Abstract

Soleen Saeed Ahmed, Rashid F. Hadid and Tariq Taher Seleman

Twenty-one isolates of Pseudomonas aeruginosa were collected from burns hospital laboratories in Duhok City. They were identified using the API 20E system, biochemical and morphological characteristics. All isolates had multiple resistance to ampicillin, tetracycline, rifampicin, amoxicillin, chloramphenicol, cefotaxime, erythromycin, penicillin, neomycin, streptomycin, trimethoprim and gentamycin, and were sensitive to ciprofloxacin. The minimum inhibitory concentrations (MICs) of two curing agents, sodium dodecyl sulphate (SDS) and ethidium bromide, used in this study were determined and the results indicated that the curing percentage and efficiency of each curing agent was determined. From treatment with 700 µg/ml ethidium bromide, it was observed that no cured cells were obtained for all antibiotics used, whereas in the treatment done for three incubation times using SDS at a concentration of 1% (W/V) with different incubation periods as curing agent, the bacterial colonies that lost their antibiotics resistance appeared with different curing rates. The results showed 75 - 100% of curing for streptomycin and gentamycin with little effect on erythromycin and trimethoprim (0 - 8%), while SDS had variable effect on other antibiotics resistance in some isolates. In addition, curing of plasmid DNA by elevated temperature (45°C) was carried out and the results revealed high percentage of curing for all antibiotics resistance as they were compared with that induced by the action of SDS and ethidium bromide. The percentages of bacterial colonies that lost their antibiotic resistance were 55 - 100% for curing to all antibiotic resistance in the six tested isolates.