Sharp Rise in High-Virulence Bordetella pertussis with Macrolides Resistance in Northern China.

Objective: To elucidate the evolution of antigen genotype and antimicrobial resistance distribution of () from 2019 to 2023 in northern China.

Methods: Polymerase chain reaction (PCR) amplification and sequencing were utilized to identify the seven antigen genotypes (). E-test and Kirby-Bauer (K-B) disc diffusion were employed to determine the minimum inhibitory concentration (MIC) and zone of inhibition for against antimicrobial agents. Subsequently, 50 isolates were chosen for multi-locus variable-number tandem-repeat analysis (MLVA) typing and whole-genome sequencing.

Results: A total of 442 isolates were determined. The strains with high virulence harboring allele surged from 13.5% (21/155) in 2019-2021 to 93.0% (267/287) in 2022-2023. Concurrently, the erythromycin resistance (ERBP) in isolates markedly rose from 42.9% (9/21) in 2019-2021 to 100% (267/267) in 2022-2023. Compared to isolates, the majority of isolates (76.0%,219/288) exhibited the genotype, which differed more in alleles from the vaccine strain (). Among the 442 confirmed patients, the children aged 3-14 years escalated rapidly from 13.5% in 2019 to 45.6% in 2023. The MT28 strains was responsible for 66.0% (33/50) of the tested ones, in which ERBP was prevalent at 87.9% (29/33). All the present sequenced -ERBP strains (31/31) were clustered into the sub-lineage IVd.

Conclusions: These results suggested the clonal spread of -ERBP lineage of with high virulence and macrolides resistance could be an important cause of the recent pertussis resurgence in China. Furthermore, the increased cases among preschool and school-aged children underscores the importance of booster vaccination in this population.