Clostridium Flashcards
What is botulism?
A rare and potentially fatal paralytic illness
Caused by the botulinum toxin produced by the bacteria Clostridium botulinum
What bacteria causes botulism?
Clostridium botulinum
Produces botulinum toxin
What are the types of botulism?
Foodborne botulism - ingestion of food containing botulinum toxin
Wound botulism - spores enter body via wound
Infant botulism - bacteria develop in infant intestine and releases toxin into intestine
What group of people are most commonly affected by wound botulism?
People who inject street drugs
How long does it take for symptoms of botulism to appear after ingestion of toxin?
Symptoms usually appear between 18-36 hours after ingestion of toxin
However this can range from a few hours to several days, depending on the amount of toxin consumed
What is the ultimate effect of botulinum toxin?
Prevent release of acetylcholine at the neuromuscular junction, resulting in flaccid paralysis
What is infant botulism, what age does it affect and why?
Infant botulism - spores develop in the infant intestine and release botulinum toxin
Affects children under 6 months of age. After this age protective immune system mechanisms have developed which prevent damage
What is the mortality rate for botulism?
5-10%
What is the usual first symptom of infant botulism?
Constipation
How can Clostridium botulinum be classified?
C. botulinum can be divided into four phenotypically distinct groups, denoted I-IV
Can also be classified into 7 serotypes, denoted A-G, based on the toxin it produces. There are 7 different antigenically and serologically different botulinum toxins
How many botulinum toxins are there?
There are 7 serologically and antigenically different botulinum toxins, denoted A-G
In 2013 it was revealed an 8th toxin, H, had been discovered. Little information has been released since this announcement
What is the eighth botulinum toxin and why is little known about it?
In October 2013, it was revealed an 8th botulinum toxin had been discovered. This was the first new botulinum toxin to be discovered in 40 years
Further information has not been released due to fears the toxin could be abused as a bioweapon and due to lack of a known antitoxin
What are the proteolytic and non-proteolytic botulinum toxins?
Types A, and some of B & F are proteolytic
Types E, and some of B, C, D & F are non-proteolytic
Why do non-proteolytic botulinum toxins often go undiscovered?
Proteolytic botulinum toxins (A and some of B & F) produce a putrefactive smell and digest meat
Non-proteolytic botulinum toxins (E and some of B, C, D, & F) do not produce a smell so go undiscovered if they are in your food
Which botulinum toxin types affect humans?
Humans: A, B, E, and (rarely) F. Type F is associated with contaminated fish
Animals: C & D
None: G
Why is it recommended not to give honey to children under 1 year old?
It is hard to treat this food for botulism (heat to 85C for more than 5 minutes)
Children under 1 year (particularly < 6 months) are more at risk for infant botulism because they lack proper protective mechanisms
How can heat be used to destroy botulism toxin?
Toxin can be easily destroyed by heating food to 85C for more than 5 minutes
What type of bacteria is Clostridium botulinum?
Large, Gram positive, rod-shaped (bacilli), motile, obligate anaerobe (oxygen is poisonous to cell) that forms spores
When do bacteria form spores and where are C. botulinum spores found?
Spores are formed when bacteria are under stress
C. botulinum spores are found in the soil and in silt (sediment of streams/lakes/coastal waters). Spores can live for many years
When does Clostridium botulinum produce botulinum toxin?
Toxin is produced in favourable conditions: warm temperature, moisture, protein source, anaerobic environment. Spores become active and produce toxin
Spores can produce toxin but conditions needed for this (anaerobic, low-salt, -sugar, -acid environment at ambient temperatures) are rarely obtained. This means botulism is uncommon
How many toxin types do C. botulinum normally produce?
Usually, bacteria only produce one toxin type
However bacteria that produce multiple have been reported. These are donated like: Bf, where type B toxin was found in excess of type F
What are the symptoms of botulism?
Flaccid paralysis
Blurred/double vision Ptosis (drooping eyelid) Nausea, vomiting, diarrhoea and/or constipation Cramps Respiratory difficulty
What is the usual direction of spread of paralysis in botulism cases?
Paralysis typically starts in the facial muscles and then spreads to the limbs.
In severe forms, paralysis reaches respiratory muscles which results in respiratory failure and death.
