| Mycoplasma gallisepticum is a chronic respiratory disease of poultry caused by Mycoplasma gallisepticum.It often causes immunosuppression in infected chickens,and then secondary infection or mixed infection of other pathogens,such as infectious bronchitis,Newcastle disease,avian influenza,colibacillosis,etc.,which causes great economic losses in poultry industry.Mycoplasma gallisepticum can be transmitted through vertical transmission and horizontal transmission.At present,drug control,immunization and management promotion are still the main measures to prevent and control the disease.In this study,the epidemiological investigation of Mycoplasma gallisepticum in large-scale chicken farms in Jiangsu Province was carried out.It was found that Mycoplasma gallisepticum infection was common in Jiangsu Province,and then Mycoplasma gallisepticum was isolated and cultured.It was found that Mycoplasma could be isolated from trachea and throat swab,but the isolation rate of trachea was about 2 times higher than that of throat swab,which provided the basis for collecting high-quality clinical samples The successful diagnosis,treatment and prevention of Mycoplasma gallisepticum can provide reference for clinical prevention and control of Mycoplasma gallisepticum.The main contents of the study are as follows:Content 1:Epidemiological survey of Mycoplasma gallisepticum in large-scale chicken farms in Jiangsu Province.In order to understand the infection of Mycoplasma gallisepticum in large-scale chicken farms in Jiangsu Province,14 non Immunized Chicken Farms in Jiangsu province were collected in 2018-2019,with a total of 3112 blood samples.ELISA was used to detect the infectious antibody of Mycoplasma gallisepticum,and the detection results were analyzed.Results:1720 positive samples were detected,the positive rate was 55.27%.The positive rate of serum antibody in different chicken farms was different,the lowest was only 17.83%,the highest was 83.28%.All the 14 chicken farms tested had positive samples,with the infection rate of 100%.Among them,7 farms with the positive rate lower than 30%and 3 farms with the proportion of 21.43%,7 farms with the positive rate between 30%and 70%,accounting for 50.0%,and 4 farms with the positive rate higher than 70%,accounting for 28.57%.The positive rate of Mg infective antibody in different areas is quite different,among them,the highest is in Central Jiangsu,which is 70.25%,followed by Southern Jiangsu,which is 57.0%,and the lowest is in Northern Jiangsu,which is only 39.90%.There were some differences in the positive rate of Mg serum antibody in different weeks of age,among which the highest was 0-10 weeks of age,reaching 60.02%,followed by 10-20 weeks of age(55.92%),20-40 weeks of age(55.03%),40-60 weeks of age(53.42%)and>60 weeks of age(49.83%).This study basically found out the infection of Mg in large-scale chicken farms in Jiangsu Province,so as to provide a basis for the formulation and implementation of the prevention and control strategy of Mycoplasma gallisepticum.Content 2:Isolation and identification of Mycoplasma gallisepticum.In order to isolate MG from chicken farms,100 throat swabs and 25 windpipes of chickens suspected of Mycoplasma gallisepticum were collected from a certain chicken farm in Jiangsu Province.Then,PCR identification of Mycoplasma gallisepticum and Mycoplasma synoviae(MS)was carried out on the samples with medium discoloration.Finally,sequence comparison was carried out with 16S universal primers of Mycoplasma to further identify the isolated pathogen.Results:41 samples were discolored,accounting for 35.96%,including 28 throat swabs and 13 tracheal tissues.Among 41 discolored samples identified by PCR,25(61.0%)were mycoplasma gallisepticum,22(53.6%)were Mycoplasma bursae,and 6(14.6%)were both positive.The sequencing results of 16S universal primers were consistent with those of PCR.A total of 47 mycoplasma strains were isolated,the isolation rate was41.2%.Among them,25 strains were mycoplasma gallisepticum and 22 strains were mycoplasma synoviae,the isolation rate was 21.9%and 19.3%,respectively.According to the statistics of different samples,17 strains of Mycoplasma gallisepticum and 14 strains of mycoplasma synoviae were isolated from throat swab,the isolation rates were 18.5%and 15.2%respectively,the total isolation rate was 33.7%;8 strains of Mycoplasma gallisepticum and 8 strains of mycoplasma synoviae were isolated from trachea,the isolation rates were the same of 36.3%,the total isolation rate was 72.7%.Compared with throat swab,the separation rate of tracheal tissue is about one time higher.Conclusion:Throat swab and tracheal tissue are good samples for Mycoplasma gallisepticum separation,which can be used for clinical mycoplasma separation.The separation rate of tracheal tissue is about twice as high as that of throat swab.At the same time,we should pay attention to the identification of mycoplasma synoviae during sample separation.Content 3:Mycoplasma gallisepticum infection can lead to major financial losses for poultry producers.In this paper,a case of breeder’s respiratory disease caused by Mycoplasma gallisepticum was diagnosed.Firstly,Mycoplasma gallisepticum infection was confirmed by autopsy changes and pathogen detection,Then,Mycoplasma gallisepticum wild strain was obtained by isolation and identification.Finally,the epidemic control measures based on tavancomycin tartrate and doxycycline hydrochloride were formulated and implemented,and the preventive measures were mainly immunization with live Mycoplasma gallisepticum vaccine.Results:yellow exudate was found in the lesion air sac,and Mycoplasma gallisepticum was positive in 3 tissue samples;4 Mycoplasma gallisepticum strains were isolated from 5 trachea tissue samples,and the MIC of the isolated strains showed that tavanillin tartrate and doxycycline hydrochloride were more sensitive.According to the results of pathogen detection and MIC,the incidence rate and mortality rate of Mycoplasma chick were obviously decreased after the formulation and implementation of control and prevention measures.Conclusion:the epidemic situation caused by Mycoplasma gallisepticum was successfully controlled,which provided reference for clinical diagnosis and treatment of Mycoplasma gallisepticum. |
