Clostridium tetani is an anaerobic bacterium that produces a potent toxin that can cause the serious disease tetanus in humans. People typically contract tetanus through introduction of the Clostridium tetani spores via a puncture wound or even a cut. After the introduction of spores, they germinate and become viable bacterial cells in the wound, multiplying and producing the tetanus toxin.
Origin
Clostridium tetani spores are ubiquitous in nature, but are found most often in soil that is contaminated with feces from humans or animals. Clostridium tetani is a harmless resident of human and animal intestines.
Identification
Clostridium tetani is rarely isolated in bacteriological cultures from wounds. Clostridium tetani, like most clostridia, are strict anaerobes that die quickly when exposed to air. If growth is exhibited, it appears as a swarming or spreading colony in anaerobic cultures. The Gram stain appearance is very classic, producing a large terminal spore, often considered as giving the appearance of a "tennis racket" or "drumstick."
Disease
Tetanus is characterized by painful muscular contractions, particularly in the neck muscles. Spasms are also a common characteristic, with opisthotonos, or an involuntary arching of the back commonly. Tetanus is also known as "lockjaw" because patients have difficulty opening the jaw. "Risus sardonicus" is another characteristic, in which the person has a facial expression or smile resembling the Joker from Batman. According to Dr. M.P. Joyce of the Centers for Disease Control and Prevention, depending on the age of the person and the quality of care available, tetanus can be fatal between 10 and 80 percent of the time.
Incubation
After the introduction of Clostridium tetani spores into a wound, disease may occur anywhere between a few days to several weeks or months depending on the extent and location of the wound. Most cases of tetanus occur within 14 days. Heavily contaminated wounds are more likely to produce shorter incubation times, more severe disease and a worse outcome for the patient. Tetanus produces no immunity, so repeat infections with Clostridium tetani can and do occur.
Prevention
The best way to prevent infection with tetanus is through immunization. The use of the tetanus vaccine gives protection from tetanus for up to 10 years. The education of the public on the importance of completion of vaccination and the hazards of puncture wounds need to be emphasized. The need for vaccination may be required after receiving a wound, and your physician will make that determination.
References
- Todar's Online Textbook of Bacteriology: Clostridium tetani
- "Control of Communicable Diseases Manual"; David Heymann; 2008
