All human Shiga toxin-producing Escherichia coli (STEC) non-O157 strains (n ‫؍‬56]) were represented by more than one isolate. Of these strains, O103:H2 isolates were divided into seven, O26:H11 isolates were divided into four, and the rest within a serotype were divided into two genotypes in PFGE. In PCR, 31 (55%) of the 56 strains were positive for the stx 2 gene only and 24 strains (43%) were positive for stx 1 only. One strain (O43:H2) carried both stx 1 and stx 2 . Forty-two strains (75%) produced enterohemolysin, and 39 strains (70%) possessed the eae gene. Of the latter 39 strains, 36 (92%) were enterohemolytic, whereas only 6 (35%) of the 17 isolates lacking the eae gene were enterohemolytic (P < 0.001). The majority of the strains (44 strains, 79%) were sensitive to all 12 antimicrobials tested. Of the 56 strains, 20 (36%) were associated with small family outbreaks in nine families and 14 (25%) were associated with recent travel abroad.

Altogether, 173 Shiga toxin-producing Escherichia coli (STEC) serotype O157 (n ‫؍‬ 111) and non-O157 (n ‫؍‬ 62) isolates from 170 subjects were screened by PCR-restriction fragment length polymorphism for eight different stx genes. The results were compiled according to serotypes, phage types of O157, production of Stx toxin and enterohemolysin, and the presence of eae. The stx genes occurred in 11 combinations; the most common were stx 2 with stx 2c (42%), stx 2 alone (21%), and stx 1 alone (16%). Of the O157 strains, 64% carried stx 2 with stx 2c versus 2% of the non-O157 strains (P < 0.001). In the non-O157 strains, the prevailing gene was stx 1 (99% versus 1% in O157 strains; P < 0.001). In addition, one strain (O Rough:H4:stx 2c ) which has not previously been described as associated with hemolytic-uremic syndrome (HUS) was found. Ten stx-positive virulence profiles were responsible for 71% of all STEC infections. Of these profiles, five accounted for 71% of the 21 strains isolated from 20 patients with HUS or thrombotic thrombocytopenic purpura (TTP). The strains having the virulence profile that caused mainly HUS or TTP or bloody diarrhea produced Stx with titers of >1:128 (90%) more commonly than did other strains (51%; P < 0.001). These strains were also more commonly enterohemolytic (98% versus 68% for other strains; P < 0.001) and possessed the eae gene (100%) more commonly than did other strains (74%; P < 0.001). A particular virulence profile, O157:H7:PT2:stx 2 :stx 2c :eae: Ehly, was significantly more frequently associated with HUS and bloody diarrhea than were other profiles (P ‫؍‬ 0.02) and also caused the deaths of two children. In this study, the risk factors for severe symptoms were an age of <5 years and infection by the strain of O157:H7:PT2 mentioned above.Shiga toxin-producing Escherichia coli (STEC) cells have emerged as new food-borne pathogens of clinical and public health concern (35). The most epidemic STEC serogroup has been O157, but about 200 other STEC serogroups have been identified (http://www.microbionet.com.au/frames/feature /vtec/brief01.html). Shiga toxins (Stx1 and/or Stx2) have a prominent role in the pathogenesis of STEC bacteria (15,20,26). The clinical picture of a STEC infection may vary from an asymptomatic state to bloody diarrhea and severe life-threatening complications such as hemolytic-uremic syndrome (HUS) or thrombotic thrombocytopenic purpura (TTP) (35). Children and elderly people have been more susceptible to STEC infections than healthy adults (32). It is estimated that the incidence of HUS varies from 2.0 to 3.0 cases per 100,000 children under 5 years of age (15) and from 0.9 to 1.2 cases per 100,000 in children under 18 years of age (5, 43).The pathogenesis of STEC infection in humans is not fully understood. It is considered to be multifactorial and dependent on several bacterial virulence factors such as enterohemolysin (Ehly) and the eae gene, in addition to host factors (6,35). A recent discovery of a quorum-sensing system, mediated by self-produced...

Molecular characterization and subtyping show genetic diversities within clonal complexes.

IntroductionCarbapenemase-producing Enterobacteriaceae (CPE) have rarely been reported in dogs, and never in animals in Finland. However, in April 2015, two meropenem-resistant Escherichia coli were identified from two dogs in one family. Both dogs suffered from chronic otitis externa. Methods: Epidemiological and molecular investigations (pulsed-field gel electrophoresis (PFGE), multilocus sequence typing) were conducted to investigate the source of infection and transmission routes. Results: In both dogs and one family member New Delhi metallo-beta-lactamase (NDM-5)-producing multidrug-resistant ST167 E. coli was found. Whole genome sequencing confirmed that the isolates were identical or only had one or two allelic differences. Additionally, the dogs and humans of the family carried an identical extended-spectrum beta-lactamase (ESBL) CTX-M-group 9 E. coli ST69 strain, indicating interspecies transmission. While the original source remains unclear, human-to-canine transmission is possible. No carbapenems had been administered to the dogs, but exposure to numerous other antimicrobials likely sustained the bacteria and supported its propagation in the canine host. Conclusion: To our knowledge, canine clinical NDM-5 E. coli in Europe, and confirmed CPE transmission between dogs and humans have not been previously reported. The screening of veterinary Enterobacteriaceae isolates for carbapenem resistance is highly recommended.

Lukinmaa S, Nakari UM, Eklund M, Siitonen A. Application of molecular genetic methods in diagnostics and epidemiology of food-borne bacterial pathogens. 2004:112;908-29.Salmonella enterica, Campylobacter and Yersinia species, Shiga toxin-producing Escherichia coli (STEC), Listeria monocytogenes and Clostridium perfringens are the bacterial pathogens constituting the greatest burden of food-borne disease in Finland. Several molecular genetic methods have been applied to diagnose, discriminate and survey these bacteria. PCR, PCR-RFLP and PFGE are the most widely and successfully used. However, these methods are unable to replace conventional and internationally standardised phenotyping. Electronic database libraries of the different genomic profiles will enable continuous surveillance of infections and detection of possible infection clusters at an early stage. Furthermore, whole-genome sequence data have opened up new insights into epidemiological surveillance. Laboratory-based surveillance performed in a timely manner and exploiting adequate methods, and co-operation at local, national and international levels are among the key elements in preventing food-borne diseases. This paper reviews different applications of molecular genetic methods for investigating enteric bacterial pathogens and gives examples of the methods successfully used in diagnostics and epidemiological studies in Finland.