24.3 Bacterial infections of the gastrointestinal tract  (Page 8/18)

Vibrio vulnificus is found in warm seawater and, unlike V. cholerae , is not associated with poor sanitary conditions. The bacteria can be found in raw seafood, and ingestion causes gastrointestinal illness. It can also be acquired by individuals with open skin wounds who are exposed to water with high concentrations of the pathogen. In some cases, the infection spreads to the bloodstream and causes septicemia. Skin infection can lead to edema, ecchymosis (discoloration of skin due to bleeding), and abscesses. Patients with underlying disease have a high fatality rate of about 50%. It is of particular concern for individuals with chronic liver disease or who are otherwise immunodeficient because a healthy immune system can often prevent infection from developing. V. vulnificus is diagnosed by culturing for the pathogen from stool samples, blood samples, or skin abscesses. Adult patients are treated with doxycycline combined with a third generation cephalosporin or with fluoroquinolones , and children are treated with TMP/SMZ .

Two other vibrios, Aeromonas hydrophila and Plesiomonas shigelloides , are also associated with marine environments and raw seafood; they can also cause gastroenteritis. Like V. vulnificus , A. hydrophila is more often associated with infections in wounds, generally those acquired in water. In some cases, it can also cause septicemia. Other species of Aeromonas can cause illness. P. shigelloides is sometimes associated with more serious systemic infections if ingested in contaminated food or water. Culture can be used to diagnose A. hydrophila and P. shigelloides infections, for which antibiotic therapy is generally not needed. When necessary, tetracycline and ciprofloxacin , among other antibiotics, may be used for treatment of A. hydrophila , and fluoroquinolones and trimethoprim are the effective treatments for P. shigelloides .

Campylobacter jejuni Gastroenteritis

Campylobacter is a genus of gram-negative, spiral or curved bacteria. They may have one or two flagella. Campylobacter jejuni gastroenteritis , a form of campylobacteriosis , is a widespread illness that is caused by Campylobacter jejuni . The primary route of transmission is through poultry that becomes contaminated during slaughter. Handling of the raw chicken in turn contaminates cooking surfaces, utensils, and other foods. Unpasteurized milk or contaminated water are also potential vehicles of transmission. In most cases, the illness is self-limiting and includes fever, diarrhea, cramps, vomiting, and sometimes dysentery . More serious signs and symptoms, such as bacteremia, meningitis, pancreatitis, cholecystitis, and hepatitis, sometimes occur. It has also been associated with autoimmune conditions such as Guillain-Barré syndrome , a neurological disease that occurs after some infections and results in temporary paralysis. HUS following infection can also occur. The virulence in many strains is the result of hemolysin production and the presence of Campylobacter cytolethal distending toxin (CDT), a powerful deoxyribonuclease (DNase) that irreversibly damages host cell DNA.