title: Screening for toxigenic Escherichia coli in stool samples of diarrhoeal patients by polymerase chain reaction.
abstract: Escherichia coli (E. coli) are normal flora of the intestines of most animals, including humans. Most strains are harmless and beneficial to host by preventing the establishment of pathogenic bacteria within the intestine. However, some E. coli strains can cause a wide variety of intestinal and extra-intestinal diseases, such as diarrhoea, urinary tract infections, septicaemia, neonatal meningitis and renal complications. Several virulence factors including toxins, adhesins, serine proteases, etc. have been reported in these highly adapted clones. The present study was designed to enumerate toxin genotype through PCR assay in local clinical isolates of E. coli. A total of 37 E. coli strains were collected from different clinical laboratories of Karachi and examined for the presence of shiga toxin 1 (stx1) and shiga toxin 2 (stx2) genes of Eenterohemorrhagic E. Coli (EHEC) and heat stable (st) and healt labile (lt) toxin genes of enterotoxigenic E. Coli (ETEC). It was observed that 16 strains out of 37 carried one or more type of toxin genes. The presence of stx1 gene was significantly higher as it was positive in 10 isolates compared to others toxins. Two in above stx1 positive strains were also carrying for stx2 gene. Six out of 37 isolates were positive for lt gene, and none of the strains are carrying st gene. Although, the study was carried out with fewer isolates, yet it demonstrated the trend of dispersion of toxin genes and findings can be used to correlate the gastro-intestinal infections and their complications in Pakistan.
authors.affiliation: Department of Microbiology, Jinnah University for Women, Karachi, Pakistan.
authors.forename: Benish
authors.initials: B
authors.lastname: Nawaz
authors.affiliation: Department of Microbiology, Jinnah University for Women, Karachi, Pakistan.
authors.forename: Anum
authors.initials: A
authors.lastname: Ali
authors.affiliation: Department of Biochemistry, University of Karachi, Pakistan.
authors.forename: Muhammad Noman
authors.initials: MN
authors.lastname: Syed
authors.affiliation: Food and Marine Resources Research Center, PCSIR Laboratories Complex, Karachi, Pakistan.
authors.forename: Abdul Basit
authors.initials: AB
authors.lastname: Khan
mesh_terms: D001427:Bacterial Toxins / Q000235:genetics* / Q000302:isolation & purification; D001431:Bacteriological Techniques; D004269:DNA, Bacterial / Q000235:genetics* / Q000302:isolation & purification; D003967:Diarrhea / Q000175:diagnosis / Q000382:microbiology*; D054307:Enterotoxigenic Escherichia coli / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D004768:Enterotoxins / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000175:diagnosis / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000302:isolation & purification; D005243:Feces / Q000382:microbiology; D005838:Genotype; D006801:Humans; D016133:Polymerase Chain Reaction; D022622:Shiga Toxin 1 / Q000235:genetics / Q000302:isolation & purification; D022641:Shiga Toxin 2 / Q000235:genetics / Q000302:isolation & purification; D054323:Shiga-Toxigenic Escherichia coli / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity
chemical_list: D001427:Bacterial Toxins; D004269:DNA, Bacterial; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D022622:Shiga Toxin 1; D022641:Shiga Toxin 2; C034151:heat stable toxin (E coli); C027538:heat-labile enterotoxin, E coli