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How a MRSA strain came to flourish
February 21st, 2012
04:29 PM ET

How a MRSA strain came to flourish

How did MRSA, a persistent and  deadly bug, become the drug-resistant bacteria vexing medical and public health experts?

The answer is in the genes.  Researchers have pinpointed how a common strain found in livestock, called Staphylococcus aureus CC398 bounced from humans, when it was treatable, to animals where it became antibiotic resistant. 

Drug-resistant staph infection has been linked to the over use of antibiotics in livestock.  This is the first study to chart the genetic link between that and its consequences in humans.

MRSA, methicillin-resistant Staphylococcus aureus, is a type of staph bacteria that is resistant to common antibiotics. Staph infection can be especially deadly when it occurs in people who have weak immune systems.  But it’s usually treatable through antibiotics.  The problem with MRSA is that it's a superbug – unable to be treated or cured with the usual antibiotics.

MRSA has resulted in 278,000 hospitalizations and more than 18,000 deaths in 2005, according to one study.

In a study published Tuesday in online journal mBio, researchers from Translational Genomics Research Institute in Arizona, Statens Serum Institut in Denmark, and several other institutions, sequenced the genes of this particular bacteria.

The strain, Staphylococcus aureus CC398 started in humans and was still treatable with antibiotics, said Lance Price, director of the Center for Food Microbiology and Environmental Health Translational Genomics Research Institute in Arizona.

It  spread to livestock, which are usually pumped with antibiotics, to keep them healthy. “The lineage appears to have undergone a rapid radiation in conjunction with the jump from humans to livestock, where it subsequently acquired tetracycline and methicillin resistance,” according to the study.

 Methicillin and tetracycline are among the most common antibiotics used to treat staph infections.

The problem is in the way animals are raised and pumped with antibiotics, said Price, the lead author of the study.  He said that farmers and ranchers give millions of pounds of antibiotics to farm animals to make them grow faster and to prevent - rather than treat - diseases.

It’s a controversial practice that has been banned in the European Union since 2006 because it contributes antibiotic resistance.

Farmers and workers surrounded by livestock are exposed to MRSA, which thrives in cluttered, congested and unclean feeding operations, Price said.  They tend to be “overcrowded, have tons of contact, compromised skin, and they’re filthy.  Now think about introducing an antibiotic in that setting,” he said.

“I couldn’t engineer a better system for creating drug-resistant bacteria or a superbug, than introducing antibiotics into a concentrated animal feeding operation,” Price said.  “It’s begging for disaster.”

Earlier this year, the FDA prohibited one class of antibiotics in cattle, pigs, chickens and turkeys starting April 5, 2012, but some critics say this only restricts one class of drugs and that more regulation is needed to prevent more deadly strains.

“It’s underscoring that as we’re using millions of antibiotics, we’re selecting for drug resistant bacteria to come back and haunt us,” Price said.


soundoff (47 Responses)
  1. JimPurdy.blogspot.com

    I'm not worried about pig-sty germs making me sick and putting me in the hospital. I'm more worried about the unsanitary pig-sty conditions in hospitals.

    In recent years, every time I've been in a hospital, it takes about 2 days for me to get a hospital-acquired staph infection, 2 more days to get MRSA, 2 more days to get VRE, and then doctors want to keep me in the hospital until my insurance benefits expire - or I expire, whichever comes first.

    If I have a choice between being around pigs or being around hospitals, I'll take the pigs.

    February 21, 2012 at 17:14 | Report abuse | Reply
    • Valentijn

      Did you miss the part where MRSA was created in the "pig sty"? If that hadn't happened, hospitals would be a safer place to be.

      February 22, 2012 at 09:41 | Report abuse |
    • Jorge

      If I had that choice Jim, I'd beg the pigs to block the stench of politicians and CAFO CEOs while I was with them.

      February 22, 2012 at 10:04 | Report abuse |
    • andrew.peter

      Valentijn – MRSA was NOT created in pig stys. MRSA was first discovered in hospitals in the 50's. Don't believe every "news" article you read. They get money for you reading.

      February 22, 2012 at 13:33 | Report abuse |
    • Bryan

      andrew.peter...drug resistant MRSA was created out of "pig sty's". The article clearly states that MRSA originated from humans. The MRSA that poped up in Hospitals in the 1950's was not drug resistant.

      February 22, 2012 at 16:01 | Report abuse |
    • ComeOnMan9

      Er honey, the place I work they test for MRSA on the git go! Hospital infections aint cute no more, that crap is expensive. The US government says if the patient get an infection while they are there, they/we aint paying.

      February 22, 2012 at 19:24 | Report abuse |
    • Terry

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      February 23, 2012 at 03:38 | Report abuse |
    • whtswrngwths

      Mrsa...is a bunch of crap. When you get infected an treat quickly...there's no problem. Its people who get cut open, and get a deep infection that don't make it. And these morons that think they just have a big zit growing. This being said...friggin farmers should not be allowed to jam antibiotics in their animals!

      February 23, 2012 at 11:23 | Report abuse |
  2. Mike Conrad

    But this is impossible. The livestock industry, justifying their use of antibiotics, has stated for years that these are two separate components of bacteria and that bacteria pathogenic to humans could never originate in the livestock component. Certainly, such a prominent industry would never mislead the public.

    February 21, 2012 at 18:13 | Report abuse | Reply
    • JW Anderson

      Of course not! They are a non-profit public service industry.

      February 21, 2012 at 18:44 | Report abuse |
    • Janer

      And we wonder why we have 'big government'. There's not an industry out there that would just 'do the right thing' without regulation. makes me crazy

      February 22, 2012 at 12:39 | Report abuse |
  3. Norma Tyler

    so human is getting weak immune system by what they feed animal and when they get sick we eat the meat.Somebody need to tell the truth about whats going on.

    February 21, 2012 at 23:05 | Report abuse | Reply
    • Hugh Jass

      No, the animals caught it from us, but they were all on antibiotics so only a tiny few got sick. The ones that got sick got sick despite the animals being on antibiotics, meaning they were immune to the antibiotics. Then we caught it back from the animals and we can't kill it with antibiotics now. It's NOT the meat.

      February 22, 2012 at 16:29 | Report abuse |
  4. MEDICINE CABINET

    WHAT A MESS! THIS WAS A INTINTIONAL EXPERIMENT! PEOPLE ARENT FOOLED ANYMORE I WISH THE AWARENESS WOULD OF CAME SOONER

    February 22, 2012 at 02:42 | Report abuse | Reply
  5. IDDoc

    Until these 'journalists' learn to differentiate between CA-MRSA and nosocomial MRSA these types of articles are virtually useless. There is a huge difference between the two bugs.

    February 22, 2012 at 07:32 | Report abuse | Reply
    • MRSAResearcher

      Less difference than you think. Most hospitals just play semantics: symptoms under 48 hours of admission its CA, 48 hours or later, its considered hospital acquired. There is abundant research to show that genetically, the CA strains are replacing the HA strains in clinical settings.

      February 22, 2012 at 07:51 | Report abuse |
    • jcbmd

      I agree wholeheartedly with both of your comments. The public doesn't understand, because the journalists never include the full story. There is a big difference in these bacteria clinically. The community acquired strain, which has developed from overuse of antibiotics in livestock and by doctors, is very invasive, and can attack healthy people with normal immune systems. Fortunately it responds well to simple incision and drainage, and 2 old generic antibiotics when necessary. The hospital version is completely different. It arose from overuse of antibiotics in the hospital. It is much less invasive and primarily infects immune compromised people, or people with indwelling catheters or surgical implants. It however is harder to diagnose and much harder treat. The biggest risk, and it will happen, is the exchange of genetic material between these two strains of staph, and even worse exchange with resistant strains of enterococcus and pneumococcus. That will result in untreatable strains of several different invasive bacteria, and will push us back into the pre-antibiotic era.

      February 22, 2012 at 11:37 | Report abuse |
    • andrew.peter

      MRSAResearcher – That's because some hospitals are doing a good job of preventing infection, and so HA-MRSA is not keeping pace with the CA-MRSA. It's only logical, which setting is more controllable.

      February 22, 2012 at 13:36 | Report abuse |
    • MRSAResearcher

      Andrew, CA-MRSA has a stronger resistance than the predominant HA strains, it's merely an organism evolving and not hospital cleanliness. Furthermore, HA strains tend to be central line or other intravenous line infections which, you guessed it- are more likely to kill the patients, thus reducing chance of further transmission. It's classic infectious disease modeling, the faster an organism kills its host, the less likely the chances that it can be passed on.

      February 22, 2012 at 16:53 | Report abuse |
  6. Jorge

    Perhaps when the crap that we consume today, both material and virtual, finally brings on a Modern Plague and does us justice, the crap that is contemporary economic practice will give way to a better time.

    February 22, 2012 at 10:00 | Report abuse | Reply
  7. Myto Senseworth

    Over use of antibiotics is bad. We have known this for years, but it still happens. It's not just our anamals. People are given antibiotics for almost any reason.... Like I have said before....Don't worry about over population or food shortages, the medical profession will kill most of us off because of bad practices and bad drugs.

    February 22, 2012 at 10:10 | Report abuse | Reply
  8. Mike

    Cows are ruminants which means they evolved to eat only grass. When fed corn and soybeans to fatten them quickly they get sick, hence the needfor antibiotics. It's inhumane, unhealty and just wrong. The meat from a grass fed cow is much safer, more nutritional and morally acceptable than factory farm meat. Buy from farms that raise their animals humanely on pasture as nature intended and you'll be much better off. CNN didn't post my first comment, lets see if this passes their censors...

    February 22, 2012 at 10:10 | Report abuse | Reply
  9. Matt

    Methicillin is not used for staph infections. Other penicillins and cephalosporins are used if they will work for a given infection.

    February 22, 2012 at 10:15 | Report abuse | Reply
    • cd

      I think it's the point that methicillin was the drug of choice prior to the evolution of resistant strains. MRSA is a general term for any staph strain resistant to broad spectrum beta-lactams. Vancomycin and linezolid are the most often used drugs to treat CA/HA MRSA these days.

      February 22, 2012 at 10:43 | Report abuse |
    • jcbmd

      Methicillin, a penicillin, was specifically designed for staph. If a strain of staph aureus is resistant to methicillin, it is also resistant to all other penicillins and cephalosporins. This resistance has developed due to overuse of antibiotics in the livestock industry and by doctors trying to keep demanding, but uneducated patients happy by prescribing antibiotics for viral infections. Antibiotics should be banned from use in the livestock industry, and doctors must say NO.

      February 22, 2012 at 11:20 | Report abuse |
  10. Frank

    Anyone in my family dies from antibiotic resistant bacteria and I will sue them from he11 to breakfast! They are KNOWINGLY doing this so that MAKES THEM LIABLE FOR MANSLAUGHTER...

    February 22, 2012 at 11:26 | Report abuse | Reply
    • Hugh Jass

      Go back to sleep, Grampa. Nobody's giving you MRSA. It was all a bad dream.

      February 22, 2012 at 16:20 | Report abuse |
    • Margeaux

      Frank, I posted below about my mum. We talked to a litigation lawyer and he said, 1. the case will be in the courts forever, 2. you won't get any $$ out of a hospital and 3. you won't be able to definitely prove it. Now this was in Canada so might be different in the states.

      February 23, 2012 at 02:39 | Report abuse |
  11. Concerned Dad

    The public needs to be informed about MRSA with the same passion given to that of the FLU. It's a shame that these articles only cover the tip of the iceberg based on a study from 2005! This SUPERBUG and CDIF will certainly take it's tool on man kind in the not so distant future. I am not trying to be an alarmist, but the fact of the matter is VRSA is also out there (research it)...Watering down an important topic does the populous no good – the FLU is all over the news as should this SUPERBUG be also!!!

    February 22, 2012 at 12:40 | Report abuse | Reply
    • cd

      While you're spot on regarding MRSA and other antibiotic resistant bacteria, most people have a very low risk of acquiring MRSA outside of a hospital. Prisons and even daycare facilities are thought to be reservoirs for CA-MRSA, but CA-MRSA strains are much less dangerous to healthy people in the community than a hospital patient that acquires the infection through a central line. The flu is much more common and kills dramatically more people a year in the US than MRSA.

      February 22, 2012 at 13:00 | Report abuse |
    • Margeaux

      CD, While the flu may kill more people, you will never get accurate stats about MRSA infections. On my mum's death certificate, it said pnemonia. She only get it because she was bedridden with the MRSA infection. So, any stats you may look at will never be accurate.

      February 23, 2012 at 02:52 | Report abuse |
  12. andrew.peter

    This is only sensational journalism trying to pressure farmers to drop the antibiotics.

    Any little research will show that Hopsital-Acquired MRSA, or HA-MRSA, began within years of introducing methicillin in hospitals. This was in the 50's, and it was introduced because the bacteria had already become resistant to Penicillin. The Community-Acquired MRSA, or CA-MRSA, prevalent in the USA is not this CC398 written about in the article, but a CC8 strain designated as ST8:USA300 or ST1:USA400.
    I'm supportive of restricting antibiotic use, but this is just too sensational to be considered journalism. This is not the end of the world.

    February 22, 2012 at 13:28 | Report abuse | Reply
    • jcbmd

      Agree, but this is the tip of the iceberg. Overuse of antibiotics is a problem everywhere. I'd love to see some good journalism about the emergence of resistant pneumococcus after the introduction of the weak, long acting cephalosporins such as cefaclor, and the emergence of CA-MRSA after the introduction of the weak, long acting macrolide azithromycin, zithromax, the placebo of choice for many physicians. Interesting thoughts that can never really be proved.

      February 22, 2012 at 15:35 | Report abuse |
    • Hugh Jass

      "Any little research will show that Hopsital-Acquired MRSA, or HA-MRSA, began within years of introducing methicillin in hospitals. " You are so desperate to push your point of view that you are ignoring the article itself, which is about new research. Too much bias means you probably have a financial interest or OCD on the topic, and makes us skip your posts.

      February 22, 2012 at 16:26 | Report abuse |
    • cdn

      While I don't want to say this is sensational journalism, it's not very surprising or novel. These researchers aren't the first to sequence and track strains of MRSA, that's been going on for a couple years now on a much grander scale. This is just a small story in attempt to throw gasoline on the fire.

      February 22, 2012 at 17:00 | Report abuse |
  13. alex

    well, if greedy MEN who feel they should be the sole supplier of beef in the east...would perhaps stop being so greedy and lets have farms that supply areas where they are. So all this "I need to have 10 thousand head stuffed into an area for 50 cows" nonsense end and all the cows would be much healthier. It the same with Chicken, I personally don't eat a chicken breast that bigger than my own or even 1/2 the size, that's not how God made the chicken and if you buy any frozen from tyson, it taste like rubber and doesn't cook, heck the dog wouldn't eat it. So again, we don't one supplier, we need many spread out...oh wait, wouldn't that create jobs in America?

    February 22, 2012 at 13:57 | Report abuse | Reply
    • Hugh Jass

      Chickens are huge today because we've been breeding them larger since the Thirties. Eat the small ones and let the big ones breed. It's NOT from hormones, although a lot of places use them. They are just big chickens.

      February 22, 2012 at 16:23 | Report abuse |
  14. M1sf1ts

    My cousin recently had a child from home. A few days later her stomach hurt. She went to the hospital. She had Staph. She was placed in a medcally induced coma for about a month. In the meantime, the doctors amputated her arms, legs, and removed a few internal organs. Google Katy Hayes.

    February 22, 2012 at 15:52 | Report abuse | Reply
    • lily123

      Katy Hayes has a strep infection. Nothing to do with this.

      February 22, 2012 at 19:04 | Report abuse |
  15. c s

    MRSA happens like every other germ becomes antibiotic resistant. Evolution. Of course some people believe that evolution is only a theory and has nothing to do with life. Unfortunately some of these people have a great deal of power and decide that making MONEY is more than saving lives.

    Any farmer who uses anti-biotic for disease prevention in their farming practices, cares only about MONEY. Any politician who prevents the FDA from banning antibiotics from being used wrong, cares only about MONEY. Any drug company that promotes using antibiotics for disease prevention in farm animals, cares only about MONEY.

    So in the end, MONEY is much more important than human or animal health.

    February 22, 2012 at 15:54 | Report abuse | Reply
  16. Hugh Jass

    "Of course some people believe that evolution is only a theory and has nothing to do with life. Unfortunately some of these people have a great deal of power " I guess you aren't going to vote for more santorum, right?

    February 22, 2012 at 16:23 | Report abuse | Reply
  17. Sue

    We really should ban antibiotics in animal husbandry. Unfortunately, the big pharmas aren't still eying to find newer more effective antibiotics for the resistant strains since it is not a big money maker for them. As more bugs become resistant, there will be few new drugs coming to fight them. Over use of antibiotics end up in our water supplies as well. We are creating the perfect environment for resistance to develop... We need to be more careful. I don't think this is sensationalistic journalism, just a cautionary truth.

    February 22, 2012 at 22:58 | Report abuse | Reply
  18. Margeaux

    My mum got MRSA in the hospital. She had had surgery and when she wasn't getting better, they blamed her and said she was depressed and gave her antidep. This was a woman who had never been down a day in her life. Then, yhey discovered that she had the MRSA infection. When she still didn't get better, they blamed our family and said that one of us had it and kept exposing her to it. So, we all got tested for it. None of us had it. Then, when she died, they said that it was because she was older and sick. Her operation had been an ulcer. Something one can get at any age. Nothing to do with her age. Rather than blame their own unsanitary conditions, they blamed her and us until the day she died.

    February 23, 2012 at 02:36 | Report abuse | Reply
  19. John Hall

    A wonderfull article on the fate of antibiotics!
    I have taken a product which cures MYRSA. Yes my disease and thank God I refused the antibiotics the doc prescribed.
    The product is A NATURAL PRODUCT taken topically and internally. I also recovered from Malignant Melanoma in the lymph from 3 years ago. Wrote a book on the natural foods and supplements I took: BEATING CANCER CAN BE FUN (Cancer fighting strategies for first time diagnosed cancer patients) on Amazon, ebook, NOOK and at B&N stores.

    February 23, 2012 at 11:06 | Report abuse | Reply
  20. Nevenas Hiltunenn

    YouTube consists of not only humorous and humorous video lessons but also it contains educational related video clips.

    July 17, 2012 at 05:02 | Report abuse | Reply
  21. Daniel Jones

    MRSA is a very serious condition but is treatable. Check this link out http://www.staph-infection-resources.com/mrsa-secrets-revealed.html

    July 24, 2012 at 14:37 | Report abuse | Reply
  22. Dewayne Argubright

    Intestinal troubles after operation may be a indicator of a staph infection, according to the Mayo Clinic. Vomiting and feelings of nausea after surgical treatment may result from toxic shock syndrome, that is a serious problem brought on by widespread staph infection. Individuals who have a feeding tube implanted immediately after surgery have got a bigger chance of getting staph infections as a result of contamination of the tube.-

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    February 6, 2013 at 10:02 | Report abuse | Reply

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