Isolation and molecular identifcation of Avibacterium paragallinarum in suspected cases of infectious coryza

Abstract

Isolation and identifcation of Avibacterium paragallinarum , the causative agent of infectious coryza, is considered achallenging task in laboratories with limited specialties. In the present study, 14 commercial layer fowls showing the typical symptomsof infectious coryza were subjected to primary isolation followed by polymerase chain reaction confrmation of suspect colonies(culture-PCR). Direct PCR assays on infraorbital sinus swab samples were also carried out. Tirty-fve suspected cases of infectiouscoryza in commercial broiler chickens were also screened using direct PCR on infraorbital sinus swabs. In culture-PCR, only 1 of the4 suspected isolates was confrmed as Av. paragallinarum . In comparison, in direct PCR, 5 layer samples were shown to be positive forAv. paragallinarum . All of the broiler samples were negative in the direct PCR assay. Our fndings indicate that primary isolation incombination with PCR can be a simple method for diagnosis of infectious coryza, although with a lower sensitivity than direct PCR.While direct PCR is comparably the more rapid and sensitive test, there will be instances in which the bacterial isolate is needed forfurther use. Hence, the culture-PCR method can be a practical and simple approach, especially in laboratories with limited specialty inidentifcation of this fastidious organism.