Clinical Findings
Signs and Symptoms
Patients with septicemia, wound infections, or ear infections caused by a Vibrio species frequently have a history of shellfish ingestion or saltwater exposure. Clinical manifestations vary depending on the site of infection. Healing wounds, in appropriately exposed individuals, may become secondarily infected by marine vibrios. Suppuration may occur, and subcutaneous abscesses may form. A spreading, violaceous appearance around the wound, which is warm to the touch is indicative of cellulitis. The clinical findings of V alginolyticus-associated otitis media are nonspecific. Findings in V alginolyticus-associated otitis externa include a reddened, often painful external auditory canal.
In immunocompromised and debilitated patients, especially those with liver cirrhosis, a septicemia syndrome, with multiple bullous skin lesions may occur. This is usually caused by V vulnificus and is often fatal. V vulnificus, which may be introduced by the ingestion of raw or undercooked shellfish, may transmigrate the intestinal mucosa and invade the bloodstream with little or no gastrointestinal symptomatology. Infected patients often develop signs and symptoms of septic shock, such as fever, chills, and hypotension. Shortly thereafter, erythematous skin lesions occur, which develop into hemorrhagic vesicles-bullae and finally ulcerate. Although this syndrome is rare, it is important to recognize it, since its mortality rate is ~ 50%.
Laboratory Findings
Hematopoietic findings are variable and may demonstrate either leukocytosis or leukopenia with left-shifted hematopoiesis. The isolation of vibrios from patients with extraintestinal disease is usually not difficult. The selective and differential agars are not required since the sites of culture are normally sterile. Vibrios causing extraintestinal disease are usually isolated on routine 5% sheep’s blood agar. If an extraintestinal Vibrio infection is suspected, the microbiology laboratory should be notified. The supplementation of media with 1% NaCl may aid in the more rapid identification of the Vibrio species.
Imaging
Ultrasound or computerized tomography guidance may be useful for identifying and assisting in drainage of deep abscesses.
Differential Diagnosis
Improperly cared for wounds may be colonized and infected by a variety of bacteria. When these wounds have been exposed to salt water or the patient has recently eaten raw or undercooked shellfish, a vibrio infection should be considered.
Although immunocompromised patients may be infected by a variety of microbes, an extraintestinal vibrio infection should be considered when skin lesions and a sepsislike syndrome are present in association with the recent ingestion of raw or undercooked shellfish.
Complications
The diarrhea that results from noncholera vibrio infections rarely results in significant dehydration, except in children and the elderly. The hydration status of pregnant women should be carefully monitored to prevent severe dehydration and possible fetal loss.
Extraintestinal vibrio infections may result from septicemia following ingestion of raw shellfish or from direct inoculation of marine vibrios. If septicemia occurs, metastatic foci of infection may be present in virtually any organ. The consequences of extraintestinal vibrio infections during pregnancy are unclear because of the paucity of cases.
Treatment
Primary Therapy
Enteritis caused by V parahaemolyticus is usually self-limited and requires no therapy. In severe cases of noncholera Vibrio gastroenteritis, the principles of cholera therapy should be followed. Patients with extraintestinal disease due to V vulnificus, and V alginolyticus should undergo appropriate wound debridement and abscess drainage as indicated and should be treated with antimicrobial agents (Box 4). Patients with systemic symptomatology may also require extensive supportive measures for survival.
Antimicrobial Therapy
Antimicrobial therapy does not shorten the duration of noncholera enteritis and is not recommended in uncomplicated cases. If enteritis is complicated by septicemia, specific antimicrobial therapy should be determined based on the antimicrobial susceptibility profile.
Extraintestinal vibrio infections may be treated with tetracycline, cefotaxime, or possibly ciprofloxacin until the antimicrobial susceptibility profile becomes available.
Prognosis
The prognosis for noncholera gastroenteritis is usually excellent. The prognosis may become guarded in children, the elderly, and pregnant women with severe dehydration.
If appropriate surgical and medical therapy is given, the prognosis for extraintestinal Vibrio infections is usually good in the immunocompetent host. In immunocompromised patients, especially those with cirrhosis or diabetes mellitus, the prognosis is guarded to poor.
Prevention & Control
Noncholera vibrio enteritis and many cases of extraintestinal vibrio infections may easily be avoided by abstinence from raw shellfish (Box 5). The thorough cooking of shellfish renders it safe for consumption. Regardless of the hazards, raw oysters and clams remain popular in many parts of the world. Warnings concerning the possible health hazards should be posted in plain view in restaurants that serve these dishes, and additional caution should be directed specifically to individuals with liver disease or other immunocompromising conditions. Individuals with healing wounds should avoid exposing the wounds to seawater.
Large-scale commercial oyster and clam farming is becoming more established. In the future, this may present additional hazards. The colonization of an entire mollusk bed by pathogenic vibrios could occur if abundant shellfish are present in close proximity. Additionally, the spread of pathogenic vibrios among mollusk beds could result if numerous beds are located in close proximity. This could result in large numbers of contaminated shellfish being present in the same harvest and could result in epidemics. Therefore, in the future, adequate monitoring systems may be needed more than ever before to prevent possible outbreak situations.