Clostridium

Question 1

What environment do clostridia thrive in?

What environmental conditinons are unfavourable?

Answer 1

Clostridia thrive in deep compact soil and when they feel the stress of fresh oxygenated air they produce spores which are metabolically inert and extremely resilient to the environment

Question 2

What could are clostridia when Gram stained?

Answer 2

Purple

Question 3

What toxin is produced by clostridium Botulinum?

Answer 3

Botulinum Toxin→Botulism

Question 4

What effect does Botulinum Toxin have upon ingesting a food product contaminated with it?

Answer 4

1. Botulinum toxin binds to nerves and inhibits muscle contraction
2. There are 8 distinct types of the toxin (names A-H) and they vary in the toxicity
3. The neurone takes in the Botulinum toxin by endocytosis and creates a vesicle within the neurones cytoplasm
4. The toxin excapes the vesicle and cleaves SNARE proteins whose function are to promote fusion of vesicles containing acetylcholine to the plasma membrane where they get released into the synapse totransmit a signal to the muscle
5. Without SNARE proteins, acetylcholine is not released so no signal is sent out by the affected nerves
6. Resulting in complete muscle relaxation and flaccid paralysis

Question 5

What muscles are affected by Botulinum toxin?

Answer 5

• The muscles controlled by the 12th cranial nerve: muscles that control the face, eye movements chewing and swallowing
• Nerves of the autonomic nervous system that rely on acetylcholine are also affected

Question 6

TRUE or FALSE: Botulism can cause Bulbar Palsay

Answer 6

TRUE

• This is the impairment of cranial nerves 9, 10, 11 and 12
• Over time there may be a descending paralysis

Question 7

What do symptoms of Botulism include?

Answer 7

• Double vision
• Drooping eyelids
• Inability to make facial expressions
• Difficulty swallowing
• Dry mouth
• Postural hypotension
• Nausea
• Vomiting
• Constipation

These symptoms can progress to complete flaccid paralysis which can be fatal if it affects the respiratory muscles

Question 8

Describe the diagnosis of Botulinum

Answer 8

• Dianosis is largely by serum analysis for Botulinum Toxin.
• This involves growing Clostridum Botulinum in culture but is rarely successful.
• This is because anaeorbes are difficult to grow in a lab setting.

Question 9

What is the treatment for Botulism?

Answer 9

• Assitance with breathing
• Passive immunization with an antitoxins that catch free toxin molecule in the bloodstream before they can damage the neuronal proteins
• Two types of antitoxins exist:

Trivalent (Covers toxins A,B and E)

Heptavalent (Covers toxins A,B,C,D,E,F,G)

Question 10

What is the most common form of food related botulism?

Answer 10

Infant Botulism (floppy baby syndrome)

• Newborns and infants have poorly developed gut flora therefore their gut is vulnerable to colonization by Clostridium Botulinum
• These bacteria will continue to produce their toxin directly in the intestine → causing botulism

Question 11

Why should honey be avoided by children under 12 months?

Answer 11

Honey has been identified as a potential for Clostridium Botulinum spores

Spores are also found in poorly preserved (tinned) food products

Question 12

Which two types of Botulinum toxins are less toxic?

Answer 12

A and B

• They can induce long lasting neuromuscular junction block
• They are sometimes diluted and injected in rigid muscle to relax it

Question 13

Name some diseases that are improved by Botulism Toxin?

Answer 13

• Hyperhydrosis (excessive sweating)
• Achalasia (a disorder of the gullet (oesophagus) where it loses the ability to move food along). The valve at the end of the gullet also fails to open
• Focal dystonia (involuntary muscle spasms)

Question 14

What is the aesthetic use of Botulism Toxin?

Answer 14

Botox

Helps smoothen out wrinkles

Question 15

Explan the mode of action of tetanospasmin produced by Clostridium Tetani

Answer 15

1. Tetnospamin works by entering inhibitory neurones (Renshaw cells)
2. Once inside, tetanospasmin cleaves SNARE proteins that function to fuse neurotransmitter containing vesicles with the plasma membrane
3. Cleavage of the SNARE proteins prevents the release of inhibitory neurotransmitters such as glycine and GABA
4. The alpha motor neurone countinuously sends the signal for contraction to the muscle
5. This causes muscle rigidity and spasm

Question 16

How do spores of Clostridum Tetani often introduced into the body?

Answer 16

Through penetrating trauma (e.g.puncture wounds)

Puncture wounds are usually anaerobic and warm therefore provide optimal conditons for growth of C.Tetani

Question 17

Desccribe the spasms caused by Tetanus

Answer 17

• Sudden
• Powerful
• Long lasting
• Painful (can result in muscle tears of one fractures)

Question 18

What is the classical Tetanic triad of symptoms?

Answer 18

1. Trismus (lockjaw- mild→severe spasms of he lower jae)
2. Risus Sardonicus“sardinian grin” (abnormal looking sustained grin caused by facial muscle spasm)
3. Opisthotonus which is th severe spasm of all muscles in the body simultaneously resulting on a high arched back

Question 19

TRUE or FALSE:

Tetanus affects skeletal, smooth and cadiac muscle function

Answer 19

FALSE

Tetanus only affects skeletal muscle therefore smooth and cardiac muscle continue to functin normally

Question 20

What are the symptoms of tetanus?

Answer 20

Many f these symptoms arive from sympathetic activity

• Drooling
• Excessing sweating
• Fever
• Difficulty swallowing
• Breathing problems
• Irregular urination and defacation

Question 21

What are rare forms of tetanus?

Answer 21

Local tetanus

• The persistant spam is located around the area of the injury
• This consistant persists for a few months but will gradually subside with <1%

Cephalic tetanus

• This is limited to muscles supplied by cranial nerves
• This can occur in the case of head trauma such as skull fractures, eye injuries, middle ear infections and even tooth extractions
• This type is more likely than others to cause death

Question 22

When does neonatal tetanus occur?

Answer 22

• In newborns with mothers that have not been immunised from tetanus.
• This occurs when the umbillical cord is cut by non-sterile instruments then the newborn can develop highly lethal neonatal tetanus
• Newborns with immunised mothers are protected via passive immunity

Question 23

How is tetanus diagnosed?

Answer 23

Based on clinical appearance→the spatula test

This involves touching the posteria pharyngeal wall with a wooden spatula and observing the effect

• A postive test results in involuntary contraction of the jaw and biting down hard on the spatula due to the lower threshold for muscle spasms in patients with tetanus
• A negative test result would be a normal gag reflex

Tetanus toxin can also be found in the serum using a bioassay

Question 24

How is tetanus treated?

Answer 24

• Tetanus is usually treatment in teatanus immune globulin (TIG) which is an antitoxin that binds to tetanospamin
• Muscle relaxants
• Pain medication
• Supportive care measures are taken while the immune system clears the infection

Full recovery can take a few months of intensive care as the body’s neurones slowly heal

Question 25

How can tetanus infection be prevented?

Answer 25

By the tetanus toxoid vaccine to generate active immunity

Tetanus vaccines in children adolescents are given in the form of a triple vaccine which covers Dipetheria, tetanus, and pertussis in a single vaccine