Adherence patterns and adherence-related DNA sequences in Escherichia coli isolates from children with and without diarrhea in São Paulo city, Brazil
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Published on: March 10, 2020
T A Gomes1, M A Vieira, C M Abe
1Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo, Escola Paulista de Medicina, São Paulo, S.P., Brazil, CEP 04023-062. tatgomes.dmip@epm.br
Insights
This study found no direct link between specific Escherichia coli adherence patterns or DNA sequences and acute diarrhea in young children. Current detection methods for adherent E. coli showed poor correlation, highlighting the need for improved diagnostic approaches.
Area of Science:
- Microbiology
- Genetics
- Pediatric Infectious Diseases
Background:
- Escherichia coli (E. coli) can cause various infections, including diarrhea, particularly in young children.
- Adherence patterns and specific DNA sequences are used to identify potentially pathogenic E. coli strains.
- The diagnostic accuracy of these methods in clinical settings requires further evaluation.
Purpose of the Study:
- To evaluate the correlation between adherence patterns and adherence-related DNA sequences in E. coli isolates from children with and without diarrhea.
- To assess the effectiveness of current diagnostic methods for identifying adherent E. coli in a clinical research setting.
Main Methods:
- Analysis of 1,801 E. coli isolates from 200 children with diarrhea and 200 age-matched controls in São Paulo, Brazil.
- Classification of adherence patterns: diffuse, aggregative, localized, and others.
- Use of DNA probes to detect specific adherence-related gene sequences.
Main Results:
- DNA probes showed high specificity but variable sensitivity for detecting adherent E. coli.
- Bioassays and DNA probe assays showed poor correlation, indicating diagnostic method limitations.
- Diffuse adherence patterns and the daaC probe were most frequent in patients, followed by aggregative adherence and the EAEC probe.
- No specific adherence pattern or DNA sequence combination was definitively associated with acute diarrhea.
Conclusions:
- Current methods for identifying adherent E. coli, including adherence assays and DNA probes, exhibit limitations and poor correlation.
- The optimal method for detecting adherent E. coli in clinical research remains uncertain.
- No direct association was found between specific E. coli adherence characteristics and acute diarrhea in the studied pediatric population.
Abstract:
The correlation between various adherence patterns and adherence-related DNA sequences in Escherichia coli isolates from 1- to 4-year-old children with and without diarrhea in São Paulo, Brazil, was evaluated. A total of 1,801 isolates obtained from 200 patients and 200 age-matched controls were studied. The adherence patterns found were classified as diffuse, aggregative, aggregative in a 6-h assay, aggregative predominantly in coverslips, localized, localized-like, and noncharacteristic. In general, the DNA sequences used as probes showed excellent specificities (>93%), but their sensitivities varied. Thus, the results of bioassays and assays with DNA probes normally used to search for adherent E. coli did not correlate well, and the best method for the identification of these organisms in the clinical research setting remains controversial. Isolates presenting diffuse adherence or hybridizing with the related daaC probe, or both, were by far the most frequent in patients (31.5, 26.0, and 23.0%, respectively), followed by isolates presenting aggregative adherence or hybridizing with the related EAEC probe, or both (21.5, 13.0, and 10.5%, respectively). None of the different combinations of adherence patterns and adherence-related DNA sequences found were associated with acute diarrhea.
