Case Study: Tetanus
Background Information: Tetanus is an infection that usually occurs when the anaerobic bacterium Clostridium tetani enters the body through a contaminated wound. When these bacteria lyse, they release tetanus neurotoxin (TeNT). TeNT enters peripheral nerve endings via endocytosis and is transported back through the axons until it reaches the spinal cord or brainstem. The toxin exits the peripheral nerve and enters inhibitory neurons inside the central nervous system. Once inside the inhibitory neuron, TeNT prevents the release of gamma-aminobutyric acid (GABA) and glycine.
Symptoms of tetanus include jaw stiffness, difficulty swallowing, and muscle spasms (i.e., rapid, uncontrollable muscle contractions). In advanced cases, spasms may be severe enough to fracture bones. In the United States since 1947, reported tetanus cases have declined by more than 95%, and deaths resulting from tetanus have declined by more than 99%. This reduction is directly attributable to widespread immunization.
Case Report: JG is a 38-year-old man presenting to the urgent care clinic with a complaint of jaw discomfort and inability to open his mouth fully for three days. He states that he hit his right shin with the claw end of a hammer 10 days ago while working at a construction site. The hammer had penetrated deep through the skin and although the wound hurt and bled, he had not sought medical attention.
JG has no history of medical or surgical procedures, has no known allergies, and is not currently taking any medications. He received his primary tetanus series in childhood, but his last booster was more than ten years ago. JG's vital signs on admission are presented below:
MC Normal Range
Blood pressure 125/70 mmHg 90/60 to 120/80 mmHg
Heart rate 88 bpm 60 to 100 bpm
Respiratory rate 16 breaths/min 12 to 18 breaths/min
Temperature 98.5°F 96.3°F t0 99.3°
Q1. Why does the inability to release glycine and/or GABA in the central nervous system lead to muscle spasms? Does this explain JG's symptoms?
Q2. Predict the most common cause of death in tetanus patients and justify your prediction based on how the disease affects skeletal muscles.
Q3. Botulinum toxin is a potent neurotoxin produced by the bacterium Clostridium botulinum. This toxin inhibits the release of acetylcholine, the neurotransmitter used by somatic motor neurons to trigger muscle contractions. How would the symptoms of a patient with botulism differ from the symptoms experienced by a patient with tetanus?