Staphylococcus aureus functions as the main food-borne disease agent that generates enterotoxigenic staphylococci which trigger gastroenteritis through toxin production in food. The substances produced by these organisms escape their cells to trigger gastrointestinal symptoms so they receive the name enterotoxins. The biological threat from Staphylococcal enterotoxins persists after heat treatment at 100°C for one hour and produces incapacitation that lasts between several days and two weeks. The Staphylococcal enterotoxins (SEs) group includes heat-stable secreted proteins that belong to the superantigen family. Staphylococcus aureus toxins produce staphylococcal food poisoning (SFP) which has become a leading foodborne illness worldwide. The toxins demonstrate heat and acidic resistance and digestive enzyme tolerance which allows them to function after food processing and cooking. Scientists have identified more than 20 distinct SEs and SE-like proteins which include SEA, SEB, SEC, SED, SEE and additional variants.
Staphylococcal enterotoxins (SEs) represent a wide range of toxins which Staphylococcus aureus produces through more than 20 identified serotypes. The classification of these toxins occurs through evaluation of their physicochemical and immunological characteristics.
The initial group of SEs was identified as classical enterotoxins. The major serotypes within this group consist of SEA, SEB, SEC, SED and SEE. The food poisoning outbreaks are primarily caused by SEA which stands as one of the most prevalent and dangerous serotypes. The classical toxins have received extensive research which proves their role in foodborne illnesses. The primary cause of staphylococcal food poisoning stems from Staphylococcus aureus proteins known as Staphylococcal Enterotoxins (SEs) which function as superantigens to induce emesis. All enterotoxins belong to the same category yet they exhibit different structural characteristics and varying levels of potency and disease associations.
Table 1. Unique features of some common SEs.
| Feature | SEA | SEB | SEC | SED | SEE |
| Food Poisoning | Most common cause of food poisoning outbreaks globally. | Common, but less so than SEA as a cause of food poisoning. | Relatively common, especially in some atypical food poisoning incidents. | Common, particularly in food poisoning linked to dairy products. | Uncommon, has high similarity to SEA but is rarely a primary causative agent. |
| Potency | Most potent, causing food poisoning at very low doses. | Extremely potent, often studied for use in bioweapons due to its ability to cause illness via inhalation. | Potent, with several subtypes (e.g., SEC1, SEC2, SEC3). | Potent, and a dominant cause of food poisoning in certain regions. | Potent, but its pathogenicity has been studied less compared to SEA. |
| Disease Association | Primarily associated with food poisoning. | In addition to food poisoning, linked to non-menstrual Toxic Shock Syndrome (TSS). | Primarily associated with Toxic Shock Syndrome (TSS) and animal mastitis. | Associated with food poisoning and some cases of Toxic Shock Syndrome. | Primarily associated with food poisoning, but its toxicity may be lower than SEA. |
| Molecular Features | ~27 kDa. | ~28 kDa. | ~25 kDa. | ~26 kDa. | ~26 kDa. |
| Primary Sources | Found frequently in cheese, baked goods, and meat products. | Common in meat, dairy products, and salads. | Found in dairy, meat, and cheese, also linked to animal infections. | Primarily found in dairy products, especially cheese. | Less frequently isolated, mainly found in specific food poisoning cases. |
Molecular biology techniques have enabled scientists to identify various new enterotoxins which have expanded the enterotoxin family. The new enterotoxins discovered include SEG, SEH, SEI, SEJ, SEK, SEL, SEM, SEN, SEO, SEP, SEQ, SER, SES, SET, SEU, SEV, and SEIX. Some of these novel enterotoxins, such as SE1K through SE1Q, have been shown to exhibit emetic activity in animal studies. However, compared to traditional enterotoxins, direct studies linking many novel enterotoxins to human food poisoning are still understudied. The total number of reported enterotoxins has reached 23 to 24.
The International Nomenclature Committee for Staphylococcal Superantigens (INCSS) proposed that only toxins demonstrating emetic effects after oral administration in a primate model should be specifically classified as SEs. Conversely, other toxins associated with Staphylococcal food poisoning, which either do not exhibit emetic properties in this model or have not undergone testing, should be labelled as "staphylococcal enterotoxin-like" (SEl) superantigens.
Figure 1. The structure diagram of SEs and SEls in each Group. (Shen, 2025)
The amino acid sequences and structural features of SEs and SEls enable their classification into four phylogenetic groups which include TSST-1, SElX, SElY in Group I and SEB, SEC, SEG, SEU, SElU2, SEl27, SE02 in Group II and SEA, SED, SEE, SEH, SEJ, SEN, SEO, SEP, SE01 in Group III and SEI, SEK, SEL, SEM, SEQ, SER, SES, SET, SElV, SEl26 in Group V (NB: Group IV contains superantigens from streptococcal bacteria). Staphylococcal Enterotoxins (SEs) Mechanisms of Action
The stomach does not destroy SEs which then enter the intestinal tract to initiate emetic effects that trigger immune system responses mainly through vomiting. The binding of enterotoxins to epithelial cells creates membrane damage which enhances intestinal permeability and produces gastrointestinal symptoms. The immune system homeostasis and enteric nervous system interact with various enterotoxins at extremely low concentrations to produce vomiting diarrhea and intestinal inflammation. The gastrointestinal tract submucosal mast cells release histamine which causes these reactions. The primary cells affected by SEs exist in the intestinal tract mast cell population and the neurotransmitter 5-hydroxytryptamine (5-HT) or serotonin functions as a crucial factor in emesis induction. The SEs demonstrate superior T-cell activation properties which differentiate them from standard peptide antigens. The processing of traditional antigens by antigen-presenting cells differs from SEs because they activate T cells through a distinct mechanism.
Figure 2. SE superantigens bind directly to the receptor. (Cieza, 2024)
SEs are considered superantigens because of their ability to inhibit the immune response, block and destroy B and T cells in the phagocytosis process, and manipulate the innate and adaptive responses of the host immune system. In the case of airway infection, superantigen SEs bind directly to the β-domain variable of the TCR (T-cell receptor) molecule β (βTCRV), interacting with the regions of the T cell scaffold and MHC (major histocompatibility complex) class II on the surface of APCs (antigen-presenting cells). This results in activation of polyclonal T cells and overproduction of T cell cytokines, including IL-4, IL-5, and IL-13 (Figure 2). IL-5 is responsible for eosinophilic inflammation, while IL-4 and IL-13 induce B-cell activation and class change to immunoglobulin E (IgE), promoting local polyclonal IgE response and increased total IgE serum levels.
The detection methods for staphylococcal enterotoxins differ in their sensitivity levels and practicality and application scope. Traditional animal bioassays for toxin detection remain expensive and raise ethical concerns while providing insufficient sensitivity for regular use but molecular techniques including PCR, qPCR and WGS enable reliable enterotoxin gene identification without direct toxin measurement and require pathogen isolation. The practical application of polymer-based biosensors and aptamers remains restricted because these detection methods are still experimental and experience interference from matrix components. The detection sensitivity of earlier immunological methods (OSP, RIA, latex agglutination) was insufficient but ELISA became the gold standard because it offers accuracy and simplicity and works with various samples and detects both traditional and non-traditional enterotoxins through sandwich formats with polyclonal and monoclonal antibodies. The commercial application of hydrogel-based immunobiochips for multiplex toxin detection remains restricted despite their demonstrated potential for this purpose.
References
| Target | Cat. No. | Product Name | Host | Application | |
| SEA | DAG-WT619 | S. aureus Enterotoxin Type A Toxoid | S. aureus | ELISA | Inquiry |
| DAG-WT626 | Recombinant Staphylococcus aureus Enterotoxin A (SEA) | E. coli | ELISA | Inquiry | |
| SEB | DAGB111 | S. aureus Enterotoxin Type B Toxoid | S. aureus | ELISA | Inquiry |
| DAG-WT627 | Recombinant Staphylococcus aureus Enterotoxin B (SEB) | E. coli | ELISA | Inquiry | |
| SEC | DAG-WT621 | S. aureus Enterotoxin Type C2 Toxoid | S. aureus | ELISA | Inquiry |
| DAG-WT622 | S. aureus Enterotoxin Type C3 Toxoid | S. aureus | ELISA | Inquiry | |
| DAG-WT628 | Recombinant Staphylococcus aureus Enterotoxin C (SEC) | E. coli | ELISA | Inquiry | |
| SED | DAG-WT623 | S. aureus Enterotoxin Type D Toxoid | S. aureus | ELISA | Inquiry |
| DAG-WT629 | Recombinant Staphylococcus aureus Enterotoxin D (SED) | E. coli | ELISA | Inquiry | |
| SEE | DAG-WT624 | S. aureus Enterotoxin Type E Toxoid | S. aureus | ELISA | Inquiry |
| DAG-WT630 | Recombinant Staphylococcus aureus Enterotoxin E (SEE) | E. coli | ELISA | Inquiry |
| Target | Cat. No. | Product Name | Size | Species | Application | Detection Sample | |
| S. aureus Enterotoxins | DEIA-CL032 | Human Staphylococcus Aureus Enterotoxins (SE) ELISA Kit | 48T, 96T | Human | Quantitative | serum, plasma, tissues Homogenate, Feces, urine, Body Fluids | Inquiry |
