Penicillin
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Penicillin |
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Different species of penicillium
Penicillin was one of the first antibiotics to be discovered. It is recognized as the safest of all antibiotics. It is widely used i all countries. Fleming’s discovery of penicillin paved the way for the use of antibiotic therapy in treating infectious diseases.
History of Penicillin
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While experimenting with the bacterium Staphylococcus in 1928, Alexander Fleming observed that colonies of the bacterium failed to grow in those areas that had been accidentally contaminated by the mold Penicillium notatum. Fleming isolated the mold and grew it in a fluid medium. He discovered a substance in the mold that prevented the growth of the bacterium. He found out that Penicillin was non-toxic but could inhibit the growth of disease-causing bacteria. Due to lack of necessary chemical means, Fleming was unable to isolate and identify sufficient amounts of the active substance so as to be used on humans. It wasn't until 1939, during WW2, that Fleming’s discovery underwent much refinement when Ernst Boris Chain and Howard Walter Florey carried it further into isolation, purification, testing and quantity production. “Towards the 1950s, scientists added various chemical groupings to the core of the penicillin molecule to generate semisynthetic versions.” Thus, a range of penicillins was produced and used to treat various diseases caused by bacteria. |
The Penicillins
The penicillins may be classified into two groups; the biosynthetic penicillins -also referred to as “the naturally occurring penicillins”- (“those formed during the process of mold fermentation”) The biosynthetic penicillins include penicillin G (benzylpenicillin) , penicillin V and benzathine penicillin. Biosynthetic penicillins are important in chemotherapy. They are used in treating streptococcal sore throat, tosillites, pneumococcal pneumonia, endocardites caused by some streptococci, syphilis, gonorrhea, meningococcal infections and infections that are caused by some anaerobic organisms.The second class is the semisynthetic penicillins (those in which the structure of a chemical substance --6-aminopenicillinic acid—found in all penicillins is altered in various ways). Some of the semisynthetic penicillins may be given as oral medication. Several microorganisms were proved to be resistant to biosynthetic penicillins, which led to the production of penicillinase-resistant penicillins (penicillinase is an enzyme that inactivates the antibiotic). Examples of these include methicillin, oxacillin, nafcillin, cloxacillin and dicloxacillin. To extend the usefulness of the penicillins in the treatment of infections, the broad-spectrum of penicillins was produced, including ampicillin, amoxicillin, carbenicillin and ticarcillin. They are used to treat urinary tract infections as well as typhoid and enteric fevers.
DefectsThe main side effects of penicillin are notably allergic or hypersensitivity reactions, including skin rashes, hives, swelling and allergic shock. These are prevented by switching to alternative medications.
