AUTHOR=Zhang Yue , Yang Hao , Guo Long , Zhao Mengfei , Wang Fei , Song Wenbo , Hua Lin , Wang Lei , Liang Wan , Tang Xibiao , Peng Zhong , Wu Bin 

TITLE=Isolation, Antimicrobial Resistance Phenotypes, and Virulence Genes of Bordetella bronchiseptica From Pigs in China, 2018–2020

JOURNAL=Frontiers in Veterinary Science

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2021.672716

DOI=10.3389/fvets.2021.672716

ISSN=2297-1769

ABSTRACT=<p><italic>Bordetella bronchiseptica</italic> is a leading cause of respiratory diseases in pigs. However, epidemiological data of <italic>B. bronchiseptica</italic> in pigs particularly in China, the largest pig rearing country in the world is still limited. We isolated 181 <italic>B. bronchiseptica</italic> strains from 4259 lung samples of dead pigs with respiratory diseases in 14 provinces in China from 2018 to 2020. The average isolation rate of this 3-year period was 4.25% (181/4259). Antimicrobial susceptibility testing performed by disc diffusion method revealed that most of the <italic>B. bronchiseptica</italic> isolates in this study were resistant to ampicillin (83.98%), while a proportion of isolates were resistant to cefotaxime (30.39%%), chloramphenicol (12.71%), gentamicin (11.60%), florfenicol (11.60%), tetracycline (8.84%), amoxicillin (8.29%), tobramycin (6.63%), ceftriaxone (4.97%), and cefepime (0.55%). There were no isolates with resistant phenotypes to imipenem, meropenem, polymyxin B, ciprofloxacin, enrofloxacin, and amikacin. In addition, ~13.18% of the isolates showed phenotypes of multidrug resistance. Detection of antimicrobial resistance genes (ARGs) by PCR showed that 16.57% of the <italic>B. bronchiseptica</italic> isolates in this study was positive to <italic>aac(3)-IV</italic>, while 3.87%, 2.21%, 1.10%, 0.55%, 0.55%, and 0.55% of the isolates were positive to <italic>aac6'-Ib, rmtA, bla</italic><sub>TEM</sub>, <italic>bla</italic><sub>SHV</sub>, <italic>oqxB</italic>, and <italic>tetA</italic>, respectively. Detection of virulence factors encoding genes (VFGs) by conventional PCR showed that over 90% of the pig <italic>B. bronchiseptica</italic> isolates in this study were positive to the five VFGs examined (<italic>fhaB</italic>, 97.24%; <italic>prn</italic>, 91.16%; <italic>cyaA</italic>, 98.34%; <italic>dnt</italic>, 98.34%; <italic>betA</italic>, 92.82%). These results demonstrate <italic>B. bronchiseptica</italic> as an important pathogen associated with pig respiratory disorders in China. The present work contributes to the current understanding of the prevalence, antimicrobial resistance and virulence genes of <italic>B. bronchiseptica</italic> in pigs.</p>