Discover Magazine improved greatly after it was sold by Time Warner to Kalmbach Publishing. Discover Magazine http://discovermagazine.com now has many in-depth articles which are very well written. This science magazine is so good it is well worth subscribing to this monthly magazine. It is clear and easy to understand, a feat not always achieved by the New York Times. You need to be a subscriber to get to the real substance of these monthly articles.
Jim Kawakami, April 12, 2011, http://jimboguy.blogspot.com
Discover Magazine Blog: Gram Negative Bacteria, including 20 common ones for Cholera, Pneumonia, Dysentery, have developed a gene which is resistant to a drug of last resort
Based on an article in Lancet:
April Discover Magazine, 2011. What’s the News: A gene that makes bacteria resistant to up to 14 antibiotics has been discovered in bacteria in drinking water and street puddles in the Indian capital of New Delhi by a research team from the University of Cardiff in Wales. Scientists were already aware that microbes bearing this gene, which produces an enzyme called NDM-1, were infecting people in India, but it had been thought that such bacteria were mainly picked up in hospitals. This study shows that the gene, which is capable of jumping from species to species, is loose in the environment.
What’s the Context:
- NDM-1 is in a class of enzymes that are known culprits in the spread of drug-resistance: the beta-lactamases. The first beta-lactamase, penicillinase, was discovered in 1940 ($, pdf). These enzymes give resistance to antibiotics like cephamycins, carbapenems, and penicillin, which have similar chemical structures.
- The study is fueling fears that the NDM-1 gene could easily jump into bacteria around the world. Recently, a separate team of scientists showed that Swedish tourists returning from India had bacteria with beta-lactamases in their guts that they hadn’t had before the trip. And as the current study found that the gene for NDM-1 skipped easily among bacterial species, the researchers are calling for greater action to fight drug-resistant bacteria in developing countries.
- Indian officials have spoken out against the study, in part over fears that it will damage India’s tourism industry. In an AP article, V.M. Katoch, director-general of the Indian Council of Medical Research, said, “We know that such bacteria with genes are in the atmosphere everywhere. This is a waste of time. The study is creating a scare that India is a dangerous country to visit. We are condemning it.”
- This isn’t the first time we’ve heard of NDM-1: the gene has been on scientists’ radar since 2008, when it was first identified in a Swedish tourist returning from India. (For more background on the gene, see Scientific American’s coverage.)
Not So Fast:
- The term “superbug” has been racing from media outlet to media outlet. But this is a bit of a misnomer: this isn’t a single new bacteria species endowed with phenomenal resistance, it’s a gene that can bestow it.
- The difference is important. Dealing with a gene that can make any number of disease-causing bacteria resistant may be more difficult than focusing on just one species of bug—especially as the team found the gene in 20 types of bacteria, including those that cause dysentery and cholera. But the study’s findings suggest that the gene is much more likely to jump to new bacteria while outside the host (at temperatures typical of India’s climate, transfers were high; at body temperature, they dropped off). It would be interesting to see whether the fact that the gene needs lower temperatures to transfer could used to prevent its spread: if the transfer happens in drinking water, then better water treatment might help delay the formation of new resistant strains.
Reference: Toleman, M. et al. Dissemination of NDM-1 positive bacteria in the New Delhi environment and its implications for human health: an environmental point prevalence study. The Lancet Infectious Diseases, Early Online Publication, 7 April 2011. doi:10.1016/S1473-3099(11)70059-7
April 8th, 2011 9:45 AM Tags: antibiotic resistance, beta-lactamase, India, infectious disease, NDM-1, pharmaceuticals, superbugs, The Lancet
by Veronique Greenwood in Environment, Health & Medicine, Living World | 5 comments | RSS feed | Trackback >
March 2011 Discover Magazine: Why We Need a Healthy Gut Because Antibiotics are Rapidly Becoming Useless Due to Large Use in Animal Farms http://discovermagazine.com/ … Heavy use of antibiotics can lead to antibiotic resistance, but researchers now speculate that antibiotics can also upset the balance of the microbial community, allowing disease to take over rather than fighting it. Michael Cotten, another neonatologist on the Duke project, analyzed the duration of antibiotic therapy given to 4,039 premature babies at 19 treatment centers across the country and found that prolonged use of the drugs is associated with increased risk of necrotizing enterocolitis and death. Antibiotics probably also prevent beneficial bacterial communities from forming in infants.
Last year, Stanford microbiologist David Relman published a study that illustrated the potentially devastating impact of antibiotics on the microbiome. He gave three healthy adults a five-day course of the antibiotic Cipro, then another course six months later, and monitored the state of the microbiome after each treatment. The gut flora of all three subjects gradually recovered from the impact of the antibiotic treatment but never returned to their original state—they had different compositions and were less diverse. “We don’t know if these differences matter to health,”
Relman says. “But in general, you’d be concerned about a change.” He had chosen Cipro because it has limited effectiveness against most species of bacteria in the gut, but it still affected one-third to one-half of the microbial flora in the subjects. “Knocking out one organism could have a ripple effect on the lives of others,”
This is especially concerning given that the number of different microbial species in the intestines may be important in countering pathogens. “The greater the diversity, the lower the probability that pathogens can invade and persist,” says Richard Ostfeld, a disease ecologist at the Cary Institute of Ecosystem Studies in New York. “If all the niches are taken up in the gut, it might be hard for them to get hold.”
This is especially concerning given that the number of different microbial species in the intestines may be important in countering pathogens. “The greater the diversity, the lower the probability that pathogens can invade and persist,” says Richard Ostfeld, a disease ecologist at the Cary Institute of Ecosystem Studies in New York. “If all the niches are taken up in the gut, it might be hard for them to get hold.” …
Specially packaged mixtures of microbes, known as probiotics, may also prove useful for balancing microbes in the gut (See “Bugs for Breakfast,” page 4). Probiotics are now generally sold as health food supplements, and many of them are promoted as magic bullets that can improve metabolism or bolster immunity. Since they are as yet unregulated by the FDA, though, it is impossible for the consumer to know exactly what is inside; labels on over-the-counter products can be deceptive. Scientists who have tested them have often found something quite different from what the product promises. Nevertheless, carefully regulated probiotics, which introduce nonpathogenic competitors to disease, could be effective at balancing the gut microbiome. …
The Duke group is still puzzling over how to translate their microbiome findings into practical treatments for premature infants. But at least one procedure that allows doctors to manipulate the gut microbiome is already here. A team led by University of Minnesota immunologist and gastroenterologist Alexander Khoruts has recently demonstrated spectacular success with fecal transplants, which introduce healthy stool microbes into a diseased bowel. An obscure and poorly understood procedure, it was first developed in the 1950s, well before anyone grasped the importance of the gut microbiome.
Khoruts and his colleagues reported last summer that they were able to use a fecal transplant to treat and apparently cure a woman with a life-threatening Clostridium difficile infection, which causes severe inflammation of the colon. The patient had an extremely poor prognosis: Suffering from chronic diarrhea, she had lost 60 pounds over eight months. “All antibiotics were failing, and she was in really bad shape,” Khoruts says. In a last-ditch effort to improve her condition, he mixed a small sample of the patient’s husband’s stool with saline solution and injected it into her colon. Within 24 hours her diarrhea had stopped. After a few days, the symptoms were gone.
In studying this patient’s progress, Khoruts was initially surprised to find that there was a nearly complete replacement of the woman’s microbial flora with her husband’s microbes. “By the time these patients get to this desperate treatment point, they’ve taken so many antibiotics that their microbiome has been decimated,” he says. “So when we transplant the new bacteria, they simply move in to occupy the empty space.” Before Khoruts and his team performed the procedure, no research had been done on how fecal transplants work or how they impact the microbiome. “Since then we’ve done another 23 patients,” he reports, “all with dramatic stories.” …