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In vitro Antibiotic Susceptibility, Virulence Genes Profiles and Integrons of Streptococcus suis Isolates from Pig Herds in Liaoning Province of China
Yueting Guo, Ruoqi Li, Xiaodong Sun, Zehui Zhang, Huichao Zheng, Linxuan Han, Yinan Cui, Dexian Zhangɸ* and Mingchun Liuɸ*

1Key Laboratory of Livestock Infectious Diseases in Northeast China, Ministry of Education, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, China
ɸ These two authors contribute equally to this research.
*Corresponding author:;


Streptococcus suis (S. suis) is an important zoonotic agent, leading to sepsis, meningitis, arthritis, encephalitis, and pneumonia both in swine and humans. This study aims to illustrate the antimicrobial susceptibility, integron genes, and virulence gene profiles of Streptococcus suis from pigs in Liaoning province of China. The results indicated that virulence genes including gdh, pgdA, srtA, gapdh, and dltA, were positive in all S. suis isolates, and sly, manN, and purD were carried by 68.18, 63.64, and 68.18% of isolates, respectively. A variety of virulence gene profiles were observed in this study. Most S. suis isolates were non-susceptible to chlortetracycline (17/22), tetracycline (20/22), marbofloxacin (19/22), erythromycin (17/22), azithromycin (15/22), penicillin (16/22), oxacillin (18/22), ceftiofur(14/22), and timicosin (18/22) by the broth microdilution method. Although no isolate was non-susceptible to all tested antimicrobial agents, 81.82% (18/22) of isolates were non-susceptible to at least 7 tested antimicrobial agents in this study, and all isolates were non-susceptible to at least three antimicrobial agents tested in this study. In this study, 95.45% of isolates were positive for Integrase intI I, which indicated that intI I, such as drfA1 and aadA1, may be involved in multidrug resistance. Our results indicated that caution should be paid when choosing antimicrobial agents in pig herds in this area as multi-resistance has emerged, and mobile genetic elements such as drfA1 and aadA1 may be involved in resistance of S. suis isolates.

To Cite This Article: Guo Y, Li R, Sun X, Zhang Z, Zheng H, Han L, Cui Y, Zhang D and Liu M, 2022. In vitro antibiotic susceptibility, virulence genes profiles and integrons of streptococcus suis isolates from pig herds in Liaoning Province of China. Pak Vet J, 42(1): 117-121.


ISSN 0253-8318 (Print)
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