How to detect Escherichia coli
Jan 25, 2025
Source: Cainiu Health
Dr. Shen Yonghua
Introduction
This method utilizes the possibility of urinary tract infections caused by Escherichia coli (E. coli), indirectly determining the presence of E. coli infection through urinalysis. A midstream clean-catch urine sample should be collected and sent to the laboratory for qualitative, semi-quantitative, or quantitative chemical analysis. This method is simple to perform and can be used for rapid screening of E. coli contamination in the urinary tract.
Under normal circumstances, Escherichia coli can be detected using methods such as routine stool examination and culture, urinalysis, blood culture, enzyme-linked immunosorbent assay (ELISA), and polymerase chain reaction (PCR). The specific details are as follows:
1. Routine Stool Examination and Culture: This method involves collecting a patient's fecal sample, inoculating it onto specific culture media, and incubating under suitable conditions to observe and identify the growth of Escherichia coli. Fresh fecal samples are collected and sent to the laboratory for microscopic examination and bacterial culture. This method allows direct observation of bacterial presence and serves as an important basis for diagnosing intestinal infections.
2. Urinalysis: This method utilizes the possibility of urinary tract infections caused by Escherichia coli to indirectly determine the presence of infection through urinalysis. A midstream clean-catch urine sample should be collected and sent to the laboratory for qualitative, semi-quantitative, or quantitative chemical analysis. This method is simple to perform and can be used for rapid screening of urinary tract contamination by Escherichia coli.
3. Blood Culture: In cases of severe infection, Escherichia coli may enter the bloodstream and cause infectious diseases such as sepsis. Blood culture can detect Escherichia coli in the blood. Venous blood samples are collected and immediately inoculated into sterile culture bottles, kept at appropriate temperatures, and sent for testing promptly. This method helps determine the presence of severe infectious diseases such as sepsis.
4. Enzyme-Linked Immunosorbent Assay (ELISA): This method uses the principle of specific antibody-antigen binding by preparing specific antibodies against Escherichia coli and determining the presence of Escherichia coli in the sample through a series of colorimetric reactions. The sample is combined with specific antibodies, followed by a color reaction and result observation. This method offers high specificity and sensitivity and is relatively easy to perform.
5. Polymerase Chain Reaction (PCR): This method is based on DNA amplification technology. Specific primers are designed according to the unique gene sequences of Escherichia coli, and PCR amplification is used to detect the presence of Escherichia coli by amplifying the corresponding DNA fragments. DNA is extracted from the sample, amplified via PCR, and the amplified products are detected. This method is rapid and sensitive, capable of detecting minute amounts of Escherichia coli, although it requires higher experimental conditions and technical expertise.
When performing tests related to Escherichia coli, patients should avoid taking antibiotic medications to prevent interference with test results.
