Isolation, Extraction, and Characterization of Verotoxin-producing Escherichia coli O157:H7 from Diarrheal Stool Samples
Abstract
Background: Escherichia coli O157:H7 infection causes hemorrhagic colitis and
is diagnosed based on symptoms such as cramps, stomach pain, and watery
diarrhea. Shiga-like toxins (Verotoxin) produced by Escherichia coli O157:H7 damages
endothelial cells of both kidney and brain, causing renal dysfunction and neurological
problems.
Methods: The present study focuses on identifying the prevalence of Verotoxinproducing Escherichia coli O157:H7 among diarrheal inpatients at Erode Government
Hospital, India, and its antibiogram. Further, the Verotoxins were characterized by
using SDS-PAGE analysis. A total of 123 diarrheal stool samples were collected, and
37 of them (30.08% of the total samples) were found to have the presence of E. coli.
The organisms were identified based on their colony morphology on various media,
cell morphology, and biochemical tests. The Shiga-like toxin production was identified
by non-fermentation of sorbitol on SMAC agar plates. Confirmation of Shiga-like toxin
was performed using agglutination assay.
Results: In total, 12 isolates showed agglutination and these isolates were confirmed
to be E. coli O157:H7. The molecular weight of the Verotoxin was found to be between
20 and 29 kD. The antibiogram profile of the four isolated strains against 10 standard
antibiotics was determined.
Conclusion: The results of this study show the occurrence of drug resistance on
hemorrhagic colitis causing E. coli O157:H7
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