Study On The Drug Resistance Of Streptococcus In The Main Links Of Pig Industry Chain In Western Liaoning Province And Its Transmission

ObjectiveIn this study,we define the causes and development tendency of the drug resistance of streptococcus,explore the connection between the drug resistance of streptococcus in the pig industry chain of western Liaoning Province,study on the rule of the transmission for the drug resistance of streptococcus between congeneric species and alien species to prevent the generation of drug resistance and its elimination,and improve the damages for animal disease control and public health security that caused by the generation of bacterial drug resistance.Thus,this study provide theoretical basis to guide the clinical rational use of drugs,enhance the treatment effect,as well as formulate targeted control measures.MethodsThe 163 strains of streptococcus suis and 8 strains of human streptococcus are isolated from a certain key pig farm,the corresponding slaughterhouse in the lower stream,and its covered pork sales market in western Liaoning province.Streptococcus suis strains are isolated using streptococcus culture medium,morphological observation,biochemical test,and 16 Sr RNA gene detection method should be used to identify the streptococcus.Antibacterial drugs and drug sensitivity test of antimicrobial agents has been experienced by microdilution method and criteria of judgment according to the CLSI formulation and analyse results of enterococci sample detection.The conclusion is come from the comparison of antimicrobial resistance of Streptococcus isolated situation of the industrial chain,a comparative analysis of the type of resistance and resistance ratio.A higher rate of drug resistance detection of drug resistance gene analysis is chosen,and we detect rate of species and drug resistance gene of Streptococcus resistance genes,resistance genes and get the conclusion by comparing the gene sequence homology by analyzing the common drug resistance gene.Through comparing and analyzing the drug resistance of streptococcus suis,drug resistance genes,and homologous drug resistance genes of the main links in pig industry chain,it illustrates that the drug resistance of streptococcus suis has undergone transmission in the pig industry chain.In order to ensure the antimicrobial resistance of Streptococcus and spread in lateral level to get resistant strains isolated as donor,sodium azide resistant Escherichia coli,Streptococcus J53 ATCC 29212 are as the receptor bacteria plasmid to conduct the conjugation experiment,which involves detecting and analyzing the drug resistance and resistance gene sequencing of the experimentally obtained transconjugants.ResultsDrug sensitivity test results show that the separation of antibacterial drugs in the industrial chain of swine streptococcus and the observation of 9 drug resistance(tylosin,streptomycin,ciprofloxacin,tetracycline,lincomycin,gentamicin,penicillin,erythromycin,polymyxin)and 10 veterinary antimicrobial drugs(penicillin,amoxicillin,quinupristin,tetracycline,cotrimoxazole,cefotaxime,erythromycin,clindamycin,vancomycin,levofloxacin).In order to detect the resistance genes of the isolates,3 kinds of related genes of the same drug resistance rate were selected for the detection of the 9 main genes.Consequences: the 6 kinds of isolatedbacterial strain with carrying common resistance genes are observed,including tet L,Mcr-1,Erm B,tet O,tet M,Mef A/E,wherein the separation of autotrophic pig farms,slaughterhouses and sales of swine streptococcus of the tetracycline resistance gene tet L was the highest which are 91.89%,82.35% and 90.48% respectively.Separation of pig farms,slaughterhouses and autotrophic sales of swine streptococcus to polymyxin resistant gene Mcr-1 and macrolide resistance genes Erm B and Erm A detection rate is higher,reached more than 50%.The detection rateof the tetracycline resistance gene of Streptococcus tet L and macrolide resistant Erm B gene was up to 100%,the polymyxin resistant gene Mcr-1 and macrolide resistant gene Mef A/E rate was 50% and 62.5%.The detection rate of high resistance genes tet L,Erm B and Mcr-1 homology comparison analysis.The results showed that the separation of autotrophic pig farms,slaughterhouses,sales of swine streptococcus and isolated pig streptococcus autotrophic human resistance genes tet L and Erm B homology,which had reached more than 97%,and the separation of autotrophic pig farms,slaughterhouses,sales of tet L resistance gene homology comparison results reached 100%.The above result showed that the streptococcus that was isolated from three main links of pig industry chain in western Liaoning Province had common apparent resistance for various commonly used veterinary antibiotics and the antibacterial drugs for human use.Meanwhile,various kinds of similar drug resistance genes were detected,and the similar drug resistance genes with high detection rate had high homology.This result manifested that the bacterial drug resistance and its drug resistance gene had been transmitted in all links of the pig industry chain.Plasmid conjugation experiment showed that the resistance genes tet L and Erm B were detected in the zygote.The detecting results of drug resistance of zygote indicated that zygote corresponding with streptomycin,tetracycline,Lin Kemei has produced a description of erythromycin resistance,which has illustrated that Streptococcus resistance gene can be transferred by plasmids among different sources of Streptococcus and in the way of plasimd in different species resulting in the spread of drug resistance.Conclusions1,The streptococcus suis was isolated from main links of pig industry chain in western Liaoning Province which had generated common drug resistance for various veterinary antibiotics and the antibacterial drugs for human use,and carried the common drug resistance genes with high homology.The results suggested that the drug resistance of streptococcus suis had undergone transmission in pig industry chain.Meanwhile,through testing the drug resistance and drug resistance genes of streptococcus suis and human streptococcus in the pig farm,as well as homology,the result demonstrates that the drug resistance and drug resistance genes of various antibacterial drugs have been transmitted between pigs and human beings.2.Together with the conjugation experiment,it proved that the tet L and Erm B drug resistance genes carried by the streptococcus in main links of pig industry chain of western Liaoning Province could be spread among congeneric species and alien species of bacteria through plasmid mediate.Therefore,it further illustrates the possibility of the drug resistance of streptococcus being spread in all links of pig industry chain or between pigs and human beings.