วันเสาร์ที่ 12 มิถุนายน พ.ศ. 2553

Meat Microbes

As we saw earlier, bacteria absorb their food from other livings things or from decaying matter. Many bacteria can digest protein, so they live on meat. With the right supply of food, bacteria multiply quickly, so a small piece of meat can hold millions of bacteria.

Food poisoning

We know that most bacteria are harmless and even useful. But some of these microscopic organisms can also be very harmful. Several bacteria that infect meat can give people food poisoning. Most kinds of food poisoning have the same horrible symptoms. People feel nauseous, and they vomit a lot. They get really bad stomachaches and diarrhea. People usually recover after a few days, but sometimes they develop more serious illnesses.

Bad bacteria

Let’s look at some of the bacteria in meat that make us sick. Salmonella bacteria can invade all kinds of meat.

They are common in chicken, so eggs can be infected, too. It takes fewer than 20 Salmonella cells to make someone sick. Campylobacter jejuni is even more common than Salmonella in chicken. People infected with this bacterium get terrible diarrhea. Usually it goes away by itself, and people may not know what caused the illness.

Good and bad E. coli

Some forms of the bacterium Escherichia coli (E. coli for short) are healthy. They live in our intestines and fight other, harmful bacteria. But one type of E. coli that lives in cattle intestines can make people sick. When beef is ground into hamburger, the E. coli often infects meat and gets passed on to humans. Other harmful types of E. coli come from infected chicken or even vegetables.



Antibiotics are substances that can kill bacteria in your body. We use them as medicines when we get sick from bacterial infections. In the photo below, an antibiotic is destroying an E. coli cell wall. Farmers and ranchers add antibiotics to animal feed to prevent illness in cows, pigs, and sheep. But some bacteria are getting so used to antibiotics that the antibiotics can’t kill them anymore. So when bacteria cause infections, antibiotics may not be able to kill the bacteria and make people better.