| Colibacillosis refers to any localized or systemic infection caused entirely or partly by avian pathogenic Eschelichia coli (APEC),including septicaemia, granuloma (Hjarre'sdisease), air sac disease, chronic respiratory disease (CRD),avian cellulitis, swollen head syndrome, peritonitis ,salpingitis, osteomyelitis/synovitis, panophthalmitis, andomphalitis/yolk sac infection. Colibacillosis in mammals is most often a primary enteric disease, whereas colibacillosis in poultry is typically a secondary localized orsystemic disease occurring when host defence has been impaired or overwhelmed. Collectively, infections caused by Eschelichia coli (E.coli) are responsible for significant economic losses to the poultry industry in many parts of the world. Antimicrobial plays very important role incontrolling diseases caused by Escherichia coli ,along with the widely use of antibiotics. Antibitic resistance to bacteria is getting worse. There are a significantly increasing tendency of multi-resistance .The resistance of Escherichiacoli has raised several concerns relatied to human health and the development of poultry industry.1 .Isolation and identification of ducks pathogenicity E.coli and the drug sensitivity testSamples of the ducks died of Colibacilosis were collected from the breeding fields in Sichuan province and Chongqing. Bacteria were isolated and identified by biochemistry identification in the lab. Finally; 65 avian pathogenic E.coli strains were identified. The O serotyping of these bacteria strains were performed by slide agglutination and cuvette agglutination using the standard 0 antiserum. The results of O serotype test showed that all the strains isolated from ducks belonging to 15.serotypes,and the predominant O serotypes were 078,01,021 and 093. 13 isolates were not serotyped. There existed some differences between strains isolated from different areas, and the 078 is the main serotype in most of the places where the bacteria strains isolated.Twenty-one antibiotic scrips popular in clinic were selected to the drug sensitivity test. By the K-B round scrips method, 65 bacteria strains were detected the antibiotic sensitive. And the data were analysed according to the standard recommended by NCCLS (National committee of clinical and laboratory standard). The results were compared with the result of ATCC25922 which was set as control strain. The results show that antibiotic-resistance of the strains is very popular. Resistance profiles suggest that LM and EM may be the most resistant antimicrobial agents tested in this study. The resistant rate of them was 96.5%.There were more than 70% of the strains was resistanted to LM, EM, RA, SF, AMP, SMZ,AMX ,TE and STR..About 81.5% of the strains resist to more than ten drugs in our test. Comparatively, some antibiotics such as TOB, CTX ,and GM and so on have good effect to the bacteria strains. There were some differences in the resistance to the antibiotics among those strains isolated from different areas.and we found that there was some relationship the patterns evident of antibiotic resistance of the strains and the areas of the strains.2. Detection of some drug resistance genes from pathogenicity E.coli in duckAntibiotics have become less effective over time. Detect the sequences of resistant gene aphA, rpsL, rrsA , bla-TEM, SHV,Dhps, gyrA, parC and int I by .PCR.The products of 475 bp and 322 bp, 1606 bp, 858 bp,861 bp,849 by bp,540 bp,265 bp,280 bp were obtained for the respective genes.The results of molecular epidemiology of these drug resistant genes of 65 E.coli isolates showed that 100 percent tested strains had gyrA and parC gene. The positive ratio of aphA,Dhps and rpsL were more than eighty percent, the rrsA, bla-TEM and SHV were 13.8%, 46.2%, 27.7% respectively. Nearly 98.5% of total tested strains had more than three resistant genes. At the most some strains were detected eight resistant genes positive. Most of the isolate have 3 to 5 resistant genes. The positive ratio of A int I was 78.5%. All data indicated that the more and more serious drug resistance was related to the prevalence of drug resistant genes. These results indicated that more and more serious drug resistance was related to the prevalence of drug resistant genes. Therefore control the resistant gene shift to human from avian is important for public health.3.Detection of HSP70 mRNA from pathogenicity E.coli in duckATCC25922 for control and YY1 strain were incubated at 37℃for 2 hours,then incubated at 42℃for 3 hours later,and collected the bacterias. RT-PCR showed the HSP70mRNA of ATCC25922 and YY1 isolated increased following heat shock-Detect the expression of the HSP70 mRNA of isolates by RT-PCR,the result shows that HSP70 can be used to biomarker for drug resistance .
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