They are produced in nature by soil bacteria and fungi. This gives the microbe an advantage when competing for food and water and other limited resources in a particular habitat, as the antibiotic kills off their competition.
An antibiotic can also be classified according to the range of pathogens against which it is effective. Penicillin G will destroy only a few species of bacteria and is known as a narrow spectrum antibiotic. Tetracycline is effective against a wide range of organisms and is known as a broad spectrum antibiotic. Bacteria are termed drug-resistant when they are no longer inhibited by an antibiotic to which they were previously sensitive. The emergence and spread of antibacterial-resistant bacteria has continued to grow due to both the over-use and misuse of antibiotics.
If a strain of a bacterial species acquires resistance to an antibiotic, it will survive the treatment. As the bacterial cell with acquired resistance multiplies, this resistance is passed on to its offspring. In ideal conditions some bacterial cells can divide every 20 minutes; therefore after only 8 hours in excess of 16 million bacterial cells carrying resistance to that antibiotic could exist. Although there are similarities between bacteria and human cells, there are many differences as well.
For example, human cells do not have cell walls, while many types of bacteria do. The antibiotic penicillin works by keeping a bacterium from building a cell wall. Bacteria and human cells also differ in the structure of their cell membranes and the machinery they use to build proteins or copy DNA. Some antibiotics dissolve the membrane of just bacterial cells. Others affect protein-building or DNA-copying machinery that is specific to bacteria. Different families of antibiotics have different ways of killing bacteria.
Below are descriptions of a few types of antibiotics and their mechanisms of action. Beta-lactam antibiotics kill bacteria that are surrounded by a cell wall.
Bacteria build cell walls by linking molecules together—beta-lactams block this process. Without support from a cell wall, pressure inside the cell becomes too much and the membrane bursts. Examples of beta-lactams include penicillin and cephalosporin, which are used to treat many types of bacterial infections. Ribosomes build proteins in both bacteria and human cells, but there are differences between bacterial and human ribosomes.
Macrolides block only bacterial ribosomes and prevent them from building proteins. Erythromycin, which is commonly used to treat respiratory tract and skin infections, is a macrolide. Quinolones include antibiotics like ciprofloxacin and levofloxacin, which are used to treat infections like bronchitis and pneumonia.
When bacteria begin to copy their DNA, quinolones cause the strands to break and then prevent the breaks from being repaired. Your pediatrician may prescribe penicillin for your child for prevention of acute rheumatic fever.
Sometimes, a child who has been bitten by a dog, another animal, or even another person will be given medicines to prevent an infection from developing. When youngsters are hospitalized for a surgical procedure, they may be given medicines before their operation to prevent an infection from developing at the site of the surgical incision. Typically, these drugs are given to children no more than 30 minutes before the operation.
If your pediatrician believes that your child can benefit from taking medicines as a preventive measure, your pediatrician will choose them carefully and prescribe them for the shortest possible period.
This strategy will reduce the chances that use of these drugs will contribute to the problem of antimicrobial resistance. You may be trying to access this site from a secured browser on the server. Please enable scripts and reload this page. Turn on more accessible mode. Turn off more accessible mode.
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