Isolation, Identification and Partial Characterization of Plasmid DNA of Different Bacterial Species Isolated from Clinical Specimens of Patients Suffering from Diarrhea

Out of 200 fecal specimens from patients admitted to the various hospitals in Erbil city suffering from acute and persistent diarrhea, it was found that the bacterial pathogens were recovered from 69 patients representing 34.5%. All bacterial isolates were identified by unique features of morphological, cultural, biochemical and serological characteristics. The enteropathogenic Escherichia coli (EPEC) was the most common group isolated from 33(16.5%) of the patients followed by Salmonella, Klebsiella, Enterobacter, Proteus, Morganella in ratios 13(6.5), 7(3.5), 6(3%), 2(1%), 2(1%) respectively. In addition, amplification of plasmid DNA content by antibiotics in some isolated bacterial species has been studied and the results showed enormous increase in plasmid DNA concentrations in amplified cultures of Klebsiella oxytoca, Salmonella and E. coli isolates after treatment with 150 g/ml chloramphenicol reaching to more than six folds of increase when compared with their concentrations in unamplified cultures. Also, in amplified cultures of other K. oxytoca and E. coli isolates but in presence of 150 g/ ml tetracycline, the folds of plasmid DNA amplification appear to be in the range of 6.87 to 11.25.