Standard procedures at a state-of-the-art plant that produced unpasteurized juices were inadequate to eliminate contamination with E. coli O157:H7. This outbreak demonstrated that unpasteurized juices must be considered a potentially hazardous food and led to widespread changes in the fresh juice industry.
Recent taxonomic advances have now implicated several different Vibrio species as human pathogens. While the most common clinical presentation of Vibrio infection continues to be gastroenteritis, an increasing number of extraintestinal infections are being reported, particularly in immunocompromised individuals. Detection of Vibrio infections requires a good clinical history and the use of appropriate isolation and identification procedures by the laboratory to confirm illnesses attributed to Vibrio species. Except for Vibrio cholerae O1 and Vibrio parahaemolyticus, there is little direct evidence linking the production of a myriad of cell-associated or extracellular factors produced by each species with human disease and pathogenesis. Many questions regarding pathogenic Vibrio species remain unanswered, including their frequency and distribution in environmental specimens (water, shellfish), infective doses, virulence potential of individual isolates, and markers associated with such strains.
Cases of adult botulism (n = 309) were studied to identify clinical differences between toxin types and to evaluate the sensitivity of diagnostic laboratory testing. Patients with illness from type E toxin had the shortest incubation periods. Sporadic case-patients were more severely ill: 85% required intubation compared with only 42% in multiperson outbreaks. Of patients with type A botulism, 67% required intubation compared with 52% with type B and 39% with type E. Toxin testing was positive for 40%-44% of serum and stool specimens obtained within 3 days of toxin ingestion and for 15%-23% of specimens obtained thereafter, while 37% of stool specimens obtained > 3 days after toxin ingestion were positive by culture. Patients with type A botulism have more severe illness. In general, specimens obtained early are more likely to be positive by toxin assay, and stool cultures are more sensitive than toxin detection for specimens obtained later in the illness.
The objective of this study was to develop a rapid, simple method for enhanced detection and isolation of low levels of Escherichia coli O157:H7 from leafy produce and surface water using recirculating immunomagnetic separation (RIMS) coupled with real-time PCR and a standard culture method. The optimal enrichment conditions for the method also were determined. Analysis of real-time PCR data (C(T) values) suggested that incubation of lettuce and spinach leaves rather than rinsates provides better enrichment of E. coli O157:H7. Enrichment of lettuce or spinach leaves at 42 degrees C for 5 h provided better detection than enrichment at 37 degrees C. Extended incubation of surface water for 20 h at 42 degrees C did not improve the detection. The optimized enrichment conditions were also employed with modified Moore swabs, which were used to sample flowing water sites. Positive isolation rates and real-time PCR results indicated an increased recovery of E. coli O157:H7 from all samples following the application of RIMS. Under these conditions, the method provided detection and/or isolation of E. coli O157:H7 at levels as low as 0.07 CFU/g of lettuce, 0.1 CFU/g of spinach, 6 CFU/100 ml of surface water, and 9 CFU per modified Moore swab. During a 6-month field study, modified Moore swabs yielded high isolation rates when deployed in natural watershed sites. The method used in this study was effective for monitoring E. coli O157:H7 in the farm environment, during postharvest processing, and in foodborne outbreak investigations.
More than 80 of 230 participants (>34.7%) at a literary conference became ill with acute gastroenteritis 3 to 14 h after a catered meal. Attack rate data implicated cheese tortellini as the suspect food (p=0.0087). Selective plating of partially prepared and finished tortellini produced Staphylcoccus aureus counts of 6.0 × 107 and 1.0 × 106 CFU per gram, respectively. Enterotoxin, phage typing, antibiotic sensitivity testing, and other biotyping studies were applied to S. aureus isolates from the suspect food and the single food-handler involved. All isolates reacted identically by all criteria, and each isolate produced both type A and C staphylococcal enterotoxins. Type A enterotoxin (0.90 ug/100 g) alone was detected in samples of the suspect food. The production of type C enterotoxin by the outbreak strain was delayed approximately 4 h relative to production of enterotoxin A when grown in Heart Infusion broth (pH 5.5). This study serves as an example of selective enterotoxin production by S. aureus in suspect foods which can be misleading to outbreak investigators.
A review of three "emerging" foodborne pathogen groups is presented, including Campylobacter jejuni/coli, Yersinia enterocolitica, and foodborne Vibrio sp.
Fifteen laboratories took part in a collaborative study to validate a method for enumerating Escherichia coli 0157:H7. The method is based on use of a hydrophobic grid membrane filter and consists of 24 h presumptive enumeration on SD-39 Agar and serological confirmation to yield a confirmed E. coli 0157:H7 count. Six food products were analyzed: pasteurized apple cider, pasteurized 2% milk, cottage cheese, cooked ground pork, raw ground beef, and frozen whole egg. The test method produced significantly higher confirmed count results than did the reference method for milk, pork, and beef. Test method results were numerically higher than but statistically equivalent to reference method results for cheese, cider, and egg. The test method produced lower repeatability and reproducibility values than did the reference method for most food/inoculation level combinations and values very similar to those of the reference method for the remaining combinations. Overall, 94% of presumptive positive isolates from the test method were confirmed serologically as E. coli 0157:H7, and 98% of these were also biochemically typical of E. coli 0157:H7 (completed test). Corresponding rates for the reference method were 69 and 98%, respectively. On the basis of the results of this collaborative study and the precollaborative study that preceded it, it is recommended that this method be adopted official first action for enumeration of E. coli 0157:H7 in meats, poultry, dairy foods, infant formula, liquid eggs, mayonnaise, and apple cider
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.