title: Screening of the novel colicinogenic gram-negative rods against pathogenic Escherichia coli O157:H7.
abstract: OBJECTIVE
  Escherichia coli (E. coli) O157:H7 is gram-negative enteric pathogen producing different types of Shiga toxin. This bacterium is the most corporate cause of haemorrhagic colitis in human. Administration of antibiotics (particularly sulfa drugs) against this pathogen is a debatable topic as this may increase the risk of uremic syndrome; especially in children and aged people. Around the world, microbiologists are in search of alternative therapeutic methods specially probiotics against this pathogen. In the present study, we have focused on the investigation of alternate bio-therapeutics (probiotics) for the treatment of patients infected with E. coli O157:H7. This study is based on the identification of colicin-producing gram-negative bacteria (particularly enterobacteriaceae) which can competently exclude E. coli O157:H7 from the gut of the infected individual.
  
  
  METHODS
  Hundred samples from human, animal faeces and septic tank water were analysed for nonpathogenic gram-negative rods (GNRs).
  
  
  RESULTS
  Out of these samples, 175 isolates of GNRs were checked for their activity against E. coli O157:H7. Only 47 isolates inhibited the growth of E. coli O157:H7, among which majority were identified as E. coli. These E. coli strains were found to be the efficient producers of colicin. Some of the closely related species i. e., Citrobacter sp, Pantoea sp. and Kluyvera sp. also showed considerable colicinogenic activity. Moreover, colicinogenic species were found to be nonhaemolytic, tolerant to acidic environment (pH 3) and sensitive to commonly used antibiotics.
  
  
  CONCLUSIONS
  Nonhaemolytic, acid tolerant and sensitive to antibiotics suggests the possible use of these circulating endothelial cells (CEC) as inexpensive and inoffensive therapeutic agent (probiotics) in E. coli O157:H7 infections.
authors: H
authors: H
authors: Mushtaq
authors: Institute of Biotechnology and Genetic Engineering, University of Agriculture Peshawar, Peshawar, Khyber Pakhtunkhwa, Pakistan.
authors: J
authors: J
authors: Bakht
authors: N
authors: N
authors: Bacha
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000898:Antibiosis; D052978:Disk Diffusion Antimicrobial Tests; D019453:Escherichia coli O157; D005243:Feces / Q000382:microbiology; D006090:Gram-Negative Bacteria; D006801:Humans; D008826:Microbial Sensitivity Tests; D019936:Probiotics
chemical_list: D000900:Anti-Bacterial Agents