The Catastrophe of Antibiotic Resistance

March 6, 2015

By Medical Discovery News

The Catastrophe of Antibiotic Resistance

The World Health Organization has categorized antibiotic resistance as “a major global threat” and multidisciplinary research teams estimate it could lead to 10 million deaths each year by 2050. Bacteria that cause disease in humans can become resistant to the drugs used to treat them, and this poses a growing problem to public health.

Antibiotics were first introduced in the 1940s with the discovery and development of penicillin and saved many people from otherwise life-threatening infections. This one class of drugs has had an incredible impact on decreasing the severity of infections and saving lives.

Lately antibiotics have become overused and misused, which has allowed bacteria to mutate in ways that render antibiotics relatively powerless. Bacteria were one of the earliest life forms on Earth and remain one of the most successful, present everywhere from Arctic glaciers to geothermal springs. Because they are masters of adaptation, exposure to antibiotics causes the bacteria to accumulate mutations that will allow them to ignore the action of the antibiotics. That’s why doctors should only prescribe an antibiotic in the likelihood of a bacterial infection, and why it’s important to take all of the prescribed doses of an antibiotic. Otherwise, you can give the bacteria enough contact with the antibiotic to mutate but not enough to kill them, and they can come back stronger.

Half the use of antibiotics does not come from a doctor’s office or hospital, but a farm. Chickens, pigs, cows, and other livestock raised for food production are fed antibiotics to prevent infections and for faster weight gain. Many countries now ban this practice, and in 2013 the U.S. Food and Drug Administration (FDA) asked pharmaceutical companies to voluntarily curtail the sale of antibiotics directly to famers. Today, 26 pharmaceutical companies will only issue antibiotics for animals with a veterinarian’s prescription.

Infections by drug-resistant bacteria can be twice as likely to result in hospitalization and death. And while some bacteria are resistant to a single antibiotic, others are resistant to many. Methicillin-resistant Staphylococcus aureus (MRSA), multi-drug-resistant Neisseria gonorrhea, and multi-drug-resistant Clostridium difficile are superbugs taking a devastating toll worldwide. Some bacteria have mutated against all forms of antibiotics normally used to treat them, leaving no effective treatment options. Such infections are occurring around the globe in both rich and developing countries.

Legislation in the U.S. Congress proposes to permanently ban antibiotics that are used in humans from being used in livestock as well.  However, some argue that there is not a clear link between the antibiotic-resistant bacterial strains generated in livestock practices and those seen in human disease, which requires more intense research to answer. Whatever the outcome, the emergence and spread of antibiotic-resistant bacteria must be stopped. We also desperately need to develop new antimicrobials human use.

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Silent Mad Cow

Feb. 28, 2014

By Medical Discovery News

Ten years after bovine spongiform encephalopathy (BSE), commonly called mad cow disease, was diagnosed in cattle in Britain, the British government admitted that it could be transferred to humans in a new form called variant Creutzfeldt Jakob disease (vCJD).

Cases of BSE spread to cattle in other countries, and more people in different countries were being diagnosed with vCJD. By 2004, the U.S. had passed various laws to eliminate BSE-infected cattle from the market. However, to this day, there are still sporadic reports of cows diagnosed with BSE both in the U.S. and abroad.

BSE and vCJD are neurological diseases that arise from prion plaques that form in the brain. Prions are simply misfolded proteins. This can be caused by a genetic mutation, spontaneous misfolding, or consuming infected beef. These misfolded proteins can convert healthy or normal proteins into misfolded ones. Once they appear, abnormal prion proteins aggregate, or clump together. Investigators think these protein aggregates may lead to loss of brain cells and other brain damage. Areas of the brain’s grey matter are slowly displaced and the brain develops holes or a spongy appearance, hence the name spongiform. There is no treatment or cure and eventually the damage is severe enough to lead to death. 

Initially cattle acquired the prion proteins in feed supplements made from infected sheep brains and spinal cord tissues. Once regulators understood the source, they passed laws banning the process of feeding dead animals to livestock. Unlike meat contaminated with bacteria, cooking does not destroy prion proteins. In an effort to eliminate prions from the food supply, the U.S. Department of Agriculture has imposed a rule that the brains and spinal cords of cattle must be removed prior to processing into edible meat. 

There have been 175 people in Great Britain diagnosed with vCJD and an additional 49 people in 11 other countries. A large study indicates that 1 in 20,000 people in Britain (30,000 total) carry the misfolded prion proteins and are at risk of developing vCJD. These new results suggest that many people in Britain may be carrying the prions but are symptomless, at least for now. This could also mean that these cases are silent carriers, who will not develop clinical vCJD. It remains a mystery that only time and additional studies will solve. 

Since there is no blood test for vCJD, carriers could unwittingly pass on this disease to others when they give blood. Earlier research suggested that the incubation period for vCJD was about eight years, but now scientists think that there are at least three types of the misfolded prion proteins, with different incubation periods and different types of prion disease.

Blood tests need to be developed to protect against the inadvertent transmission of vCJD. Better farm and food practices and laws will also help eliminate other sources of prion disease. Scientists in a number of countries are exploring potential treatments for these disorders.

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