Insight into phylogenomic bias of bla or bla dissemination amongst carbapenem-resistant Pseudomonas aeruginosa.

OBJECTIVES

Pseudomonas aeruginosa (P. aeruginosa) are ubiquitous opportunistic pathogens that combine intrinsic and acquired multidrug resistance phenotypes. Due to different types of acquired genes, carbapenem resistance has been expanding in this species. This study hypothesised that the spread of carbapenem resistance among P. aeruginosa is influenced by phylogenomic features, being distinct for different genes.

METHODS

To test this hypothesis, the genomes of P. aeruginosa harbouring bla or bla genes were compared. The bla gene was selected because, although frequent, it is almost restricted to this species and bla gene due to its wide interspecies distribution. A group of genomes harbouring the genes bla (n = 116) or bla (n = 27), available in GenBank, was characterised based on core phylogenomic analysis, functional categories in the accessory genome and mobile genetic elements flanking the selected genes.

RESULTS

Most bla gene hosts belonged to multilocus sequence types (ST) ST111 (n = 32 of 116) and ST233 (n = 27 of 116) and were reported in Europe (n = 75 of 116). The bla gene hosts were distributed by different STs (ST38, ST773, ST235, ST357 and ST654), frequently from Asia (n = 11 of 27). Significant differences in the prevalence of functional protein/enzyme annotations per number of accessory genomes were observed between bla+ and bla+. The bla gene was frequently inserted in the Tn402-like and Tn21 transposons family and rarely in IS6100, while bla gene was preferentially flanked by ISAba125 and ble genes or associated with IS91 insertion sequence.

CONCLUSION

The hypothesis that carbapenem resistance gene acquisition is not random among phylogenomic lineages was confirmed, suggesting the importance of phylogeny in the dissemination of antibiotic resistance genes.