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[Present status and advances in detecting Shiga toxin-producing Escherichia coli O157]
1Department of Clinical Pathology, Kobe City General Hospital.
Abstract:
Currently, detection of Shiga toxin-producing Escherichia coli(STEC) in stool samples is based on the isolation method in most clinical laboratories. The procedures are as follows: i) isolation with selective agar plates, ii) biological test with differential media, iii) serological test of anti-O antisera, iv) detection of toxin or toxin gene. These procedures take 4 days, therefore more rapid method is required. In the near future, a rapid detection method that detects STEC directly from stool samples will be introduced. Polymerase-chain reaction (PCR), enzyme-linked immuno-sorbent assay (ELISA), detection of serum anti-O157 antibodies are now available in clinical laboratories. Result of PCR for detection Shiga toxin gene and serum anti-O157 antibodies are described. Fifteen stool and serum samples from patients suspected of STEC infection were examined. With the culture and PCR method, 2 patients were positive by both methods and the results were confirmed in both cases. Six patients were positive by the antibodies detection method. From these results, the PCR method using stool samples was useful as a rapid detection method in clinical laboratories. Detection of serum antibodies has been simplified and is not an expensive method. Therefore, the method is useful for clinical diagnosis of STEC infection, especially, for diagnosing HUS or after antimicrobial agents have been administered to patients.
Insights
Rapid detection of Shiga toxin-producing Escherichia coli (STEC) is crucial. Polymerase-chain reaction (PCR) on stool samples offers a faster alternative to traditional methods, aiding timely clinical diagnosis of STEC infections.
Area of Science:
- Microbiology
- Clinical Diagnostics
- Molecular Biology
Background:
- Traditional Shiga toxin-producing Escherichia coli (STEC) detection involves a multi-step isolation process from stool samples, typically requiring four days.
- Existing methods include selective agar plating, biological tests, serological typing, and toxin/gene detection, which are time-consuming.
- There is a clinical need for more rapid diagnostic methods for STEC infections.
Purpose of the Study:
- To evaluate the utility of Polymerase-chain reaction (PCR) for the rapid detection of STEC directly from stool samples.
- To compare PCR results with traditional culture methods and serum antibody detection for STEC infection diagnosis.
Main Methods:
- Analysis of fifteen stool and serum samples from patients suspected of STEC infection.
- Utilized Polymerase-chain reaction (PCR) for Shiga toxin gene detection in stool samples.
- Employed traditional culture methods and serum anti-O157 antibody detection for comparison.
Main Results:
- Two patients tested positive for STEC using both culture and PCR methods, with confirmed results.
- Six patients showed positive results via serum antibody detection.
- The PCR method demonstrated utility as a rapid detection technique for STEC in clinical settings.
Conclusions:
- Polymerase-chain reaction (PCR) offers a significantly faster method for STEC detection compared to conventional isolation techniques.
- Serum antibody detection is a simplified and cost-effective method valuable for clinical diagnosis, particularly for Hemolytic Uremic Syndrome (HUS) or post-antimicrobial treatment cases.
- Rapid diagnostic tools like PCR are essential for timely intervention and management of STEC infections.