甘肃张掖、金昌地区犊牛腹泻致病菌的分离鉴定、致病性及耐药性分析OA

This study aimed to investigate the species,pathogenicity,and antibiotic resistance prevalence of the primary pathogenic bacteria from diarrhea calves in Zhangye and Jinchang regions of Gansu province,providing a reference for local prevention and treatment.A total of 41 samples(27 fecal samples,4 milk samples,10 soil samples)were collected from 6 cattle farms in Zhangye and Jinchang.Pathogenic bacteria were isolated and identified by bacterial culture,Gram staining,growth characteristic identification,and 16S rRNA gene sequencing.Pathogenicity tests and Kirby-Bauer(K-B)disk diffusion were utilized to confirm pathogenicity and antibiotic resistance.The results showed that 4 pathogenic strains were isolated from 41 samples,among which JC01,JC02,and JC03 were identified as Escherichia coli,and JC04 was identified as Klebsiella pneumoniae.Homology analysis indicated that JC01 was most closely re-lated to Escherichia coli strain U 5/41,while JC04 showed the highest homology with the standard strain Klebsiella pneumoniae subsp.ozaenae.Pathogenicity studies indicated that both JC01 and JC04 exhibited strong pathogenicity,causing severe pathological damage to the spleen and jejunum.Antibiotic susceptibility testing revealed that the 3 E.coli strains exhibited high resistance to β-lactams(88.89%),macrolides(100%),tetracyclines(100%),lincosamides(100%),and sulfonamides(100%).The K.pneumoniae strain was fully resistant to β-lactams,aminoglycosides,macro-lides,tetracyclines,lincosamides,and sulfonamides,remaining susceptible only to cefoxitin,ofloxacin,and norfloxa-cin.In conclusion,the primary pathogens causing diarrhea in calves in the Zhangye and Jinchang were E.coli and K.pneumoniae,both of which exhibited strong pathogenicity and broad-spectrum,high-level antibiotic resistance.