First study on capsular serotypes and virulence factors of Pasteurella multocida isolates from Phan Rang sheep in Vietnam

Research (Published online: 14-02-2023)

6. First study on capsular serotypes and virulence factors of Pasteurella multocida isolates from Phan Rang sheep in Vietnam

Phu Van Nguyen, Cong Tuan Le, Xuan Huy Nguyen, Tuan Manh Nguyen, and Kim Cuc Thi Nguyen

Veterinary World, 16(2): 281-290

Phu Van Nguyen: Institute of Biotechnology, Hue University, Road 10, Phu Thuong, Thua Thien Hue, Vietnam.

Cong Tuan Le: Department of Environmental Science, University of Sciences, Hue University, Thua Thien Hue, Vietnam.

Xuan Huy Nguyen: Department of Science, Technology and International Relations, Hue University, Thua Thien Hue, Vietnam.

Tuan Manh Nguyen: Institute of Life Science, Thai Nguyen University of Agriculture and Forestry, Quyet Thang, Thai Nguyen, Vietnam.

Kim Cuc Thi Nguyen: Institute of Biotechnology, Hue University, Road 10, Phu Thuong, Thua Thien Hue, Vietnam.

doi: www.doi.org/10.14202/vetworld.2023.281-290

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Article history: Received: 07-10-2022, Accepted: 05-01-2023, Published online: 14-02-2023

Corresponding author: Kim Cuc Thi Nguyen

E-mail: ntkcuc.huib@hueuni.edu.vn

Citation: Nguyen PV, Le CT, Nguyen XH, Nguyen TM, and Nguyen KCT (2023) First study on capsular serotypes and virulence factors of Pasteurella multocida isolates from Phan Rang sheep in Vietnam, Veterinary World, 16(2): 281–290.

Abstract

Background and Aim: Pasteurella multocida is considered as a main factor mediating pneumonic pasteurellosis in ruminants, including sheep. It is also a current threat to Phan Rang sheep in Vietnam. This study aimed to characterize P. multocida isolated from Phan Rang sheep, their antibiotic resistance profile, and the prevalence of some virulence-associated genes of these strains.

Materials and Methods: Bacteria were isolated on brain heart infusion, 10% sheep blood agar plates, and screened by biochemical tests. The polymerase chain reaction technique was used with specific primers to identify P. multocida, the presence of virulence-associated genes, and serotypes of isolates. Antimicrobial susceptibility and biofilm formation of isolates were examined using the disk diffusion method and crystal violet-based method, respectively.

Results: A total of 41 P. multocida strains were isolated from 485 samples from clinically sick and healthy sheep. Of the isolates, 58.53% were serotype A, 9.75% were serotype B, and 31.71% were serotype D. Healthy animals were infected with serotype D only. All 15 virulence genes were identified in all strains isolated from clinically sick sheep, while strains isolated from healthy sheep carried 11/15 virulence genes tested. Among virulence-associated genes exbB, exbD, tonB, ompA, oma87, fimA, hgbA, and nanB were detected in over 90% of isolates, whereas hgbB, nanH, tbpA and pfhA were less frequent. Interestingly, pmHAS and tadD were highly prevalent in capsular type A strains, whereas the toxA gene was detected in capsular type D strains only. All of the isolated strains were fully susceptible to enrofloxacin, ciprofloxacin, neomycin, and ofloxacin. About 92.68% were susceptible to chloramphenicol and 90.24% to amikacin, but there was high resistance to erythromycin, tetracycline, and amoxicillin. Our results reveal that 53.65% of 41 isolates could produce biofilm, whereas 46.34% could not.

Conclusion: Pasteurella multocida from Phan Rang sheep possess many virulence genes and resistance to several common antibiotics such as erythromycin, tetracycline, and amoxicillin. The results are an important warning regarding antibiotic resistance of P. multocida.

Keywords: antimicrobial resistance, biofilm formation, capsular type, Pasteurella multocida, Phan Rang sheep.