P
|
enicillins
are a group of antibacterial drugs that attack a wide range of bacteria. They
were the first drugs of this type that doctors used. The discovery and
manufacture of penicillins have changed the face of medicine, as these drugs
have saved millions of lives.
Penicillium fungi are the source
of penicillin, which people can take orally or via injection.
People across the globe now widely use penicillins to treat infections and
diseases.
Fast facts on penicillin
· Penicillins were
the first antibiotic that doctors used.
· There are
several antibiotics in the penicillin class.
· Experts credit
Alexander Fleming with discovering penicillins.
· Penicillin works
by interfering with bacteria cell walls.
· Less than 1
percent of people are dangerously allergic to penicillin.
Function
Penicillins work by bursting the cell wall of bacteria.
Drugs in the penicillin class work by indirectly bursting bacterial cell
walls. They do this by acting directly on peptidoglycans, which play an
essential structural role in bacterial cells.
Peptidoglycans create a mesh-like structure around the plasma membrane of
bacterial cells, which increases the strength of the cell walls and prevents
external fluids and particles from entering the cell.
When a bacterium multiplies, small holes open up in its cell walls as the
cells divide. Newly-produced peptidoglycans then fill these holes to
reconstruct the walls.
Penicillins block the
protein struts that link the peptidoglycans together. This
prevents the bacterium from closing the holes in its cell walls.
As the water concentration of the surrounding fluid is higher than that
inside the bacterium, water rushes through the holes into the cell and the
bacterium bursts.
History
People generally attribute the discovery of penicillins to Alexander
Fleming. The story goes that he returned to his laboratory one day in September
1928 to find a Petri dish containing Staphylococcus bacteria
with its lid no longer in place.
The dish had become contaminated with a blue-green mold called Penicillium notatum. Fleming noted that there was a clear
ring surrounding the mold where the bacteria had been unable to grow.
By discovering this mold and recognizing its use, Fleming set the wheels
in motion to create one of the most useful drugs in medical history.
In March 1942, Anne Miller became the first civilian to receive successful
treatment with penicillin. She narrowly avoided death following severe
infection after a miscarriage.
Although Fleming technically discovered the first antibiotic, scientists
had to do a lot of work before penicillins could become available for general
use.
Scientists with a superior laboratory and a deeper understanding of
chemistry than Fleming carried out the bulk of the work. Howard Florey, Norman
Heatley, and Ernst Chain performed the first in-depth and focused studies on
the drug.
In Fleming's Nobel Prize acceptance speech, he warned that the overuse of
penicillins might, one day, lead to
bacterial resistance. This has since become a problem.
Resistance
Contrary to popular opinion, it is not the person who develops resistance
to penicillins but the bacteria itself.
Bacteria have been around for billions of years. During this time, they
have endured extreme environments and, as a result, are highly adaptable. They
also regenerate very rapidly, making relatively quick genetic changes possible
across a population.
There are three common ways in which bacteria can develop an immunity to
penicillin:
·
Penicillinase:
Bacteria are sometimes able to produce penicillinase, an enzyme that degrades
penicillins. This ability can spread throughout the bacterial population via a
small ring of DNA in a process called conjugation. This is the bacterial
equivalent of sexual reproduction, where individual organisms share new genetic
information between them.
·
Altered
bacterial structure: Some bacteria can subtly change the format of the
penicillin-binding proteins in their peptidoglycan wall so that penicillins can
no longer bind to it.
·
Penicillin
removal: Other bacteria develop systems to export penicillins. Bacteria have
efflux pumps that they use to release substances from the cell. The repurposing
of some of these pumps can allow the cell to dispose of penicillins.
Side effects
Nausea is a common side effect of taking penicillins.
The most commmon side effects of taking penicillins include:
·
diarrhea
·
nausea
·
a headache
·
skin
rashes and hives
Less common side effects include:
·
shortness
of breath or irregular breathing
·
joint
pain
·
sudden
lightheadedness and fainting
·
puffiness
and redness of the face
·
scaly,
red skin
·
vaginal
itching and discharge, due to either a yeast infection or bacterial
vaginosis
·
sore
mouth and tongue, sometimes with white patches
·
abdominal
cramps, spasms, tenderness, or pain
Rare side effects include:
·
anxiety, fear, or
confusion
·
a
sense of impending doom
·
hallucinations
·
yellowing
of the eyes and skin
·
a sore throat
·
unusual
bleeding
·
diarrhea
and reduced urination
·
convulsions
Risks
Although the use of penicillins is widespread, some issues or
contraindications can occur, as with any drug:
·
Breast-feeding: People who
are breast-feeding may pass small amounts of penicillin to the child. This can
result in the child experiencing allergic reactions, diarrhea, fungal
infections, and skin rash.
·
Interactions: Some other
drugs can interact with penicillins. Checking with a doctor before taking
multiple medications is vital.
·
Bleeding
problems: Some
penicillins, such as carbenicillin, piperacillin, and ticarcillin, can make
pre-existing bleeding problems worse.
·
Oral
contraceptives: Penicillins
can interfere with birth control pills, increasing the risk of unwanted
pregnancy.
·
Cystic
fibrosis: People
with cystic fibrosis are more prone to fever and
skin rashes when taking piperacillin.
·
Kidney
disease: Individuals
with kidney disease have an increased risk of side effects.
·
Methotrexate: Methotrexate
disrupts cell growth and can treat several conditions, including leukemia and
some autoimmune diseases. Penicillins prevent the body from disposing of this
drug, potentially leading to severe complications.
·
Phenylketonuria: Some
stronger, chewable amoxicillin tablets contain high levels of aspartame that
the body converts to phenylalanine. This is dangerous for anyone with phenylketonuria.
·
Gastrointestinal
problems: Patients
with a history of stomach ulcers or other intestinal diseases might be more
likely to develop colitis when taking penicillins.
Penicillin
allergy
Some people have an allergy to penicillins.
Allergic reactions to penicillin typically lead to hives, wheezing, and
swelling, particularly of the face.
Around 10 percent of people
report an allergy to penicillins but the real figure is closer to 1 percent,
and only around 0.03 percent exhibit
life-threatening allergic responses.
Alcohol and
penicillin
Certain antibiotics, such as metronidazole and tinidazole, have severe
reactions with alcohol. However, this is not the case with penicillins.
Penicillins have saved countless lives throughout their history of use in
medicine. However, doctors are now worried about the increase in antibiotic
resistance. Only time will tell how the antibiotics of the future will overcome
this hurdle.
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