Climate Change And The Rise Of Vibrio

Vibrio is a genus of pathogenic bacteria that naturally occur in marine and estuarine environments globally. Vibrio vulnificus, Vibrio parahaemolyticus, and Vibrio cholerae are some of the Vibrio species that can cause vibriosis, a serious illness in humans. Environmental factors such as temperature, salinity, and pollution have been shown to influence the occurrence and growth of Vibrio spp. in aquatic ecosystems. For instance, industrial wastewater, petroleum pollution, and plastic contamination are significant threats to global marine biosecurity due to their toxic and persistent nature. Additionally, metal pollutants and other toxicants found in municipal wastewaters can also impact Vibrio populations. Climate change is expected to contribute to the increasing trend of vibriosis cases, as seen with the rise in V. vulnificus wound infections in the eastern United States over the last few decades.

Climate change increases Vibrio populations

Vibrio is a genus of pathogenic bacteria that naturally occurs in marine and estuarine environments globally. Vibrio vulnificus and Vibrio parahaemolyticus are two potential human pathogens. Vibrio vulnificus infections can be fatal if left untreated. Vibriosis includes illnesses caused by many species of Vibrio bacteria, including Vibrio cholerae, which causes cholera.

The incidence of vibriosis is rising globally, and changing climatic conditions are influencing environmental factors that enhance the growth of pathogenic Vibrio spp. in aquatic ecosystems. For instance, in the eastern United States between 1988 and 2018, V. vulnificus wound infections increased eightfold, and the northern case limit shifted northwards by 48 km per year. This trend of increased vibriosis is expected to continue due to climate change.

Water temperature is a critical factor influencing the growth of Vibrio populations. In Chesapeake Bay, Maryland, water temperature showed a linear correlation with the genetic markers for Vibrio vulnificus (vvhA) and Vibrio parahaemolyticus (tlh). Two critical temperature thresholds were observed: an initial increase in detectable numbers (>15°C) and a second, more significant increase at higher temperatures (>25°C).

Other environmental parameters that impact Vibrio populations include salinity and total chlorophyll a. Salinity, in particular, influences the detection of the genetic markers tlh and vvhA, with higher salinity associated with an increased number of positive samples. Additionally, the seasonality of occurrence plays a role in Vibrio populations, with higher numbers typically observed from May through October when water temperatures are warmer.

In summary, climate change, specifically rising water temperatures, is a key driver of increasing Vibrio populations in aquatic ecosystems. Other factors such as salinity, chlorophyll levels, and seasonal variations also influence Vibrio populations. The rise in Vibrio cases has significant implications for public health, as infections can lead to serious illnesses like vibriosis and cholera, and in some cases, cause fatal outcomes.

Vibrio infections from raw or undercooked seafood

Vibrio infections are often caused by the consumption of raw or undercooked seafood, with oysters, mussels, clams, scallops, and crab meat being common sources. Vibrio bacteria thrive in warm, salty waters, such as the Gulf of Mexico and the Atlantic and Pacific Oceans, and can contaminate seafood and seawater. Eating raw or undercooked seafood or exposing open wounds to seawater are the primary routes of Vibrio infection.

Vibrio vulnificus and Vibrio parahaemolyticus are the most common species causing infections in the United States. While most healthy individuals experience symptoms similar to a stomach bug, including diarrhoea, cramps, nausea, and vomiting, those with underlying medical conditions, such as liver disease, diabetes, or a weakened immune system, are at higher risk of developing severe infections. Vibrio vulnificus, in particular, has a high mortality rate of 30-50% if left untreated.

To prevent Vibrio infections, it is crucial to follow food safety guidelines and safe wound care practices. Seafood should be thoroughly cooked, and proper personal protective equipment should be worn to prevent cuts and scrapes when handling seafood or entering seawater. It is also important to monitor environmental parameters, such as temperature, salinity, and chlorophyll levels, as they influence the occurrence of Vibrio species.

The incidence of vibriosis is rising globally, with changing climatic conditions enhancing the growth of pathogenic Vibrio species in aquatic ecosystems. As a result, routine monitoring of Vibrio species and environmental factors is essential to provide early warnings to the public when the risk of infection is high.

In summary, Vibrio infections from raw or undercooked seafood can have severe health consequences, especially for individuals with pre-existing medical conditions. Preventative measures, including proper cooking of seafood and wound care, are crucial to reducing the risk of Vibrio infections. With the increasing incidence of vibriosis, ongoing monitoring of environmental factors and public awareness are vital to mitigate the impact of this pathogenic bacterium.

Vibrio infections from open wounds exposed to seawater

Vibrio is a genus of pathogenic bacteria that naturally occurs in marine and estuarine environments worldwide. Vibrio vulnificus is a species of Vibrio that can cause fatal infections in humans. While Vibrio infections from seawater entering open wounds are rare, they can be life-threatening.

Vibrio vulnificus thrives in warm, brackish waters, which are a mixture of saltwater and freshwater. It is a halophile, meaning it thrives in salty environments. The incidence of Vibrio increases with water temperature, with two critical thresholds observed: an initial increase in detectable numbers at temperatures above 15°C, and a second increase in maximum counts at temperatures above 25°C. This is why most people get vibriosis during the summer months.

Vibrio vulnificus infections can occur when seawater enters a wound, cut, sore, or puncture. People who wade or swim in seawater with open wounds or breaks in their skin may be at risk of infection. Infections typically begin within 1 to 3 days of exposure but can occur as late as 7 days after. Symptoms include redness, pain, and swelling at the site of the wound, fever, and a general feeling of being unwell. Fluid-filled blisters and deep ulcers may also develop, and severe tissue destruction may occur, requiring aggressive surgical cleaning of the wound or even amputation.

People with certain chronic conditions are at a higher risk of developing severe Vibrio infections. These conditions include liver diseases such as hepatitis, cirrhosis, haemochromatosis, and liver cancer, as well as chronic kidney disease and diabetes. Additionally, people with conditions that impair the immune system are more susceptible to severe infections. Men are also more likely to develop serious infections than women, although the reason for this is unknown.

To prevent Vibrio infections from seawater exposure, it is important to avoid entering saltwater or brackish water if you have open wounds. Cover wounds with waterproof bandages if they could come into contact with seawater. If seawater exposure occurs, immediately wash wounds thoroughly with soap and clean running water.

Using Vibrio natriegens to bioremediate complex organic pollutants

Industrial wastewater, petroleum pollution, and plastic contamination are significant threats to global marine biosecurity due to their toxic, mutagenic, and persistent nature. Bioremediation using microorganisms has been challenging because of the complexity of organic pollutants and limited tolerance to saline stress. Vibrio natriegens is a generally safe microorganism suitable for use in biotechnology, and several engineering tools have been developed for it.

Su et al. engineered a V. natriegens strain for the remediation of multiple organic pollutants. The authors selected nine known degradation gene clusters targeting various organic pollutants, including monocyclic pollutants (benzene, toluene, and phenol), dicyclic pollutants (naphthalene and biphenyl), and heterocyclic pollutants (dibenzofuran and dibenzothiophene). The engineered strain can bioremediate five organic pollutants (biphenyl, phenol, naphthalene, dibenzofuran, and toluene) covering a broad substrate range, from monocyclic to multicyclic compounds, in industrial wastewater samples.

A synthetic biology approach was used to engineer V. natriegens into a strain capable of bioremediating complex organic pollutants in saline wastewater and soils. The competence master regulator gene tfoX was inserted into chromosome 1 of the V. natriegens strain Vmax and overexpressed to enhance DNA uptake and integration. Degradation gene clusters were chemically synthesized and assembled in yeast. A genome engineering method was developed to transfer five gene clusters (43 kb total) into Vmax.

The engineered V. natriegens strain has the potential to bioremediate a range of complex organic pollutants, including those found in industrial wastewater and petroleum refinery waste, thereby addressing notable threats to marine biosecurity.

The Microtox® chronic toxicity test for metal pollutants

The Microtox® chronic toxicity test is a microbial toxicity test that uses the marine bioluminescent bacterium Vibrio fisheri as the test organism. It was developed by Strategic Diagnostic Inc. (formerly Azur Environmental) to address the shortcomings of existing microbial toxicity tests, which often lack the sensitivity to detect metals and other toxicants in watersheds at current part-per-billion concentrations.

The test is easy to perform and inexpensive. It uses the bioluminescent properties of V. fisheri to detect the presence of toxic substances. In the presence of toxicants, the luminescence of the bacteria changes, which is linked to cellular respiration. This change in luminescence can be used to calculate a percentage of light inhibition that directly correlates with toxicity.

The Microtox® chronic toxicity test has been specifically used to measure the toxicity of 13 priority pollutant metals to V. fisheri. These metals include As, Se, Cd, Cr (III and VI), Cu, Pb, Sb, Ag, Tl, Zn, Be, Hg, and Ni. The test can also be used to understand the effects of EDTA and fulvic acid on copper toxicity.

The Microtox® chronic toxicity test is a valuable tool for assessing the toxicity of metal pollutants in municipal wastewaters and receiving waters, where metal concentrations are often much lower (ppb) than in other environmental samples. It provides a more sensitive alternative to standard toxicity tests that rely on eukaryotic species and can be labour-intensive and expensive.

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