Isolation and identification of E-coli 0157:H7 amongst Sudanese patients with bloody diarrhea and in animals

Abstract

E.coli 0157:H7 is present as a commensal in the intestine of animals and as a pathogen in human beings. It causes bloody diarrhoea due to the secretion of a verotoxin which may lead to lethal complications.
Objective: This study is aimed at determining the presence of this organism in animals and patients. Methods: Rectal swabs were collected from 250 cows. Stool specimens were obtained from 200
patients presenting with macroscopically or microscopically bloody diarrhoea. All specimens were cultured on sorbitol MacConkey agar and incubated at 37°C overnight. Non-sorbitol fermenting colonies were identified by different biochemical and serological tests as E.coli 0157:H7. Antibiotic sensitivity was done for the isolates using ampicillin, cephalexin, ciprofloxacin, co-trimoxazole, gentamicin, and tetracycline. Results: Patients (n = 10, 5%) with bloody diarrhoea were found to harbour E.coli 0157:H7 in their stools. All isolates (in humans) were resistant to ampicillin. Eight (80%) were resistant to tetracycline and cephalexin, six (60%) to co-trimoxazole, and four (40%) to gentamicin. All isolates were sensitive to ciprofloxacin. Sixty percent of the human isolates were resistant to three antibiotics and 40% to four antibiotics. Twenty of the cows (8%) were found to be carriers of E.coli
0157:H7. All isolates (in animals) were resistant to ampicillin, five (25%) to tetracycline and cephalexin and four (20%) to co-trimoxazole. All animal isolates were sensitive to gentamicin and ciprofloxacin. Thirty five percent of the animal isolates were resistant to two antibiotics and 25% to three antibiotics. Conclusion: The isolation of E.coli 0157:H7 from animals and patients should direct the attention
of physicians and paediatricians to consider the possibility of infection and complications by this organism.

Key words: Antibiotic sensitivity, sorbitol MacConkey agar, serological tests.