Despite the rising menace of bacteria—at roughly 19,000 a year, more Americans die from drug-resistant Staphylococcus aureus infections than from HIV/AIDS—the microorganisms do deserve some credit for their cleverness. Antibiotic-resistant strains reared their heads 60 years ago, and ever since scientists have been struggling to develop second-generation drugs that attack not the bacteria themselves—which promotes resistance—but rather their cell-to-cell communication with one another. Progress has been slow, however, as bacteria have once again proved more complex than anticipated. But now insights from social evolutionary biology may finally point the way to outsmarting the microbes—by exploiting certain members to undermine the entire group.
Forty years ago scientists discovered that some bacteria send and receive messages—in the form of small molecules—to and from surrounding cells. This kind of communication, called quorum sensing, enables bacteria to monitor their population density and to modulate their behavior accordingly. When there are enough cells around to create a “quorum,” bacteria begin producing proteins known as virulence factors that sicken their hosts. They can also grow into aggregates called biofilms that render them up to 1,000 times more resistant to antibiotics.
Quorum sensing is now known to be widespread in the bacterial world, and many researchers hope to develop ways to disrupt it. Kim Janda, a chemical biologist at the Scripps Research Institute in La Jolla, Calif., calls this strategy a “stealth approach.” Antibiotics kill bacteria or prevent them from growing, enabling resistant mutants to thrive; drugs that disrupt quorum sensing, on the other hand, would spare the microbes’ lives, simply preventing them from causing disease or building biofilms.
The problem is that good quorum-sensing inhibitors have been hard to find. The molecules that bacteria use for communication are often species-specific, so developing universal inhibitors is difficult. Moreover, disruptors found to work well in animals have proved toxic to humans. And some researchers worry that these drugs would be efficacious only at the start of an infection, before a quorum had been reached. As a result of these challenges, few pharmaceutical companies have invested in communication-related drug strategies. “People are a little wary of it,” says Helen Blackwell, a chemist at the University of Wisconsin–Madison.
In January, however, University of Edinburgh evolutionary biologist Stuart West and his colleagues announced that they had devised a new idea based on a known quorum-sensing nuance: not all bacteria in a given population communicate normally. So-called signal-blind mutants produce low-level signals but do not respond to them, whereas signal-negative mutants respond to signals but do not produce them.
These cheats still reap the benefits of quorum sensing because their neighbors cooperate, but they conserve a lot of energy relative to their peers. As a result, they thrive and replicate quickly—causing subsequent generations to contain larger and larger proportions of cheats. But once these cheats become too prevalent, communication is so rare that the population cannot reach a quorum, and its overall virulence drops.
West and his colleagues recently infected a group of mice with normal Pseudomonas aeruginosa—a bacterium commonly associated with hospital infections—and infected two other groups with mixtures of half normal Pseudomonas and half signal-blind or signal-negative cheats. Seven days later the mice infected with the mixtures were twice as likely to be alive as compared with the mice infected with normal strains. “It seems crazy, but it’s feasible to think that maybe if you’ve got an infection, you could put in a mutant social cheat,” and it could help cure you, West says.
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Add CommentExcellent research, guys.
Reply | Report Abuse | Link to thisWith medical institutional infections in particular, sometimes death is a good thing- for a vicious multi-cellular organism.
Reply | Report Abuse | Link to thisThere are a variety of different types of bacterial infections one can get from many different sources, yet some locations are more common than others. If bacteria are not beneficial for your health, as many bacteria are, they should die in order to restore your health.
Bacteria are a simple life form, yet are incredibly productive and efficient. As with other life forms, they exist to reproduce, and does so about every hour. Bacteria mutate, evolve, and adapt according to the host in which they exist.
To do this, it fully utilizes all available resources and energy to develop the protein that is essential for its survival in their host. Bacteria need exactly 7 genes to produce the essential ribosomes for their existence. Any more or less genes than 7, the bacteria is not maximizing its efficiency to survive and reproduce. Amazing.
Strep infections are caused by what are called gram positive bacteria, and they are the most common bacteria that infect other humans. . Group A strep infections can cause diseases such as strep throat and pneumonia. Also, staph bacterial infections are gram positive as well that potentially infect humans, and do so often.
Of all pathogenic, or disease-causing bacteria that exist, it is the MRSA, the methicillin resistant staff aureus bacteria, that are most concerning to health care providers in particular. This is because MRSA bacterial infections are the most difficult to cure when a patient suffers from their damage from being infected by these bacteria.
Another difficult situation is when a patient is infected by VRE, Vancomycin Resistant Enterococci, which is another type of gram positive bacteria that exist.
These MRSA and VRE bacteria are difficult to eradicate due to the fact that most antibiotics that are available to rid the patient of other bacterial infections, MRSA and VRE are resistant to the effectiveness of these antibiotics.
MRSA and VRE infected patients are quite challenging for the health care provider who is attempting to cure patients infected with these particular bacterial infections.
In many situations, pathogenic bacteria infect a patient already within a medical institution for another disease. When this occurs, it is called a nosocomial infection.
Greater than 5 percent of nosocomial infections are determined to be MRSA infections, it has been reported. As a result, there are about 100,000 serious hospital infections, as well as about 20,000 deaths from MRSA infections annually.
Since there are several types of pathogenic bacteria that exist, a diagnostic test called a culture and sensitivity is usually performed at a clinical laboratory to assure the correct antibiotic is selected for treatment, as the bacteria are identified with this diagnostic method.
Typically, fluid from the area suspected of being infected is obtained from the patient suspected to have an infection and smeared on what is called a petrie dish. And then these dishes are incubated for 2 to 3 days. Gram positive bacteria stain during this process a dark violet or blue. Gram negative bacteria would be pink in color, and are capable of harm as well to a human being.
When the culture is complete, technology that is available offers recommendations on the appropriate class or brand of antibiotic to treat the pathogenic bacteria present in another person- presuming the bacteria will not be resistant to the antibiotic recommended, as this happens on occasion.
Usually, classes of antibiotics that are used to treat gram positive strep infections that are not VRE or MRSA bacteria are cephalosporins, macrolides, or general penicillins. If the microbe that is causing the infection is resistant to the antibiotic from such classes that are administered to the infected patient, other options should be considered for anti-microbial therapy.
With two very powerful antibiotics in particular, which are methicillin and vancomycin, their frequent use in infected patients has resulted in VRE and MRSA bacteria that are now resistant to these antibiotics.
When a patient is infected with VRE or MRSA bacteria, other selections for antimicrobial therapy that provide more efficacy should be selected for a patient infected with these types of infections. Such brands and types of antibiotics for MRSA and VRE bacteria include Zyvox, which has both IV and oral dosage options, and an antibiotic called Cubicin.
However these antibiotics for antibiotic resistant bacteria are given usually due to infections that have progressed to a more serious nature within a patient infected in such a way, so a cure is not immediate when these antibiotics are selected for such patients.
Progressive medical conditions with such infected patients include sepsis, or blood infection, osteomyelitis, or bone infection, as well as pneumonia, which is a serious lung infection. A hospital stay is normally required with such patients infected with MRSA and VRE infections that cause such diseases.
This is because when the antibiotics that potentially cure the patient of these microbes are selected, they are usually given via IV administration, and are administered normally for several days, if not several weeks.
There are numerous classes and types of antibiotics available, yet bacterial resistance to most of these antibiotics, with the exception of the two mentioned earlier, constantly remain a serious concern for the health care provider, and the MRSA and VRE infected patient.
With MRSA at the top of the list of concerns for the health care providers, this infection continue to occur progressively, which amplifies the concerns of others.
Medical institutions should possibly consider quarantine for those patients at their locations that have been determined to be infected with the MRSA and VRE bacteria more often in the future.
http://www.cdc.gov/ncidod/dhqp/ar_mrsa_spotlight_2006.html
Dan Abshear
Has anyone considered the importance of probiotics in the war against these antibiotic-resistant bacteria? I take Natren Probiotics everyday to protect myself... www.truthaboutprobiotics.com
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