Staphylococcal enterotoxins in the etiopathogenesis of mucosal autoimmunity within the gastrointestinal tract.

The staphylococcal enterotoxins (SEs) are the products of Staphylococcus aureus and are recognized as the causative agents of classical food poisoning in humans following the consumption of contaminated food. While illness evoked by ingestion of the SE or its producer organism in tainted food are often self-limited, our current understanding regarding the evolution of S. aureus provokes the utmost concern. The organism and its associated toxins, has been implicated in a wide variety of disease states including infections of the skin, heart, sinuses, inflammatory gastrointestinal disease, toxic shock, and Sudden Infant Death Syndrome. The intricate relationship between the various subsets of immunocompetent T cells and accessory cells and the ingested material found within the gastrointestinal tract present daunting challenges to the maintenance of immunologic homeostasis. Dysregulation of the intricate balances within this environment has the potential for extreme consequences within the host, some of which are long-lived. The focus of this review is to evaluate the relevance of staphylococcal enterotoxin in the context of mucosal immunity, and the underlying mechanisms that contribute to the pathogenesis of gastrointestinal autoimmune disease.

Detection of staphylococcal enterotoxin B in milk and milk products using immunodiagnostic lateral flow devices.

Staphylococcal enterotoxin B (SEB) is an extracellular pyrotoxin produced by Staphylococcus aureus, a known etiologic agent of food poisoning in humans. Lateral flow immunochromatographic devices (LFDs) designed for the environmental detection of SEB were adapted for use in this study to detect SEB in milk containing 2% fat, chocolate-flavored milk, and milk-derived products such as yogurt, infant formula, and ice cream. The advantage of using LFDs in these particular food products was its ease and speed of use with no additional extraction methods needed. No false positives were observed with any of the products used in this study. Dilution of the samples overcame the Hook effect and permitted capillary flow into the membrane. Thus, semisolid products such as ice cream and some yogurts, and products containing thickeners needed to be diluted using a phosphate-buffered saline-based buffer, pH 7.2. SEB was easily detected at concentrations of 5 microg/mL and 500 ng/mL when the LFDs were used. SEB was also reliably detected at concentrations below 5 and 0.25 ng/mL, which may induce serious disease.

Detection of target staphylococcal enterotoxin B antigen in orange juice and popular carbonated beverages using antibody-dependent antigen-capture assays.

There is a critical need for qualitative and quantitative methodologies that provide the rapid and accurate detection of food contaminants in complex food matrices. However, the sensitivity of the assay can be affected when antigen-capture is applied to certain foods or beverages that are extremely acidic. This study was undertaken to assess the effects of orange juice and popular carbonated soft drink upon the fidelity of antibody-based antigen-capture assays and to develop simple approaches that could rescue assay performance without the introduction of additional or extensive extraction procedures. We examined the effects of orange juice and a variety of popular carbonated soft drink beverages upon a quantitative Interleukin-2 (IL-2) enzyme-linked immunosorbent assay (ELISA) assay system and a lateral flow device (LFD) adapted for the detection of staphylococcal enterotoxin B (SEB) in foods. Alterations in the performance and sensitivity of the assay were directly attributable to the food matrix, and alterations in pH were especially critical. The results demonstrate that approaches such as an alteration of pH and the use of milk as a blocking agent, either singly or in combination, will partially rescue ELISA performance. The same approaches permit lateral flow to efficiently detect antigen. Practical Application: The authors present ways to rescue an ELISA assay compromised by acidity in beverages and show that either the alteration of pH, or the use of milk as a blocking agent are not always capable of restoring the assay to its intended efficiency. However, the same methods, when employed with lateral flow technology, are rapid and extremely successful.

Effect of thermal processing during yogurt production upon the detection of staphylococcal enterotoxin B.

This research was conducted to examine the inherent properties of yogurt contaminated with staphylococcal enterotoxin B (SEB). Two types of yogurts were produced for this study. Type I yogurts were produced by adding SEB at the start of yogurt production, and type II yogurts were produced by adding SEB after the milk base had been boiled. Biochemical characteristics inherent to yogurt, including pH, lactic acid and acetaldehyde concentrations, were analyzed weekly for each batch beginning at a time just after production and throughout a storage period of at least 4 weeks. The presence of toxin during yogurt production did not result in any significant biochemical or physical changes in yogurt. However, we were unable to detect SEB toxin in type I yogurt using a commercially available enzyme-linked immunosorbent assay (ELISA). In contrast, SEB was easily detectable by our ELISA in type II yogurt samples. Higher levels of SEB were recovered from type II yogurt that had been stored for 1 week than from type II yogurt that had been stored for any other length of time. These results indicate that the biochemical characteristics of yogurt did not change significantly (relative to control yogurt) in the presence of either thermally processed SEB or native SEB. However, the ability to detect SEB by ELISA was dependent on whether the toxin had been processed.