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Detection of low-enterotoxin-producing Staphylococcus aureus strains
1Department of Food Microbiology and Toxicology, University of Wisconsin, Madison 53706.
Abstract:
Culture supernatant fluids from 26 (23.6%) monkey feeding test-positive Staphylococcus aureus strains, negative for enterotoxins by gel diffusion, were positive by enzyme-linked immunosorbent assay for one or more of the identified enterotoxins. Staphylococcal enterotoxin D (SED) was produced by 23 (88.5%) strains, SED and SEA were produced in two strains, and SED and SEC were produced in one strain. One strain produced only SEA, and two strains produced only SEC.
Insights
Many Staphylococcus aureus strains can produce dangerous enterotoxins, even if initial tests are negative. Enzyme-linked immunosorbent assay (ELISA) detected staphylococcal enterotoxins in strains that were previously considered negative, highlighting the need for sensitive detection methods.
Area of Science:
- Microbiology
- Food Safety
- Immunology
Background:
- Staphylococcus aureus is a common bacterium that can cause foodborne illnesses.
- Some strains of S. aureus produce toxins called enterotoxins, which can lead to illness.
- Traditional methods for detecting enterotoxins may not be sensitive enough.
Purpose of the Study:
- To investigate the presence of enterotoxins in Staphylococcus aureus strains that were negative by gel diffusion.
- To evaluate the effectiveness of enzyme-linked immunosorbent assay (ELISA) for detecting staphylococcal enterotoxins.
Main Methods:
- Culture supernatant fluids from 26 S. aureus strains, positive by monkey feeding test but negative for enterotoxins by gel diffusion, were analyzed.
- Enzyme-linked immunosorbent assay (ELISA) was used to detect the presence of specific enterotoxins (SEA, SED, SEC).
Main Results:
- 26 (23.6%) of the tested S. aureus strains produced one or more enterotoxins, despite being negative by gel diffusion.
- Staphylococcal enterotoxin D (SED) was the most common, produced by 23 (88.5%) strains.
- Combinations of SED with SEA or SEC were detected in some strains, and some strains produced only SEA or SEC.
Conclusions:
- Enzyme-linked immunosorbent assay (ELISA) is a more sensitive method for detecting staphylococcal enterotoxins compared to gel diffusion.
- A significant proportion of S. aureus strains can produce enterotoxins undetectable by standard gel diffusion methods.
- These findings underscore the importance of using sensitive detection techniques to ensure food safety and prevent staphylococcal food poisoning.