Tetanus and Botulism

Question 1

What is anaerobic bacteria?
Examples?

Answer 1

Require reduced oxygen tension for growth, failing to grow on the surface of solid media in 10% CO2 in air.
e.g. clostridium, bacteroides and peptostreptococcus

Question 2

What is microaerophilic bacteria?
Examples ?

Answer 2

Can grow in 10% CO2 or under anaerobic or aerobic conditions
e.g. Campylobacter jejuni - food poisoning

Question 3

What is facultative bacteria?
Examples?

Answer 3

Can grow in the presence or absence of air
e.g. salmonella typhi - typhoid fever

Question 4

Name the infections caused by different anaerobes?

Answer 4

1. bacteroides (anaerobe)
   - Intra abdominal
   - Pelvic
2. clostridium (anaerobe)
   - Tetanus
   - Gas gangrene
   - Food poisoning
3. Pepto streptococcus (anaerobe)
   - Oral
   - Genital tract (female)
4. Campylobacter jejuni (microaerophilic)
   - food poisoning
5. salmonella typhi (facultative)
   - typhoid fever

Question 5

What is botulism?

Answer 5

Severe sometimes fatal food poisoning caused by ingestion of toxin produced by Clostridium botulinum
- In infants, it may be caused by specific types of clostridia obtained from soil or inhaled spores, causing growth of the bacteria in the infant’s intestine

Question 6

3 types of botulism?

Answer 6

food-borne
wound
infant

Question 7

Botulism is characterized by what symptoms?

Answer 7

Characterized by nausea, vomiting, disturbed vision and paralysis

Question 8

What is botulinum toxin?
Function?

Answer 8

a neurotoxin that blocks the ability of motor nerves to release acetylcholine
- 8 C. botulinum toxin types known
= A, B, C(Cy, C2), D, E, F and G

Question 9

Botulinum toxin that affect man?

Answer 9

A, B, E and F

Question 10

Botulism toxin that affects animals?

Answer 10

C and D

Question 11

Describe paralysis caused by botulinum toxin?

Answer 11

All the toxins cause paralysis of different severity
- Paralysis starts with muscles of face spreading towards the limbs

Question 12

How does botulinum toxin work?

Answer 12

1. enters cells as vesicles
2. cleaves SNARE proteins
3. Inhibits the release of acetyl choline from the motor nerve ending leading to flaccid paralysis
4. Acetyl choline used to transfer signals from nerve cells to muscle cells and effective for muscle contraction
5. Toxin binds to axons near the neuromuscular regions
6. Patients die of respiratory failure if paralysis affect the chest muscle and the diaphragm

Question 13

Botulinum toxin is also believed to be produced by?

Answer 13

1. C. argentinense
2. C. butyricum
3. C. baratii

Question 14

Incubation period of food Bourne C. Botulinum?

Answer 14

18 to 36 hours of eating contaminated food, with extremes of four hours to eight days

Question 15

Symptoms of food Bourne botulism?

Answer 15

1. Blurred or double vision and difficulty swallowing and speaking
2. Gastrointestinal problems include constipation, nausea, and vomiting
3. In later stages the patient experiences weakness or paralysis, starting with the head muscles and progressing down the body
4. Breathing becomes increasingly difficult
5. Without medical care, respiratory failure and death are very likely

Question 16

How do infants get botulism?

Answer 16

Infants younger than 12 months are vulnerable to C. botulinum colonizing the intestine
1. Infants ingest spores in honey or simply by swallowing spore-containing dust or dirt
2. Spores germinate in the large intestine and once colonized, toxin is produced and absorbed into the infant’s body from the entire intestinal tract

Question 17

Symptoms of infant botulism?

Answer 17

1. constipation, lethargy, and poor feeding
2. Difficult in sucking and swallowing (thus eating)
3. Breast engorgement experienced by the nursing mother
4. Overall weakness and cannot control head movements
5. Because of the flaccid paralysis of the muscles, the baby appears floppy
6. Breathing is impaired, and death from respiratory failure is a very real danger

Question 18

Causes of wound botulism?

Answer 18

Cases linked to trauma such as
1. severe crush injuries to the extremities
2. surgery
3. illegal drug use
Occurs when Clostridia colonize an infected wound and produce botulinum toxin

Question 19

Symptoms of wound botulism?

Answer 19

1. are similar to food-borne botulism
2. Gastrointestinal symptoms may be absent
   - Symptoms usually appear four to 18 days after an injury occurs

Question 20

Neurological symptoms of botulism?

Answer 20

1. Descending paralysis
2. Peripheral flaccid muscle
3. paralysis that descends caudally
   - Typically begins in frequently used muscles
4. Pupils
   - accommodation paralysis
   - mydriasis
   - diplopia
5. Pharynx
   - dysarthria
   - dysphagia
6. Autonomic nervous system
   - xerostomia
7. Infants may present with
   - ptosis
   - floppy movements
   - general weakness
   - poor feeding (weak sucking)

Question 21

Gastrointestinal symptoms of botulism?

Answer 21

1. gastrointestinal discomfort
2. nausea, and vomiting
3. later followed by constipation
   - Only present in 30% of cases of foodborne botulism
   - Constipation is often the first symptom of infant botulism
   - Absent in wound botulism

Question 22

Laboratory diagnosis of botulism?

Answer 22

Rapidly identify botulinum toxin in samples from serum, vomit, gastric acid, stool, or suspicious foods

Question 23

Treatment of botulism?

Answer 23

1. antitoxin derived from horse serum
   - antitoxin (effective against toxin types A, B, and E) inactivates only the botulinum toxin that is unattached to nerve endings
2. human botulism immune globulin (BIG) is the preferred treatment in infants antitoxin can provide protection against A and B toxins for approximately four months
3. Respiratory support: a tracheostomy may be necessary
4. Gastric lavage

Question 24

What is tetanus?

Answer 24

Toxemia caused by a specific neurotoxin produced by Clostridium tetani in necrotic tissue

Question 25

What animals are susceptble to tetanus?

Answer 25

1. Almost all mammals are susceptible to this disease
   - Birds are quite resistant; the lethal dose for pigeons and chickens is 10,000-300,000 times greater (on a body wt basis) than that for horses
2. Horses are the most sensitive of all species

Question 26

Describe the causative agent of tetanus?
Where is it found?

Answer 26

• C tetani, an anaerobe with terminal, spherical spores
• is found in soil and intestinal tracts

Question 27

How is C. tetani introduced into the body?

Answer 27

Introduced into the tissues through wounds, particularly deep puncture wounds, that provide a suitable anaerobic environment
Note: Sometimes, the point of entry cannot be found because the wound itself may be minor or healed

Question 28

Describe suitable conditions for C. tetani to flourish?

Answer 28

• The spores of C tetani are unable to grow in normal tissue or even in wounds if the tissue remains at the oxidation-reduction potential of the circulating blood
• Suitable conditions for multiplication occur when a small amount of soil or a foreign object causes tissue necrosis.

Question 29

Describe the release of tetanus toxin?

Answer 29

1. The bacteria remain localized in the necrotic tissue at the original site of infection and multiply
2. As bacterial cells undergo autolysis, the potent neurotoxin is released

Question 30

What is the tetanus toxin?
Describe its entry?
Components?

Answer 30

• Synthesized by C. tetani growing on either deep contaminated wounds or wounds containing foreign objects
• The neurotoxin is a zinc-binding protease that cleaves synaptobrevin, a vesicle-associated membrane protein
• Toxin coded on a plasmid
• Has 2 components (tetanospasmin and tetanolysin)
• When produced the toxin is inactive: Activity induced by proteolytic enzymes

Question 31

What is ascending tetanus?

Answer 31

Toxin absorbed by the motor nerves in the area of entry and passes up the nerve tract to the spinal cord

Question 32

What is descending tetanus?

Answer 32

If more toxin is released at the site of the infection than the surrounding nerves can take up, the excess is carried off by the lymph to the bloodstream and thus to the CNS where it causes descending tetanus

Question 33

Consequences of tetanus toxin?

Answer 33

1. The toxin causes spasmodic, tonic contractions of the voluntary muscles by interfering with the release of neurotransmitters from presynaptic nerve endings
2. The spasms may be so severe as to cause bone fractures
3. Spasms affecting the larynx, diaphragm, and intercostal muscles lead to respiratory failure
4. Involvement of the autonomic nervous system results in cardiac arrhythmias, tachycardia, and hypertension

Question 34

What happens when the tetanus toxin reaches the brain?

Answer 34

Toxin reaching the brain inhibits synthesis of glycine
- This result in contractions of antagonistic muscles
- The contractions can be severe to break the muscles or bones
- Uncontrolled contractions can affect the respiratory system

Question 35

Incubation period of tetanus?

Answer 35

varies from one to several weeks but usually averages 10-14 days

Question 36

Tetanus clinical presentation?

Answer 36

1. Localized stiffness, often involving the masseter muscles and muscles of the neck, the lower limbs, and the region of the infected wound;
2. General stiffness becomes pronounced ~1 day later, and tonic spasms and hyperesthesia become evident
3. Reflexes increase in intensity, and the patient is easily excited into more violent, general spasms by sudden movement or noise
4. Spasms of head muscles cause difficulty in apprehension and mastication of food, hence the common name, lockjaw
5. Spasms of the neck and back muscles cause extension of the head and neck
6. Sweating is common

Question 37

Tetanus treatment and prevention?

Answer 37

1. Any wound that results in a break in the skin should be cleaned with soap and running water
2. Antibiotics to kill the bacteria, tetanus booster shot, if necessary, and occasionally, antitoxin to neutralize the toxin
3. supportive measures
4. sedatives such as diazepam (Valium) to control muscle spasms
5. IV rehydration because, as muscles spasm constantly, increased metabolic demands are placed on the body
6. Tetanus vaccine given in infancy and booster vaccine to at risk population