Superbugs Around Us and How They Come About

As we know, anything in life is not 100% perfect. Computers “act up”, Disinfectant sprays reading “kills 99.9% of germs”, and even human error prevents things being totally precise. It’s safe to say when regarding bacteria and infections, all people want 100% results. However, because of miscalculations, natural occurrences, and environmental cesspools, “superbugs”, have formed. Sounding like something out of a comic book, superbugs are formed as a result of the use of antibiotics. Some bacteria cells survive the exposure to antibiotics, and in turn, become immune to certain widely used drugs to treat bacterial infections.

These bacterial species can become stronger due to the stress that antibiotics inflict on bacterial cells, causing them to mutate. In general, the probability of mutation occurring by chance is about one out of every million copies of a gene of a bacterium. The ability for these prokaryotic cells to change offers harmful effects on humans because 100% of them are not dying. Vancomycin-resistant Staphylococcus aureus (VRSA), a strain of MRSA, or otherwise known as staph infection, arose from mutation. Vancomycin is the drug of last resort for this infection, proposing the educated guess of the possibility of more mutations and another antibiotic-resistant strain, leaving no drug to treat it.

Resistant genes are also made apparent by gene transfer. Humans reproduce sexually; traits are transferred vertically from parent to child. Prokaryotes do not reproduce sexually, but they exchange DNA between cells. This is known as horizontal gene transfer.  There are three ways horizontal gene transfer can occur: conjugation, transduction, and transformation.  

Conjugation requires cell-to-cell contact, and is common with E. coli. When E. coli cells become in contact with one another, plasmids are transferred. The best known plasmid capable of transfer is the F Plasmid, F for fertility factor. Cells that contain F plasmids are known as F+ cells, and cells that do not have the F plasmid cells are called F- cells. During the process of conjugation in E. coli, the F+ donor cell comes in contact with the F- recipient cell, and a pilus is formed on the F+ cell, acting as a the conjugation bridge. The F plasmid is replicated in the donor cell, displacing a parental strand, which gets transferred to the recipient cell and replicated once more. The F plasmid’s DNA is copied into the F- cell, changing it to an F+ cell. The new F+ cell then has the capability to use the same technique to transfer DNA as the original donor cell. The process is known as the rolling-circle replication.

Transduction is seen as an accident. When a phage infects a cell, it injects its DNA into the cell, and the phage DNA is replicated, and the host DNA is degraded. Phage particles are then packaged with DNA and released. When the phage package their DNA, they can package host DNA instead of phage DNA, producing a transducing phage. When the transducing phage infects a new cell, it only injects a piece of chromosomal DNA, which is incorporated by homologous recombination. The new cell contains DNA from the donor. The transducing phage incorporates its DNA into a cell, resulting in change in the genetic makeup of the cell to be like the donor cell, rather than phages being released as explained before.

Transformation occurs when one cell dies and releases its contents to its surroundings. These DNA fragments and be taken up in another cell and the DNA is incorporated by homologous recombination. The cell then contains DNA from the donor cell.

Antibiotic resistance can also occur due to contact with animals. Animals raised for food are given antibiotics either to promote growth, like Ractopamine, which promotes lean muscle growth, or to treat infections. “When you give low-dose antibiotics for growth promotion or for prophylaxis of infection, you end up killing off the susceptible bacteria, whether they’re E. coli, salmonella, campylobacter, or other bacteria,” says Robert S. Lawrence, M.D., director of the Center for a Livable Future at the Johns Hopkins Bloomberg School of Public Health in Baltimore. “And you continue to select for those bacteria that, through spontaneous mutations or transfer of genes from other resistant bacteria, allow them to be resistant to antibiotics.” This is an example for the “cesspools” mentioned before. Because of the close living quarters of the animals, it is a breeding ground for new antibiotic resistant bacteria cells to form.

Another breeding ground is hospitals. Since superbugs evolve from the heavy use of antibiotics, hospitals are a culprit. Also, considering the amount of open wounds and tubes carrying blood, that is another reason why hospitals are susceptible to antibiotic resistant superbugs. College campuses are another environment superbugs enjoy because of the unwashed clothing and sheets, being exposed to so many people, frequently used cafeteria trays, and even beer pong cups.

http://www.consumerreports.org/cro/pork0113.htm
http://www.thedailybeast.com/articles/2010/08/12/superbug-facts-to-know-as-ndm-1-emerges.html

Nanoparticle vs. Superbug

On Monday, April 4, 2011, IBM announced information on their development of a new technology that combats and conquers drug-resistant bacteria. This drug-resistant bacteria, aka superbugs, are responsible for thousands of deaths every year. The most famous example of a superbug is MRSA. The researchers at IBM developed a new nanoparticle that essentially breaks down the cell membrane of drug-resistant bacteria, leaving the cell to biochemically degrade harmlessly inside the body. The new technology works by using "biodegradable plastic to engineer electrically charged nanoparticles that in turn attract to the bacteria’s opposite charge, in turn destroying the membrane walls hence the cell entirely." Other antibiotics work to destroy the DNA of the bacteria, which is almost always effective. Sometimes, however, not all of the bacteria is destroyed, and the remaining bacteria develops a resistance to the anitbiotics previously used, leading to a strain of superbugs. The new medicine developed by IBM destroys the bacteria's cell membrane, allowing it to degrade inside the body. Since the medicine is also composed of only organic materials, the human body can safely dispose of it, meaning that there are no side effects like most medicines can have. This new system was testing on mice infected with MRSA and proved to be very successful. IBM is in the process of setting up human trials with several pharmaceutical companies.

This article made me very happy! Hearing that someone finally had a breakthrough in developing medicine to fight drug-resistant bacteria gives me hope that breakthroughs for other diseases such as cancer or HIV/AIDS can happen as well. This discovery can lead to saving thousands and even millions of lives! Hopefully they can get the CDC to approve this new medicine rather soon so we don't have to worry about the new superbug in hospitals anymore (see "Superbug Runs Rampant").

Superbug Runs Rampant

Lately there have been stories on the news about a "superbug" that has infected many patients in hospitals across the country, even killing some of them. One news station reports on a case in Birmingham, Alabama, where 19 people were infected in 6 different hospitals; 9 of them were killed. A superbug is a type of bacteria infection that is resistant to antibiotics, the classic example being MRSA. Currently the most infected region of the country is around Los Angeles, California. In the Alabama case, health officials discovered that the outbreak was linked to a batch of IV bags produced by Meds IV in Birmingham. The IV was fed directly into the bloodstream of hospital patients, and the resulting infection was caused by serratia marcescens, "a bacteria that typically strikes patients with a compromised immune system." This is not the first time an outbreak of superbugs has occurred. Five years ago, a similar outbreak spread through hospitals in both California and New Jersey. The bacteria can be treated if caught early. This superbug is strong though, causing 60% of all infections in ICUs across the country.

I found this article not only interesting but also scary. I had never heard of the outbreak 5 years ago, so this was new to me. I had first heard the story on 6ABC news, but couldn't find their online article. It scared me because my boyfriend is currently stationed in southern California, merely 2 hours away from Los Angeles, which is said to be the most infected region. I hope they can figure out a cure to this soon.