Abed Ahmed H, El-Seedy Fawzy R, Hassan Hany M, Nabih Ashraf M, Khalifa Eman, Salem Salwa E, Wareth Gamal, Menshawy Ahmed M S
Bacteriology, Mycology and Immunology Department, Faculty of Veterinary Medicine, Beni-Suef University, Beni Suef 62511, Egypt.
Animal Reproduction Research Institute, Giza 12511, Egypt.
Vet Sci. 2020 Nov 10;7(4):174. doi: 10.3390/vetsci7040174.
(.) and () are the most two common pathogenic bacterial agents causing pneumonia in calves. Both bacteria are associated with significant economic losses in the cattle industry due to high morbidity and mortality rates, especially in the case of severe infections. The objectives of the present study were to perform serotyping and genotyping, as well as characterization of the virulence-associated genes in 48 bacterial isolates; 33 and 15 . All strains were isolated from pneumonic cattle calves showing respiratory manifestations such as fever, nasal discharges, and rapid breathing in North Upper Egypt governorates (Beni-Suef and El-Fayoum). PCR was applied as a confirmatory test using a specific universal gene, 1, and 2 for and , respectively. The results show that 29 (87.9%) and 15 (100%) isolates were positive for the corresponding universal gene. The results of serotyping indicate that 86.2% of isolates belonged to serotype B:2, while 13.8% were untyped. Meanwhile, 60% and 40% of isolates belonged to serotype 2 and serotype 1, respectively. Investigation of virulence-associated genes showed that all the tested isolates harbored B, 87, and A genes. Four isolates harbored both and C genes and of these, three isolates harbored the gene. Sequencing of A gene of and C gene of in the current strains indicated a great homology with strains uploaded in gene banks from different hosts and localities worldwide.
（.）和（）是引起犊牛肺炎最常见的两种致病细菌病原体。由于发病率和死亡率高，这两种细菌都给养牛业带来了巨大的经济损失，尤其是在严重感染的情况下。本研究的目的是对48株细菌分离株进行血清分型和基因分型，以及对与毒力相关的基因进行表征；33株（.）和15株（.）。所有菌株均从埃及上埃及省（贝尼苏韦夫和法尤姆）出现发热、鼻分泌物和呼吸急促等呼吸道症状的患肺炎犊牛中分离得到。使用特异性通用基因分别对（.）和（.）进行PCR作为确证试验，（.）用基因1，（.）用基因2。结果显示，29株（87.9%）（.）和15株（100%）（.）分离株对应通用基因呈阳性。血清分型结果表明，86.2%的（.）分离株属于B:2血清型，而13.8%未分型。同时，（.）分离株的60%和40%分别属于2型和1型血清型。对与毒力相关基因的研究表明，所有测试的（.）分离株都含有B、87和A基因。4株（.）分离株同时含有（.）和C基因，其中3株还含有（.）基因。对当前菌株中（.）的A基因和（.）的C基因进行测序，结果表明与全球不同宿主和地区基因库中上传的菌株具有高度同源性。
