Faeces
Faeces is a big problem with relation to disease, but why?
The digestion of food goes through several stages. Food is chewed and is broken
down and absorbed during the transport from mouth to anus. Most of the food’s
nutrients are absorbed in the small intestine. The large intestine holds mainly waste
material. It is also home to over 1 kg of bacteria. These bacteria are called
commensal bacteria, which are symbiotic. They break down the last remnants of the
food before discharge as faeces. Without these bacteria in our colon we would not
be able to digest food. This is why taking antibiotics indiscriminately leads to
digestive problems because they kill the good bacteria as well as any infectious
bacteria.
E coli are commensal bacteria. It is only when faeces enters the atmosphere that
pathogenic bacteria are born. They mutate with atmospheric bacteria, viruses and
other particles, resulting in disease-causing bacteria. So E. coli start as good
bacteria but mutate into several deadly variants, called serotypes. E. coli releases
toxin into the bloodstream which causes haemolytic uraemic syndrome (HUS) and
eventual renal failure.
It has been suggested that all organisms on this planet, from viruses to the largest
mammals, follow the route as first demonstrated by Charles Darwin. Natural
selection or survival of the fittest can be observed in all species. Bacteria mainly live
with us as good organisms rather than pathogens. It is thought that bacteria become
pathogens as a way of survival, perhaps due to environmental or human changes.
Raw meat harbours pathogens due to the insanitary conditions in abattoirs, where
there are splashes and spillages of faeces and intestinal fluids onto clean meat. All
meat that is bought must be considered as infected and treated accordingly. This
treatment refers to the way the meat is handled and to the final cooking temperature.
Cooking to a high enough temperature will kill the pathogens that are on the infected
meat.
Untreated water such as rivers, streams, lakes, canals and the sea all contain
pathogenic bacteria. Apart from pathogenic bacteria there will be protoctists, viruses
and fungal spores present. Do not be tempted to drink untreated water whilst out
walking or camping. The contamination comes from contact with the environment
such as soil and air. Faeces from birds, invertebrates, vertebrates and other
organisms decaying in the water cause it to be affected. If you are tempted to drink
the natural water supply you must ensure you treat it first. This can include such
processes as boiling, using chlorine tablets or iodine drops. The water from a cold,
running mains supply is safe to drink as it has been chlorinated, a process which kills
bacteria.
Be careful with soil contamination. All soil contains pathogenic bacteria and therefore
care must be taken when using raw vegetables. They must be washed well, peeled
and washed again before using as a raw product. If the vegetables are to be cooked,
bacteria will be destroyed.
Not all bacteria are harmful; in fact the majority are harmless. We also need bacteria
and other microorganisms for survival on this planet. We use bacteria in
biotechnology, we use them in food, we have them in our colon and we use them in
the manufacture of vaccines and drugs. Some bacteria are used in the manufacture
of artificial fuel.
There are three different types of bacteria, the good, bad, and the ugly! The good
ones we need, the bad ones cause illness and the ugly ones are the spoilage
bacteria which cause food or drink to perish all rot.
Food Poisoning Bacteria
Some examples of food poisoning bacteria include:
- Salmonella, which was discovered in the 19th century by a scientist
named Daniel Salmon. Salmonella spp come in over 2,500 different
strains known as serotypes or species (spp). Many of the serotypes are
named after where they were discovered. Salmonella Montevideo caused
food poisoning with a major chocolate manufacturer in the UK.
Salmonella
- Two types of Clostridia are known to cause food poisoning. Namely
Clostridium perfringens and Clostridium botulinum. C botulinum is
responsible for producing the world’s most virulent toxin, known as Botox.
1g of Botox can kill up to 100,000 people. There were experiments carried
out during the Second World War by the British in Porton Down, Salisbury,
to use Botox as a biological weapon. It was never, however, used. Botox
can cause death in young infants. This is called infant botulism. If infants
under three months old ingest C botulinum spores they can die. C
botulinum spores can be found in many natural foods such as honey. That
is why it is important not to feed any to children less than three months,
although honey labels state not to feed to children less than 12 months, for
further safety. During the manufacture of honey, bees’ inadvertently pickup
C botulinum spores from hedgerows, soil and plants and contaminate the
honey.
Bacillus cereus is well known from causing rice poisoning. Cooked rice
from a takeaway or rice prepared incorrectly can lead to B cereus
poisoning.
Staphylococcus aureus and other bacteria start off as commensals.
Humans are caked in these bacteria from head to toe. They act as
protective bacteria. As these bacteria grow they release chemicals which
prevent infection from other pathogens. They are, however, opportunistic
and can cause infection through a small cut. If we cough or sneeze over
food; or over handle food without washing hands, then we can
contaminate food with our bacteria. The bacteria will grow in the food and
release toxins, which will poison the consumer.
Other bacteria which cause foodborne disease include: E. coli, Listeria and
Campylobacter.
In the UK in the late 1990s a voluntary system was introduced for egg
producers to vaccinate their flocks of chickens. This allowed them to put
lion stamps on their eggs. Salmonella has almost been eradicated from
poultry and eggs. The main problem with poultry tends to be
Campylobacter contamination, which is the biggest cause of diarrhoea in
the UK. Eggs without lion stamps should be avoided as they could be
infected with Salmonella enteridis. (Infected eggs very rarely cause illness
if eaten as a cooked product. The bacteria are only present in the white of
the egg. Providing the eggs are cooked sufficiently to congeal the white
then they are safe to eat. The bacteria will not penetrate the membrane
surrounding the yoke. The problem is products made from raw egg which
are allowed to remain at ambient temperature for example, tiramisu,
mayonnaise, and mousses can cause food poisoning. By whisking the
eggs the bacteria in the white of the egg are allowed to come into contact
with the yoke, which is a good food supply for the bacteria.)