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Evaluation of a rapid screening assay for bacterial identification (Dot-ELISA) in fecal samples from children
E Boccatto1, S A dos Santos, N A Mazieri
1Instituto da Criança, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, Brasil.
Insights
A new Dot Enzyme-Linked Immunosorbent Assay (Dot-ELISA) effectively detects fecal bacterial enteropathogens in infants. This rapid screening method shows high concordance with traditional stool cultures, aiding early diarrhea diagnosis.
Area of Science:
- Microbiology
- Immunology
- Pediatric infectious diseases
Background:
- Bacterial enteropathogens are a leading cause of acute gastroenteritis in infants.
- Early and accurate diagnosis of bacterial enteropathogens is crucial for effective treatment and management of diarrhea in children.
- Traditional stool culture methods can be time-consuming, delaying diagnosis and treatment.
Purpose of the Study:
- To standardize a Dot Enzyme-Linked Immunosorbent Assay (Dot-ELISA) for detecting fecal bacterial enteropathogen antigens.
- To evaluate the efficacy of a rapid screening assay for key enteropathogens: enteropathogenic Escherichia coli (EPEC), enteroinvasive Escherichia coli (EIEC), Salmonella spp., and Shigella spp.
- To compare the diagnostic performance of the Dot-ELISA with traditional stool culture methods.
Main Methods:
- A Dot-ELISA assay was developed and standardized for detecting bacterial enteropathogen antigens in fecal samples.
- 250 children under 36 months, including 162 with acute gastroenteritis, were enrolled in the study.
- Fecal samples were analyzed using both the Dot-ELISA and conventional stool culture for comparative analysis.
Main Results:
- The Dot-ELISA demonstrated high concordance with stool culture: Kappa (k) index of 0.8859 for EPEC, 0.9055 for EIEC, 0.7932 for Salmonella spp., and 0.7829 for Shigella spp.
- These concordance values indicate an almost perfect agreement for EPEC and EIEC, and substantial agreement for Salmonella spp. and Shigella spp.
- Antigenic preparations were optimized through deproteinization by heating and lipopolysaccharide (LPS) antigen concentration using ethanol-acetone precipitation and heating with sodium EDTA to enhance test performance.
Conclusions:
- The standardized Dot-ELISA is a reliable and rapid method for the early diagnosis of bacterial enteropathogen infections in infants.
- The assay shows significant concordance with traditional stool culture, making it a valuable tool for clinical settings.
- Further optimization of antigenic preparations can improve the sensitivity and specificity of this immunological diagnostic test for pediatric gastroenteritis.
Abstract:
With the objective of standardizing a Dot Enzyme-Linked Immunosorbent Assay (Dot-ELISA) to detect antigens of fecal bacterial enteropathogens, 250 children, aged under 36 months and of both sexes, were studied; of which 162 had acute gastroenteritis. The efficacy of a rapid screening assay for bacterial enteropathogens (enteropathogenic Escherichia coli "EPEC", enteroinvasive Escherichia coli "EIEC", Salmonella spp. and Shigella spp.) was evaluated. The fecal samples were also submitted to a traditional method of stool culture for comparison. The concordance index between the two techniques, calculated using the Kappa (k) index for the above mentioned bacterial strains was 0.8859, 0.9055, 0.7932 and 0.7829 respectively. These values express an almost perfect degree of concordance for the first two and substantial concordance for the latter two, thus enabling this technique to be applied in the early diagnosis of diarrhea in infants. With a view to increasing the sensitivity and specificity of this immunological test, a study was made of the antigenic preparations obtained from two types of treatment: 1) deproteinization by heating; 2) precipitation and concentration of the lipopolysaccharide antigen (LPS) using an ethanol-acetone solution, which was then heated in the presence of sodium EDTA.