Genotype characteristics of two non traveler sources burkholderia pseudomallei strains isolated from clinical patients for the first time in Chongqing, China

In 2024, two cases of melioidosis were discovered in Chongqing, China. This was the first instance of non-traveler infection cases being found in this region. The strain characteristics and phylogenetic relationships of the two B. pseudomallei (CQ2024Bp-001 and CQ2024Bp-002) remained poorly understood. An antibiotic sensitivity test, genomic sequencing, prediction of virulence genes and ARGs, wgSNP, and MLST were performed for the two strains. The results indicated that the two strains had significant genetic differences (17197 SNPs), and CQ2024Bp-002 was a novel sequence type (ST2149). CQ2024Bp-001 carried bla_OXA-59 and bla_OXA-57, while CQ2024Bp-002 only carried bla_OXA-59. Despite carrying β-lactam resistance genes, both strains were sensitive to common antibiotics (TIM, CAZ, MEM, MH, LEV, SXT, and CPL). Their virulence genes differed, with CQ2024Bp-002 lacking boaB and wzt2. The clustering analysis based on wgSNP revealed that the two strains were distant from each other. These findings suggest that under the influence of global warming, non-endemic areas of melioidosis are gradually developing conditions suitable for the reproduction and transmission of B. pseudomallei, potentially leading to an increase in melioidosis cases. It highlights the need for an active monitoring system to be established in climate-sensitive areas to prevent and control the potential regional epidemic of melioidosis.