24.3 Bacterial infections of the gastrointestinal tract  (Page 10/18)

Antibiotics can be used to treat the infection. However, unique to H. pylori, the recommendation from the US Food and Drug Administration is to use a triple therapy. The current protocols are 10 days of treatment with omeprazole , amoxicillin , and clarithromycin (OAC); 14 days of treatment with bismuth subsalicylate , metronidazole , and tetracycline (BMT); or 10 or 14 days of treatment with lansoprazole , amoxicillin , and clarithromycin (LAC). Omeprazole, bismuth subsalicylate, and lansoprazole are not antibiotics but are instead used to decrease acid levels because H. pylori prefers acidic environments.

Although treatment is often valuable, there are also risks to H. pylori eradication. Infection with H. pylori may actually protect against some cancers, such as esophageal adenocarcinoma and gastroesophageal reflux disease. Martin J. Blaser. “Disappearing Microbiota: Helicobacter pylori Protection against Esophageal Adenocarcinoma.” Cancer Prevention Research 1 (2008) 5: pp. 308–311. http://cancerpreventionresearch.aacrjournals.org/content/1/5/308.full.pdf+html. Ivan F. N. Hung and Benjamin C. Y. Wong. “Assessing the Risks and Benefits of Treating Helicobacter pylori Infection.” Therapeutic Advances in Gastroenterology 2 (2009) 3: pp, 141–147. doi: 10.1177/1756283X08100279.

Clostridium perfringens Gastroenteritis

Clostridium perfringens gastroenteritis is a generally mild foodborne disease that is associated with undercooked meats and other foods. C. perfringens is a gram-positive, rod-shaped, endospore-forming anaerobic bacterium that is tolerant of high and low temperatures. At high temperatures, the bacteria can form endospores that will germinate rapidly in foods or within the intestine. Food poisoning by type A strains is common. This strain always produces an enterotoxin , sometimes also present in other strains, that causes the clinical symptoms of cramps and diarrhea. A more severe form of the illness, called pig-bel or enteritis necroticans , causes hemorrhaging, pain, vomiting, and bloating. Gangrene of the intestines may result. This form has a high mortality rate but is rare in the United States.

Diagnosis involves detecting the C. perfringens toxin in stool samples using either molecular biology techniques (PCR detection of the toxin gene) or immunology techniques (ELISA). The bacteria itself may also be detected in foods or in fecal samples. Treatment includes rehydration therapy, electrolyte replacement, and intravenous fluids. Antibiotics are not recommended because they can damage the balance of the microbiota in the gut, and there are concerns about antibiotic resistance. The illness can be prevented through proper handling and cooking of foods, including prompt refrigeration at sufficiently low temperatures and cooking food to a sufficiently high temperature.

Clostridium difficile

Clostridium difficile is a gram-positive rod that can be a commensal bacterium as part of the normal microbiota of healthy individuals. When the normal microbiota is disrupted by long-term antibiotic use, it can allow the overgrowth of this bacterium, resulting in antibiotic-associated diarrhea caused by C. difficile . Antibiotic-associated diarrhea can also be considered a nosocomial disease . Patients at the greatest risk of C. difficile infection are those who are immunocompromised, have been in health-care settings for extended periods, are older, have recently taken antibiotics, have had gastrointestinal procedures done, or use proton pump inhibitors, which reduce stomach acidity and allow proliferation of C. difficile . Because this species can form endospores , it can survive for extended periods of time in the environment under harsh conditions and is a considerable concern in health-care settings.