Vibrio Vulnificus: Risk Factors, Diagnosing and Treatment

Introduction

Vibrio vulnificus is a bacterium in the same family as ones that cause Vibrio parahaemolyticus and cholera. It usually lives in warm seawater and is a part of a group of vibrios that are referred to as, 'halophilic,' because they need salt. V. vulnificus may cause disease in people who consume contaminated seafood, or have an open wound that is exposed to seawater.

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Among those who are healthy, ingestion of V. vulnificus can cause diarrhea, vomiting and abdominal pain. In people who are immunocompromised, especially those with chronic liver disease, V. vulnificus can infect a person's bloodstream, causing a severe and life-threatening illness characterized by chills, fever, blistering skin lesions and lowered blood pressure. V. vulnificus bloodstream infections are fatal around half the time. It may cause an infection of the skin when open wounds are exposed to warm seawater. The infections might lead to skin breakdown and ulceration. People who are immunocompromised are at increased risk for invasion of the organism into their bloodstream and possibly - fatal complications.

V. vulnificus is a rare cause of disease, yet it is also under-reported.

Between the years of 1988-2006, the Centers for Disease Control and Prevention (CDC) received reports of more than 900 V. vulnificus infections from the Gulf Coast states, where the majority of instances happen. Prior to the year 2007, there was no national surveillance system for V. vulnificus, although the CDC collaborated with the states of:

• Texas
• Florida
• Alabama
• Louisiana
• Mississippi

In order to monitor the number of instances of V. vulnificus infections in the Gulf Coast region. In the year 2007, infections caused by V. vulnificus and additional Vibrio species became nationally notifiable.

People at Increased Risk

People who are immunocompromised, particularly people with chronic liver disease, are at risk for V. vulnificus when they consume raw seafood - especially oysters.

A recent study revealed that people with these pre-existing medical conditions were 80 times more likely to develop V. vulnificus bloodstream infections that were healthy people.

The bacterium is often times isolated from oysters and other shellfish in warm coastal waters during the summer. Since it is naturally found in warm marine waters, people with open wounds may be exposed to V. vulnificus via direct contact with ocean water.

There is no evidence for person-to-person transmission of the bacterium.

Diagnosing V. Vulnificus

V. vulnificus infections are diagnosed by wound, blood, or stool cultures.

Notifying the laboratory when the infection is suspected helps because a unique growth medium should be used to increase the diagnostic yield.

Doctors should have an increased level of suspicion for the organism when people present with fever, illness, or shock after eating raw seafood - particularly oysters, or with a wound infection following exposure to seawater.

Treating V. Vulnificus

If a doctor suspects V. vulnificus, treatment should be initiated promptly because antibiotics improve a person's survival chances.

Intense attention should be given to the site of the wound; amputation of a person's infected limb is at times necessary.

Clinical trials for the management of V. vulnificus infections have not been performed.

The antibiotic recommendations below come from documents published by experts in infectious diseases; they are based upon animal models and case reports.

Culture of the person's wound or hemorrhagic bullae is recommended and all V. vulnificus isolates should be forwarded to a public health laboratory. Blood cultures are recommended if the affected person has hemorrhagic bullae, is febrile, or presents with any signs of sepsis. Treatment of V. vulnificus also includes antibiotic therapy:

Doxycycline, 100 mg. PO/IV two times each day for 7-14 days, as well as a third-generation cephalosporin such as ceftazidime 1-2 g. IV/IM every 8 hours.

A single agent regimen with a fluoroquinolone such as ciprofloxacin, levofloxacin, or gatifloxacin has been reported to be at least as effective in animal models as combination drug regimens with cephalosporin and doxycycline.

Children, in whom fluoroquinolones and doxycycline are contraindicated, may be treated with trimethoprim-sulfamethoxazole with aminoglycoside.

Any necrotic tissue needs to be debrided. Severe instances might require limb amputation or fasciotomy.

Oysters and Safety

While oysters may be legally harvested only from waters that are free from fecal contamination, even legally harvested oysters might be contaminated with V. vulnificus because the bacterium is present naturally in marine environments. V. vulnificus does not change the taste, appearance, or odor of oysters.

Timely and voluntary reporting of V. vulnificus infections to the CDC and to regional offices of the Food and Drug Administration (FDA) help collaborative efforts to improve investigation of these infections.

Regional FDA specialists with expert-level knowledge of shellfish help state officials with, 'tracebacks,' of shellfish and when notified quickly about instances, are able to sample harvest waters to find potential sources of infection and to close oyster beds when issues are identified.

Ongoing research might help with predicting environmental or other factors that increase the chance that oysters carry pathogens.

Facts and Statistics

Vibrio vulnificus, an extremely virulent bacteria, is present in marine environments such as estuaries, brackish ponds, or coastal areas, V. vulnificus is related to V. cholerae, the causative agent of cholera. Vibrio vulnificus is an extremely virulent bacteria that can cause:

• Acute gastroenteritis from eating raw or undercooked shellfish;
• Necrotizing wound infections of injured skin that is exposed to contaminated marine water;
• Invasive septicemia after eating raw or undercooked shellfish, especially oysters.
• Vibrio vulnificus is an opportunistic human pathogen that is highly lethal and is responsible for the overwhelming majority of reported seafood-related deaths in the United States.
• A review of 459 U.S. cases reported by the FDA between 1992 and 2007 revealed that 51.6% of the patients died. 85.6% of the cases were male.
• Of 180 cases in 2002 to 2007 for which FDA data were available, 92.8% of patients had consumed raw oysters prior to the onset of symptoms and 95.3% had some pre-existing disease(s).