| Abstract [eng] |
Shiga toxin-producing Escherichia coli (STEC) is one of the most common foodborne pathogens, characterized by the synthesis of Stx1 and/or Stx2 toxins. STEC is associated with numerous human diseases worldwide, ranging from mild diarrhea to hemorrhagic colitis (HC), hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP). Cattle are considered the primary source of STEC and humans usually become infected by consuming contaminated food or water, through the environment or by direct contact with animals. One of the main sources of STEC infection in humans is undercooked meat and meat products, especially ground beef. This study identified 40 cases of beef contamination with STEC bacteria. The majority of the strains were isolated from frozen minced beef for hamburgers. Analysis of sequencing data identified 2 Stx1 subtypes (a and c) and 6 Stx2 subtypes (a, b, c, d, e, f). Eight strains were found to produce the Stx2a toxin, which is considered the most toxic and is associated with severe forms of the disease. The analyzed strains exhibited a diversity of serotypes, including not only typical serotypes (O26:H11, O45:H2, O111:H8, O113:H4, O128:H2, O157:H7), but also uncommon serotypes (O9:H30, O20:H8, O83:H42, O87:H8, O101:H18, O148:H8, O168:H10). The most frequently detected serotypes were O111:H8, O148: H8 and O157:H7. Analysis of virulence genes showed that the STEC strains not only produced Shiga toxin but also other toxins such as subtilase cytotoxin, colicins, and heat-stable enterotoxin. Additionally, it was observed that the isolates exhibited the highest resistance to aminoglycoside class antibiotics, while the lowest resistance was found to quinolone and macrolide class antibiotics. Due to their genetic characteristics, the isolated STEC strains pose a threat to food safety and public health. Whole-genome sequencing (WGS) of STEC strains provides comprehensive insights into pathogen virulence, antibiotic resistance, and helps identify outbreak sources. It is recommended to apply WGS not only in conventional public health areas but also in food contamination monitoring systems. |
