| Pseudomonas aeruginosa is an extremely common opportunistic pathogen in clinical and production,with a complex drug resistance mechanism.With the application of antibiotics,drug-resistant bacteria can evolve selectively,and the emergence of multidrug-resistant strains leads to the increasingly serious drug resistance problem of Pseudomonas aeruginosa,which seriously threatens the health of humans and animals.In view of the unknown epidemiology and drug resistance of dairy cow mastitis pathogens in large-scale pastures in some areas of Jiangsu,this study used bacterial culture and 16SrDNA methods to isolate and identify pathogenic bacteria from clinical mastitis samples in Jiangsu,aiming to clarify some parts of Jiangsu Province.The prevalence of Pseudomonas aeruginosa originating from dairy cow mastitis in the region,combined with the genus and drug resistance analysis of the pathogenic bacteria,gave an optimized treatment plan,and revealed the epidemiological basis of the pathogenic bacteria in the pasture-induced mastitis infection in Jiangsu region,so as to provide an Provide theoretical basis for effective control of mastitis in dairy cows and scientific prevention and treatment.By determining the drug resistance phenotype of Pseudomonas aeruginosa,β-lactam resistance gene carrying and distribution of virulence genes,and on the basis of drug susceptibility test,MLST molecular typing of Pseudomonas aeruginosa was carried out,and the mammary glands of dairy cows in some areas of Jiangsu were analyzed.The main drug resistance genotypes,virulence genes and prevalence of ESBLs of Pseudomonas aeruginosa from inflammatory origin,to explore the correlation between drug resistance and virulence,and to provide reference for the prevention and control of the spread of ESBLs-producing Pseudomonas aeruginosa in pastures.The result is as follows:In this study,three large-scale farms in central Jiangsu（Yang zhou,Tai zhou）and southern Jiangsu（Zhang jiagang）were selected,and a total of 68 milk samples for clinical mastitis were collected.The bacterial isolation and identification results showed that pathogenic bacteria were detected in 61 milk samples.The detection rate of the overall samples was 89.71%;the number of isolated strains was 260,of which 52 were Pseudomonas aeruginosa,and the detection rate of Pseudomonas aeruginosa was 20%;102 were Staphylococcus aureus,and the detection rate was 39.13;46 strains of Klebsiella pneumoniae,with a detection rate of 17.66%;30 strains of Escherichia coli,with a detection rate of 11.48%.According to the 2021 edition of CLSI guidelines,the KB disc diffusion method was used to deter 分钟 e the susceptibility of 52 Staphylococcus strains to 11 antibiotics.The results showed that Pseudomonas aeruginosa was severely resistant to lincomycin,penicillin,amoxicillin and cefotaxime.,the drug resistance rates reached 100.0%,98.1%,59.6%,and 50.0%,respectively.Sensitive to ciprofloxacin,tetracycline,piperacillin,imipenem and meropenem.Multi-drug resistance was do 分钟 ated by 5-drug resistance,accounting for 30.77%.The primary screening of ESBLs-producing Pseudomonas aeruginosa was carried out by the double-disc method.Of the 52 tested Pseudomonas aeruginosa strains,8 strains produced ESBLs enzymes,and the positive rate was 15.38%.The identification results of seven main ESBLs genes showed that the detection rate of HSV gene was the highest,which was 96.15%.The detection rate of GES was 36.54%,the detection rate of TEM was 11.54%,and the detection rate of VEB and CTX was 5.77%.At the same time,52 strains of Pseudomonas aeruginosa did not carry OXA and PER genes.MLST typing results showed that ST277 was the dominant type of Pseudomonas aeruginosa.The results of virulence genes showed that exoS,exoT,exoY and pyo virulence genes were all positive,and the four virulence genes were significantly correlated with the drug resistance gene SHV（P<0.01）.This study revealed the widespread existence of Pseudomonas aeruginosa in clinical cases of dairy cow mastitis through epidemiological investigation of dairy cow mastitis sources and analysis of drug resistance phenotypes and virulence genes in pastures in some areas of Jiangsu,and the existence of multiple resistance As an opportunistic pathogen,Pseudomonas aeruginosa’s prevalent distribution,drug resistance and virulence characteristics are extremely important for clinically ensuring the health of dairy cows’mammary glands.The research results provide an effective experimental basis for the prevention and treatment of clinical mastitis in dairy cows in Jiangsu. |
