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1. Antibiotic resistance trends among Vibrio vulnificus and Vibrio parahaemolyticus isolated from the Chesapeake Bay, Maryland: a longitudinal study

   https://doi.org/10.1128/aem.00539-24  

   Morgado, Michele E; Brumfield, Kyle D; Chattopadhyay, Suhana; Malayil, Leena; Alawode, Taiwo; Amokeodo, Ibiyinka; He, Xin; Huq, Anwar; Colwell, Rita R; Sapkota, Amy R (June 2024, Applied and Environmental Microbiology)

   Elkins, Christopher A (Ed.)

   ABSTRACT Antibiotics are often used to treat severeVibrioinfections, with third-generation cephalosporins and tetracyclines combined or fluoroquinolones alone being recommended by the US Centers for Disease Control and Prevention. Increases in antibiotic resistance of both environmental and clinical vibrios are of concern; however, limited longitudinal data have been generated among environmental isolates to inform how resistance patterns may be changing over time. Hence, we evaluated long-term trends in antibiotic resistance of vibrios isolated from Chesapeake Bay waters (Maryland) across two 3-year sampling periods (2009–2012 and 2019–2022).Vibrio parahaemolyticus(n= 134) andVibrio vulnificus(n= 94) toxR-confirmed isolates were randomly selected from both sampling periods and tested for antimicrobial susceptibility against eight antibiotics using the Kirby-Bauer disk diffusion method. A high percentage (94%–96%) ofV. parahaemolyticusisolates from both sampling periods were resistant to ampicillin and only 2%–6% of these isolates expressed intermediate resistance or resistance to third-generation cephalosporins, amikacin, tetracycline, and trimethoprim-sulfamethoxazole. Even lower percentages of resistantV. vulnificusisolates were observed and those were mostly recovered from 2009 to 2012, however, the presence of multiple virulence factors was observed. The frequency of multi-drug resistance was relatively low (6%–8%) but included resistance against antibiotics used to treat severe vibriosis in adults and children. All isolates were susceptible to ciprofloxacin, a fluoroquinolone, indicating its sustained efficacy as a first-line agent in the treatment of severe vibriosis. Overall, our data indicate that antibiotic resistance patterns amongV. parahaemolyticusandV. vulnificusrecovered from the lower Chesapeake Bay have remained relatively stable since 2009.IMPORTANCEVibriospp. have historically been susceptible to most clinically relevant antibiotics; however, resistance and intermediate-resistance have been increasingly recorded in both environmental and clinical isolates. Our data showed that while the percentage of multi-drug resistance and resistance to antibiotics was relatively low and stable across time, someVibrioisolates displayed resistance and intermediate resistance to antibiotics typically used to treat severe vibriosis (e.g., third-generation cephalosporins, tetracyclines, sulfamethoxazole-trimethoprim, and aminoglycosides). Also, given the high case fatality rates observed withVibrio vulnificusinfections, the presence of multiple virulence factors in the tested isolates is concerning. Nevertheless, the continued susceptibility of all tested isolates against ciprofloxacin, a fluoroquinolone, is indicative of its use as an effective first-line treatment of severeVibriospp. infections stemming from exposure to Chesapeake Bay waters or contaminated seafood ingestion. 

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2. Climate change and Vibrio vulnificus dynamics: A blueprint for infectious diseases

   https://doi.org/10.1371/journal.ppat.1012767  

   Jayakumar, Jane M; Martinez-Urtaza, Jaime; Brumfield, Kyle D; Jutla, Antarpreet S; Colwell, Rita R; Cordero, Otto X; Almagro-Moreno, Salvador (December 2024, PLOS Pathogens)

   Newton, Hayley (Ed.)

   Climate change is having increasingly profound effects on human health, notably those associated with the occurrence, distribution, and transmission of infectious diseases. The number of disparate ecological parameters and pathogens affected by climate change are vast and expansive. Disentangling the complex relationship between these variables is critical for the development of effective countermeasures against its effects. The pathogenVibrio vulnificus, a naturally occurring aquatic bacterium that causes fulminant septicemia, represents a quintessential climate-sensitive organism. In this review, we useV.vulnificusas a model organism to elucidate the intricate network of interactions between climatic factors and pathogens, with the objective of identifying common patterns by which climate change is affecting their disease burden. Recent findings indicate that in regions native toV.vulnificusor related pathogens, climate-driven natural disasters are the chief contributors to their disease outbreaks. Concurrently, climate change is increasing the environmental suitability of areas non-endemic to their diseases, promoting a surge in their natural populations and transmission dynamics, thus elevating the risk of new outbreaks. We highlight potential risk factors and climatic drivers aggravating the threat ofV.vulnificustransmission under both scenarios and propose potential measures for mitigating its impact. By defining the mechanisms by which climate change influencesV.vulnificusdisease burden, we aim to shed light on the transmission dynamics of related disease-causing agents, thereby laying the groundwork for early warning systems and broadly applicable control measures. 

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3. Pathogenic Vibrio Species Are Associated with Distinct Environmental Niches and Planktonic Taxa in Southern California (USA) Aquatic Microbiomes

   https://doi.org/10.1128/mSystems.00571-21  

   Diner, Rachel E.; Kaul, Drishti; Rabines, Ariel; Zheng, Hong; Steele, Joshua A.; Griffith, John F.; Allen, Andrew E.; Seyler, Lauren Marie (August 2021, mSystems)

   Bernstein, Hans C. (Ed.)

   ABSTRACT Interactions between vibrio bacteria and the planktonic community impact marine ecology and human health. Many coastal Vibrio spp. can infect humans, representing a growing threat linked to increasing seawater temperatures. Interactions with eukaryotic organisms may provide attachment substrate and critical nutrients that facilitate the persistence, diversification, and spread of pathogenic Vibrio spp. However, vibrio interactions with planktonic organisms in an environmental context are poorly understood. We quantified the pathogenic Vibrio species V. cholerae , V. parahaemolyticus , and V. vulnificus monthly for 1 year at five sites and observed high abundances, particularly during summer months, with species-specific temperature and salinity distributions. Using metabarcoding, we established a detailed profile of both prokaryotic and eukaryotic coastal microbial communities. We found that pathogenic Vibrio species were frequently associated with distinct eukaryotic amplicon sequence variants (ASVs), including diatoms and copepods. Shared environmental conditions, such as high temperatures and low salinities, were associated with both high concentrations of pathogenic vibrios and potential environmental reservoirs, which may influence vibrio infection risks linked to climate change and should be incorporated into predictive ecological models and experimental laboratory systems. IMPORTANCE Many species of coastal vibrio bacteria can infect humans, representing a growing health threat linked to increasing seawater temperatures. However, their interactions with surrounding microbes in the environment, especially eukaryotic organisms that may provide nutrients and attachment substrate, are poorly understood. We quantified three pathogenic Vibrio species monthly for a duration of 1 year, finding that all three species were abundant and exhibited species-specific temperature and salinity distributions. Using metabarcoding, we investigated associations between these pathogenic species and prokaryotic and eukaryotic microbes, revealing genus and amplicon sequence variant (ASV)-specific relationships with potential functional implications. For example, pathogenic species were frequently associated with chitin-producing eukaryotes, such as diatoms in the genus Thalassiosira and copepods. These associations between high concentrations of pathogenic vibrios and potential environmental reservoirs should be considered when predicting infection risk and developing ecologically relevant model systems. 

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4. Long-term declines in chlorophyll a and variable phenology revealed by a 60-year estuarine plankton time series

   https://doi.org/10.1073/pnas.2311086121  

   Thibodeau, Patricia S; Puggioni, Gavino; Strock, Jacob; Borkman, David G; Rynearson, Tatiana A (May 2024, Proceedings of the National Academy of Sciences)

   Long-term ecological time series provide a unique perspective on the emergent properties of ecosystems. In aquatic systems, phytoplankton form the base of the food web and their biomass, measured as the concentration of the photosynthetic pigment chlorophylla(chla), is an indicator of ecosystem quality. We analyzed temporal trends in chlafrom the Long-Term Plankton Time Series in Narragansett Bay, Rhode Island, USA, a temperate estuary experiencing long-term warming and changing anthropogenic nutrient inputs. Dynamic linear models were used to impute and model environmental variables (1959 to 2019) and chlaconcentrations (1968 to 2019). A long-term chladecrease was observed with an average decline in the cumulative annual chlaconcentration of 49% and a marked decline of 57% in winter-spring bloom magnitude. The long-term decline in chlaconcentration was directly and indirectly associated with multiple environmental factors that are impacted by climate change (e.g., warming temperatures, water column stratification, reduced nutrient concentrations) indicating the importance of accounting for regional climate change effects in ecosystem-based management. Analysis of seasonal phenology revealed that the winter–spring bloom occurred earlier, at a rate of 4.9 ± 2.8 d decade⁻¹. Finally, the high degree of temporal variation in phytoplankton biomass observed in Narragansett Bay appears common among estuaries, coasts, and open oceans. The commonality among these marine ecosystems highlights the need to maintain a robust set of phytoplankton time series in the coming decades to improve signal-to-noise ratios and identify trends in these highly variable environments. 

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5. The Organosulfur Compound Dimethylsulfoniopropionate (DMSP) Is Utilized as an Osmoprotectant by Vibrio Species

   https://doi.org/10.1128/AEM.02235-20  

   Gregory, Gwendolyn J.; Boas, Katherine E.; Boyd, E. Fidelma (February 2021, Applied and Environmental Microbiology)

   Stabb, Eric V. (Ed.)

   ABSTRACT Dimethylsulfoniopropionate (DMSP), a key component of the global geochemical sulfur cycle, is a secondary metabolite produced in large quantities by marine phytoplankton and utilized as an osmoprotectant, thermoprotectant, and antioxidant. Marine bacteria can use two pathways to degrade and catabolize DMSP, a demethylation pathway and a cleavage pathway that produces the climate-active gas dimethylsulfide (DMS). Whether marine bacteria can also accumulate DMSP as an osmoprotectant to maintain the turgor pressure of the cell in response to changes in external osmolarity has received little attention. The marine halophile Vibrio parahaemolyticus contains at least six osmolyte transporters, namely four betaine carnitine choline transport (BCCT) carriers (BccT1 to BccT4) and two ATP-binding cassette (ABC) family ProU transporters. In this study, we showed that DMSP is used as an osmoprotectant by V. parahaemolyticus and by several other Vibrio species, including Vibrio cholerae and Vibrio vulnificus . Using a V. parahaemolyticus proU double mutant, we demonstrated that these ABC transporters are not required for DMSP uptake. However, a bccT null mutant lacking all four BCCTs had a growth defect compared to the wild type (WT) in high-salinity medium supplemented with DMSP. Using mutants possessing only one functional BCCT in growth pattern assays, we identified two BCCT family transporters, BccT1 and BccT2, that are carriers of DMSP. The only V. parahaemolyticus BccT homolog that V. cholerae and V. vulnificus possess is BccT3, and functional complementation in Escherichia coli MKH13 showed that V. cholerae VcBccT3 could transport DMSP. In V. vulnificus strains, we identified and characterized an additional BCCT family transporter, which we named BccT5, that was also a carrier for DMSP. IMPORTANCE DMSP is present in the marine environment, produced in large quantities by marine phytoplankton as an osmoprotectant, and is an important component of the global geochemical sulfur cycle. This algal osmolyte has not been previously investigated for its role in marine heterotrophic bacterial osmotic stress response. Vibrionaceae species are marine species, many of which are halophiles exemplified by V. parahaemolyticus , a species that possesses at least six transporters for the uptake of osmolytes. Here, we demonstrated that V. parahaemolyticus and other Vibrio species can accumulate DMSP as an osmoprotectant and show that several BCCT family transporters uptake DMSP. These studies suggest that DMSP is a significant bacterial osmoprotectant that may be important for understanding the fate of DMSP in the environment. DMSP is produced and present in coral mucus, and Vibrio species form part of the microbial communities associated with corals. The function of DMSP in these interactions is unclear, but it could be an important driver for these associations, allowing Vibrio proliferation. This work suggests that DMSP likely has a more important role in heterotrophic bacteria ecology than previously appreciated. 

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