Tác dụng của Penicillin pptx

Penicillin "The Wonder Drug" When discussing the antibiotic breakthrough of penicillin, the name which is most often associated with its discovery tends to be Alexander Fleming. While this is not completely false, there are many other factors as well as persons which aided in uncovering penicillin’s full potential in human uses. Penicillin was not created overnight. In fact, over a decade had passed from the time that Alexander Fleming first noticed the seemingly odd culture of gram-positive bacteria in 1928 to the first human test in 1941. As there are many different accounts and versions of the penicillin story, some of the details may differ. However, one piece of information which stays constant is that Alexander Fleming was not alone in creating the wonder drug, penicillin. I have found the following sites to be very thorough in describing the discovery, production, and uses of penicillin. I have included a summary of the general information regarding penicillin, for a more in depth description please visit these other sites. Tom Volk - Mycology - University of Wisconsin, La Crosse George Wong - Botany - Hawaii The Discovery: The story which most people are familiar with entails Alexander Fleming accidently leaving a culture dish of Staphylococcus aureus bacteria uncovered for a number of days. When returning to the bacteria, Fleming noticed mold had begun to grow as well. He incorrectly names named the fungus Penicillium rubra. (Later it was re-named by Charles Thom as Penicillium notatum which was found to be the same species as Penicillium chrysogenum). What made this fungus growth interesting was that the bacteria ceased to exist in the area near it. Below is a quote from Alexander Fleming which was referenced in Judith Kaye’s book, The Life of Alexander Fleming. "On this particular occasion, the mould which developed appeared to be dissolving the bacteria. That was very unusual, so instead of casting out the contaminated culture with appropriate language, I made some investigations and the more I investigated it the more interesting it became” (Fleming). Now, you may be wondering what a fungus prohibiting the growth of bacteria has to do with saving people’s lives. It may surprise you to learn that most deaths prior to the use of penicillin were due to bacterial infections, not bleeding to death or other occurrences. Fleming recognized that inhibiting the growth of bacteria could potentially be used to lessen the number of bacterial related deaths. This is where one must decide if Fleming should be credited for the discovery of penicillin. Is this initial, chance production of a mold which prohibits the growth of some bacteria enough to give Fleming credit for the miracle drug penicillin? Most people agree that Fleming should be credited merely for realizing that something odd did in fact occur. Had Fleming thrown the culture out and not recognized the importance of it, the production of penicillin would have been greatly delayed. However, it was later scientists which revealed the human uses of the mold in the form of antibiotics. Over ten years later, in 1939, Oxford University scientists (Ernst Chain and Howard Florey) were able to reproduce the mold which was seen on Fleming’s contaminated culture and use it in mice to treat infections. In 1941 the first human trial took place. The man who was being treated died due to a lack of penicillin. The arrival of World War II sparked interest in the new antibiotic, and there was search to find a source which could provide a sufficient amount of penicillin. Interestingly, there was a woman hired for the sole purpose of finding different molds with hopes of finding a high penicillin concentration. Some accounts say that the final source was moldy liquor; others say it was due to a melon which was brought to the scientists. Whatever the source, this new abundance of penicillin combined with Louis Pasteur’s Germ Theory of Disease (infectious diseases are caused by germs) greatly decreased the number of deaths due to bacterial infections in WWII and continues to be used today. In 1945 Alexander Fleming, Ernst Chain, and Howard Florey received the Nobel Prize in physiology/medicine for their work with the fungus Penicillium chrysogenum and the benefits yielded to mankind. How Does It Work? Penicillin works on gram-positive bacteria. These bacteria contain a cell wall made of peptidoglycan, and it is this cell wall which penicillin reacts with to weaken the bacteria and ultimately destroy it. The Future of Penicillin: As you are probably aware, the effects of penicillin are not as great as they once were. This is due to a number of factors which are all summed up in penicillin resistance. In other words, the bacteria are becoming immune to the effects of penicillin. This is brought on by many things which all are linked back to good ol’ Charles Darwin and his theory on selection of the fittest. When patients are given penicillin antibiotics and stop taking the medication after “feeling better”, there are some bacteria which survive the initial dosage and live on to reproduce other bacteria with the same traits. Other people feel that penicillin is too readily prescribed, and this allows for more bacteria to become immune to it. Because of the bacterial resistance, scientists are continually looking for new sources for antibiotics as well as changing the old chemical structures. . The Future of Penicillin: As you are probably aware, the effects of penicillin are not as great as they once were. This is due to a number of factors which are all summed up in penicillin resistance there are many other factors as well as persons which aided in uncovering penicillin s full potential in human uses. Penicillin was not created overnight. In fact, over a decade had passed from. of the penicillin story, some of the details may differ. However, one piece of information which stays constant is that Alexander Fleming was not alone in creating the wonder drug, penicillin.