Pathogens of Concern: Keeping Our Patients Safe in Endoscopy

Endospores

Endospores are a resistant, dormant, survival form of bacteria. They are resistant to high temperatures, most disinfectants, low level radiation and drying. Endospores can survive thousands of years until environmental stimuli trigger germination. Most high level liquid disinfectants require a longer time and specific instructions to kill spores. However, many of the spores that are found in the body are in the vegetative state and are susceptible to high level disinfection. Examples of spore-producing organisms include those that cause anthrax, tetanus, botulism and gangrene.

Bacillus anthractis is a disease of domesticated and wild animals. There are three types of anthrax: skin (cutaneous), lungs (inhalation) and digestive (gastrointestinal). Humans become infected by the disease Anthrax through contact with infected animals, their hides or meat.

Humans can become infected with anthrax by handling hides, meat or products from infected animals or by breathing in anthrax spores from infected animal products (like wool, for example). People also can become infected with gastrointestinal anthrax by eating undercooked meat from infected animals. In most cases, early treatment with antibiotics can cure cutaneous anthrax. Even if untreated, 80 percent of people who become infected with cutaneous anthrax do not die. Gastrointestinal anthrax is more serious because between one-fourth and more than half of cases lead to death. Inhalation anthrax is much more severe. In 2001, about half of the cases of inhalation anthrax ended in death.

Clostridium tetani spores are found in large concentrations in the environment. Clostridia are also anaerobes and Clostridium tetani can be part of the normal flora of the human colon. The disease caused by C. tetani is known as tetanus and is the result of the release of a toxin called tetanospasmin that causes intense muscle spasm. It generally occurs after a cut, puncture wound or scratch from an object contaminated with the bacteria. As little as 100 nanograms can kill an adult. A vaccine is available for prevention, but it is ineffective for treatment of an acute infection. Antiserum is the only antidote for tetanospasmin toxin.

Clostridium botulinum is a spore forming anaerobic bacterium that causes food poisoning. Food borne botulism occurs when the food is contaminated with either spores or toxin. Improperly preserved food and contaminated honey are associated with this disease. Botulism toxin is a neurotoxin which blocks the transmission of nerve impulses to muscle causing a flaccid paralysis.

Clostridium difficile is an opportunistic, spore-forming, gram-positive, anaerobic bacillus. It is transmitted from one patient to another through direct or indirect contact, through the oral ingestion of its vegetative cells or endospores (i.e. the fecal-oral route) or from a contaminated environment or medical device. C. difficile may be found as a part of the normal intestinal flora and approximately 3% of healthy adults carry C. difficile without evidence of disease. C. difficile poses a particular risk for hospitalized patients where environmental contamination with C. difficile spores has been found. In fact, the primary reservoirs of C. difficile are infected and colonized patients in hospitals and long-term care facilities. C. difficile produces two types of toxins that attack the colon wall causing ulcerations.

The setting of a contaminated environment coupled with the use of broad spectrum antibiotics can produce a situation that upsets the balance of normal colon bacteria. In the case of C. difficile, the patient may develop mild diarrhea or progress to the more serious and sometimes fatal pseudomembranous colitis. The treatment is long and difficult, using potent antibiotics and requiring lengthy hospital stays. This infection can leave the patient weak and debilitated for a long period, lengthening recovery from surgery or other medical conditions.

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It is of interest that Botulism toxin is being used as a treatment for achalasia (an esophageal obstruction that develops due to failure of the esophagogastric sphincter to relax, causing the upper esophagus to fill with retained food). Botox blocks nerve impulses to the lower esophageal sphincter causing it to relax. Botox injections are also used to reduce the appearance of facial wrinkles.

 

An endospore is a resistant, dormant, survival form of bacteria.

The release of a toxin called tetanospasmin

Clostridium botulinum (Botox)

Contaminated hospital environment, broad spectrum antibiotics, immunosuppression

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