Isolation and identification of Haemophilus paragallinarum type B from a chicken farm
Zhang Lixian
Xu Yindi
Wang Zhifang
Bai Hongjie
Jiao Wenqiang
You Yi
Zhu Wenhao
Xu Feng
Abstract：This study aimed to provide a reference for the prevention and treatment of Haemophilus paragallinarum infection.A bacterial strain was isolated from the infraorbital sinus and tissue samples of diseased laying hens in a chicken farm in Xinxiang City,Henan Province.The isolate was characterized through symptom observation,clinical autopsy,bacterial isolation and culture,PCR sequencing,and antimicrobial susceptibility testing.The results showed that the isolate formed small,gray-white,translucent,dewdrop-like colonies on TSA medium supplemented with calf serum and NAD.Gram staining revealed Gram-negative bacteria with diverse morphologies,including rod-shaped,coccobacilli,and elongated filamentous forms.PCR amplification and sequencing demonstrated a nucleotide homology of 96.30%～99.05%with Haemophilus paragallinarum strains in GenBank.The isolate exhibited 98.94%homology with the reference strain VRDC/AV pg/H40(type B)from NCBI,confirming it as Haemophilus paragallinarum type B.Antimicrobial susceptibility testing indicated high sensitivity to azithromycin,cefotaxime,ceftriaxone,gentamicin,amikacin,rifampicin,and erythromycin.The study indicates that the isolates exhibited high homology with the Haemophilus paragallinarum type B reference strains published in NCBI and demonstrated notable pathogenicity.These findings underscore the necessity for heightened vigilance and proactive implementation of biosafety protocols in poultry production systems to mitigate associated risks.
Keywords：Haemophilus paragallinarumBacterial isolation and identificationAntimicrobial susceptibility test
Publication Date：2025-05-15
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：5( 12-16 )