Recreational hot springs as environmental reservoir of potential multidrug-resistant pathogens

Hot springs and spas are emerging as potential health hazards due to the presence of conditions supporting a diverse flora of opportunistic pathogens and the lack of regulations in numerous countries. In particular, skin infections related to strains of the bacterial genus Acinetobacter and Pseudomonas represent a growing threat. We used amplicon sequencing, shotgun metagenomic and microbial isolates to investigate the presence, distribution and antimicrobial resistance profile of putative pathogens in 29 naturally occurring and recreational hot springs from Costa Rica. Our results show that sequences related to the genus Acinetobacter and Pseudomonas were preferentially present in fluid samples from recreational hot springs relative to springs with less human influence, with abundances up to 68 % and 2.6 %, respectively, in the 16S rRNA data and 50 % and 5 % in metagenomic data for recreational hot springs. Strains of P. aeruginosa isolated from 4 recreational hot springs show a more diverse profile of antibiotic resistance compared to laboratory reference strains, with multidrug resistant strains comprising up to 30 % of the isolates. The potential for multidrug resistant pathogens in the wider microbial community is confirmed by the high diversity of antibiotic resistance genes (ARG) identified in the metagenomic sequences. Our results indicate that human activities play a key role in the occurrence of opportunistic pathogens, with recreational hot springs harboring significantly higher abundances of multidrug resistant opportunistic pathogens. Our data show that recreational hot springs represent an environmental reservoir of potential multidrug-resistant pathogens, with important implications for public health.