Evaluación de técnicas moleculares e inmunoenzimáticas para la detección de escherichia coli enterohemorrágico en brotes de toxi infecciones alimentarias / Evaluation of molecular and immunoenzymatic assays for detecting enterohemorrhagic escherichia coli in food borne outbreaks

Background: Enterohemorrhagic Escherichia coli (EHEC), is an emergent pathogen that causes sporadic infections and outbreaks of gastroenteritis associated with consumption of contaminated food products. Because detection of EHEC in diarrhea patients is not routinely performed, infection is most probably underestimated. Aim: To compare three techniques to detect EHEC: Colony hybridization with DNA probes, polymerase chain reaction (PCR) for the detection of stx1 and stx2 genes and immunoenzymatic detection by ELISA (Premier EHEC) of Stx1 and Stx2 toxins. Material and methods: Four outbreaks of food-borne gastroenteritis were studied including 16 patients and 78 strains of E coli. Twenty one (26,9 percent) strains, hybridized with the stx1 probe, 1 (1,3 percent) hybridized only with the stx2 probe and 36 (46,1 percent) with both probes. PCR amplification for cytotoxin genes was observed in 6 strains (7,7 percent) from the second outbreak studied. The immunoenzimatic assay detected the cytotoxins in 18 (23,0 percent), of the 78 studied strains. Agreement between probes and ELISA was 44,8 percent, between PCR and probes 34,7 percent and 82,4 percent between ELISA and PCR. Conclusions: These results indicate a variable yield among different EHEC detection techniques. Considering PCR as the gold standard, ELISA technique showed a better sensitivity and specificity than probes

Situación epidemiológica de las enfermedades transmitidas por alimentos en Santiago de Chile: período 1999-2000 / Survey of foodborne diseases in the Metropolitan Area of Chile

Background: Foodborne diseases are becoming an important cause of morbidity in Chile. In the Metropolitan Region of Chile, the Environmental Health Service started a surveillance program for foodborne diseases in 1994. In 2000, this program was complemented with an etiologic study of individuals involved in outbreaks. Aim: To report the incidence of foodborne outbreaks in the Metropolitan Region of Chile and its causative agents. Results: One hundred ninety outbreaks of foodborne diseases were reported in 1999 and 260 in 2000. The Southern Metropolitan health service had the higher incidence rates (7.5 in 1999 and 8.2 in 2000). The mean attack rates were 25 percent in both periods, affecting 1248 individuals in 1999 and 1774 in 2000. In 18 percent of outbreaks, a pathogen was identified; the most frequent agents were Salmonella Spp, Staphylococcus aureus and Shigella. In 15 percent of subjects, the cause was histamine or chemical agents. In the rest of the cases, the cause was not identified. The foods with higher risk of causing foodborne diseases were hot prepared dishes, home made goat cheese and meats. Conclusions: The incidence rates of foodborne disease in Metropolitan Area of Chile are high and maybe underestimate, only in a low rate of outbreaks was possible to have samples for etiologic studies. For a better understanding of this problem, timely notification of foodborne diseases must be encouraged and educational campaigns about the proper manipulation of food items must be implemented