Molecules of Life - Discussing Antibiotic Resistance
Molecules of Life - Discussing Antibiotic Resistance
Just like Fleming said, “one sometimes finds what one is not looking for”, the existence of antibiotics were found by him in this interesting way. This opens the era for the antibiotics. However, under the glorious effects that antibiotics can give people, in the modern time, so widely used by people all around the world, a severe problem comes to us, the antibiotic resistance.
Antibiotic resistance is a type of drug resistance where a microorganism is able to survive the exposure to an antibiotic. Genes can be transferred between bacteria in a horizontal fashion by conjugation, transduction, or transformation. Thus a gene for antibiotic resistance which had evolved via natural selection may be shared. Evolutionary stress such as exposure to antibiotics then selects for the antibiotic resistant trait. Many antibiotic resistance genes reside on plasmids, facilitating their transfer. If a bacterium carries several resistance genes, it is called multiresistant or, informally, a superbug or super bacterium. ----(1)
In this way, we can better understand why some bacteria are becoming “stronger” and “more powerful”. It is the way of natural selection just like us. We, human beings, after a very long period of time of natural selection, can achieve the technology and civilization we have now. In the competition with other animals, human beings learnt how to use tools, to use languages, and to better use hands.
Here are some examples of Antibiotic resistance:
Methicillin-resistant Staphylococcus Aureus (MRSA)
MRSA is a type of staph bacteria that is resistant to certain antibiotics called beta-lactams. These antibiotics include methicillin and other more common antibiotics such as oxacillin, penicillin, and amoxicillin. In the community, most MRSA infections are skin infections. More severe or potentially life-threatening MRSA infections occur most frequently among patients in healthcare settings. While 25% to 30% of people are colonized in the nose with staph, less than 2% are colonized with MRSA (Gorwitz RJ et al. Journal of Infectious Diseases. 2008:197:1226-34.). ----(2) MRSA was first detected in Britain in 1961 and is now common in hospitals. MRSA was responsible for 37% fatal cases of sepsis in the UK in 1999, up from 4% in 1991. Many years later, people found another kind of antibiotic called Linezolid, that was in effect against MRSA in 1990’s, whose resistance was found in Staphylococcus aureus in 2003.
Streptococcus pyogenes infections can usually be treated with many different antibiotics. Early treatment may reduce the risk of death from invasive group A streptococcal disease. However, even the best medical care does not prevent death in every case. For those with very severe illness, supportive care in an intensive care unit may be needed. For persons with necrotizing fasciitis, surgery often is needed to remove damaged tissue. Strains of S. pyogenes resistant to macrolide antibiotics have emerged, however all strains remain uniformly sensitive to penicillin.
Resistance of Streptococcus pneumoniae to penicillin and other beta-lactams is increasing worldwide. The major mechanism of resistance involves the introduction of mutations in genes encoding penicillin-binding proteins. Selective pressure is thought to play an important role, and use of beta-lactam antibiotics has been implicated as a risk factor for infection and colonization. Streptococcus pneumoniae is responsible for pneumonia, bacteremia, otitis media, meningitis, sinusitis, peritonitis and arthritis.Penicillin-resistant pneumonia caused by Streptococcus pneumoniae (commonly known as pneumococcus), was first detected in 1967, as was penicillin-resistant gonorrhea. Resistance to penicillin substitutes is also known as beyond S. aureus. By 1993 Escherichia coli was resistant to five fluoroquinolone variants. Mycobacterium tuberculosis is commonly resistant to isoniazid and rifampin and sometimes universally resistant to the common treatments. Other pathogens showing some resistance include Salmonella, Campylobacter, and Streptococci.
Enterococcus faecium is another superbug found in hospitals. Penicillin-Resistant Enterococcus was seen in 1983, vancomycin-resistant enterococcus (VRE) in 1987, and Linezolid-Resistant Enterococcus (LRE) in the late 1990s.
Situations here are clear to us that while we are given protection under several antibiotics, the risks that these powerful drugs are bringing to us is technically getting higher and higher. Ironically, an antibiotic being found somehow means we have to find another new antibiotic to kill the antibiotic-resistant bacteria. The circulation goes on and on with no end we can see.
First found as a very useful and effective way to control the growth of some bacteria, being appreciated for its ability people have never seen before, antibiotics became the “angel” to human beings to relieve suffer and to control some microorganisms. Well, the “side effect” wasn’t known at that time, which leads to the abuse, which is responsible for the “evolution” of some bacteria. The stronger and more powerful one antibiotic can be, the stronger and even more powerful one bacterium can become. This two-side sword hurts both sides but our human beings are under the risks and attacks coming from several bacteria right now. No one can simply tell whether antibiotics have become “devil” to us since before the discovery, bacteria were weak and not that powerful. Just like pains always come with development of technologies in history, pains caused by this development finally come to us in the antibiotic field. Since we don’t know how hard a bacterium could become, even one that is immune to every antibiotic, we need to think properly about this issue. When eventually one bacterium becomes undefeatable, the antibiotics will become the devil with super resistance.
(1) http://en.wikipedia.org/wiki/Antibiotic_resistance Wikipedia
(2) http://www.cdc.gov/mrsa/ Centers for Disease Control and Prevention
(3)http://www.experiment-resources.com/history-of-antibiotics.html Experiment Resource