Isolation and identification of Pasteurella multocida from geese in Guangdong,detection of antimicrobial resistance phenotype and drug resistance gene and correlation analysis
To investigate the prevalence,antimicrobial sensitivity,carrying of antimicrobial resistance genes,and the correlation between resistance phenotypes and resistance genes of Pasteurella multocida(Pm)from geese in Guangdong area,193 heart blood and liver samples of suspected Pm-infected geese collected from Guangdong from 2019 to 2022 were streaked and inoculated into different culture mediums to isolate bacteria.After purification,the KMT1 gene of the isolates was amplified by PCR and sequenced.The five capsular genes and eight lipopolysaccharide genes of the isolates were amplified by multiplex PCR to analyze the capsular typing and lipopolysaccharide typing of the isolates.The results showed that 83 strains of goose-derived Pm were isolated,of which 82 were of capsule type A,and one could not be classified by capsular typing;the lipopolysaccharide types were all L1.The antimicrobial sensitivity of the isolates was tested using the K-B disc diffusion method.Fifteen antimicrobial resistance genes of seven classes were detected by PCR,including β-lactams(blaCTX-M,blaTEM,blaOXA),aminoglycosides(aadA1,aph(3')Ila),quinolones(qnrA,qnrB,qnrS),florfenicol(floR),tetracyclines(tetM,tetX),macrolides(ermF,ereD),and sulfonamides(sul1,sul3).The correlation between resistance phenotypes and corresponding resistance genes was analyzed using the chi-square test for two-sample rates in a completely randomized design in SPSS22.The results of antimicrobial sensitivity test showed that the 83 strains of goose-derived Pm were highly sensitive to various drugs,with more than 63%of the strains being sensitive to quinolones ciprofloxacin and ofloxacin,aminoglycosides gentamicin and amikacin,β-lactams ceftriaxone,sulfonamides compound sulfamethoxazole,and macrolides azithromycin.More than 50%of the strains were resistant to aminoglycosides streptomycin and kanamycin,and 49.40%(41/83)and 46.99%(39/83)of the strains were resistant to aminoglycosides neomycin and tetracyclines tetracycline,respectively.The detection of resistance genes showed the presence of qnrB,sul3,blaTEM,aadA1,aph(3')Ila,ereD,ermF,tetM,floR,with detection rates of 9.63%,27.71%,28.92%,48.19%,14.46%,49.40%,3.61%,1.20%,and 32.53%,respectively.No resistance genes qnrA,qnrS,sul1,tetX,blaCTX-M,blaOXA were detected.Correlation analysis showed that the aadA1 gene had a highly significant correlation with resistance to neomycin,streptomycin,kanamycin,and amikacin in Pm(P<0.001);the blaCTX-M and floR genes had a certain correlation with resistance to cefotaxime and florfenicol,respectively(P<0.05).The above results demonstrated that the predominant genotype of Pm in Guangdong area is A:L1,which is sensitive to multiple antimicrobial agents,and the carrying rate of resistance genes is not high,with only some drug resistance phenotypes being related to resistance genes.This study provides a reference for the monitoring and prevention of goose-derived Pm disease in Guangdong and lays the foundation for research on the resistance mechanism of Pm.
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