Rapid culture-free identification and molecular typing of Shiga toxin-producingEscherichia coliby PCR-RFLP

E. coli O157:H7 and other toxigenic strains: the curse of global food distribution

It is estimated that there are approximately 76 million illnesses, 325,000 hospitalizations, and 5,200 deaths in the US each year attributed to foodborne outbreaks with a total cost of 10-83 billion US dollars a year. While the rates of foodborne disease have remained relatively constant over the last few years, there have been large outbreaks associated with either a component of commercially prepared food or outbreaks that span between states or even countries. With the world population expecting fresh produce year round, organic produce, and exotic foods, these global outbreaks have the potential to increase in number and severity. There needs to be a means to both rapidly identify these outbreaks, screen our food supply, as well as prevent these outbreaks. This article will discuss the global nature of this problem associated with our food and water supply as well as explain potential ways to solve this international problem.

Evaluation of a PCR-restriction fragment length polymorphism (PCR-RFLP) assay for molecular epidemiological study of Shiga toxin-producing Escherichia coli

In this study, we have evaluated our recently developed polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay for the molecular subtyping of Shiga toxin-producing Escherichia coli (STEC). A total of 200 STEC strains including O157 (n=100), O26 (n=50), O111 (n=10), and non-O26/O111/O157 (n=40) serogroups isolated during 2005-2006 in Japan, which were identified to be clonally different by pulsed-field gel electrophoresis (PFGE) were further analyzed by the PCR-RFLP assay in comparison to PFGE. Ninety-five of O157, 48 of O26, five of O111 and 19 of non-O26/O111/O157 STEC strains yielded one to three amplicons ranging from 6.0 to 15.5 kb in size by the specific primer set targeting region V which is located in the upstream of stx genes. These strains were classified into 41 (O157), 8 (O26), 4 (O111) and 17 (non-O26/O111/O157) groups based on the RFLP patterns obtained by subsequent restriction digestion, respectively. Although the discriminatory power of PCR-RFLP assay was somewhat less than that of PFGE, it is more convenient for molecular subtyping of STEC strains especially for O157, the most important serogroup implicated in human diseases, as well as to identify the outbreak-associated isolates because of its simplicity, rapidity, ease and good reproducibility.

Escherichia coli O157: what every internist and gastroenterologist should know

Infections with Escherichia coli O157:H7 have gained media attention in recent years because of cases associated with unusual sources (eg, produce and swimming pools). Although most adults recover without sequelae, children and the elderly are more likely to develop complications (eg, hemolytic uremic syndrome and death). The diagnosis typically has been made by culture; however, newer hand-held immunoassays and polymerase chain reaction technology have led to more rapid detection of this important pathogen in stools, food, and water. Treatment is largely supportive; nonetheless, new methods to neutralize or bind toxin, such as probiotics, monoclonal antibodies, and recombinant bacteria, are showing promise to treat patients infected with E. coli O157:H7. The role of antibiotics in relation to this condition remains unclear.