Mollusks, Mortality, and Associated Myths

Vibrio vulnificus has often been associated with tropical, third world geographical locations; however, certain regions of the United States may also experience such diseases and clinical practitioners need to be familiar with their diagnosis and treatment. Below, we provide a brief review on Vibro vulnificus, signs and symptoms of infection, diagnosis, treatment, recommendations on prevention, and 2 case reports to illustrate these points. Additionally, certain myths surrounding this bacterium are clarified.


Introduction
Vibrio vulnificus has often been associated with tropical, third world geographical locations; however, certain regions of the United States may also experience such diseases and clinical practitioners need to be familiar with their diagnosis and treatment. Below, we provide a brief review on Vibro vulnificus, signs and symptoms of infection, diagnosis, treatment, recommendations on prevention, and 2 case reports to illustrate these points. Additionally, certain myths surrounding this bacterium are clarified.

Background
This organism was first described in 1976 by Reichelt et al. and named "Beneckea vulnifica" [1]. A subsequent first case series published in 1979 by Blake et al. reported 39 incident cases of human pathogenesis associated with a newly discovered, theretofore unnamed, lactose-fermenting Vibrio species designated L+ Vibrio [2]. The two designations were later discovered to belong to the same organism, which was later renamed Vibrio vulnificus [3].
Vibrio vulnificus is a gram-negative, rod-shaped, facultative anaerobic, halophilic organism found in warm seawater worldwide [4]. In the United States, it grows best when the water temperature is between 20 °C and 30 °C and thus grows better in the Gulf Coast than the cooler waters of the Atlantic and Pacific [5]. It most commonly resides in the tissues of oysters as a result of their filtration feeding [5]. One oysters may shed up to one million V. vulnificus cells per day [5]. People may become infected by ingestion of raw oysters (primary septicemia) or through wound contamination (secondary septicemia) from crabs, oyster shells, rocks, or other marine related sources typically during the warmer months between April and October. However, 40% of documented cases occur from September through April [6].

Signs and Symptoms
Primary septicemia typically presents after ingestion of raw infected oysters. Approximately 10-20% of the United States population consumes raw shellfish at least once each year resulting in 95 reported cases of human infection, 85 hospitalizations, and 35 deaths annually [5,7]. If infected, patients may develop fever, chills, nausea, hypotensive shock, and formation of specific skin lesions ( Figure 1) [8]. Skin lesions typically present as ecchymoses, characteristic hemorrhagic blisters, or necrotic ulcerations. These patients require prompt hospitalization and ICU care, as mortality risk is greater than 50% [7][8][9]. It is important to note that patients at greatest risk for this type of primary infection are typically middle-aged males with underlying disease (e.g., diabetes, malignancy, renal insufficiency, and liver disease) [9].
In secondary septicemia, pathogenesis occurs due to open wound contamination. A rapidly progressing cellulitis ensues with marked local swelling and hemorrhagic bullae ( Figure 2) and may be accompanied by fever and chills [9]. Case fatality rates for this type of exposure are significantly lower at 15% [9]. Similar to primary septicemia, risk factors include chronic disease (e.g., liver and alcohol-related) [9] and immunocompromised state [7].

Diagnosis and Treatment
If infection is suspected, blood and wound or hemorrhagic blister fluid cultures should be immediately performed [7]. Treatment involves rapid initiation of antibiotics including doxycyline (100 mg, IV or oral, twice daily for 7-14 days) and a third generation cephalosporin such as ceftazidine (1-2 g, IV every eight hours) [7]. Utilization of a single antibacterial agent such as fluoroquinolone (e.g., levofloxacin, ciprofloxacin, or gatifloxacin) may be as effective. In children, for whom doxycycline and fluoroquinolone are contraindicated, trimethoprimsulfamethoxazole plus an aminoglycoside are recommended. Additionally, necrotic tissue should be debrided [7].

Recommendations
Recommendations to reduce infection include avoiding raw seafood juice, raw oyster, and raw shellfish consumption altogether, but especially in immunocompromised individuals and those with liver disease. Contrary to common belief, the bacterium does not alter the taste, appearance, or odor of seafood and is not associated with human fecal waste or pollution [6,9]. Additionally, no amount of alcohol, hot sauce, or "months with the letter R" (i.e., September, October,