Partial description of plasmid content in bacteria Serratia marcescens isolated locally

This study involved isolation oftwenty eight primary isolates of thegenus Serratia from different clinical human infections from differenthospitals in Mosul city . After microscopic examination and diagnosisusing biochemical tests, cultural characters and API 20 E system ,elevenisolates of Serratia marcescens were identified from them .Amplificationof plasmid DNA content in S.marcescens isolates were tested in presenceof chloramphenicol (1 OO}l/ml), tetracycline and starvation . The isolatesshowed variation in their ability to amplify their plasmid DNA content inthe presence of chloramphenicol and by starvation as compared withunamplfied cultmes. While in presence of tetracycline (150 )1/ml) onlyone isolate out of seven showed this characteristic. Phages isolated fromsewage water were used to control viabiLity of bacterial isolates. Theresults showed that these phages appear to be ineffective on theseisolates.