GENETIC TRANSFORMATION IN ANTIBIOTIC RESISTANT ESCHERICHIA COLI O157:H7

SUMMARY: Five hundred stool samples were collected from patients with diarrhea (infants and children under ten years of age) admitted to the Pediatric and Maternity Hospital in Erbil City from March 2007 to September 2007. The samples were cultured on different culture media and according to the colony morphology, biochemical reactions and by the use of API 20E system, 35 (7%) were diagnosed as E.coli I, 8 (1.6%) E.coli II, 17 (3.4%) E.coli III, 22 (4.4%) E.coli IV, 8 (1.6%) Shigella dysenteriae, 16 (3.2%) Salmonella arizonae, 12 (2.4%) Salmonella typhi and 6 (1.2%) Vibrio cholerae. In addition, cases of Entamoeba histolytica 175 (35%), Giardia lamblia 102 (20.4%) and Hymenolepis nana 2 (2.4%) were identified. No infectious agents were found in 75 (15%) of the samples. 22 (4.4%) of the samples had mixed infections. The sensitivity of E.coli O157:H7 isolate to different antibiotics was performed. There was a variation in the resistance ranging from 8.5-90%. The determination of the site of genes responsible for the antibiotic resistance in E.coli O157:H7 was performed using the genetic transformation method for E.coli DH5α laboratory strain with the DNA that is absent from the highly resistant strains, E.coli O157:H7 4 and E. coli O157:H7 6. The transformation process succeeded when using the plasmid DNA for strain 4 and failed when using strain 6. It was evident that the genes responsible for resistance to the following antibiotics were located on the plasmid DNA: amoxicillin, amoxiclav, ampicillin, cephalexine, cefixime, cefotaxime, doxycyclin, gentamycin, nalidixic acid, nitrofurantoin, rifampicin, streptomycin and tetracycline. Whereas the genes responsible for the following antibiotic resistance were located on the chromosome: amikacin, erythromycin, chloramphenicol, ciprofloxacin, tobramycin and trimethoprim.