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Published on: May 2, 2018
Transcriptomic Changes and satP Gene Function Analysis in Pasteurella multocida with Different Levels of Resistance
Xue-Song Li1,2, Yu Qi1,2, Jun-Ze Xue1,2
1Department of Veterinary Medicine, College of Animal Science and Technology, Jilin Agricultural University, Xincheng Street No. 2888, Changchun 130118, China.
Abstract:
Pasteurella multocida (Pm) is one of the major pathogens of bovine respiratory disease (BRD), which can develop drug resistance to many of the commonly used antibiotics. Our earlier research group found that with clinical use of enrofloxacin, Pm was more likely to develop drug resistance to enrofloxacin. In order to better understand the resistance mechanism of Pm to enrofloxacin, we isolated PmS and PmR strains with the same PFGE typing in vitro, and artificially induced PmR to obtain the highly resistant phenotype, PmHR. Then transcriptome sequencing of clinically isolated sensitive strains, resistant and highly drug-resistant strains, treated with enrofloxacin at sub-inhibitory concentrations, were performed. The satP gene, of which the expression changed significantly with the increase in drug resistance, was screened. In order to further confirm the function of this gene, we constructed a satP deletion (ΔPm) strain using suicide vector plasmid pRE112, and constructed the C-Pm strain using pBBR1-MCS, and further analyzed the function of the satP gene. Through a continuously induced resistance test, it was found that the resistance rate of ΔPm was obviously lower than that of Pm in vitro. MDK99, agar diffusion and mutation frequency experiments showed significantly lower tolerance of ΔPm than the wild-type strains. The pathogenicity of ΔPm and Pm was measured by an acute pathogenicity test in mice, and it was found that the pathogenicity of ΔPm was reduced by about 400 times. Therefore, this study found that the satP gene was related to the tolerance and pathogenicity of Pm, and may be used as a target of enrofloxacin synergistic effect.
Insights
The satP gene in Pasteurella multocida is crucial for enrofloxacin resistance and pathogenicity. Deleting this gene significantly reduces bacterial tolerance and virulence, suggesting it as a target for synergistic antibiotic effects.
Area of Science:
- Veterinary Microbiology
- Antimicrobial Resistance Research
- Molecular Biology
Background:
- Pasteurella multocida (Pm) is a key pathogen in bovine respiratory disease (BRD).
- Pm frequently develops resistance to antibiotics like enrofloxacin, necessitating research into resistance mechanisms.
- Previous work indicated a link between enrofloxacin use and increased Pm resistance.
Purpose of the Study:
- To elucidate the molecular mechanisms behind Pasteurella multocida's enrofloxacin resistance.
- To identify specific genes involved in the development of drug resistance and pathogenicity.
- To evaluate the potential of identified genes as targets for novel therapeutic strategies.
Main Methods:
- Isolation and characterization of Pasteurella multocida strains with varying enrofloxacin resistance levels (PmS, PmR, PmHR).
- Transcriptome sequencing to identify differentially expressed genes under enrofloxacin pressure.
- Construction and analysis of a satP deletion mutant (ΔPm) to assess gene function in vitro and in vivo.
- Phenotypic assays including resistance rate determination, MDK99, agar diffusion, mutation frequency, and acute pathogenicity tests in mice.
Main Results:
- The satP gene exhibited significantly altered expression correlating with increased enrofloxacin resistance.
- The ΔPm mutant showed markedly reduced in vitro resistance and tolerance to enrofloxacin compared to wild-type strains.
- Pathogenicity assays revealed a substantial decrease (approximately 400-fold) in the virulence of the ΔPm mutant in a mouse model.
- The satP gene was identified as a key factor influencing both enrofloxacin tolerance and Pm pathogenicity.
Conclusions:
- The satP gene plays a significant role in Pasteurella multocida's tolerance to enrofloxacin and its ability to cause disease.
- Targeting the satP gene could be a viable strategy for developing synergistic treatments to combat bovine respiratory disease.
- Understanding the function of satP provides insights into antimicrobial resistance mechanisms in veterinary pathogens.
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