h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Hi Lemony.You said you were biomedical scientist.Does this mean that you work on DNA and if it is so which is your latest discovery you have done.

Hi arsenal,

I am a biomedical scientist and I work in a microbiology lab. We don't do any research work in our lab as it is a busy, routine NHS lab for testing patient specimens. We do perform tests which look for specific genes such as the mecA gene in MRSA, but we don't actually research into new genetic codes.

What do you do?

Lemony

I em sure that your job is very interesting.But are you exposed to any danger,because i think working on such a object might bring you quite an unpleasant suprise.

Hiya,

The only dangers we come across really are from aerosols, which are bacteria in the air, when you take the lid off a liquid sample, and also sharps injuries from using syringes.

The only time aerosols would be a problem is when handling the bacteria that cause TB, meningitis and certain types of food poisoning, in particular Mycobacterium tuberculosis, Neisseria meningitidis, and Eschericia coli O157.

For these types of bacteria we use a safety cabinet which is in a room under negative pressure, where the air flows away from the worker into the cabinet and up through a filter.

Obviously a lot of it is common sense. We handle a lot of blood samples, so we take the usual precautions anyone would use when handling blood.

Were you referring to the dangers of MRSA?
There is almost no danger at all with handling actual cultures of bacteria. MRSA is one of the safest ones to be honest. You can pick up some of the food poisoning bugs such as Salmonella and shigella from the cultures but you would be really unlucky!

I hope this has answered your question. If not, ask away and I will be only too happy to reply.

Lemony

Hi Lemony.I em glad that you take all precautionary measures needed for your protection and that you would like to answer all my questions.You mentioned of mecA gene in MRSA.Does it mean that you have already identified this gene or some others which you think are related to MRSA?I em asking you this because if MRSA is mainly created by overuse of antibiotics(assertion which I personally think is not quite correct)you have to concentrate your search more in area different from this one of genetics.Because here I want to remind something important-genetics is study in biology of how the characteristics of living things are passed through the GENES=(specific chemical patterns)from parents to children.Here i want to come back for a while ,if MRSA is created by antibiotic usage which MEANS its not INHERITED disorder,you have to look for other reason which make MRSA appear and exist.

Happy Saturday Arsenal

Right then, where do I begin.....

The only difference between a normal Staphylococcus aureus and an MRSA (Multi Resistant Staphylococcus Aureus) is the antibiotics that can be used to treat it. As the name suggests Multi Resistant means that it is resistant to many of the usual antibiotics that are used to treat infections, including Methicillin (which the 'M' also stands for)

On the surface of the bacteria are proteins which the antibiotics have to bind to in order for them to work. An alteration or mutation in this protein caused by a change in the genetic code can result in the antibiotic becoming ineffective in killing the bacteria.

This is where the mecA gene comes in.
The usual antibiotic for treating staphs which are resistant to penicillin is Flucloxacillin (methicillin), which binds to a protein called penicillin binding protein 2 (PBP2). The altered version of this protein is known as PBP2' and the gene which is resposible for creating this protein is the mecA gene which was discovered a few years ago now.

In thinking about the genetics behind this, please don't think that it is inherited through families. We have to concentrate on the genetics of the bacteria - our genetic make up has nothing to do with it.

When bacteria divide, it is exponential, therefore 1.2.4.8.16.32 etc, so the numbers become enormous in no time at all. I can't remember what the mutation rate is but when you are dealing with multi million figures, mutations occur frequently.

Usually when a patient is treated for an infection they take the full course of antibiotics and all the bacteria are killed - end of story.

If just one of those bacteria ends up with a genetic mutation and ends up producing the mecA gene, then that one will divide in 2,4,8,16 and the antibiotic ends up being useless as it can't attach to the protein on the surface of the mutated bacteria.

The overuse of antibiotics is a difficult one to explain, but I can assure you that it is a problem. It is not related to inheritance between parents and children.

I hope the information I have given you is ok - if you need me to rephrase it or try and explain about the antibiotic overuse then let me know and I will try to explain further.

Lemony

Thank you very much Lemony. I do not want you to get bored.You know after work one would like to hear something else.But you are right when you say that your work is very interesting.You said protein known as PBP2 is located and the gene responsible for creating this protein is the mecA gene.OK let me first think over what you just have writen to me because i em not specialist like you and i need time to be able to assmilate better all this scientific information.

No, no, don't worry, you take as much time as you need to understand it all, I really don't mind answering questions, it keeps me on my toes.
The only way you can understand scientific information like this is if you hear it from somebody who does the job day in day out and not necessarily from the media - who sometimes confuse the issue.

Yes i know that Lemony but i have no other choise.So the only source of geting such information is from the media.My interest in biology origins from my childhood but it turned out to be not enough because i wanted to know more.I wanted to know how the space was created everything about the origin of the universe.It was my dream Lemony.But the attraction of the biology remained in me like big curiosity. What moreI can say is that i em very glad that you are so kind to me.

Hey, no problem

Soon I have read Lemony that scientists have isolated gene which were coded for illness whose name i can't remember now.Since you already know about the existence of mecA gene then can you isolate it from the whole structure of DNA?

Sorry, I don't understand exactly what you mean.