| In livestock production, piglet diarrhea is a kind of important disease endangering health of piglets, the main pathogenic bacteria for E.coli, the pathogenic E.coli can cause intestinal infection, human and animal infectious diseases. Large hog industry in Sichuan and Chongqing, the high morbidity and mortality, poor clinical drug curative effect, causing immense economic loss to the nursery.To assess piglet diarrhoea with the E.coli infection status from swine farms in Sichuan and Chongqing area, this study in November 2011 to May 2012 of 18 prefecture-level city as 43 large-scale swine farms in Sichuan and Chongqing acquisition diarrhea disease epidemic materials, through differential medium discrimination to cultivate, combined with the cultural character, thallophytic form, and biochemical tests identified 273 E.coli strains; meanwhile, through serotyping and ESBLs, drug resistance, virulence genes detection research, systematically analyzes the separation by E.coli strains related characteristics, and comparative analysis of the relationship between each other.The serum agglutination test of 273 E.coli strains serotype identification of 205 stereotypes, belonging to 43 serotypes, O138 (12.2%) was the highest detection rate, followed by O20 (6.83%),O8 (6.34%), O60 (5.85%), O141 (5.85%), according to the results obtained in different regions of the dominant serotype has bigger difference;273 E.coli strains to 16 commonly used antimicrobial agents were tested. The results show that the test strains appear serious multidrug resistant, most strains were 5-fast and above, the total proportion of 97.07%, up to 16-fast, a majority of the 9-fast,10-fast,12-fast and 14-fast, a total proportion of 42.12%.273 E.coli strains has 157 kinds of different drug spectrotyping, Amikacin and Ceftazidime have the strong bacteriostasis function, sensitive strains accounted for 53.11%,49.45%, Lincomycin, Ampicillin, Sulfadiazine, Tetracycline, Erythromycin was highly resistant, resistance rates of 80% or more;ESBLs detection for 273 E.coli strains,using the CLSI recommended synergism between Kirby-Bauer method and enzyme repression. The results showed that 273 E.coli strains detected 94 positive detection and the detection rate was 34.43%, Deyang, Guangyuan, Fuling have a higher detection rate of over 87%. ESBLs producing strains resistant to most antibiotics was significantly higher than that of non-ESBLs producing strain, and multi-drug resistance was mainly distributed in more than 7-fast, and the proportion of multi-resistant from 11-fast to 16-fast was higher than the proportion of non-ESBLs strains;Multiplex PCR methods to check out the four virulence genes(LT, STaP, STb, Stx2e) of E.coli. Results showed that the PCR method chould be performed fast and efficient detection, and detected in 84 of 273 E.coli strains carrying the virulence gene with one or more, and the detection rate was 30.77%. Failed to detect the StaP genes, the other detectable virulence gene combination type were Stx2e, STb, STb+LT, LT+Stx2e and LT,each detected of the positive strains in 38.1%,25%,22.62%,10.71%and 3.57%. STb+ LT gene type combination is more popular amongst O138, O20 and O64; STb gene more present in the O138, O20 and O141; Research findings showed ESBLs strains with the superiority serotype and virulence genes had a consistency on number of strains, and the drug resistance is directly related with virulence gene distribution did not see. |
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