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Comparison of DNA hybridization and PCR assays for detection of putative pathogenic enteroadherent Escherichia coli
Isabel C A Scaletsky1, Sandra H Fabbricotti, Katia R Aranda
1Department of Microbiology, Immunology, and Parasitology, Universidade Federal de São Paulo, Escola Paulista de Medicina, São Paulo, SP, Brazil CEP 04023-062. scaletsky@ecb.epm.br
Insights
This study compared DNA probes and PCR primers for identifying E. coli in children. Typical enteropathogenic E. coli (EPEC) strains with EAF and BFP were linked to acute diarrhea.
Area of Science:
- Microbiology
- Molecular Biology
- Pediatric Infectious Diseases
Background:
- Escherichia coli (E. coli) causes various infections, particularly in young children.
- Accurate identification of pathogenic E. coli strains is crucial for effective treatment and epidemiological studies.
- Different molecular methods exist for E. coli identification, but their comparative performance varies.
Purpose of the Study:
- To analyze the correlation between adherence patterns and molecular methods (DNA probes, PCR primers) for identifying E. coli.
- To evaluate the efficacy of different methods in detecting specific E. coli pathotypes in pediatric isolates from Brazil.
- To determine which molecular techniques are most reliable for clinical research and laboratory screening.
Main Methods:
- Analysis of 1,428 E. coli isolates from children under 2 years old in Brazil.
- Comparison of DNA probes (EAF) and HEp-2 adhesion assay for typical EPEC detection.
- Evaluation of DNA probes and PCR assays for diffusely adhering E. coli (DAEC) and enteroaggregative E. coli (EAEC).
- Assessment of "bundle-forming pilus" (BFP) and EAEC PCR assays as screening tools.
Main Results:
- The EAF probe demonstrated comparable performance to the HEp-2 assay for typical EPEC detection.
- DNA probes for DAEC and EAEC exhibited low sensitivities (64% and 50%).
- The HEp-2 assay remains the gold standard for identifying DAEC and EAEC in clinical research.
- BFP and EAEC PCR assays showed potential as screening methods for typical EPEC and EAEC.
- Only typical EPEC strains possessing both EAF and BFP were significantly associated with acute diarrhea.
Conclusions:
- The EAF probe and HEp-2 assay are reliable for identifying typical EPEC.
- Molecular methods like BFP and EAEC PCR can serve as effective screening tools for specific E. coli strains.
- Accurate identification of E. coli pathotypes is essential for understanding their role in pediatric diarrhea.
Abstract:
The correlation of the different adherence patterns with DNA probes and PCR primers for the identification of Escherichia coli was analyzed in isolates from children, less than 2 years of age with or without diarrhea, from different regions of Brazil. A total of 1,428 isolates obtained from 338 patients and 322 control children were studied. The enteropathogenic E. coli (EPEC) adherence factor (EAF) probe was shown to be as good as the HEp-2 adhesion assay for the detection of typical EPEC strains. The DNA probes used to detect diffusely adhering E. coli and enteroaggregative E. coli (EAEC) showed low sensitivities (64 and 50%, respectively), and the best method of identifying these organisms in clinical research remains the HEp-2 adherence assay. The "bundle-forming pilus" (BFP) and the EAEC PCR assays could be used instead of the DNA probes as a screening method for typical EPEC and EAEC carrying the EAEC probe sequence in the clinical laboratory. In our study, only typical EPEC strains that carried EAF and BFP were associated with acute diarrhea.