1. Penicillin
Juan Sebastian Guzman
9c

2. What is penicillin?
It is a group of antibiotics They include penicillin
procaine penicillin benzathien penicillin, and
penicillin V. Penicillin antibiotics are historically
significant because they are the first drugs that
were effective against many previously serious
diseases such as syphilis and infections caused by
staphylococci and streptococci . Penicillin are still
widely used today, though many types of bacteria
are now resistant. All penicillin are beta-lactam
antibiotics and are used in the treatment of
bacterial infections caused by susceptible, usually
Gram-positive, organisms.

3. How Does Penicillin work?
• By destroying the cell wall of the microorganism. It does this
by inactivating an enzyme necessary for the cross linking of
bacterial cell walls. The enzyme is known as transpeptidase.
It accepts the penicillin as a substrate, it then alkanolates a
nucleophilic oxygen of the enzyme, rendering it inactive. Cell
wall construction stops and the bacteria soon die. The
antibiotic nature of the penicillin is due to the strained -
lactam ring, on opening the ring strain is relieved this makes
penicillin more reactive than ordinary amides.

4. Types of penicillin
• Natural Penicillin
• The natural penicillin include penicillin G and penicillin V. Penicillin G, also known as benzyl
penicillin, is not stable in an acidic environment, such as in the stomach. Therefore, this penicillin is
usually administered by injection although it does come in pill form.
• Amino penicillin
• The group of Aminopenicillins includes amoxicillin, ampicillin and bacampicillin. Although
aminopenicillins are not as active as the natural penicillin, their expanded spectrum of
effectiveness makes them medically useful. The aminopenicillins are also tolerant of acid and
can therefore be taken orally.
Resistant Penicillin
• These medications, including cloxacillin, dicloxacillin, nafcillin, methicillin and
oxacillin, are very effective in treating these gram-positive coccid bacteria in
the Staphylococcal group but are not the best pills to choose for other bacteria
due to their lower level of activity compared to other penicillin.

5. How was the peniclillin discovered and
developed?
• Alexander Fleming, a Scottish bacteriologist in London,
discovered penicillin by mistake when he was trying to
study staphylococci bacteria in 1928. He was running
experiments with the bacteria in his laboratory at
London's St. Mary's Hospital, and set a laboratory dish
containing the bacteria near an open window. Upon
returning to the experiment, he found that some mold
blown in through the open window onto the dish,
contaminating the bacteria.