Question

You are an EMT and are called to the home of Kevin, a 13 week old boy who has become listless and is having trouble breathing. The parents reported that Kevin used to smile, but lately he has not smiled, nor has he had other noticeable facial expressions in the last two days. Kevin’s eyes are open when you arrive, but he does not seem to be focusing. You place your outstretched finger under his fingers and he fails to grasp it. You lift his foot and it drops back to the mattress. The parents report that he has not had a bowel movement in three to four days.

1. What is your diagnosis (disease name and causative agent), based on Kevin’s symptoms and why? (5 pts)
2. If this is indeed the case, do you start treatment here at Kevin’s home, or should you transport him to the local hospital? Why? (2 pts)
3. What should be administered to Kevin at the earliest opportunity and why? (2 pts)
4. How do babies acquire this condition? (2 pts)
5. Although the diagnosis should be confirmed with laboratory tests, the tests should probably not be performed in the local hospital lab. Why not? (2 pts)
6. What virulence factor is solely responsible for the symptoms Kevin is experiencing? Explain in specific detail the mechanism of action of this virulence factor. (4 pts)
7. What is a related virulence factor, made by a related organism, which causes the exact opposite symptoms? Explain in specific detail the mechanism of action of this virulence factor and explain how it causes the opposite symptoms. Name the disease caused by this factor and the organism that makes this virulence factor. (5 pts

Answer 1

ANSWER 1

This is a case of Infant Botulism.

Symptoms of the baby which supports the diagnosis are-

• Listless indicating generalised paralysis
• Troubled breathing indicating respiratory insufficiency
• No facial expressions
• No bowel movement indicative of constipation
• Hypotonia of limbs
• Non focussing eyes - indicative of blurred vision or double vision and ptosis

Infant botulism is an intestinal toxemia caused by botulinum neurotoxin.

The disease results after colonisation of spores of the bacterium in  infant’s large intestine, and production of botulinum neurotoxin.
Neurotoxin binds to cholinergic nerve terminals and hinders acetylcholine release, resulting in bulbar palsy, hypotonia, and a symmetric, descending, flaccid paralysis.

The causative agent is Clostridium botulinum

The characteristics of bacteria are

• Gram-positive
• rod-shaped
• anaerobic
• spore-forming,
• motile bacterium with the ability to produce the neurotoxin botulinum.

ANSWER 2

A baby with botulism should be treated in the hospital as it is a medical emergency.

The Case is managed in hospital ICU to ensure assistance with breathing by providing ventilatory support  and proper antitoxin administration as well as iv fluids which are not possible at home.

ANSWER 3

Treatment is urgent administration of antitoxin called botulism immunoglobulin intravenously (BIGIV).

Early administration of antitoxin improves recovery rate and survival chances as the disease is extremely fatal.

A ventilator to assist the baby’s breathing might also be  required.

Intravenous (IV) fluids if the baby has difficulty in feeding.

ANSWER 4.

Babies acquire Infant botulism by ingesting C. botulinum spores which are present in the soil and occasionally on unwashed products.

The most common identifiable way of ingrsting spores  is by ingesting honey.

ANSWER 5

The test should not be performed in local hospital lab because the toxin is lethal and to dangerous to handle as it's a potent neurotoxin.

ANSWER 6

Botulinum toxin , a neurotoxin, acts by blocking nerve function and leads to respiratory and musculoskeletal paralysis.
The toxin acts by blocking the production or release of acetylcholine at synapses and neuromuscular junctions.

Death occurs due to respiratory failure

Symptoms include double vision, blurred vision, drooping eyelids, slurred speech difficulty in swallowing, dry mouth and muscular weakness.

ANSWER 7

Related organism which produces just opposite effects is Clostridium tetani

While botulism is characterized by a descendant flaccid paralysis, tetanus consists in spastic paralysis.
MECHANISM OF ACTION OF TETANUS TOXIN

Tetanus neurotoxin binds to the presynaptic membrane of the neuromuscular junction and block neurotransmitter release from spinal inhibitory interneurons.

This leads to spastic paralysis .