Term
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Definition
• Gram-positive bacilli, that occurs singly, in pairs, or in chains
• Forms endospores
• Bacillus anthracis is a strict pathogen of animals and humans
– Primarily a disease of herbivores, but humans can contract the disease from infected animals
– Humans contract the bacteria via on of three routes
• Inhalation of spores
• Inoculation of spores into the body through a break in the skin
• Ingestion of spores |
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Term
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Definition
• Gram-positive endospore-forming bacillus
• Spores can survive in the environment for decades
• Virulence due to a 3-component toxin and a protein capsule
• Virulence factors encoded on 2 plasmids: pXO1 and pXO2
• Disease in humans has 3 forms:
• Inhalation: (Pulmonary) also called ‘woolsorter’s disease; toxin is absorbed and induces capillary thrombosis and cardiovascular shock.
• Gastrointestinal: From ingestion of contaminated meat; rare but serious.
• Cutaneous: Marked by eschar (black, necrotic) skin lesions; usually not fatal. |
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Term
| Diagnosis, Treatment, and Prevention of Anthrax |
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Definition
• Diagnosis
– Presence of large, nonmotile, Gram-positive bacilli in clinical samples of the lungs or skin
• Treatment
– Ciproflaxacin and many other antimicrobials are effective against B.anthracis
• Prevention
– Control the disease in animals
– An anthrax vaccine is available but requires multiple doses and boosters |
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Term
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Definition
• Large release at a Bioweapons facility in Sverdlovsk (1979).
• Resulted in 79 cases of anthrax and 68 deaths (86% mortality).
• In the fatal cases, the interval between onset of symptoms and death averaged 3 days. Early detection is imperative.
• No deaths in those that developed cutaneous anthrax.
• Aum Shinrikyo cult dispersed aerosols of anthrax and botulism throughout Tokyo on at least 8 occasions (1990-1995). |
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Term
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Definition
• Based on primate data, the LD50 for humans is estimated to be between 2,500 and 55,000 inhaled spores.
• Human data exists showing that a dose of 500 spores does not generally result in disease.
• During World War II, British used Gruinard Island off the Scottish coast to experiment with anthrax explosives. Viable spores persisted for 36 years. Decontamination took over 8 years.
• Prevention focus is on vaccination and detection |
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Term
| Disesease Caused by Bacillus |
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Definition
• Anthrax infection is treated effectively with ciprofloxacin, penicillin or tetracycline. However, death can still result due to toxemia.
• Prevented by vaccination of animals and burning infected carcasses; and by gas-sterilizing imported hides and fur.
• Other important Bacillus species include:
• B. cereus- Responsible for food poisoning in cooked foods such as rice, beans, and potato dishes. Symptoms like Staphylococcal food poisoning.
• B. subtilis- Produces bacitracin |
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Term
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Definition
• Gram-positive, anaerobic, endospore-forming bacillus
• Ubiquitous in soil, water, and the gastrointestinal tracts of animals and humans
• The presence of endospores allows for survival in harsh conditions |
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Term
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Definition
• Commonly grows in the digestive tracts of animals and humans
• Produces 11 toxins that have various effects on the body and can result in irreversible damage. Causes the following Diseases:
– Food poisoning
• Benign disease characterized by abdominal cramps and watery diarrhea
– Gas gangrene
• Endospores are introduced into the body through some traumatic event
• The endospores germinate and cause necrosis that is often accompanied by foul-smelling gaseous bacterial waste products |
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Term
Clsotridium perfringens
Gas Gangrene
Diagnosis, Treatment, and Prevention |
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Definition
• Prevention
– Difficult to prevent because it is so common
– Proper cleaning of wounds can often prevent gas gangrene |
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Term
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Definition
• Common member of the intestinal microbiota
• Opportunistic pathogen in patients treated with broad-spectrum antimicrobial drugs
– Minor infections can result in a self-limiting explosive diarrhea
– Serious cases can cause pseudomembranous colitis
• Can result in perforation of the colon, leading to massive internal infection by fecal bacteria and eventual death |
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Term
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Definition
• Diagnosed by isolating the organism from feces or by demonstrating the presence of toxins via immunoassay
• Minor infections are usually resolved by discontinuing use of antimicrobial drugs
• Serious cases are treated with antibiotics
• Proper hygiene is critical for limiting nosocomial infections |
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Term
| Antibiotic-Associated Colitis |
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Definition
| Caused by Clostridium difficile |
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Term
| Diseases Caused by Clostridium |
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Definition
• Botulism
– Disease caused by ingesting preformed toxin produced by C. botulinum growing in low-acid foods. Incubation period is short and depends on amount of toxin ingested.
– Infant botulism may involve honey consumption.
– Botulism toxin is most potent poison known (1g is fatal for a human)
– Treatment is by administration of polyvalent antitoxin.
– Prevented by proper food preparation and storage procedures. Toxin is destroyed by heat. |
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Term
| The Action of Botulism Toxin |
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Definition
• Botulism is not an infection, but an intoxification caused by the botulism toxin
• 3 forms of botulism
– Food-borne botulism
• Usually occurs due to the consumption of toxin in home-canned foods or preserved fish
• Can result in a progressive paralysis that results in death due to the inability to inhale
– Infant botulism
• Results from the ingestion of endospores, which germinate, and colonize the gastrointestinal tract due to the lack of sufficient numbers of normal microbiota
• Symptoms include constipation and “failure to thrive”, but paralysis and death are rare
– Wound botulism
• Wound becomes contaminated with endospores
• Symptoms are the same as with food-borne botulism |
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Term
| Diagnosis, Treatment, and Prevention of Botulism |
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Definition
• Diagnosis
– Symptoms of botulism are diagnostic
– Confirm diagnosis by culturing the organism from food, feces, or the patient’s wound
• Treatment
– Can involve three approaches
• Administer antibodies against botulism toxin to neutralize toxin in the blood
• Administer antimicrobial drugs to kill clostridia in infant botulism cases
• Prevention
– Proper canning of food
– Infants < 1 should not consume honey |
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Term
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Definition
• Endospore-forming, obligately anaerobic, Gram-positive rod
• Ubiquitous in soil, dust, and the GI tract of animals and humans
• Tetanus results when the bacterial endopsores germinate and produce tetanus toxin
• Tetanus results in spasms and contractions that can result in death because patients can’t exhale |
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Term
| Diseases Caused by Clostridium |
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Definition
• Tetanus = Lock jaw
– Disease is caused by toxin produced by organisms growing in an anaerobic wound (incubation period is 4-10 days)
– C. tetani spores are abundant in soils contaminated with animal wastes
– Treatment is composed of antitoxin, wound cleansing, and antibiotics.
– Prevented by the vaccine (DPT for children; DT for adults). |
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Term
| Diagnosis, Treatment, and Prevention of Tetanus |
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Definition
• Diagnosis
– Characteristic muscular contraction
– The bacteria is rarely isolated from clinical samples because it grows slowly and is sensitive to oxygen
• Treatment
– Thorough cleaning of wounds to remove endospores
– Passive immunization with immunoglobulin directed against the toxin
– Administration of antimicrobials
– Active immunization with tetanus toxoid |
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