Botulism

Infant botulism.

Wound botulism.

Foodborne botulism.

Adult intestinal toxemia.

Injection botulism.

Biological warfare/inhalational botulism (Category A biological threat).

Incidence

• In USA, approximately 145 cases are reported each year: infant botulism 65%, wound 20%, and foodborne 15%; adult intestinal colonization and iatrogenic botulism rare.

• Foodborne outbreaks of two or more persons occur most years, and are usually caused by home-preserved foods with low-acid content (pH ≥4.6, although toxin will not be formed in acidic foods, low pH will not degrade any preformed toxin). Foods implicated differ between countries, reflecting local eating habits and food preservation procedures. Improper handling of commercially prepared foods has also been implicated (canned, fermented, salted, and smoked), including unrefrigerated infused cooking oils, baked potatoes wrapped in foil and left sitting out before eating, and ready-to-eat foods in low-oxygen packaging. Low temperature, high salt, and low pH prevent growth of bacteria and toxin formation. Food samples associated with suspect cases should be sealed, stored, and sent to labs.

Dx late, incorrect or missed

• Differential Dx: For adults, myasthenia gravis, Eaton-Lambert, Guillain-Barre, virus attacking brain/spinal cord, CVA, organophosphate exposure, tick paralysis, other neurotoxin; may need brain scan, spinal fluid examination, and EMG, tensilon test to rule out other causes; for infants, sepsis, failure to thrive, dehydration, encephalitis, and metabolic disease

• Nonspecific history and physical findings: classic adult symptoms include double vision, drooping eyelids, slurred speech, difficulty swallowing, dry mouth, muscle weakness; infants appear lethargic, feed poorly, are constipated, and have a weak cry and poor muscle tone—if untreated, symptoms may progress to cause paralysis of the respiratory muscles, arms, legs and trunk; fever and loss of consciousness are not associated symptoms

• Onset of foodborne botulism: usually 12-18-36 h after eating contaminated food, but can be as early as 4 to 6 h or as late as 8 to 10 d

• Laboratory result takes d to wk and should be used only as confirmation; treat before confirmation; tests are performed at some state health department labs and at CDC

• Triad: Bulbar symptoms, resp compromise, and dilated pupils

Prolonged weakness requiring prolonged support

Enteral nutrition: Desired but problematic due to gastroparesis and bowel paralysis

Aspiration risk

Elevated potassium if immobile in ICU

Arrhythmias

Hyperkalemia, arrhythmias, and then cardiac arrest

Prolonged weakness necessitating prolonged intubation and leading to nosocomial infection

Skin breakdown

Botulism is a rare but serious neuroparalytic illness caused by a nerve toxin (BoNT) produced by the rod-shaped gram-positive bacterium Clostridium botulinum (and sometimes by strains of Clostridium butyricum and Clostridium baratii ), commonly found in soil. C. botulinum grows best in low-oxygen conditions; spores survive in a dormant state until exposed to conditions that support growth. Seven types of toxins (A to G), but only A, B, E, and rarely, F cause illness in humans; three different intracellular protein targets; and different durations.

In infant between 2 wk and 1 y old, occurs by ingestion of spores, which grow in intestine and release toxin, usually by honey ingestion, or associated with parent who works with soil or with living in rural areas.

Occurs in wounds of IV/skin popping drug users (or any traumatized tissue contaminated with organisms) in which there is local infection and absorption of produced toxin. There is increased incidence over the last several years in IV drug users (black tar heroin), especially in California.

Foodborne: Improperly preserved or cooked food, even properly cooked food left at improper temperature, allows germination and toxin production by contaminating spores; consumption of food with preformed toxin results in absorption of potent neurotoxin; with education and control of food industries, now uncommon in USA; ingestion of infected inadequately cooked wildlife poses at least potential risk. Foodborne botulism can be a public health emergency.

Intestinal: Spore colonization possible in adults as well if normal gut flora has been altered by surgery or antibiotic therapy.

Cosmetic injections (black market toxin, Botox overdose, or spread beyond injection site) or cerebral palsy (Botox overdose or spread beyond injection site) are a cause.

Inhalational: Genetically engineered toxin, development of biological warfare (at-risk locations). Concern is inadequate stocking of antidotes worldwide and inadequate preparation and medical support. Biological warfare in Iraq has led to organization of task forces such as Scorpio at the national/regional level to stockpile antidotes. Median lethal dose for humans has been estimated at 2 nanograms/kg, approximately three-times greater than in foodborne cases. If inhalation exposure is suspected, additional exposure must be prevented by removal and storage of clothing in plastic until it can be washed, as well as immediate showering and decontamination of those exposed.

Waterborne: Could theoretically result from ingestion of water contaminated with preformed toxin, but risk is low if common water treatment processes are used (boiling and disinfection with 0.1% hypochlorite bleach solution).

Botulinum toxin binds irreversibly to synaptic membrane of cholinergic nerves and prevents release of acetylcholine but not its synthesis and storage.