Antibiotic Resistance

Antibiotic Resistance


The Purdue Global Science Center
presents Antibiotic Resistance. Antibiotic resistance became a priority
area of research all around the world over the last few decades. In order to
understand how resistance occurs, we will first discuss how antibiotics work.
Antibiotics are a class of antimicrobial agents administered to combat infectious
living organisms. This includes fungi, protists, and bacteria. Though the focus
of this presentation will be with regards to bacteria, it must be noted
that antibiotic resistance can occur in all protists and fungi. Bacteria are one celled organisms that
live naturally in all environments including on and within the human body.
Many of these bacteria are harmless, but some are harmful and cause debilitating
in life-threatening infections. Antibiotics can be administered
topically, orally through injection, or intravenously. There are many different
forms of antibiotics. All aim at eliminating the microbial infection. The
first mass-produced antibiotic was originally discovered in 1928. Alexander
Fleming is credited with discovering the first antibiotic penicillin. He was
inspired to seek better cures and treatments for bacterial infections due
to his battlefield experiences during World War One. He tested a variety of
substances by growing bacterial cultures in petri dishes and then exposing the
colonies to different substances, even including tears, which contain a natural
enzyme that prohibits bacterial growth. While he had limited success
in 1928, he fortuitously discovered that a species of mold, which was a
contaminant within his experiment, prevented the growth of staph bacteria.
The petri dish here shows bacterial growth in the form of a cloudy haze. The
white discs contain substances that may prevent bacterial growth. Notice that
most of these display a halo clear of bacteria. Fleming observed a similar
pattern in the dish in which he found the fungus growing. He further
experimented with this mold called penicillium notatum and published his
results but was unable to successfully mass-produce an adequately test
penicillin. His work was further advanced by the
biochemist Ernst Chain who was ultimately able to mass-produce
and test the antibiotic by injecting it into mice. Penicillin became available to
humans worldwide by the end of World War Two. Since the discovery of this first
widely available antibiotic, numerous others have been discovered, and their
uses go beyond human applications to veterinary medicine and in the raising
of livestock. Though various antibiotics have been
discovered since the 1920s, they all function in similar ways to eliminate
infections. Some antibiotics target specific strains of bacteria while
others target general classes or groups of bacteria. They may compromise the
cellular structure of the bacteria and therefore destroy them, or they may
interfere with the life processes of the bacteria. They may inhibit reproduction,
disrupt energy pathways, or prevent the production of proteins by the bacterial
cells. All of these approaches ultimately prevent the bacteria from reproducing or
surviving and therefore eventually eliminate the infection. Antibiotic resistance can develop in a
variety of ways. The natural process of genetic mutation can cause the
development of drug resistance through reproduction, which requires the
replication of DNA mutations or changes in the DNA can occur spontaneously, and
these mutations have the ability to make bacterial cells resistant to a
particular antibiotic. These bacteria are therefore not destroyed, and they can
lead to a resistant infection. Bacteria also have the ability to transfer
segments of DNA amongst one another. This can result in the spread of a gene that
causes drug resistance to bacteria previously not resistant to that drug.
Misuse of the antibiotics can also result in the formation of antibiotic
resistant strains. Antibiotics must be administered at a high enough
concentration and for a specific length of time in order to ensure the bacterial
infection is completely eliminated. If some of the infecting bacteria remain,
they will continue to reproduce and will pass on their drug resistant traits to
all future generations resulting in the development of an increasingly resistant
population of bacteria. Inadequate diagnosis of the actual infection can
lead to the prescribing of an inappropriate antibiotic further
advancing the development of the resistant bacteria. Though the
development of antibiotics has saved countless lives,
now after 50 years of widespread use of a variety of antibiotics, resistance has
become a challenge around the world. One resistant strain of bacteria is
methicillin-resistant Staphylococcus aureus, more commonly known as MRSA. It derives its name from the antibiotic methicillin previously capable of
controlling an infection caused by this bacteria. MRSA was originally identified
in 1961 and was first reported in the United States in 1968. Since then it has
become resistant to many other types of antibiotics. Vancomycin
enterococci, known as VRE, is another type of common bacterial infection within
hospitals, and it is of particular interest among researchers since it has
the ability to transfer its antibiotic resistant genes to other strains of
bacteria like the previously mentioned MRSA. Resistance is also a concern within antibiotic use for livestock, which accounts for over 50% of the antibiotic
usage in the United States. Some approaches to dealing with the problem
of antibiotic resistance are to reduce improper uses by patients as well as
incorrect diagnosis by doctors. Both of these accelerate the development of
resistant forms of bacteria. The National Institute of Allergy and Infectious
Disease, part of the Department of Health and Human Services within the National
Institute of Health, has identified a number of high-priority areas of
research including in-depth study of the already present resistant strains of the
organisms improving diagnostic techniques, creating new therapies or
treatments, including vaccines and also improving the prevention and slowing the
spread of the infectious agents.

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