Evidence of interspecific plasmid uptake by pathogenic strains of Klebsiella isolated from microplastic pollution on public beaches

Citation

Metcalf R, Messer LF, White HL, Ormsby MJ, Matallana-Surget S & Quilliam RS (2024) Evidence of interspecific plasmid uptake by pathogenic strains of Klebsiella isolated from microplastic pollution on public beaches. Journal of Hazardous Materials, 461, Art. No.: 132567. https://doi.org/10.1016/j.jhazmat.2023.132567

Abstract
Microplastic beads are becoming a common feature on beaches, and there is increasing evidence that such microplastics can become colonised by potential human pathogens. However, whether the concentrations and pathogenicity of these pathogens pose a public health risk are still unclear. Therefore, the aim of this study was to determine realistic environmental concentrations of potential pathogens colonising microplastic beads, and quantify the expression of virulence and antimicrobial resistance genes (ARGs). Microplastic beads were collected from beaches and a culture-dependent approach was used to determine the concentrations of seven target bacteria (Campylobacter spp.; E. coli; intestinal enterococci; Klebsiella spp.; Pseudomonas aeruginosa; Salmonella spp.; Vibrio spp.). All seven target bacteria were detected without the need for a pre-enrichment step; urban sites had higher bacterial concentrations, whilst polymer type had no influence on bacterial concentrations. Klebsiella was the most abundant target bacteria and possessed virulence and ARGs, some of which were present on plasmids from other species, and showed pathogenicity in a Galleria melonella infection model. Our findings demonstrate how pathogen colonised microplastic beads can pose a heightened public health risk at the beach, and highlights the urgency for improved monitoring and enforcement of regulations on the release of microplastics into the environment.

Keywords
Public Health; Plastic Pollution; Human pathogens; Plastisphere; Antimicrobial resistance; Virulence

Journal
Journal of Hazardous Materials: Volume 461