recO enhances resistance of Pasteurella multocida to fluoroquinolones

Abstract Pasteurella multocida capsular type A ( Pm A) is one of the main pathogens causing bovine respiratory disease in China. The prevention and control measures against Pm are traditionally based on the use of broad-spectrum antibiotics. Previous studies found that Pm was prone to antibiotic resistance and tolerance mutation under the action of low concentrations of antibiotics, ultimately causing difficulties in prevention and control against Pm . In this study, highly pathogenic Pm fluoroquinolone-sensitive strain P3 and fluoroquinolone-resistant strain P32 induced by sub-inhibitory concentration of enrofloxacin were selected as research objects. RNA-seq was used to screen the differential gene recO of SOS response of P3 and P32 for functional verification. In addition, through MIC, MBC, induced resistance time, time-kill curve analysis and antibiotic tolerance test, the effect of recO gene on the resistance and tolerance of Pm to fluoroquinolone was clarified. At the same time, using fluorescent reporter vector, it was found that recO gene affected SOS repair response. In conclusion, the inhibition of recO gene can not only reduce their resistance to fluoroquinolone, but also prolong the formation time of fluoroquinolone resistance. It is speculated that recO gene is a potential target of fluoroquinolone synergistic antibacterial agent.