Doctor's Notes on Tetanus
Tetanus is an infectious disease caused by contamination of wounds with the Clostridium tetani bacterial spores that live in the soil, dust, and animal waste. The bacteria can enter the body through puncture wounds, such as those caused by rusty nails, splinters, and insect bites. Any break in the skin, burns, and IV drug access sites are also potential entryways for the bacteria.
Symptoms of tetanus include muscle rigidity and spasms, irritability, muscle cramps, sore muscles, weakness, or difficulty swallowing. Facial muscles are often affected and lockjaw is common. Muscle spasms are progressive and may include a characteristic arching of the back (opisthotonus), and may be intense enough to cause broken bones and dislocated joints. In severe cases, muscle spasms may involve the vocal cords or breathing muscles, and can result in death if there is no medical intervention. In neonates symptoms of tetanus may also include irritability and poor sucking ability or difficulty swallowing.
The hallmark feature of tetanus is muscle rigidity and spasms. The median incubation period is seven days with a range from about four to 14 days. The shorter the incubation period, usually the more severe are the symptoms.
- In generalized tetanus, the initial complaints may include any of the following:
- Irritability, muscle cramps, sore muscles, weakness, or difficulty swallowing are commonly seen.
- Facial muscles are often affected first. Trismus or lockjaw is most common. This condition results from spasms of the jaw muscles that are responsible for chewing. A sardonic
smile -- medicallytermed risus sardonicus -- isa characteristic feature that results from facial muscle spasms.
- Muscle spasms are progressive and may include a characteristic arching of the back known as opisthotonus (Figure 2). Muscle spasms may be intense enough to cause bones to break and joints to dislocate.
- Severe cases can involve spasms of the vocal cords or muscles involved in breathing. If this happens, death is likely, unless medical help (mechanical ventilation with a respirator) is readily available.
- In cephalic tetanus, in addition to lockjaw, weakness of at least one other facial muscle occurs. In two-thirds of these cases, generalized tetanus will develop.
- In localized tetanus, muscle spasms occur at or near the site of the injury. This condition can progress to generalized tetanus.
- Neonatal tetanus is identical to generalized tetanus except that it affects the newborn infant. Neonates may be irritable and have poor sucking ability or difficulty swallowing.
Clostridium tetani is a gram-positive rod-shaped bacterium that is found worldwide in soil; it is usually in its dormant form, spores, and becomes the rod-shaped bacterium when it multiplies. The vegetative rods produce the spore usually at one end of the rod (Figure 1). The organisms are considered anaerobic, meaning they do not require oxygen to survive.
- Clostridium tetani is the bacterium responsible for the disease. The bacteria are found in two forms: as a spore (dormant) or as a vegetative cell (active) that can multiply.
- The spores are in soil, dust, and animal waste and can survive there for many years. These spores are resistant to extremes of temperature.
- Contamination of a wound with tetanus spores is rather common. Tetanus, however, can only occur when the spores germinate and become active bacterial cells that release exotoxins.
- The active bacterial cells release two exotoxins, tetanolysin and tetanospasmin. The function of tetanolysin is unclear, but tetanospasmin is responsible for the disease.
- The disease typically follows an acute injury or trauma that results in a break in the skin. Most cases result from a puncture wound, laceration (cut), or an abrasion (scrape).
- Other tetanus-prone injuries include the following:
- Crush wound
- IV drug users (site of needle injection)
- Wounds with devitalized (dead) tissue (for example, burns or crush injuries) or foreign bodies (debris in them) are most at risk of developing tetanus.
- Tetanus may develop in people who are not immunized against it or in people who have failed to maintain adequate immunity with active booster doses of vaccine.
Bacteria are microscopic, single-cell organisms that live almost everywhere. Bacteria live in every climate and location on earth. Some are airborne while others live in water or soil. Bacteria live on and inside plants, animals, and people. The word "bacteria" has a negative connotation, but bacteria actually perform many vital functions for organisms and in the environment. For example, plants need bacteria in the soil in order to grow.
The vast majority of bacteria are harmless to people and some strains are even beneficial. In the human gastrointestinal tract, good bacteria aid in digestion and produce vitamins. They also help with immunity, making the body less hospitable to bad bacteria and other harmful pathogens. When considering all the strains of bacteria that exist, relatively few are capable of making people sick.
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Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.