Tetanus and Botulism Flashcards
What is anaerobic bacteria?
Examples?
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
What is microaerophilic bacteria?
Examples ?
Can grow in 10% CO2 or under anaerobic or aerobic conditions
e.g. Campylobacter jejuni - food poisoning
What is facultative bacteria?
Examples?
Can grow in the presence or absence of air
e.g. salmonella typhi - typhoid fever
Name the infections caused by different anaerobes?
- bacteroides (anaerobe)
- Intra abdominal
- Pelvic - clostridium (anaerobe)
- Tetanus
- Gas gangrene
- Food poisoning - Pepto streptococcus (anaerobe)
- Oral
- Genital tract (female) - Campylobacter jejuni (microaerophilic)
- food poisoning - salmonella typhi (facultative)
- typhoid fever
What is botulism?
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
3 types of botulism?
food-borne
wound
infant
Botulism is characterized by what symptoms?
Characterized by nausea, vomiting, disturbed vision and paralysis
What is botulinum toxin?
Function?
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
Botulinum toxin that affect man?
A, B, E and F
Botulism toxin that affects animals?
C and D
Describe paralysis caused by botulinum toxin?
All the toxins cause paralysis of different severity
- Paralysis starts with muscles of face spreading towards the limbs
How does botulinum toxin work?
- enters cells as vesicles
- cleaves SNARE proteins
- Inhibits the release of acetyl choline from the motor nerve ending leading to flaccid paralysis
- Acetyl choline used to transfer signals from nerve cells to muscle cells and effective for muscle contraction
- Toxin binds to axons near the neuromuscular regions
- Patients die of respiratory failure if paralysis affect the chest muscle and the diaphragm
Botulinum toxin is also believed to be produced by?
- C. argentinense
- C. butyricum
- C. baratii
Incubation period of food Bourne C. Botulinum?
18 to 36 hours of eating contaminated food, with extremes of four hours to eight days
Symptoms of food Bourne botulism?
- Blurred or double vision and difficulty swallowing and speaking
- Gastrointestinal problems include constipation, nausea, and vomiting
- In later stages the patient experiences weakness or paralysis, starting with the head muscles and progressing down the body
- Breathing becomes increasingly difficult
- Without medical care, respiratory failure and death are very likely
How do infants get botulism?
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
Symptoms of infant botulism?
- constipation, lethargy, and poor feeding
- Difficult in sucking and swallowing (thus eating)
- Breast engorgement experienced by the nursing mother
- Overall weakness and cannot control head movements
- Because of the flaccid paralysis of the muscles, the baby appears floppy
- Breathing is impaired, and death from respiratory failure is a very real danger
Causes of wound botulism?
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
Symptoms of wound botulism?
- are similar to food-borne botulism
- Gastrointestinal symptoms may be absent
- Symptoms usually appear four to 18 days after an injury occurs
Neurological symptoms of botulism?
- Descending paralysis
- Peripheral flaccid muscle
- paralysis that descends caudally
- Typically begins in frequently used muscles - Pupils
- accommodation paralysis
- mydriasis
- diplopia - Pharynx
- dysarthria
- dysphagia - Autonomic nervous system
- xerostomia - Infants may present with
- ptosis
- floppy movements
- general weakness
- poor feeding (weak sucking)
Gastrointestinal symptoms of botulism?
- gastrointestinal discomfort
- nausea, and vomiting
- 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
Laboratory diagnosis of botulism?
Rapidly identify botulinum toxin in samples from serum, vomit, gastric acid, stool, or suspicious foods
Treatment of botulism?
- 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 - human botulism immune globulin (BIG) is the preferred treatment in infants antitoxin can provide protection against A and B toxins for approximately four months
- Respiratory support: a tracheostomy may be necessary
- Gastric lavage
What is tetanus?
Toxemia caused by a specific neurotoxin produced by Clostridium tetani in necrotic tissue
What animals are susceptble to tetanus?
- 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 - Horses are the most sensitive of all species
Describe the causative agent of tetanus?
Where is it found?
- C tetani, an anaerobe with terminal, spherical spores
- is found in soil and intestinal tracts
How is C. tetani introduced into the body?
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
Describe suitable conditions for C. tetani to flourish?
- 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.
Describe the release of tetanus toxin?
- The bacteria remain localized in the necrotic tissue at the original site of infection and multiply
- As bacterial cells undergo autolysis, the potent neurotoxin is released
What is the tetanus toxin?
Describe its entry?
Components?
- 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
What is ascending tetanus?
Toxin absorbed by the motor nerves in the area of entry and passes up the nerve tract to the spinal cord
What is descending tetanus?
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
Consequences of tetanus toxin?
- The toxin causes spasmodic, tonic contractions of the voluntary muscles by interfering with the release of neurotransmitters from presynaptic nerve endings
- The spasms may be so severe as to cause bone fractures
- Spasms affecting the larynx, diaphragm, and intercostal muscles lead to respiratory failure
- Involvement of the autonomic nervous system results in cardiac arrhythmias, tachycardia, and hypertension
What happens when the tetanus toxin reaches the brain?
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
Incubation period of tetanus?
varies from one to several weeks but usually averages 10-14 days
Tetanus clinical presentation?
- Localized stiffness, often involving the masseter muscles and muscles of the neck, the lower limbs, and the region of the infected wound;
- General stiffness becomes pronounced ~1 day later, and tonic spasms and hyperesthesia become evident
- Reflexes increase in intensity, and the patient is easily excited into more violent, general spasms by sudden movement or noise
- Spasms of head muscles cause difficulty in apprehension and mastication of food, hence the common name, lockjaw
- Spasms of the neck and back muscles cause extension of the head and neck
- Sweating is common
Tetanus treatment and prevention?
- Any wound that results in a break in the skin should be cleaned with soap and running water
- Antibiotics to kill the bacteria, tetanus booster shot, if necessary, and occasionally, antitoxin to neutralize the toxin
- supportive measures
- sedatives such as diazepam (Valium) to control muscle spasms
- IV rehydration because, as muscles spasm constantly, increased metabolic demands are placed on the body
- Tetanus vaccine given in infancy and booster vaccine to at risk population
