Antibiotics 101

Antibiotics, an introduction.  

Antibiotics are agents, either naturally occurring or synthetically produced, that kill microorganisms or inhibit their growth. This general definition allows for the further classifications of antibiotics, or antimicrobials, into classes that describe the specific microorganism that each compound targets.  Some examples of these classifications include antibacterials, antifungals, antivirals, and antiparasitics. These antibiotics have had a major impact in the medical community since their widespread usage began in the 1940s. One of the milestones in antibiotics that marked the beginning of its widespread usage was achieved by Ernst Chain and Howard Florey when they were able to develop a powdered form of penicillin by isolating its active ingredient. Penicillin remained at the forefront of antibiotics for decades and was known as the “miracle drug” because of its ability to cure people of previously fatal bacterial infections. So how exactly does penicillin work?

          Put simply, penicillin works by destroying the cell wall of bacteria. It does this by specifically targeting and inactivating the enzyme transpeptidase. Transpeptidase is responsible for the cross-linkage in the bacterial cell wall, and after a nucleophilic oxygen of the enzyme binds with penicillin rendering it inactive, the cell wall of the bacteria ruptures. For more on how this process occurs, check out this link.

          Antibiotics can be manufactured synthetically or semi-synthetically which means that they are unnatural drugs that can be made from non-living components. While semi-synthetic antibiotics are simply made by including an additional step that requires modification of the naturally produced chemicals, synthetic antibiotics are created with a new chemical manufacturing process. In order to understand how semi-synthetic and synthetic antibiotics are made, one must understand how natural antibiotics are made. A sterile and controlled environment is required to produce all kinds of antibiotics in order to prevent external contamination of the product. Natural antibiotics begin with a preparation of a culture of microorganisms. These cultures are constantly fed in fermentation tanks so that these microorganisms reproduce. After several days of supervising the process and controlling temperature, humidity, and other conditions, an antibiotic broth can be run through a filtration system so that it can be purified and the drug can be separated. After confirming that the product is not contaminated, it is ready to be sold worldwide. However, semi-synthetic drugs have a required additional step. Instead of purifying the natural product, it is put through a chemical process that alters the structure of the drug, thus making it not fully synthetic but not fully natural. These alterations of the structure are made in order to have a better effect on infecting organisms or to be better absorbed by the body. Synthetic antibiotics are simpler to produce because thesynthetic drugs are not subject to the natural variations found in living organisms that are used in fermentation tanks.

           There are many different types of semi-synthetic or synthetic antibiotics. For example, the first synthetically manufactured antibiotic is chloromycetin. This synthetically made antibiotic was used to treat ocular infections that involves the conjunctiva or cornea. However, chloromycetin is only used for serious infections when other weaker or less dangerous drugs are ineffective and therefore, chloromycetin is no longer available in the U.S. Ampicillin is a penicillin antibiotic that is derived from basic penicillin nucleus, 6-aminopenicillanic acid. This drug is used to treat infected areas such as urinary tracts. Erythromycin is another synthetically made antibiotic that is part of the macrolide antibiotics. Macrolide antibiotics slow the growth of bacteria by reducing the production of proteins needed by the bacteria to survive. This drug is mostly used by people who are allergic to penicillin. These examples of synthetically orsemi-synthetically made antibiotics are important contributors to treatment of infections of human bodies and are produced worldwide by manufacturers in order to meet the demands of patients.

          Traditionally bacteria are not resistant to antibiotics, in fact antibiotics are used to kill bacteria and other microorganisms. Bacteria tend to multiply by the billion as well as adapt and mutate often. Sometimes, these bacterial mutations make bacterium resistant to antibiotics therefore being harder to treat. Resistant bacteria that is not treated by antibiotics further multiplies. Antibiotic resistance leads to not only the misuse but also the overuse of antibiotics and vaccines which further leads to the creation of superbugsSuperbugs are formed when the gene that carries bacterial resistance is transferred or carried between bacteria so that there is a creation of bacteria with antibiotic resistant genes for many antibiotics. The most common types of superbugs are methicillin- resistant Staph aureus (MRSA) and multiple-drug or extensively drug resistant tuberculosis (MDR-TB and XDR-TB).

          Bleach is a commonly known disinfectant of bacteria. The active ingredient in bleach known as hypochlorous acid is what disinfects or causes the unfolding of proteins in bacteria which then clump together into a mass in living cells. This process is similar to the process of boiling an egg. The boiling process denaturizes the proteins of the bacteria in the egg making it safe to eat just as bleach does. As the bacterial proteins unfold, heat shock protein or Hsp33 is put into effect and protects proteins from the aggregation effect and further increases bacterial bleach resistance. Commonly, bleach’s base acidity also tends to compromise a bacteria’s lipid membrane, a process that is similar to the popping of a balloon. Overall, bleach is an extremely versatile disinfectant that kills a broad range of bacterium.

Check out this quick video on antibiotics in the meat industry.



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