| Antibiotics abuse has caused high resistance level over the years and antimicrobial resistance in bacteria has been becoming a global problem. With the horizontal transfer of antibiotic resistance genes, super bacteria is sweeping the globe, causing great damage and panic, and environmental antimicrobial resistance has been attracting more and more attention. Therefore, systemic research for the source, the dynamic process and the ecological law of antimicrobial resistance in bacteria is becoming more important. In this article, we established a continuous cultivation model both in vivo and vitro with antimicrobial concentration increased by degrees for SPF chicken, analyzed the antimicrobial resistance dynamics and the side effects of main antibiotics and presented a breeding plan to reduce antimicrobial resistance according to the hatchery condition combined with fecal bacteria transplantation experiments.1.Antimicrobial increasing continuous cultivation in vitro makes MIC normal distribution again.We measured the MIC of intestinal E. coli to commonly used antibiotics both with SPF chicken and commercial chicken using the method of 96 matrix susceptibility test, and found that there was discrete between chickens in the same hennery and different strains in one chicken, which presented normal distribution. In vitro, after we used Ampicillin and Amikacin for antimicrobial-increasing induction, both the peak and peak width of MIC frequency distribution offseted and presented normal redistribution.2.Antimicrobial increasing continuous induction in vivo changed SPF chicken intestinal flora with MIC peak move to the right.Using two common antibiotics Ampicillin and Neomycin sulfateas inducer and SPF chicken as object, the variation of intestinal flora was observed through fecal smearing, Illumina sequencing and 96 matrix susceptibility test. Neomycin sulfateas had more effects on the intestinal flora, while Ampicillin made the intestinal flora dispersed and more easier to induce high resistance strains.3.Antibiotics-caused effects on biochemistry and immunity index in SPF blood.Side effects of Ampicillin and Neomycin sulfateas were measured on SPF chicken based on the weight and index of immune organs, immune factors and routine biochemical tests. After treated with antibiotics for 21 days, chicken physiology and fecal has changed dramatically. Weight and mental state of these chickens return to normal after stopping giving antimicrobials while the index of immune factor and renal function still abnormal, presented an obvious renal toxicity.4.Fecal microbiota transplantation reduced antimicrobial resistence level.An microbiological background investigation of a hatchery, based on the collection of chick embryos and environmental samples and the separation of possible bacteria of various kinds, it was found that E. coli was the main potential pathogens and showed a high-to-low separation rate like pipped weak embryos> unpipped weak embryos> dead embryos> healthy embryos. These demonstrated that environment is the major pollution source, thus disinfection and isolation of the hatching room can protect healthy embryos from the pollution of weak or dead embryos. And the fecal microbiota transplantation experiment showed that using SPF fecal microbiota transplantation to purify chicken pathogenic microorganism could reduce antimicrobial resistance level and finally enhance chicks’competitiveness.The essence of kinetics of antibiotic resistance is an ecological problem, that is, the enrichment and diffusion of resistant bacteria and genes. The comprehensive effect of various kinds of resistance mechanisms and genes formed the group normal distribution of resistance phenotype, which, under the constant stress of antibiotics, showed the normal redistribution continuously, and there were significant differences between the kinetics of different antibiotics. There were competition between resistant genes at the bacteria, flora and host immune levels, and fecal microbiota transplantation was a macro strategy to reduce the abundance of resistant pathogens. |
