Analysis of Antigenic Gene Characteristics and Drug Resistance of Bordetella pertussis in Liaoning Province

Objective To analyze the antigenic gene characteristics and drug resistance of Bordetella pertussis isolates in Liaoning Province from 2018 to 2024.Methods Based on whole-genome sequencing data, the antigenic genotypes and 23S rRNA 2047 mutation sites of 10 B. pertussis isolates were analyzed and compared with vaccine strains.The ResFinder and CARD databases were used to predict whether the isolates carried macrolide resistance genes.A phylogenetic tree was constructed to analyze the genetic relationship between B. pertussis isolates in Liaoning Province and vaccine strains as well as epidemic strains from multiple countries and regions.The sensitivity to 8 antibiotics was detected by E-test method, and the drug resistance situation was analyzed.Results All isolates were resistant to macrolides, and were sensitive to levofloxacin, ampicillin, ciprofloxacin, compound sulfamethoxazole, and ceftriaxone. A-G mutations at the 23S rRNA 2047 site were detected in all isolates,and no macrolide resistance genes were found. Compared with vaccine strains,the same antigenic genotypes were fim2-1/fim3-1/tcfA2,while the genotypes of prn, ptxA, ptxP,and fhaB were different.Two prn deletion strains were found,and non-vaccine type ptxP3- macrolide-resistant strains accounted for 80% (8/10).The evolutionary relationship indicated that there was a relatively distant genetic distance between B.pertussis isolates in Liaoning Province and vaccine strains.Conclusion The B.pertussis isolates in Liaoning Province are severely resistant to macrolide antibiotics,and the antigenic genotypes are different from vaccine strains.Non-vaccine type ptxP3- macrolide-resistant strains have become dominant.It is suggested that continuous monitoring of the antigenic genotypes and drug resistance of B. pertussis isolates should be carried out.