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مساعدة حول .. Antibiotics

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  • مساعدة حول .. Antibiotics

    السلام عليكم .. كيفكم إن شاء الله طيبين ..

    أنا عندي بحث مهم وأحتاج منكم المساعدة ،،
    فلا تبخلوا علينا بما عندكم ،،
    ففيكم أصحاب الخبرة والإطلاع والإفادة ..

    البحث يتكلم عن ( المخاطر الصحية للمضادات الحيوية antibiotics )

    وأحتاج بعض النقاط :

    - History خلفية تاريخية عنها ..
    - تعريفها ..
    - تقسيماتها .. Classification ..
    - آلية عملها .. Mechanism of action ..
    - أماكن حدوثها .. وتأثيراتها على بعض أجهزة الجسم .. site effects ..


    فمن يستطيع المساعدة ،، سواء بمعلومة أو موقع مفيد أو دعاء بالتوفيق ..
    فله مني الشكر الجزيل .. والدعاء الذي لا ينقطع .. بالتوفيق في الدنيا والآخرة ..

  • #2
    والله انا ما بعرف شي ان شا الله الاخوان يفيدوك

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    • #3
      أخي الكريم موضوع متعلق بقسم المايكروبيولوجي أتمنى من الاخوان يفيدونك وبالتوفيق..سوف يتم نقل موضوعك..وشكرا
      http://www.arabslab.com/vb/uploaded/316_11191621547.jpg

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      • #4
        اليوم راح أضع لك بعض الروابط من هذا المنتدى

        لعلها تفيدك

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        • #5
          أنا في انتظاركم ... بارك الله فيكم ...

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          • #6
            http://www.arabslab.com/vb/showthread.php?t=2394

            http://www.arabslab.com/vb/showthread.php?t=1490

            http://www.arabslab.com/vb/showthread.php?t=1692

            http://www.arabslab.com/vb/showthread.php?t=1561

            لعلها تفيدك

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            • #7
              الله يوفقك وييسرلك
              سبحان الله وبحمده سبحان الله العظيم

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              • #8
                انصح اخي الكريم : بشراء كتاب او مذكرات لمادة المضادات الحيويه الخاصة بالدكتور : على السلامه

                الاستاذ بجامعة الملك سعود كلية العلوم ، قسم الاحياء الدقيقه

                جدا سوف يعجبك ،، واشياء كثيره بالتفصيل الممل

                ،،،،،،،،ن

                احتمال تتحصله في مكاتب او خدمات الطالب القريبه من الجامعه..
                كــــل عـــام وانــتــم بخيــــــر

                تقبل الله منا ومنكم جميع الاعمال الصالحه

                وللجميع في المنتدى وللامه الاسلاميه

                اسأل الله العافيه والمعافاة من كل شر ومكروه
                ؟؟

                اتمنى ان يسامحني كل شخص زليت عليه او غلطت
                واستودعكم الله الذي لا تضيع ودائعه



                فــــــــأمان الله الكريم الرحيم ..



                3/10/1429هـ الخميس

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                • #9
                  أشكركم جميعا .. وبارك الله فيكم .. ووفقكم في دنياكم وأخراكم ..

                  ولا مانع من الإضافات ..

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                  • #10
                    Antibiotics
                    Introduction
                    Antibiotics (Greek anti, “against”; bios, “life”) are chemical compounds used to kill or inhibit the growth of infectious organisms. Originally the term antibiotic referred only to organic compounds, produced by bacteria or molds, that are toxic to other microorganisms. The term is now used loosely to include synthetic and semisynthetic organic compounds. Antibiotic refers generally to antibacterials; however, because the term is loosely defined, it is preferable to specify compounds as being antimalarials, antivirals, or antiprotozoals. All antibiotics share the property of selective toxicity: They are more toxic to an invading organism than they are to an animal or human host. Penicillin is the most well-known antibiotic and has been used to fight many infectious diseases, including syphilis, gonorrhea, tetanus, and scarlet fever. Another antibiotic, streptomycin, has been used to combat tuberculosis.
                    II History
                    Although the mechanisms of antibiotic action were not scientifically understood until the late 20th century, the principle of using organic compounds to fight infection has been known since ancient times. Crude plant extracts were used medicinally for centuries, and there is an evidence for the use of cheese molds for topical treatment of infection. The first observation of what would now be called an antibiotic effect was made in the 19th century by French chemist Louis Pasteur, who discovered that certain saprophytic bacteria can kill anthrax bacilli. In the first decade of the 20th century, German physician and chemist Paul Ehrlich began experimenting with the synthesis of organic compounds that would selectively attack an infecting organism without harming the host organism. His experiments led to the development, in 1909, of salvarsan, a synthetic compound containing arsenic, which exhibited selective action against spirochetes, the bacteria that cause syphilis. Salvarsan remained the only effective treatment for syphilis until the purification of penicillin in the 1940s. In the 1920s British bacteriologist Sir Alexander Fleming, who later discovered penicillin, found a substance called lysozyme in many bodily secretions, such as tears and sweat, and in certain other plant and animal substances. Lysozyme has some antimicrobial activity, but it is not clinically useful.
                    Penicillin, the archetype of antibiotics, is a derivative of the mold Penicillium notatum. Penicillin was discovered accidentally in 1928 by Fleming, who showed its effectiveness in laboratory cultures against many disease-producing bacteria. This discovery marked the beginning of the development of antibacterial compounds produced by living organisms. Penicillin in its original form could not be given by mouth because it was destroyed in the digestive tract and the preparations had too many impurities for injection. No progress was made until the outbreak of World War II stimulated renewed research and the Australian pathologist Sir Howard Florey and German-British biochemist Ernst Chain purified enough of the drug to show that it would protect mice from infection. Florey and Chain then used the purified penicillin on a human patient who had staphylococcal and streptococcal septicemia with multiple abscesses and osteomyelitis. The patient, gravely ill and near death, was given intravenous injections of a partly purified preparation of penicillin every three hours. Because so little was available, the patient's urine was collected each day, the penicillin was extracted from the urine and used again. After five days the patient's condition improved vastly. However, with each passage through the body, some penicillin was lost. Eventually the supply ran out and the patient died.
                    The first antibiotic to be used successfully in the treatment of human disease was tyrothricin, isolated from certain soil bacteria by American bacteriologist Rene Dubos in 1939. This substance is too toxic for general use, but it is employed in the external treatment of certain infections. Other antibiotics produced by a group of soil bacteria called actinomycetes have proved more successful. One of these, streptomycin, discovered in 1944 by American biologist Selman Waksman and his associates, was, in its time, the major treatment for tuberculosis.
                    Since antibiotics came into general use in the 1950s, they have transformed the patterns of disease and death. Many diseases that once headed the mortality tables—such as tuberculosis, pneumonia, and septicemia—now hold lower positions. Surgical procedures, too, have been improved enormously, because lengthy and complex operations can now be carried out without a prohibitively high risk of infection. Chemotherapy has also been used in the treatment or prevention of protozoal and fungal diseases, especially malaria, a major killer in economically developing nations (see Third World). Slow progress is being made in the chemotherapeutic treatment of viral diseases. New drugs have been developed and used to treat shingles (see herpes) and chicken pox. There is also a continuing effort to find a cure for acquired immunodeficiency syndrome (AIDS), caused by the human immunodeficiency virus (HIV),
                    IIIClassification
                    Antibiotics can be classified in several ways. The most common method classifies them according to their action against the infecting organism. Some antibiotics attack the cell wall; some disrupt the cell membrane; and the majority inhibit the synthesis of nucleic acids and proteins, the polymers that make up the bacterial cell. for example :-
                    Aminoglycosides
                    These are products of actinomycetes (soil bacteria) or semi-synthetic derivatives of the natural products.
                    Examples are:
                    • streptomycin
                    • kanamycin
                    • neomycin
                    • gentamycin
                    The Chink in the Armor = the bacterial ribosome
                    The 70S bacterial ribosome differs in several ways from the 80S eukaryotic ribosome. [The aminoglycosides bind to the 30S subunit of the bacterial ribosome and
                    • interfere with the formation of the initiation complex
                    • cause misreading of the mRNA.
                    Although the eukaryotic ribosome in the cytosol is relatively unaffected by these drugs, ribosomes in the mitochondria are 70S and sensitive to their effects.


                    Tetracyclines
                    These are natural products derived from soil actinomycetes or their semi-synthetic derivatives. Examples:
                    • chlortetracycline (trade name = "aureomycin")
                    • oxytetracycline (trade name = "terramycin")
                    • doxycycline
                    The Chink in the Armor = the bacterial ribosome
                    Tetracyclines bind to the 30S subunit of the bacterial ribosome. They prevent the transfer of activated amino acids to the ribosome so protein synthesis is halted.
                    Polypeptides
                    The most common of these are the polymixins.
                    They behave as detergents, increasing the permeability of the membranes that encase bacteria and causing the contents of the bacterial cell to leak out.
                    Rifampin
                    This semi-synthetic antibiotic binds to the bacterial RNA polymerase and prevents it from carrying out its role in transcription. Its affinity for the equivalent eukaryotic enzyme is much lower. Rifampin is also known as rifampicin.
                    Cycloserine
                    Cycloserine inhibits synthesis of the bacterial cell wall but by a different mechanism than the beta-lactam antibiotics discussed above. Cycloserine is an analog of D-alanine and blocks the incorporation of D-alanine into the peptide bridges in the bacterial cell wall (look back). It is derived from an actinomycete.
                    Another method classifies antibiotics according to which bacterial strains they affect: staphylococcus, streptococcus, or Escherichia coli, for example. Antibiotics are also classified on the basis of chemical structure, as penicillins, cephalosporins, aminoglycosides, tetracyclines, macrolides, or sulfonamides, among others.
                    Aminoglycosides
                    Streptomycin is the oldest of the aminoglycosides. The aminoglycosides inhibit bacterial protein synthesis in many gram-negative and some gram-positive organisms. They are sometimes used in combination with penicillin. The members of this group tend to be more toxic than other antibiotics. Rare adverse effects associated with prolonged use of aminoglycosides include damage to the vestibular region of the ear, hearing loss, and kidney damage.
                    Aminoglycosides are typically aminosugars linked together by glycosidic linkages.
                    Macrolides
                    The macrolides are bacteriostatic, binding with bacterial ribosomes to inhibit protein synthesis. Erythromycin, one of the macrolides, is effective against gram-positive cocci and is often used as a substitute for penicillin against streptococcal and pneumococcal infections. Other uses for macrolides include diphtheria and bacteremia. Side effects may include nausea, vomiting, and diarrhea; infrequently, there may be temporary auditory impairment.

                    Chemical structure of a macrolide with a 16-membered ring
                    © John Heritage 2004, 2006
                    Sulfonamides
                    The sulfonamides are synthetic bacteriostatic, broad-spectrum antibiotics, effective against most gram-positive and many gram-negative bacteria. However, because many gram-negative bacteria have developed resistance to the sulfonamides, these antibiotics are now used only in very specific situations, including treatment of urinary-tract infection, against meningococcal strains, and as a prophylactic for rheumatic fever. Side effects may include disruption of the gastrointestinal tract and hypersensitivity. © John Heritage 2004, 2006


                    Chemical structure of sulphamethoxazole, a sulphonamide
                    Antibiotics can be classified in several ways. The most common method classifies them according to their chemical structure as antibiotics sharing the same or similar chemical structure will generally show similar patterns of antibacterial activity, effectiveness, toxicity and allergic potential.
                    Side effects of antibiotics
                    The most common side effects with antibiotic drugs are diarrhoea, feeling sick and being sick. Fungal infections of the mouth, digestive tract and vagina can also occur with antibiotics because they destroy the protective 'good' bacteria in the body (which help prevent overgrowth of any one organism), as well as the 'bad' ones, responsible for the infection being treated.
                    Rare, but more serious side effects, include the formation of kidney stones with the sulphonamides, abnormal blood clotting with some of the cephalosporins, increased sensitivity to the sun with the tetracyclines, blood disorders with trimethoprim, and deafness with erythromycin and the aminoglycosides.
                    Sometimes, particularly in older people, antibiotic treatment can cause a type of colitis (inflamed bowel) leading to severe diarrhoea. Penicillins, cephalosporins and erythromycin can all cause this problem but it is most common with clindamycin, an antibiotic usually reserved for serious infections. If you develop diarrhoea while taking an antibiotic, immediately contact your doctor.
                    Some people are allergic to antibiotics, particularly penicillins, and can develop Side effects such as a rash, swelling of the face and tongue, and difficulty breathing when they take them. Always tell your doctor or pharmacist if you have had an allergic reaction to an antibiotic; sometimes the reaction can be serious or even fatal. This is called an anaphylactic reaction.
                    Antibiotics generally do not cause major side effects. They are a relatively safe class of medications. However, like all medications, they can have various side effects.
                    Diarrhea and antibiotics: A common side effect of antibiotics is diarrhea. This is usually caused because the antibiotics have killed the "good bacteria" in the digestive system.
                    For this reason, the use of certain supplements or yoghurts containing ACIDOPHILLUS may be helpful to reduce digestive symptoms. The use of acidophillus introduces more "good bacteria" to restore a health balance to the digestive tract.
                    Thrush and antibiotics: Because antibiotics kill all bacteria, including the various "good bacteria" in the body, the overall balance of bacteria in the body is damaged by antibiotics. One major use of good bacteria in the body is to control naturally occurring fungi in the digestive tract or on the body. The absence of the good bacteria can sometimes allow an outbreak of fungi, such as thrush, to occur as a side effect of antibiotics.
                    , but more serious side-effects include kidney problems, abnormal blood clotting, increased sensitivity to the sun, blood disorders and deafness.
                    Allergies
                    Some people are allergic to antibiotics, particularly penicillin and similar medicines. They can develop side-effects such as a rash, swelling of the face and tongue, and difficulty breathing when they take them. This is called an anaphylactic reaction and it can be serious or even fatal. As an alternative to penicillin, doctors often prescribe erythromycin, which works against the same types of infections.
                    Always tell your doctor or pharmacist if you have had an allergic reaction to an antibiotic. Dale MM, Ritter JM. Pharmacology, 2003
                    Side effects
                    All antibiotics cause risk of overgrowth by non-susceptible bacteria. Manufacturers list other major hazards by class; however, the health care provider should review each drug individually to assess the degree of risk. Generally, breastfeeding is not recommended while taking antibiotics because of risk of alteration to infant's intestinal flora, and risk of masking infection in the infant. Excessive or inappropriate use may promote growth of resistant pathogens.
                    Penicillins: Hypersensitivity may be common, and cross allergenicity with cephalosporins has been reported. Penicillins are classed as category B during pregnancy.
                    Cephalopsorins: Several cephalopsorins and related compounds have been associated with seizures. Cefmetazole, cefoperazone, cefotetan and ceftriaxone may be associated with a fall in prothrombin activity and coagulation abnormalities. Pseudomembranous colitis has been reported with cephalosporins and other broad spectrum antibiotics. Some drugs in this class may cause renal toxicity. Pregnancy category B.
                    Fluroquinolones: Lomefloxacin has been associated with increased photosensitivity. All drugs in this class have been associated with convulsions. Pregnancy category C.
                    Tetracyclines: Demeclocycline may cause increased photosensitivity. Minocycline may cause dizziness. Do not use tetracyclines in children under the age of eight, and specifically avoid during periods of tooth development. Oral tetracyclines bind to anions such as calcium and iron. Although doxycycline and minocycline may be taken with meals, patients must be advised to take other tetracycline antibiotics on an empty stomach, and not to take the drugs with milk or other calcium-rich foods. Expired tetracycline should never be administered. Pregnancy category D. Use during pregnancy may cause alterations in bone development.
                    Macrolides: Erythromycin may aggravate the weakness of patients with myasthenia gravis. Azithromycin has, rarely, been associated with allergic reactions, including angioedema, anaphylaxis, and dermatologic reactions, including Stevens-Johnson syndrome and toxic epidermal necrolysis. Oral erythromycin may be highly irritating to the stomach and when given by injection may cause severe phlebitis. These drugs should be used with caution in patients with liver dysfunction. Pregnancy category B: Azithromycin, erythromycin. Pregnancy category C: Clarithromycin, dirithromycin, troleandomycin.
                    Aminoglycosides: This class of drugs causes kidney and ototoxicity. These problems can occur even with normal doses. Dosing should be based on renal function, with periodic testing of both kidney function and hearing. Pregnancy category D.
                    PROBLEMS WITH ANTIBIOTICS
                    The list of problems with antibiotics is quite long. Some are common and well known. Others are subtle but no less important. I have divided the adverse effects into nine categories:
                    1) Allergic Reactions. I used to worry every time I prescribed penicillin as an medical intern. It had been explained that every once in a while a patient would have a fatal allergic reaction to it, and that if I practiced medicine long enough someone would die in my office after a shot of penicillin. While this is uncommon, other allergic reactions to antibiotics occur frequently. Not only can the drug cause a reaction, but most antibiotics contain chemical colors, sugar and other additives that can trigger a reaction in sensitive individuals.
                    2. Destruction of normal bowel flora. Like pesticides, antibiotics kill good bugs along with the bad ones. Wide-spectrum antibiotics are notorious for this. The human intestine has a somewhat delicate ecology in which certain bugs help digest food, produce certain vitamins, and maintain a balance of organisms that prevents harmful bacteria and yeasts from multiplying.
                    Wide-spectrum antibiotics derange the normal ecology of the intestine. This can cause parasitic infection, vitamin deficiencies, loss of minerals through diarrhea, inflammation of the gut, malabsorption syndromes and development of food allergies due to defects in intestinal function.
                    3. Development of resistant bugs. An article in Science Magazine, August 1992, stated, "Doctors in hospitals and clinics around the world are losing the battle against an onslaught of new drug-resistant bacterial infections including staph, pneumonia, strep, tuberculosis, dysentery and other diseases that are costly and difficult, if not impossible, to treat".
                    Bacteria have a certain ability to mutate. Antibiotics kill bacteria that are susceptible to their action, but this leaves the field open for mutant strains to multiply even more. It is a case of survival of the fittest. The use of antibiotics actually encourages the development of the mutant, drug-resistant super-bacteria.
                    4. Immune Suppression. This may sound odd, as the purpose of antibiotics is presumably to help the immune system. However, evidence indicates that people treated with antibiotics have more repeat infections than those who are not treated. This is especially true of children whose ear infections are treated with antibiotics. Vitamin A and herbs are much more effective.
                    In fact, antibiotics do not aid the immune system. They replace one of its functions. Antibiotics act by inhibiting certain enzymatic processes of bacteria, and by changing mineral balances. Normal cells, however, are also affected. This may be one reason why antibiotics weaken the immune system. Other toxic effects of antibiotics, such as the effect upon the normal bowel flora, may also contribute to a weaker immune system.
                    The latest research on AIDS indicates that a risk factor for AIDS is an impaired immune system, which can be due to a history of repeated antibiotic use. Oops!
                    5. Overgrowth of Candida Albicans. Normally, candida albicans, a common yeast, lives peacefully in our intestines and elsewhere, in harmony with other flora that keep the yeast in check. Take an antibiotic and all this changes. By suppressing the normal flora, candida takes over and problems begin. In its mild form the result is diarrhea or a yeast infection.
                    Far more serious is the growing problem of chronic muco-cutaneous yeast infection. This is described in books such as The Yeast Connection and The Yeast Syndrome. It is a major iatrogenic illness today, and a very debilitating and potentially fatal condition. One of the prime risk factors for chronic candida infection is repeated antibiotic use.
                    6. Chronic fatigue syndrome. This is another 'new' health plague. It is associated with chronic viral illness and a weakened immune system. While its exact origins are not clear, one of the major risk factors for chronic fatigue syndrome is - you guessed it - repeated antibiotic use.
                    7. Nutrient Loss. Nutrient loss from antibiotics is due in part to diarrhea, which causes a loss of essential minerals. Destruction of friendly bacteria in the intestines can also impair the synthesis of certain vitamins in the intestines. While not a major cause of malnutrition, antibiotic usage may be another factor contributing to poor nutrition and thus a weakened body chemistry.
                    8. Treating an effect, not a cause. Antibiotics only address the end-stage result of a weakened body chemistry - bacterial invasion. The bacteria may only be there to "mop up" the biological debris that are present because the body is too weak to eliminate the poisons. Fever is one way the body burns up toxic substances. Providing it does not get out of hand, the infectious process can serve a useful purpose. Cutting short the process with antibiotics aborts the cleansing function of a fever and impairs long-term health.
                    Horse manure, you might say. No it is not. I know this because on tissue mineral tests, there are clear indicators of increased susceptibility to infections. The indicators are: 1) a low energy level, 2) a low sodium/potassium ratio, 3) toxic levels of mercury, copper, or cadmium, and 4) low zinc. In hundreds of cases, when these imbalances are corrected, the tendency for infections decreases drastically. In other words, healthy people do not get as many infections. Infections do not strike randomly. There is a logic to infections, and the underlying causes can be addressed.
                    This line of reasoning traces back to the famous debate between Pasteur and Beauchamp. Dr. Pasteur insisted that germs are the cause of disease. His colleague, Beauchamp, insisted that the health of the host was more important than the germs. On his death bed, Pasteur was said to have declared that Beauchamp was correct - "the host is everything, the germs are nothing". Orthodox medicine, however, embraced Pasteur's view, and ignored Beauchamp. It is time to focus more on the person, and less on the germs.
                    9. High cost. Millions of doctor visits and prescriptions for antibiotics add up to a major expense. While penicillin is not expensive, other newer antibiotics are quite costly. These newer antibiotics are used more frequently today due to the presence of penicillin-resistant strains of bacteria. We must also include in the cost of antibiotics the cost of allergic reactions, candida albicans infections, repeat infections, development of resistant organisms and immune suppressiThe cost is justified if life is at stake. However, if less toxic and less costly alternatives can be used, shouldn't these be tried first? Bringing health care costs under control is not just a matter of eliminating waste and inefficiency. We need methods of healing that build up the health of the people, not tear it down.
                    Gilman, Alfred. Goodman, Wolff, M. Burger1996 , Mcgraw Hill, 2001, Wolters Kluwer Co., 2002

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                    • #11
                      شكرا .. وبالتوفيق ..

                      أشكر الأخت منى السيد .. على هذا المجهود العظيم ..

                      وصراحة كلماتي عاجزة عن شكرك .. لكن سأدعو لك بالتوفيق ..

                      شكرا .. ثم شكرا ..

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