Vibrio Vulnificus

Vibrio vulnificus is a motile, halophilic (salt-requiring), Gram-negative, curved rod-shaped free-living bacterium. "Vulnificus" is a Latin word meaning "inflicting wounds." The organism is commonly isolated in warm seawater worldwide, most commonly in the Gulf of Mexico and Hawaii, but also in the marine waters off the coast of Cape Cod, and even within lakewater in New Mexico, Oklahoma and Utah. Almost all oysters harvested in the summer from the Chesapeake Bay contain the pathogen, as do 11% of crabs. The bacterium has also been isolated from plankton, shellfish, and the intestines of the bottom-feeding fish. V. vulnificus alone is responsible for 95% of all seafood-related deaths in the United States. The infection can be acquired through wound exposure or seafood consumption.

Virulence Factors

V. vulnificus is considered to be one the most virulent bacterial pathogens known. Several properties contribute to the virulence of this organism. One of the major property is the presence of a polysaccharide capsule which impairs phagocytosis and killing by immune system cells. The capsule also stimulates the release of inflammatory molecules and tumor necrosis factor which induce severe hemorrhage, tissue necrosis, and shock 4. Chronic alcohol use leads to increased peripheral circulation of proinflammatory cytokines and suppression of specific innate and cellular immune responses.

Diseases Caused by Vibrio Vulnificus

Vibrio vulnificus causes three types of disease in humans - primary septicemia, gastroenteritis, and necrotizing wound infection. These infections are infrequent and are generally limited to persons with pre-existing chronic illnesses or the immunocompromised. Liver disease, diabetes, arthritis, gastrointestinal ulcers, hematological conditions, high-dose corticosteroid therapy, and cancer are prominent risk factors. The impairment of iron metabolism and resultant iron overload associated with many of these conditions is thought to support increased V. vulnificus growth and reduced immune clearance. Vibrio vulnificus can invade through the intestinal barrier into the bloodstream causing septicemia. As a result, it has the highest case/fatality rate among foodborne pathogens 1,2



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Vibrio vulnificus can pose a small risk to otherwise "healthy" individuals, since the infection has been reported in persons without any of the above risk factors. It is estimated that about 7% of the adult population in the United States is susceptible to infection.

Patients with primary septicemia show fever, chills, often with vomiting, diarrhea, and abdominal pain as well as pain in the extremities. Within 24 hours of the infection, secondary signs appear which include redness, blisters, and bleeding under the skin. Up to 60% of these patients experience shock with systolic blood pressure below 90 mm Hg. Often the lesions become necrotic and require surgery or amputation 3.

Vibrio vulnificus
Vibrio vulnificus
Creadit: Janice Haney Carr CDC

Wound infection symptoms also include fever and chills with hypotension, nausea and vomiting seen less frequently.

In patients with gastroenteritis, diarrhea is usually watery and profuse. Liver disease and alcohol abuse are important contributors to the disease severity, but no deaths have been reported with gastroenteritis 5.

Prevention

People with liver disease, including individuals with chronic alcohol use, hemochromatosis, diabetes, organ transplants, and human immunodeficiency virus (HIV) infection, should be warned of the dangers of eating raw shellfish, especially oysters. These conditions affect the immune system and likely prevent individuals from eliciting an appropriate innate immune response when they come in contact with V. vulnificus.

References

  1. Gerald L. Mandell, JOhn E. Bennett, Raphael Dolin. Infectious Diseases
  2. World Health Organization. Risk Assessment of Vibrio Vulnificus in Raw Oysters
  3. Kathy Pond, World Health Organization. Water Recreation and Disease: Plausibility of Associated Infections
  4. Mark A. Marinella. Handbook of Cancer Emergencies
  5. Marianne D. Miliotis, Jeffrey W. Bier. International Handbook of Foodborne Pathogens
  6. Inflammatory Cytokine Response to Vibrio vulnificus Elicited by Peripheral Blood Mononuclear Cells from Chronic Alcohol Users Is Associated with Biomarkers of Cellular Oxidative Stress

 

 

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