Bacterial Resistance?

EDIT: The following is probably wrong! I have been informed by someone that it is something to do with genetic mutation. But I'll still leave what I said below because it sounded good :D

DISCLAIMER!
I am not a molecular biologist or pharmacologist/toxicologist etc. This following answer/conversation is from my knowledge and understanding of cells and systems.

Miss X says:
Don
Miss X says:
can i ask you a question
Miss X says:
about bacterial resistance
Don says:
uh, you can
Don says:
but I don't know how good my answer will be
Miss X says:
why is it use combination therapy will minimise the emergence of resistant (in HIV not bacteria)
Miss X says:
combination therapy wil give synergistic effect
Miss X says:
but how does it reduce the resistant
Don says:
because the bateria has to develop resistance to more than 1 thing
Miss X says:
oh
Miss X says:
hmmm
Don says:
the baterial cells have to spend more energy than it has to develop multiple resistances
Don says:
while singular treatments means the bacteria only has to develop resistance to one type of attack to it
Miss X says:
ok
Miss X says:
then another question
Don says:
that would be my understanding
Miss X says:
gram positive bacteria secrete beta lactamase to the environment surrounding cell, but gram negative secrete the lactamse within the cell enviroment...
Miss X says:
so how does gram negative bacteria develop more resistance to beta lactam antibiotics?
Miss X says:
intact environemnt will contribute to more resitance?
Don says:
well, I don't know what latamse is
Miss X says:
because the environemnt is not changing?
Miss X says:
its an enzyme
Don says:
what does it do?
Miss X says:
antiobiotics attack that enzyme to kill the bacteria
Don says:
no no
Don says:
what does the cell secrete
Miss X says:
beta lactamase enzyme
Don says:
yes
Don says:
but what does the enzyme do
Don says:
the bateria isn't going to secrete something that kills itself
Miss X says:
beta lactamase form the bacterial cell wall
Miss X says:
beta lactam antibiotic hydrolyse the beta lactamase, so cell wall cannot form, therefore bactrial cell death
Don says:
ok
Don says:
so then what is the "cell environment"
Don says:
ie, what is the difference between outside/inside the "environment"
Miss X says:
gram negative got extra outer membrane on top of the cell wall
Miss X says:
to prevent the beta lactamase to be secreted to the outer environment
Don says:
there is your answer
Don says:
it has an extra membrane that is not lactamase
Don says:
therefore antiobiotics that are lactamase specific first have to penetrate the membrane
Miss X says:
then why resistance develop more rapidly in gram negative
Miss X says:
than in gram positive
Miss X says:
antibiotic resistance
Don says:
because less antiobotics penetrate the membrane
Don says:
so there is not enough antibiotic to kill the cell fast enough and it develops resistance
Don says:
because it doesn't get through the membrane fast enough to lyse the cell contents
Miss X says:
oh ok
Don says:
think of resistance = immune system
Miss X says:
hmmmmmmmmmm
Don says:
we get vaccinations as humans
Don says:
our immune systems form antibodies from vaccinations because vaccinations are weak versions of the actual illness
Don says:
so, a cell that gets a weak (or low dose) amount of an antigen, will form its own antibody against it
Don says:
so when a membrane protects the cell from the influx of a large amount of antigen, it has opportunity to form antibody, thus resistance
Don says:
that is how I would interpret it
Miss X says:
so... gram positive and negative both develop resistant at same rate
Miss X says:
but gram positive get killed by antibiotics faster
Don says:
you can't make the assumption that they make it at the same rate
Don says:
it just doesn't have the opportunity to make it because there may be too much antibody for it to react soon enough
Miss X says:
hmmm
Miss X says:
ok
Miss X says:
i understand now
Miss X says:
thx Don
Miss X says:
[smiley]
Don says:
no problems