Question:
could you please explain fully how ampicillian destroys
E.coli cells?
Replies:
Ampicillin is an antibiotic belonging to the group of
beta-lactam antibiotics. These will kill Gram-negative
bacteria to which E.coli and Salmonella belong. The
antibiotic prevents the formation of peptidoglycan, an
essential building block of the cell membrane. So the
antibiotic prevents growth of cells.
You can read more about antibiotics and how bacteria
can become resistant against them at the Virtual
Bacteria of Bacteria: http://www.bacteriamuseum.org
Dr. Trudy wasenaar
Unfortunately, I don't have my micro books with me, but I'll try. Bacteria
have a unique compound in their cell walls called peptidoglycan. It is made
of 2 types of sugar residues that are cross-linked (like a chain link fence)
by tetrapeptides. Penicillin prevents the crosslinking of the sugars by
breaking the tetrapeptides. These antibiotics are more effective against
gram positive organisms (such as Staph.) than gram negative organisms (such
as E coli) because gram pos. have more peptidoglycan in their cell walls.
Some bacteria have adapted to this situation by having an enzyme called
beta-lactamase that breaks the structure of the antibiotic open rendering it
ineffective. I'm pretty sure ampicillin is a penicillin derivative and
therefore has the same mode of action, but I would check to make sure if I
were you.
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