The Research Of The Biological Characters Of The Lytic Bacteriophages Of Resistant Escherichia Coli

Escherichia coli is one of the main bacteria that can cause intestine disease, which do harm to men's and animals' such as pigs and chickens, and the diseases caused by Escherichia coli made the loss of millions. The common method to cure the disease caused by bacteria is antibiotics, but as more and more bacteria can be resistant to drug, antibiotics can't control these diseases efficiently. Although many new antibiotics were prepared to solve the drug resistance, the results were that the range of the drug resistance was larger and larger.So the new preparations must be manufactured to control this serious condition.The bacteriophage therapeutics is a new treatment, which has many functions superior to antibiotics.In this experiment, twenty-four drug-resistant pathogenic Escherichia coli were evaluated, and the drug resistance was over severry percent in average.And sixteen bateriophages of Escherichia coli were separated from sewage. The lysis pattern of these sixteen bateriophages to the twenty-four Escherichia colis was assayed. From the lysis pattern, six bacteriophages of Escherichia colis which had strong lysis effects and one Escherichia coli that is the host bacterium of the six bateriophages were choosed as the experimetal material for lysis experiment in vivo.And six strong-lysis bacteriophages and one weak-lysis bacteriophages which can all lyse the same Escherichia coli were choosed out, and the DNA of these seven bacteriophages were extracted.All the seven DNA was cutted by four endonucleases: EcoR I . EcoRV . Sal I and Pst I . And the endonuclease-cutting pattern of seven bacteriophages' DNA is analysed by SPSS,from the statistic results the lysis effects were related to the kin. The endonuclease-cutting patterns of six strong-lysis bacteriophages' DNA were similar, and collected to one kind in near distance in the diagram of genetic distance. But the weak-lysis bateriophage was far from the other six strong-lysis bacteriophages in the diagram of genetic distance.And the lysis effects of the bacteriophages in vivo is related to the way of theinjection,among all the injection pattern injecting the bacteriophages into muscle is most efficient way.And the experiments showed that after the mice were injected ten times more Escherichia coli than MLD, corresponding bacteriophages could cure the diseases caused by Escherichia coli, if the bacteriophages were injected in four hours later. Other experiments showed the rising and falling laws of the Escherichia coli and its bacteriophages. If the bacteriophages was injected alone, they would decrease to low level in blood and liver, but keep high level in spleen.If the bacteriophages were injected four hours later to cure Escherichia coli, the quantities of Escherichia coli in blood and liver and spleen would decrease to very low level in one hours, and the bacteriophages could keep high liter for a bit long time. Compared to antibiotics, bacteriophages could cure the diseases of Escherichia coli more efficiently by muscle-injection.