新疆部分地区羔羊呼吸道溶血性曼氏杆菌分离鉴定与生物学特性

Isolation,identification and biological characteristics of Mannheimia haemolytica in respiratory tract of lambs in Xinjiang

为了解新疆6月龄内羔羊呼吸道携带的溶血性曼氏杆菌(Mannheimia haemolytica,Mh)的生物学特性,本研究采集了新疆5个地区8个规模化羊场羔羊鼻拭子290份,采用常规细菌分离鉴定及PCR鉴定方法从鼻拭子中分离鉴定细菌,对分离菌株进行荚膜血清型、MLST分型、毒力基因、药物敏感性及耐药基因检测。结果显示,从290份鼻拭子中分离到14株溶血性曼氏杆菌(Mh42~Mh56),荚膜血清型中9株未定型,3株A2型,A1型和A6型各1株;ST型中5株ST16型、4株ST28型、1株ST46型,4株未定型。感染小鼠在10 h开始死亡,96 h存活率为40%,感染死亡小鼠肺脏充血肿大、部分肺脏出血。14株Mh均携带dnaN、gapA、fbpA、gs60、lktC,sodA,携带率为42.85%,均不携带plpB、tonB、ptfA、fimA。Mh42对多西环素、麦迪霉素、氟苯尼考耐药,Mh54对恩诺沙星、环丙沙星耐药,其余菌株对检测的21类药物还未产生耐药性。14株Mh未检测到耐药基因。本研究为新疆地区羔羊呼吸道溶血性曼氏杆菌的流行病学及临床防制提供参考依据。

To investigate the biological characteristics of Mannheimia haemolytica(Mh)in the respiratory tract of lambs under six months of age in Xinjiang,two hundred and ninety nasal swabs were collected from lambs in eight large-scale sheep farms across five regions of Xinjiang.The nasal swabs were subjected to conventional bacterial isolation and identification,as well as PCR identification methods to isolate and identify bacteria.The isolated strains were then tested for capsular serotype,MLST typing,virulence genes,drug sensitivity,and drug resistance genes.The results showed that out of the two hundred and ninety nasal swabs,a total of fourteen strains of Mh(Mh42-Mh56)were isolated;among the capsular serotypes,nine strains were untyped,three strains were A2 type,one strain was A1 type,and one strain was A6 type;MLST typing revealed five strains of ST16,four strains of ST28,one strain of ST46,and four strains of undetermined type.In infected mice,mortality began at 10 hpost infection,with a 40%survival rate at 96 hpost infection.The lungs of the deceased mice showed congestion,swelling,hemorrhage,and fleshy appearance.All 14 strains of Mh carried dnaN,gapA,fbpA,gs60,and lktC genes,with a carrying rate of 42.85%for sodA.None of the strains carried plpB,tonB,ptfA,and fimA genes.Mh42 showed resistance to doxycycline,midecamycin,and florfenicol,while Mh54 was resistant to enrofloxacin and ciprofloxacin.However,the remaining strains did not exhibit resistance to any of the twenty-one drugs tested.Additionally,no drug resistance gene was detected in fourteen strains of Mh.This study provides valuable insights into the epidemiology,clinical prevention,and treatment of Mh in the respiratory tract of lambs in Xinjiang.