It's just a little black mushroom, but researchers at Georgetown University Medical Center are contending that Pseudoplectania nigrella, found in the woods of northern Europe, may spawn a powerful new class of antibiotics and antivirals.
"I think we are looking at a whole new world of antibiotics," said Michael Zasloff, MD, PhD, of Georgetown University Medical Center. Zasloff and colleagues' discovery was published in the 13 October issue of Nature and reported by MedPage Today on 13 October.
What's Plectasin
"Animals and higher plants express endogenous peptide antibiotics called defensins," write the investigators in their Nature article. "These small cysteine-rich peptides are active against bacteria, fungi and viruses. Here we describe plectasin-the first defensin to be isolated from a fungus-Pseudoplectania nigrella."
According to Zasloff, plectasin was tested against a range of bacteria, including streptococcus, enterococcus and staphylococcus, and other defensins have demonstrated anti-viral activity. He added that the existence of about 200,000 other species of fungus make it likely that many more fungal defensins will be found-among which may be highly targeted antimicrobial drugs that will supersede the current generation of broad-spectrum drugs.
"I think we as physicians are going to see assembly of a large number of antimicrobial peptides targeted against specific organisms, including viruses," Zasloff said, according to MedPage Today.
The researchers used a recombinant form of plectasin produced by Danish biotech company, Novozymes, who produced the plectasin at a commercially viable price, yield and purity, Dr. Zasloff reportedly said.
What the Studies Show
In in vitro studies, recombinant plectasin showed high activity against Streptococcus pneumoniae, including strains that are resistant to conventional antibiotics. In animal studies, plectasin showed extremely low toxicity in mice, while curing them of experimental pneumonia and peritonitis caused by S. pneumoniae as effecively as established antibiotics vancomycin and penicillin.
Despite plectasin's apparently low toxicity in mice, Zasloff reportedly said that further studies are necessary to determine if plectasin is safe for humans. However, he believes it is likely that the efficacy seen in mice will also be seen in humans, as the bacterial targets would be identical. Moreover, plectasin is excreted unchanged in mice's urine, which supports its safety and efficacy.
Why a Recombinant?
Plectasin's discovery could not have occurred using conventional techniques, according to Zasloff, in which the fungi would be grown in liquid cultures and tested for antimicrobial activity.
"When this mushroom is grown in the lab, it doesn't produce much plectasin," he reportedly said. Instead, Novozymes researchers went "scouring through the genetic messages" of wild fungi to find genes that code for specific molecules. "One of them coded for what we could clearly see was a defensin."
Now, a walk near his home brings dozens of mushrooms to Zasloff's attention, according to MedPage Today. "It's hard not to go back to the lab and see what they're making."
poniedziałek, 5 listopada 2012
Women and Antibiotics
Antibiotics are safe and effective medications prescribed to treat bacterial infections.
Here are possible side effects that women should be aware of before using these medications, courtesy of the Alliance for the Prudent Use of Antibiotics:
Yeast infections.
Diarrhea, upset stomach and vaginal infections.
Decreased effectiveness of birth control pills.
Certain antibiotics should not be taken by a woman who is pregnant or nursing, unless prescribed by a physician who is familiar with the woman's condition.
Antibiotics can interact with many other medications
Here are possible side effects that women should be aware of before using these medications, courtesy of the Alliance for the Prudent Use of Antibiotics:
Yeast infections.
Diarrhea, upset stomach and vaginal infections.
Decreased effectiveness of birth control pills.
Certain antibiotics should not be taken by a woman who is pregnant or nursing, unless prescribed by a physician who is familiar with the woman's condition.
Antibiotics can interact with many other medications
Knowing when to take antibiotics - and when not to - can help fight the rise of deadly "superbugs," say experts at the United States Centers for Disease Control and Prevention.
About half of antibiotics prescribed are unnecessary or inappropriate, the agency says, and overuse has helped create bacteria that don't respond, or respond less effectively, to the drugs used to fight them.
"Antibiotics are a shared resource that has become a scarce resource," said Dr. Lauri Hicks, a medical epidemiologist at the CDC. She's also medical director a of new program, Get Smart: Know When Antibiotics Work, that had its launch this week. "Everyone has a role to play in preventing the spread of antibiotic resistance," Hicks said.
The stakes are high, said Dr. Arjun Srinivasan, CDC's associate director for health care-associated infection prevention programs. Almost every type of bacteria has become stronger and less responsive to antibiotic treatment, he said.
The CDC is urging Americans to use the drugs properly to help prevent the global problem of antibiotic resistance. To that end, the U.S. Food and Drug Administration (FDA), numerous national medical and scientific associations, as well as state and local health departments have collaborated on the CDC's Get Smart initiative.
Most strains of antibiotic-resistant bacteria are still found in health care settings, such as hospitals and nursing homes. Yet superbugs, including MRSA (methicillin-resistant staphylococcus aureus) -- which kills about 19,000 Americans a year -- are increasingly found in community settings, such as health clubs, schools, and workplaces, said Hicks.
Community-associated MRSA (CA-MRSA), a strain that affects healthy people outside of hospitals, made headlines in 2008, when it killed a Florida high school football player.
Referring to recent reports of sinusitis caused by MRSA, Hicks said that "people who would normally be treated with an oral antibiotic are requiring more toxic medications or, in some instances, admission to a hospital. We've seen this with pneumonia, too, and I worry we'll start to see it with other types of infections as well."
Other infections that resist antibiotic treatment include:
E. coli. A new strain, ST131, was a major cause of serious resistant infections in the United States in 2007, a study published this year in Clinical Infectious Diseases found. If the strain gains one more resistance gene, the study said, it may become almost untreatable.
Gonorrhea. Only one last class of antibiotics -- cephalosporin--is recommended to treat this sexually transmitted disease.
XDR-TB (extensively drug-resistant tuberculosis). While many TB strains resist at least one antibiotic used to treat them, XDR-TB is resistant to virtually all of them.
Just as antibiotic resistance is rising, the antibiotic arsenal is shrinking. The FDA has approved just 10 new antibiotics since 1998. "But in our opinion, it's as important to improve [antibiotic] use as it is to develop new drugs," said Srinivasan.
Antibiotic resistance has two main causes, said Philip Tierno, director of clinical microbiology and immunology at New York University's Langone Medical Center. The first is overprescribing.
"About six billion prescriptions are written annually in this country, about half of them for antibiotics," he said. "Of those written for antibiotics, the CDC thinks about half are improper."
Second, food animals such as chickens, cattle and hogs are given massive amounts of antibiotics, mainly to spur growth. "Of the 25 million pounds of antibiotics given to livestock per year, only three million pounds are given to treat disease," said Tierno. Earlier this year, concerns about antibiotic resistance led the FDA to recommend that farmers stop using antibiotics to promote growth in livestock.
To protect antibiotics' effectiveness, the CDC recommends the following:
Take the antibiotic exactly as prescribed, and finish it even if you start to feel better. That way, bacteria can't survive and re-infect you.
Throw out leftover antibiotics.
Don't ask your doctor for an antibiotic if you have a cold or the flu. They're caused by viruses, so antibiotics won't help.
If you think you have strep throat, ask to be tested. Only a test can tell if your sore throat is caused by a bacterial infection and thus requires an antibiotic.
Don't take an antibiotic prescribed for someone else. Taking the wrong medicine may delay the right treatment and allow bacteria to multiply.
If your child has an ear infection, watch and wait. This method is the best way to treat childhood ear infections, which are often caused by a virus, according to a new study published this week the Journal of the American Medical Association .
About half of antibiotics prescribed are unnecessary or inappropriate, the agency says, and overuse has helped create bacteria that don't respond, or respond less effectively, to the drugs used to fight them.
"Antibiotics are a shared resource that has become a scarce resource," said Dr. Lauri Hicks, a medical epidemiologist at the CDC. She's also medical director a of new program, Get Smart: Know When Antibiotics Work, that had its launch this week. "Everyone has a role to play in preventing the spread of antibiotic resistance," Hicks said.
The stakes are high, said Dr. Arjun Srinivasan, CDC's associate director for health care-associated infection prevention programs. Almost every type of bacteria has become stronger and less responsive to antibiotic treatment, he said.
The CDC is urging Americans to use the drugs properly to help prevent the global problem of antibiotic resistance. To that end, the U.S. Food and Drug Administration (FDA), numerous national medical and scientific associations, as well as state and local health departments have collaborated on the CDC's Get Smart initiative.
Most strains of antibiotic-resistant bacteria are still found in health care settings, such as hospitals and nursing homes. Yet superbugs, including MRSA (methicillin-resistant staphylococcus aureus) -- which kills about 19,000 Americans a year -- are increasingly found in community settings, such as health clubs, schools, and workplaces, said Hicks.
Community-associated MRSA (CA-MRSA), a strain that affects healthy people outside of hospitals, made headlines in 2008, when it killed a Florida high school football player.
Referring to recent reports of sinusitis caused by MRSA, Hicks said that "people who would normally be treated with an oral antibiotic are requiring more toxic medications or, in some instances, admission to a hospital. We've seen this with pneumonia, too, and I worry we'll start to see it with other types of infections as well."
Other infections that resist antibiotic treatment include:
E. coli. A new strain, ST131, was a major cause of serious resistant infections in the United States in 2007, a study published this year in Clinical Infectious Diseases found. If the strain gains one more resistance gene, the study said, it may become almost untreatable.
Gonorrhea. Only one last class of antibiotics -- cephalosporin--is recommended to treat this sexually transmitted disease.
XDR-TB (extensively drug-resistant tuberculosis). While many TB strains resist at least one antibiotic used to treat them, XDR-TB is resistant to virtually all of them.
Just as antibiotic resistance is rising, the antibiotic arsenal is shrinking. The FDA has approved just 10 new antibiotics since 1998. "But in our opinion, it's as important to improve [antibiotic] use as it is to develop new drugs," said Srinivasan.
Antibiotic resistance has two main causes, said Philip Tierno, director of clinical microbiology and immunology at New York University's Langone Medical Center. The first is overprescribing.
"About six billion prescriptions are written annually in this country, about half of them for antibiotics," he said. "Of those written for antibiotics, the CDC thinks about half are improper."
Second, food animals such as chickens, cattle and hogs are given massive amounts of antibiotics, mainly to spur growth. "Of the 25 million pounds of antibiotics given to livestock per year, only three million pounds are given to treat disease," said Tierno. Earlier this year, concerns about antibiotic resistance led the FDA to recommend that farmers stop using antibiotics to promote growth in livestock.
To protect antibiotics' effectiveness, the CDC recommends the following:
Take the antibiotic exactly as prescribed, and finish it even if you start to feel better. That way, bacteria can't survive and re-infect you.
Throw out leftover antibiotics.
Don't ask your doctor for an antibiotic if you have a cold or the flu. They're caused by viruses, so antibiotics won't help.
If you think you have strep throat, ask to be tested. Only a test can tell if your sore throat is caused by a bacterial infection and thus requires an antibiotic.
Don't take an antibiotic prescribed for someone else. Taking the wrong medicine may delay the right treatment and allow bacteria to multiply.
If your child has an ear infection, watch and wait. This method is the best way to treat childhood ear infections, which are often caused by a virus, according to a new study published this week the Journal of the American Medical Association .
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