ABSTRACT
Objective To search for the reasons of high positive rate of amotile bacteria and the diagnosis of septicemia in new-born Methods The blood was drawn from the different site of the new-born with septicemia and carricd out blood culture. The drug sensitivity test had been done by the method of paper stripdiffusion. The plasmids of bacteria were extracted rapidly by medified Birnboim method and the plasmid analyss was carried out. The plasmids's DNA of 35 epidemic strain was cut off by both restriction enzyme of Hind Ⅲ and EcoR Ⅰ. The outer membrane protein (OMP) was determined by SDS-polyacrylamide gel electrophoresis.Results There are 51 patients with positive blood culture amotile bacterium,of them, pollution; 35 cases (68．6%), septicemia: only 16 cases (31．4%),54．8% (57/104) strains bacteria have drug resistance to more of 12 drugs. 87．3% (165/189) strains bacteria have plasmids. They are cut off as 6 DNA fragments (1．9,2,4,5, 8．5 and 18Kb) by Hind Ⅲ restrietion enzyme. and as 5 DNA fragments (2,2．6,3．2, 6．3 and 22 Kb) by EcoR Ⅰrestrietion enzyme, it is showed that they come from a same clone. The epidemic strain include 10 slips OMP, but non-epidemic strain have 11 slip OMP, increase a 25Kd belt. The amotile bacteria with above-mentioned plasmid spectrum, restriction enzyme spectrum and OMP spectrum are only seen in the air, therapeutic dish and syringe needle.Conclusion The pollution is an important reason of amotile bactorium high positiye rate in new-born.Diagnosing septicemia should depend on bacteria culture, plasmid analysis restriction enzyme analysis of plasmid DNA, oMP determination and combining medical history and clinical manifestation.