EOHA ASM 2026

Abstract

Background

Vibrio bacteria are ubiquitous in marine and estuarine environments and it is expected that climate change will create increasingly good conditions for them to flourish in. They can carry, acquire and transfer different antimicrobial resistances (AMR). We identified a fosG/fosC2-related fosfomycin resistance glutathione transferase-gene in 43 Vibrio spp. strains from Europe and Asia. Fosfomycin-resistant Vibrio spp. have not yet gotten much attention, but may be of increasing importance in the future.

Objectives

To determine genetic variation in fos-gene derivates with respect to its impact on the fosfomycin phenotype.

Methods

Pulsed-field gel electrophoresis (PFGE) was performed with the restriction enzymes S1 and Sfi1. We tested for phenotypic antimicrobial resistances to 24 substances with agar disc diffusion according to CLSI standards. Long-read whole-genome sequencing (WGS) was performed using Oxford Nanopore Technologies (ONT). The fosG/fosC2-related fosfomycin resistance glutathione transferase-gene was confirmed by PCR.

Results

Interestingly, the phenotypic resistance testing revealed a high fosfomycin tolerance in all tested V. cincinnatiensis, while all other species showed a low tolerance. No link between plasmids and the location of the fosfomycin resistance gene was found. In total, thirteen variants of the fos-gene were identified. Notably, different gene variants were found to cause either a resistance or susceptible phenotype while exhibiting the same amino acid sequence. This means that besides the fos-gene other factors also contribute to the phenotypic resistance.

Conclusions

Vibrio spp. strains resistant to fosfomycin have the possibility to become a detriment to aquacultures worldwide and can thus affect the food chain, local ecosystems and consumer health. Especially with the climate change of water bodies worldwide. Further investigation is needed to specify why the same amino acid sequence can result in phenotypic resistance for some strains while not for others.

Poster