Epidemiological and environmental investigation of the 'big four' Vibrio species, 1994 to 2021: a Baltic Sea retrospective study.

BackgroundThe Vibrio genus comprises several bacterial species present in the Baltic Sea region (BSR), which are known to cause human infections.AimTo provide a comprehensive retrospective analysis of Vibrio-induced infections in the BSR from 1994 to 2021, focusing on the 'big four' Vibrio species - V. alginolyticus, V. cholerae non-O1/O139, V. parahaemolyticus and V. vulnificus - in eight European countries (Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland and Sweden) bordering the Baltic Sea.MethodsOur analysis includes data on infections, Vibrio species distribution in coastal waters and environmental data received from national health agencies or extracted from scientific literature and online databases. A redundancy analysis was performed to determine the potential impact of several independent variables, such as sea surface temperature, salinity, the number of designated coastal beaches and year, on the Vibrio infection rate.ResultsFor BSR countries conducting surveillance, we observed an exponential increase in total Vibrio infections (n = 1,553) across the region over time. In Sweden and Germany, total numbers of Vibrio spp. and infections caused by V. alginolyticus and V. parahaemolyticus positively correlate with increasing sea surface temperature. Salinity emerged as a critical driver of Vibrio spp. distribution and abundance. Furthermore, our proposed statistical model reveals 12 to 20 unreported cases in Lithuania and Poland, respectively, countries with no surveillance.ConclusionsThere are discrepancies in Vibrio surveillance and monitoring among countries, emphasising the need for comprehensive monitoring programmes of these pathogens to protect human health, particularly in the context of climate change.

Vitamin D administration leads to a shift of the intestinal bacterial composition in Crohn's disease patients, but not in healthy controls.

OBJECTIVE: Dysbiosis is a common feature in the pathogenesis of inflammatory bowel diseases (IBD). Environmental factors, such as vitamin D deficiency, seem to play a role in the intestinal inflammation of IBD. The aim of this study was to investigate whether vitamin D administration has an impact on the bacterial composition in Crohn's disease (CD) compared to healthy controls (HC). METHODS: A prospective, longitudinal, controlled interventional analysis was conducted in seven patients with CD in clinical remission and 10 HC to investigate the effect of orally administrated vitamin D on the intestinal bacterial composition using 16S ribosomal RNA gene amplicon sequencing. Clinical parameters were assessed. RESULTS: In contrast to HC, microbial communities of CD patients changed significantly during early vitamin D administration. However, a further increase in vitamin D level was associated with a reversal of this effect and additionally with a decrease in the bacterial richness in the CD microbiome. Specific species with a high abundancy were found during vitamin D administration in CD, but not in HC; the abundancy of Alistipes, Barnesiella, unclassified Porphyromonadaceae (both Actinobacteria), Roseburia, Anaerotruncus, Subdoligranulum and an unclassified Ruminococaceae (all Firmicutes) increased significantly after 1-week vitamin D administration in CD. CONCLUSIONS: Vitamin D has a specific influence on the bacterial communities in CD, but not in HC. Administration of vitamin D may have a positive effect in CD by modulating the intestinal bacterial composition and also by increasing the abundance of potential beneficial bacterial strains.

Transitions in bacterial communities along the 2000 km salinity gradient of the Baltic Sea.

Salinity is a major factor controlling the distribution of biota in aquatic systems, and most aquatic multicellular organisms are either adapted to life in saltwater or freshwater conditions. Consequently, the saltwater-freshwater mixing zones in coastal or estuarine areas are characterized by limited faunal and floral diversity. Although changes in diversity and decline in species richness in brackish waters is well documented in aquatic ecology, it is unknown to what extent this applies to bacterial communities. Here, we report a first detailed bacterial inventory from vertical profiles of 60 sampling stations distributed along the salinity gradient of the Baltic Sea, one of world's largest brackish water environments, generated using 454 pyrosequencing of partial (400 bp) 16S rRNA genes. Within the salinity gradient, bacterial community composition altered at broad and finer-scale phylogenetic levels. Analogous to faunal communities within brackish conditions, we identified a bacterial brackish water community comprising a diverse combination of freshwater and marine groups, along with populations unique to this environment. As water residence times in the Baltic Sea exceed 3 years, the observed bacterial community cannot be the result of mixing of fresh water and saltwater, but our study represents the first detailed description of an autochthonous brackish microbiome. In contrast to the decline in the diversity of multicellular organisms, reduced bacterial diversity at brackish conditions could not be established. It is possible that the rapid adaptation rate of bacteria has enabled a variety of lineages to fill what for higher organisms remains a challenging and relatively unoccupied ecological niche.