Bacterial Detection And Drug Resistance Of Escherichia Coli In Different Rearing Patterns Of Laying Hens In Hebei Province

To study the controlled technology of the environmental quality in layer house, and the method of improving the feeding management and preventing the disease.There are 3 different modes of laying hens as the research object in my study.The samples were obtained with TYK–6 microbiological aerosol samplers. They were tested by the methods of the bacteria isolation and culture, biochemical identification, glass plate agglutination, K-B disc diffusion method of drug sensitive test and agar gel electrophoresis test,compared and analyzed the bacterial contamination of the air in the henhouse of three different patterns and the biological characteristics of the airborne Escherichia coli. by which to study the bacterial concentration of the air and the distribution of particle size in the henhouse of three different patterns and the biological characteristics of the airborne and chicken Escherichia coli. Results as follows: 1. The bacterial concentration of the air and the distribution of particle size in the henhouse of three different patternsIt was very remarkable that the bacterial concentration of the air changed with the seasons under the same pattern of henhouse(P < 0.01).In the henhouse of three different patterns, the biggest variation tendency was in the bacterial concentration of the air in the semi-opened henhouse, while the lowest variation tendency was in the bacterial concentration of the air in the fully enclosed henhouse and the bacteria concentration of the air in different seasons was relatively low.It was similar that the distribution of bacterial particle among the henhouse of three different patterns. It mainly distributed in first-to-four level of the sampler, of which the distribution proportion was the highest in the first level, and was the lowest in the sixth level. 2. The isolation and identification of airborne Escherichia coli in the henhouseSeparating and identifying 109 strains of airborne Escherichia coli from nine large-scale henhouse of three different patterns, of which dominant serotypes were O65(37.61%), O101(11.93%), O2(6.42%) and the proportion of mixed serotype were 6.42%. 3. The drug resistance of airborne Escherichia coli in the henhouse109 strains of airborne Escherichia coli had a multiple drug resistance. The proportion of multi-drug-resistant strains to Ampicillin and other 11 kinds of β-lactams was more than 50%, and to Ofloxacin and other 5 kinds of fluoroquinolone drugs was more than 60%, and to Gentamicin and other 4 kinds of aminoglycoside drug was more than 50%, and to Doxycycline and Tetracycline drug were 85.32% and 82.57%, respectively, and to Chloramphenicol and Florfenicol were 77.06% and 72.48%, respectively.In the 109 strains of Escherichia coli, the drug resistance rate of 3 kinds of dominant serotype of airborne Escherichia coli were relatively high, and the phenomenon of multi drug resistance was more serious. 4. The resistance detection of Airborne and chicken Escherichia coli in the disease henhouse51 strains of airborne Escherichia coli were isolated and identified from the disease henhouse. 4 strains of Escherichia coli were isolated and identified from the liver of sick chicken(i.e. chicken Escherichia coli). The airborne and chicken Escherichia coli both contained the mixed serotype strains of O78 and O65.The result of drug resistance test showed that the phenotypic resistance of the airborne and chicken Escherichia coli in disease henhouse was similar. 5. Plasmid DNA extraction of Escherichia coliThere were some correlation relationship between the phenotypic resistance and the plasmid profiles of the airborne and chicken Escherichia coli in disease henhouseIn conclusion, the difference of bacterial concentration among the three different patterns of the henhouse was very remarkable(P < 0.01). The lowest variation tendency was in the bacterial concentration of the air in the fully enclosed henhouse. The distribution proportion of bacterial particle was the highest in the first level in the three different patterns of the henhouse. There were O65, O101, O2 of three dominant serotypes in 109 strains of airborne Escherichia coli. Furthermore, the drug resistance rate of 3 kinds of dominant serotype of airborne Escherichia coli were relatively high, and the phenomenon of multi drug resistance was more serious. The phenotypic resistance of the airborne and chicken Escherichia coli in disease henhouse was similar, which were correlated with the plasmid profiles of the airborne and chicken Escherichia coli in disease henhouse.