Vibrio vulnificus is a gram-negative bacillus that only affects humans and other primates. It is in the same family as bacteria that cause cholera. The first documented case of disease caused by the organism was in 1979.
V vulnificus is usually found in warm, shallow, coastal salt water in temperate climates throughout most of the world. It can be found in the Gulf of Mexico, along most of the East Coast of the United States, and along all of the West Coast of the United States. V vulnificus can be found in water; sediment; plankton; and shellfish, such as oysters, clams, and crabs. This organism can survive in seawater and can produce wound infections, a potentially serious problem among Asian tsunami survivors,[1] and potentially fatal necrotizing fasciitis in them and in individuals with liver cirrhosis.[2] This halophilic bacterium can also cause serious gastroenteritis after eating raw seafood.[3] Genome sequencing has been performed.[4]
See image below, as well as the article Vibrio Infections.
View Image | Vibrio infections. Early bullous lesions appear over the dorsum of the foot of a patient with cirrhosis. |
V vulnificus infects the body in 2 ways, either by exposure to contaminated seafood, such as raw oysters, or through an open wound exposed to contaminated seawater. Among healthy individuals, within 16 hours of ingestion, they experience vomiting, diarrhea, and abdominal pain. Many patients develop distinctive bullous skin lesions. In patients who are immunocompromised, particularly those with chronic liver disease (especially cirrhosis), immunosuppression, end-stage renal disease, and hematopoietic disorders, V vulnificus can cause life-threatening septic shock and blistering skin lesions. Those who are immunocompromised are at a much greater risk for contracting V vulnificus and dying from overwhelming sepsis.
Because the incidence of disease is relatively low, not all strains of V vulnificus may be equally virulent. Recent data are consistent with the existence of 2 genotypes of V vulnificus, with the C-type being a strong indicator of potential virulence.[5] The biotype 3 group of the human pathogen V vulnificus may have emerged in Israel due to genome hybridization of 2 bacterial populations. This new clonal subgroup emphasizes that the fish aquaculture environment, and possibly manmade ecological niches as a whole, may be a source of new pathogenic strains.[6]
See Pathophysiology.
It is seen in a variety of seafood. V vulnificus can grow rapidly in shellfish owing to the ambient air conditions occurring with intertidal exposure.[7] A study of Vibrio species isolated from retail shrimp in Hanoi found 201 of 202 samples were positive, with most having Vibrio parahaemolyticus (96.5%) and V vulnificus documented much less often, specifically in only 1.5%.[8] Sanitary working conditions and well-cooked shrimp should be encouraged.
V vulnificus infections are rare but underreported. Most cases are found in the Gulf Coast states, and they are most common during warm weather months. V vulnificus has been difficult to culture from North Carolina oyster samples since 2007. It may be that oysters were colonized with a more salt-tolerant bacterium during the drought, displacing V vulnificus, and may be preventing recolonization.[9] Evaluation of the graveyard skeletons of two American Civil War soldiers revealed they may have died as a result of V vulnificus septicemia.[10]
The frequency of V vulnificus infection, which is rare in Japan, was evaluated in 2008. Its prevalence varied in different districts.[11] A 2017 study from India found that 10 (38.5%) of 26 clam (Meretrix meretrix) samples obtained from the markets in the attractive tourist destination of Mangalore harbored V vulnificus.[12] Marine aquaculture has rendered V vulnificus infections relatively common all over the world.[13]
All races are affected equally.
Males and females are affected equally.
All ages are affected equally.
Vibrio vulnificus infection is an acute illness that is quickly resolved with antibiotics and does not have any long-term consequences. The prognosis is often excellent with proper treatment. However, it produces more than 95% of seafood-related deaths in the United States and has the highest fatality rate of any food-borne pathogen.[14]
Most V vulnificus infections are acute but have no long-term consequences; however, in patients who develop septic shock from infection with V vulnificus, the mortality rate is 50%. A 2017 case report describes a man becoming infected with V vulnificus after swimming in the Gulf of Mexico 5 days after the completion of a leg tattoo.[15] The patient died from septic shock; his chronic liver disease was cited as a possible contributing factor.
In rare instances, skin infection can result in necrotizing fasciitis. V vulnificus necrotizing skin and soft-tissue infections may result in multiple organ failure and death. A prediction model to estimate the case-fatality rate has been proposed.[16]
Retrospective analysis of 30 patients with necrotizing fasciitis and sepsis caused by Vibrio species and initially treated with surgical debridement or immediate limb amputation showed 11 (37%) died within several days of admission.[17] A higher mortality rate was noted with the Vibrio cholerae non-O1 group (57%) compared with the V vulnificus group (30%). Other bad prognostic signs included a systolic blood pressure of less than or equal to 90 mm Hg, decreased platelet counts, and leukopenia. The combination of hepatic dysfunction and diabetes mellitus was also associated with a poor outcome.
Predictive factors for mortality in primary septicemia or wound infections caused by V vulnificus have been accessed using a variety of parameters. Multivariate analysis has revealed that the presence of hemorrhagic bullae/necrotizing fasciitis, primary septicemia, a greater severity of illness, absence of leukocytosis, and hypoalbuminemia were the significant risk factors for mortality in V vulnificus skin and soft tissue infections.[18]
The presence of hemorrhagic bullous skin lesions, necrotizing fasciitis, primary septicemia, a greater severity-of-illness, absence of leukocytosis, and hypoalbuminemia were found to be the significant risk factors for mortality in patients with V vulnificus infection.[18]
Counsel patients who are immunocompromised to prevent exposure to V vulnificus. The high mortality associated with this septicemia suggests susceptible individuals should be forewarned by signs displayed in restaurants; physicians should educate patients with chronic liver disease about the risk of raw oyster consumption. Additionally, harvesting methods that reduce contamination by V vulnificus should be used.[19]
V vulnificus infection should be suspected in patients who give a history of ingestion of raw seafood or wound infection after exposure to seawater. Patients with V vulnificus infection report abrupt GI symptoms, such as vomiting, diarrhea, or abdominal pain, and may present with fever, chills, or shock. V vulnificus is normally found in warm estuarial and marine environments, lodging in filter feeders such as oysters. It occurs mainly in patients with chronic liver disease after the consumption of raw oysters. Partridge et al reported a case that was likely contracted from a thermal pool in Turkey, with no history of seawater or shellfish exposure.[20]
V vulnificus septicemia is the most common cause of death from seafood consumption in the United States.[19] V vulnificus septicemia may first become evident in the skin as purpura fulminans, which can take a catastrophic course without immediate and intensive empirical antibiotic treatment.[21]
V vulnificus infection is a rare cause of necrotizing fasciitis, which can be fatal.[22, 23] Necrotizing fasciitis caused by V vulnificus progresses more rapidly with clinical characteristics more fulminant than either methicillin-resistant Staphylococcus aureus or methicillin-sensitive S aureus infection.[24] The same may be true for V vulnificus as compared with Klebsiella pneumoniae–induced necrotizing fasciitis, being 2.5 days versus 5.5 days.[25]
Most patients infected with V vulnificus have bullous skin lesions, which are found on the trunk and the lower extremities (see the image below). Infection of the hand has been reported.[26] These hemorrhagic bullae can progress to necrotic ulcerations, which require surgical debridement. Edema can be present.
View Image | Vibrio infections. Early bullous lesions appear over the dorsum of the foot of a patient with cirrhosis. |
A rapid onset of cellulitis may represent infection with V vulnificus, especially if the patient had contact with seawater or raw seafood. Patients can progress to necrotizing fasciitis.[27]
Patients who are immunocompromised are at risk of septic shock from the infection, which can be fatal. Otherwise, no complications from V vulnificus infection occur.
Routine stool, wound, and blood cultures aid in the diagnosis of V vulnificus infection. A polymerase chain reaction assay is a super detection method for V vulnificus.[28]
No imaging studies are necessary to help diagnose or treat V vulnificus infection.
Antibiotics are necessary to eradicate the infection (see Medication). In case of wound infection, aggressive debridement is necessary to remove necrotic tissue. If the patient is in shock, perform necessary interventions to resuscitate the patient. V vulnificus as the etiologic agent of necrotizing fasciitis requires emergency approaches to treat potential septic shock and multiple organ failure,[29] particularly in those with preexisting medical complications, including hypotension, lactic acidosis, coagulation disorders, and thrombocytopenia.[30]
Available guidelines that may be helpful include the Practice guidelines for the diagnosis and management of skin and soft-tissue infections from the Infectious Diseases Society of America and the Diagnosis and management of foodborne illnesses: a primer for physicians and other health care professionals from the American Medical Association, American Nurses Association, American Nurses Foundation, Centers for Disease Control and Prevention, Center for Food Safety and Applied Nutrition, US Food and Drug Administration, Food Safety and Inspection Service, and US Department of Agriculture.[31, 32]
Because many patients with V vulnificus infection experience overwhelming sepsis, consultation with an infectious disease specialist is warranted. Consider consultation with an infectious disease specialist if the diagnosis is unclear or if the patient has atypical symptoms or does not respond to antibiotic treatment.
To prevent infection from V vulnificus, persons should avoid exposure to raw shellfish or thoroughly cook the shellfish. Persons should avoid cross-contamination of cooked shellfish with uncooked shellfish and eat shellfish promptly after cooking. Shellfish is best served hot.[33]
Identifying oysters that are affected by V vulnificus is difficult because the appearance, taste, color, and odor of the oysters are not affected. Through improved reporting of affected oysters, oyster beds that are affected can be identified and closed.[34]
Persons should avoid exposure of open wounds or broken skin to raw shellfish or infected waters. Patients who are immunocompromised should be especially careful to follow these guidelines because they are more susceptible to infection and complications.
Therapeutic vaccination against V vulnificus infection by active and passive immunization with the C-terminal region of the RtxA1/MARTXVv protein has been suggested by studies in mice.[35]
The goals of therapy are to eradicate the infection, to reduce morbidity, and to prevent complications. A high index of suspicion is important, as doxycycline, the antibiotic of choice, is not usually a part of the empiric therapy for septicemia. Tigecycline may be a good choice for treating invasive V vulnificus infections.[36]
If necrotizing fasciitis is suspected, early fasciotomy and culture-directed antimicrobial therapy should be performed. These patients may develop hypotensive shock, leukopenia, severe hypoalbuminemia, and underlying chronic illness, especially a combination of hepatic dysfunction and diabetes mellitus.
Clinical Context: Doxycycline is a synthetic antibiotic derived from tetracycline. It inhibits protein synthesis and thus bacterial growth by binding to 30S and possibly 50S ribosomal subunits of susceptible bacteria. Doxycycline is effective against a large number of pathogens.
Antibiotics are necessary to eradicate V vulnificus infection. Effective antibiotics may include tetracycline, third-generation cephalosporins, and imipenem.