Multiclonal Dissemination of ptxP3 Allele Macrolide-Resistant Bordetella pertussis in Okinawa, Japan.

An ongoing pertussis epidemic in Okinawa has resulted in 227 reported cases since November 2024. Between December 2024 and February 2025, clinical specimens were collected from 31 cases. We isolated 18 macrolide-resistant Bordetella pertussis (MRBP) strains, all harboring the A2047G mutation in the 23S rRNA gene, confirmed by real-time PCR. Genomic analysis was performed on 2 MRBP strains isolated in November 2024 and the 18 MRBP strains from the current survey. All MRBP strains in Okinawa formed genetically related clusters with the ptxP3 allele in China (P745) and France (FR7302). However, MRBP strains from Okinawa were divided into three clusters, each separated by at least eight SNPs, and distinct from P745 and FR7302, suggesting the multi-source dissemination of ptxP3 MRBP in Okinawa.