摘要
[Objective]The paper was to understand the resistance of commonly used clinical antibiotics to avian Escherichia coli and the inhibition of lactobacillus against pathogenic E.coli.[Method]The strain was isolated and identified by SS medium culture,microscope examination,PCR amplification and biochemical test,and the sensitivity of avian E.coli to eight antibiotics was determined by disk diffusion method.Twelve strains of avian E.coli and one strain of lactobacillus were divided into five group using in vitro liquid culture method,namely simultaneous mixed culture group of lactobacillus and E.coli,first colonization group of E.coli,first colonization group of lactobacillus,E.coli control group and lactobacillus control group,for competitive inhibition test between E.coli and lactobacillus.[Result]Totally 34 strains with similar characteristics to E.coli strains were preliminarily screened;the target band amplified by PCR was 293 bp,which was consistent with the expected size.The isolated strain could decompose maltose,sucrose,lactose,glucose,arabinose,mannitol and sorbitol;the nitrate reduction test was positive,while citrate and V-P test was negative,consistent with the biochemical characteristics of E.coli.The resistance rate of the isolates to cefalexin and tylosin was over 65%,and that to enrofloxacin and doxycycline was up to 50%;the isolates were more sensitive to apramycin,tilmicosin,neomycin and colistin,and the total resistance rate was below 15%.The inhibitory effects of mixed culture of lactobacillus and E.coli against E.coli was better than first colonization of lactobacillus at 24 h;the inhibitory effects of first colonization of lactobacillus against E.coli was better than that of mixed culture of lactobacillus and E.coli at 36 h;the inhibitory effects of mixed culture of lactobacillus and E.coli against E.coli was the best at 48 h.[Conclusion]The isolated strains of E.coli were generally resistant to eight commonly used antibiotics.Lactobacillus could inhibit the growth of avian E.coli in vitro,and first colonization of lactobacillus received the best effort.
基金
Major Science and Technology Innovation Project of Liaoning Province"Feed Quality and Safety Control and Low Protein Feed Project"(2019JH1/10200002).
