by the BBL CRYSTAL Enteric/Nonfermenter ID kit (Becton Dickinson), whereas serotyping was performed by use of polyvalent and monovalent sera obtained by rabbit immunization. The presence of O157:H7 serogroup was determined by the GLISA Singlepath E. coli O157:H7 test (Merck). The O157:H7 serogroup was not found in any of the isolated and tested strains. Serotyping pointed to the presence of an O157:K"V17"-like serogroup in 9 strains isolated from pig organs.

Escherichia coli O157:H7; sorbitol-negative; various animal species

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