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

Abstract

Bordetella bronchiseptica is a leading cause of respiratory diseases in pigs. However, epidemiological data of B. bronchiseptica in pigs particularly in China, the largest pig rearing country in the world is still limited. We isolated 181 B. bronchiseptica 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 B. bronchiseptica 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 B. bronchiseptica isolates in this study was positive to aac(3)-IV, while 3.87%, 2.21%, 1.10%, 0.55%, 0.55%, and 0.55% of the isolates were positive to aac6'-Ib, rmtA, blaTEM, blaSHV, oqxB, and tetA, respectively. Detection of virulence factors encoding genes (VFGs) by conventional PCR showed that over 90% of the pig B. bronchiseptica isolates in this study were positive to the five VFGs examined (fhaB, 97.24%; prn, 91.16%; cyaA, 98.34%; dnt, 98.34%; betA, 92.82%). These results demonstrate B. bronchiseptica 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 B. bronchiseptica in pigs.

Isolation, Identification and Drug Resistance Rates of Bacteria from Pigs in Zhejiang and Surrounding Areas during 2019–2021

“…In this experiment, Bb had the highest resistance to lincomycin, with a resistance rate of 100%, and was relatively sensitive to ciprofloxacin, with a resistance rate of 17.86%. Another report [ 23 ] showed that Bb had the highest resistance to ampicillin, with a resistance rate of 83.98%, and there were 6 antibiotics with associated resistance rates of 0% in China. E. coli was had the highest resistance to tilmicosin and lincomycin, with resistance rates of 100%, and the highest sensitivity to cefotaxime, with a resistance rate of 15.96%.…”

Are Bordetella bronchiseptica Siphoviruses (Genus Vojvodinavirus) Appropriate for Phage Therapy—Bacterial Allies or Foes?

“…Many authors such as Knezevic et al [ 34 ], suggested that MOI 10 is the most appropriate for a successful antibacterial phages effect because at this MOI each bacterium is infected by at least one phage following the Poisson distribution. However, when temperate phages are examined, the effect of different MOIs on phage lytic activity is different [ 15 , 50 ]. One example is the lambda phage, for which phage integrase activity directly depends on the concentration of cell proteases and MOI value: a low concentration of protease or high MOI values enhance integrase activity, which promotes phage entry into the lysogenic cycle.…”

“…The vaccine for B. bronchiseptica , commonly used since 1970s, is unreliable as it does not provide long-term immunity [ 11 , 12 ]. In addition, the increased degree of resistance to B. bronchiseptica isolates against commonly used antibiotics, including β-lactams, macrolides and tetracyclines, has become a serious concern [ 13 , 14 , 15 ]. In the last few years, the use of bacteriophages in the treatment of bacterial infections has gained the attention of the scientific community [ 16 , 17 , 18 , 19 ].…”