Laboratory Diagnosis of Mixed Adenovirus and Bacterial Infection in Laying Hens

Purpose To identify the pathogen of the mixed infectious disease of adenovirus and bacteria in laying hens, so as to guide the treatment of the disease in breeding farms and avoid greater economic losses.

Method Samples of heart, liver, spleen, gland, stomach, small intestine and other tissues of chickens with obvious clinical symptoms were collected aseptically. The above tissue samples were isolated and cultured with blood agar medium and MacConkoy agar medium, and the drug sensitivity test was performed, and then the pathogenic bacteria were identified by morphological methods and biochemical tests. Meanwhile, PCR/RT-PCR amplification technology and sequencing were used to identify fowl adenovirus (FAdV), infectious bursal disease virus (IBDV), newcastle disease virus (NDV) and highly pathogenic avian influenza (HPAI) H5N1 nucleic acids.

Result Escherichia coli, Staphylococcus aureus and Gallibacterium anatis were isolated and cultured. The bacterial susceptibility test results showed that the three bacteria were sensitive to colistinsulfate and doxycycline. PCR results were positive for FAdV-C-4 and negative for IBDV, NDV and H5N1.

Conclusion The chickens were mainly infected by FAdV-C-4 virus, accompanied by secondary mixed infection of E. coli, S. aureus and G. anatis, and the three bacteria were sensitive to colistinsulfate and doxycycline.