HIV (AIDS) & Salmonella

Did you know that Microorganisms use us for food, shelter and their reproduction?

• Bacteria may cause infectious diseases. Not all bacteria do this as many are in our gut. We have a huge number of bacteria as well as fungi and protists as our gut flora helping us to digest our food and keep the gut healthy.
• Bacteria are Prokaryotes; they do not have a nucleus but a loose chromosome in the cell cytoplasm. Bacteria also have a cell wall and this is the structure that many antibiotics attack.
• You need to know: the structure of a prokaryotic cell, and the functions of its organelles but focus specifically on the cell wall.

How do bacteria harm their host?

• Microorganisms can cause disease by damaging the cells of the host and by producing toxins. It’s the toxins that make us feel ill.
• You need to understand how the Salmonella species can grow on our food e.g. chicken is a classic example as well as eggs. They grow at a rapid rate and it’s when there are many millions of bacterial cells, the body cannot fight all of them. There is not enough stomach acid to destroy them and so, they pass into the gut and multiply.

Poor food hygiene practices are the cause of allowing the Salmonella bacterium to multiply. This includes incorrect cooking of foods and, unhygienic practices such as lack of proper hand-washing.

Placing uncooked chicken next to cooked foods that will not be heated through properly is also a culprit in this food-related illness. Uncooked meat juices drip on to the cooked or ready prepared food. This gives the bacterial cells a good food source and they can then multiply. People consume the cooked food and the bacteria as well.

What are the symptoms of Salmonella food poisoning?

• Sickness, diarrhoea and a generally miserable feeling accompany the symptoms of this illness.

How can Salmonella food poisoning be controlled?

Refer to the paragraph above for some ideas!

Did you know that most bacteria will give off an odour when they are numerous?

Salmonella certainly does and that can be an indication that all is not well with a food item.

Viruses

Viruses cause disease as we know. A virus can only become active when inside a host. They need the host’s DNA and cell processes to replicate.

• You should be familiar with the structure of the human immunodeficiency virus (HIV) and its replication.
• You should be able to explain (i.e., you need to be able to say why): explain the development of the symptoms of AIDS; how HIV is spread and how it may be controlled; and, why antibiotics are ineffective against viruses. HINT: A virus does not have a cell wall and needs the hosts cell to replicate

A summary of what to do with this learning:

• You should be able to evaluate evidence for links between the use of antibiotics and the development of MRSA (Methicillin-Resistant Staphylococcus aureus). and other antibiotic resistant bacteria.
• S aureus is also known as Golden Staph. A colony of these bacteria when grown on nutrient agar appear golden coloured.
• There is loads of information on the internet about S. aureus.
• Methicillin is a form of penicillin-related antibiotic.
• This is a simplistic web link for MRSA http://www.mrsa.uk.com/index.htm
• This is a web link to the Microbiology Society & a special article: http://www.sgm.ac.uk/pubs/micro_today/pdf/020803.pdf