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David Katz, M.D.

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Why Salmonella Strikes Ground Meat

Posted: 08/05/11 09:26 AM ET

You are likely aware of an outbreak of salmonella, provisionally linked at this point to ground turkey and prompting a massive recall. If so, you have likely also heard -- as if garden variety salmonella weren't bad enough -- that this particular bug is resistant to multiple antibiotics, and thus causes an infection that is very hard to treat. Thus far, the origins of this specific outbreak are uncertain. But the general origins of an antibiotic-resistant salmonella outbreak involving ground meat are not mysterious, nor are the required measures for self-defense. So let's get to it.

Salmonella is an intestinal organism and always on the short list of bugs causing food-borne outbreaks. Unlike some of the other bad actors -- shigella and various strains of E. coli -- salmonella infections, though nasty, are generally self-limited. When they are mild, recovery occurs without antibiotics. When more severe, antibiotics are usually effective. The salmonella species that most often cause food-borne outbreaks are native to various animals, and are thus called "zoonotic" infections, meaning they are passed from animal species to humans.

Why is chopped meat -- in this case, turkey -- a particular problem? Basically, because of surface area. (As an aside, I recall that whenever in doubt about the answer to a question in 7th grade biology, "increases the surface area" was likely to get at least partial credit because it is such an important biological principle. In public health, when in doubt, the best guess tends to be "age and sex.")

Intestinal bacteria that contaminate meat contaminate the portion that is exposed -- namely the surface. In general, when the exposed surface of meat is heated adequately (that temperature varies with the kind of meat, but a ballpark figure is 165Ëš F), the bacteria is killed.

There are two problems with chopped meat. First, the inside is the outside and vice versa. Chopping meat massively increases the surface area, allowing the bacteria to invade throughout. And, because meat at the very center of a burger, patty, meatball or meatloaf could well have been on the surface at some point, contaminating bacteria are only reliably killed if the temperature throughout reaches the relevant threshold. Because the entire area of chopped meat is surface area, it should be eaten well-cooked.

The second issue with chopped meat is that it generally comes from multiple animals -- in the case of ground meat prepared at centralized processing facilities, possibly quite a large number. The risks of bacterial contamination rise in this situation, because even one infected animal may contribute germs to meat being sent all over the country. When you eat un-chopped meat, the source is a single animal.

Finally, there is the issue of antibiotic resistance. This is a straight-forward case of survival of the fittest. The more bacteria are exposed to antibiotics, the more vulnerable bugs die leaving only the resistant bugs alive. Those resistant bugs then replicate and pass along their resistance. Very often, the resistance traits come along with some disadvantage, so in the absence of routine antibiotic exposure, the non-resistant bugs can come to predominate again. The propagation of antibiotic-resistant germs in our food supply, and in general, owes much to the routine dosing of feed animals with antibiotics.

Which brings us to self-defense. Worrisome though a salmonella outbreak may be, you can reliably defend yourself and your family.

Cook meat well. Temperature guidelines are readily available. In particular, be sure to heat chopped meat all the way to the center. Other options include avoiding chopped meat, and/or making your own with a small meat grinder. If you grind your own meat, you know the source is a single animal. This does not obviate the need to cook well, but reduces the likelihood of there being any bad bugs around in the first place.

Do not let uncooked meat touch any other food items in your home. This is food safety 101, but had to be said. If germs from meat get onto food that will not be cooked, then cooking the meat is no longer a reliable defense.

The other measures of self-defense depend more on the body politic. The routine use of antibiotics in feed animals should be avoided -- as should the crowding that is often the basis for this practice. If you eat meat, you might limit your intake to animals from farms you know that avoid antibiotics, crowding and any unnatural feeding practices. We would, of course, see a decline in food-borne infections if as a society we simply ate less meat overall -- but that's a topic for another day.

Even good self-defense can occasionally fail, so it's also important to know the symptoms of salmonella infection so you can get prompt medical attention if you need it.

For now, the exact origins of the current outbreak remain a mystery -- but the means of defending yourself and your family from it are not. With a word of thanks to your 7th grade biology teacher, put them to good use.

-fin

Dr. David L. Katz; www.davidkatzmd.com
www.turnthetidefoundation.org

 

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You are likely aware of an outbreak of salmonella, provisionally linked at this point to ground turkey and prompting a massive recall. If so, you have likely also heard -- as if garden variety salmon...
You are likely aware of an outbreak of salmonella, provisionally linked at this point to ground turkey and prompting a massive recall. If so, you have likely also heard -- as if garden variety salmon...
 
 
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12:26 PM on 08/09/2011
The FDA actually allows salmonella in our food under the apparently false assumption that it will be cooked off. http://eng.am/r2hiDT

Do you really think it's our best interest they have in mind?
HUFFPOST SUPER USER
Carolyn Kostopoulos
02:06 PM on 08/08/2011
when we were kids, mom went to a butcher, selected a steak and had it ground into hamburger. we knew the meat all came from one animal. we were able to eat it rare safely. these warnings to cook meat until it's dead did not exist in my youth and there were no problems because meat animals were not raised with utter disregard the way they are now. in my late 20's i actually ordered steak tartare at the kennedy center cafe. imagine doing that now!
we eat rare meat, even raw meat and certainly eat raw eggs. doing so now would be suicide.
buy your meat, eggs and milk directly from a farmer who you know treats his animals with respect by allowing them to eat their natural diet of grass. i buy ground turkey from my farmer all the time. while i'm not keen on it, my cats love it and they eat it raw
MTTM
Your microbio is MT
05:41 PM on 08/06/2011
Corporate greed and regulation don't play well together.
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rawfoodsphd
Rx for Body, Mind & Spirit
01:15 PM on 08/06/2011
The e.coli breakout in spinach several years back was actually possibly linked to run-off from a nearby factory farm. One of the worst industries that exist in this country is that of factory farming - contamination can barely be avoided with all of those animals cramped into small spaces, not to mention very apathetic and depressed employees. Raw foodists can also be prone to bacterial contamination - when I dehydrate, I always start the first hour or two at 145 degrees (this does not heat the food to that temp in such a short time) to destroy any surface bacteria.
www.rawfusionliving.com
08:00 AM on 08/06/2011
Avoid meat.
09:07 PM on 08/10/2011
Avoid generalizations.
09:08 PM on 08/05/2011
Very informative article. I had no idea that the increased surface area of chopped meat contributed to an increase in bacteria. I also didn't realize that chopped meat came from multiple animals. This is an eye opener. The take home message I assume would be to make sure that the meat is cooked through and through. Don't take the risk of getting ill. http://www.perspectivestv.com Twitter @PerspectivesGA
08:47 PM on 08/05/2011
Fascinating. Salmonella probably (at least potentiall) affects many more of us than gluten, but your gluten blog gets over a hundred comments the first day, and the salmonella has fifteen. I bet if you titled it "would genetically modified groud meat have salmonella?" you would get two thousand comments. You should write an article on gluten-fortified, gentically modified ground meat. That would provoke more discussion.
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Bluepicker1987
Progressiv­e=me, me, me paid for by you, you, you
04:21 PM on 08/05/2011
This is why I grind my own, plus it's cheaper.
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crom14
03:59 PM on 08/05/2011
I am a Veg, but must say, I do not know a meat eater that eats it well done, nor a chef that will do it.
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03:14 PM on 08/05/2011
This is why I eat venison.
03:10 PM on 08/05/2011
Actually the majority of food borne illnesses are from vegetables and leafy greens. More vegetarians get food poisoning than meat eaters.
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HerrMonk
Son of Apollo
06:11 PM on 08/05/2011
Don't let facts get in the way of a good anti-meat rant.
12:17 PM on 08/06/2011
Citation, please. Salmonella and e.coli only originate from waste. Broccoli doesn't poop, soooo...
09:11 PM on 08/10/2011
It's true. We had an outbreak in local schools linked to Mexican strawberries that had been fertilized with pig manure. A major juice company (generally good citizens so I won't name them here) had an E. coli outbreak in 1996.
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DavidMG
OWS Senior Citizen
02:36 PM on 08/05/2011
Many (not all) food borne illnesses can be avoided/minimized by eliminating/minimizing meat and/or buying local ( as it the industrial food production that spraeds it so widely0. Me favorite veg cookbook is "American Wholefoods Cuisine."
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rawfoodsphd
Rx for Body, Mind & Spirit
01:12 PM on 08/06/2011
Great points, DavidMG - While most people are not going to make a full commitment to a vegan or veg diet, even if they minimize the amount of meat, what a great shift that would make. One of the worst industries in this country is the Factory Farming - where much e.coli and salmonella originate. www.rawfusionliving.com
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darquelourd
You Get What You Play For
11:48 AM on 08/05/2011
Is it possible for a guy to follow a Rocky-like diet these days of raw eggs and raw hamburger?
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Lou Allin
Lou is the author of two series of mystery novels
12:46 PM on 08/05/2011
Double jeopardy. Why take the risk? Forty years ago I loved egg nogs and even tried raw ground round spiced up. Not for a lonnnnnnnnnnnnnng time.
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HerrMonk
Son of Apollo
06:14 PM on 08/05/2011
Yes.

People are such dweebs these days and Americans in particular are mysophobic. The irony is it's this very mysophobia and our attempt to sterilize the planet that has led to the creation of more harmful and resistant strains.
10:48 AM on 08/05/2011
wow
10:45 AM on 08/05/2011
"There are two problems with chopped meat. First, the inside is the outside and vice versa. Chopping meat massively increases the surface area, allowing the bacteria to invade throughout"......".The second issue with chopped meat is that it generally comes from multiple animals -"
Great info that never occurred to me. Maybe I will start making my own hamburger.
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crom14
04:02 PM on 08/05/2011
The other problem is the use of meat glue. Look into it.