Thursday, March 13, 2014

Antibiotic Resistance

When I was a child, antibiotics were still thought to be a miracle drug and saved my hearing in my right ear and maybe my life. Billions of microscopic bacteria normally live on the skin, in the gut, and in our mouths and throats. Most are harmless to humans, but some are pathogenic and can cause infections in the ears, throat, skin, and other parts of the body. In the pre-antibiotic era in the first half of the 20th century, people had no medicines against these common germs and as a result were often made quite ill, had severe complications or even died from bacterial infections. It has been less than 75 years that we have had antibiotics to fight these bacterial infections. Now, that miracle may be ending helped along by our excessive use and overuse of antibiotics.
Clostridium difficile, Enterobacteriaceae and Neisseria gonorrhoeae currently pose an urgent threat in the US

Less than a decade after antibiotics came into common use in medicine it began to be widely used as a feed additive in agriculture. It was discovered that antibiotics fed to young animals caused them to increase weight and grow faster on less food. To this day we don’t know exactly why that happens. Thumb through any farm supply catalogue and you are likely to see for sale medicated feet that “boosts the growth of poultry and livestock.” However, you are likely to find that medicated feed is out of stock. At the end of last year, the Food and Drug Administration (FDA) began implementing a voluntary plan with industry to phase out the use of certain antibiotics for enhanced food production. This action was taken as part of a coordinated program to preserve the effectiveness of antibiotics used to treat human illness and reduce the spread of antibiotic resistant bacteria.

Antibiotic resistant bacteria are a rapidly growing problem in the United States and the world. In 2012 at least 2 million people in the United States alone became infected with bacteria that are resistant to antibiotics and at least 23,000 of those people died as a direct result of these infections. Many more people died from other conditions that were complicated by antibiotic-resistant infections. Almost 250,000 people in 2012 required hospital care for Clostridium difficile commonly known as C. difficile. At least 14,000 people died that year in the United States from C. difficile infections including the son of an acquaintance of mine who died in San Francisco despite the availability of excellent medical care. Antibiotic use is a major contributing factor to the spread of these infections. Many of these infections could have been prevented.

As antibiotic resistance grows, the antibiotics used to treat infections do not work as well or at all. The loss of effective antibiotic treatments will not only cripple the ability to fight routine infectious diseases but will also undermine treatment of infectious complications like C. difficile in patients with other diseases. Many of the wondrous advances in modern medicine—joint replacements, organ transplants, cancer therapy, and treatment of chronic diseases such as diabetes, asthma, rheumatoid arthritis—are dependent on the ability to fight infections with antibiotics. If that ability is lost, the ability to safely offer modern medical wonders will be lost with it.

Antibiotics are among the most commonly prescribed drugs used in human medicine. However, up to 50% of all the antibiotics prescribed for people are not needed or are not optimally effective as prescribed. Antibiotics are also commonly used in food animals to prevent, control, and treat disease, and to promote the growth of food-producing animals. The use of antibiotics for promoting growth in livestock is not necessary, and the practice should be phased out. Guidance from the FDA at the end of last year plots a path towards this goal. According to the FDA it is difficult to directly compare the amount of drugs used in food animals with the amount used in humans, but there is evidence that more antibiotics are used in food production. The Pew Foundation reports that 70% of antibiotics manufactured in the United States are used in food production (though I could not identify their methodology for calculating this). The primary danger from antibiotic over use in animal feeding is from antibiotic resistant bacteria that survive to enter the food chain, not from human exposure to antibiotics in meat; however, there might be human health impact from broad low level exposure or changes in gut bacteria colonies.
from FDA

Antibiotic resistance infections have left the confines of hospitals and begun appearing in our communities without any connecting factors to the hospital population. Antibiotic-resistant infections outside of the hospital setting were rare until recently. Today, resistant infections that appear in the community include tuberculosis and respiratory infections caused by Streptococcus pneumoniae, skin infections caused by methicillin-resistant Staphylococcus aureus, and sexually transmitted infections such as gonorrhea. Right now the biggest of these threats in the United States are Streptococcus pneumoniae (pneumococcus) and MRSA infections. Multidrug-resistant and extensively drug-resistant tuberculosis (MDR and XDR TB) infections are an increasing threat outside of the United States and could spread very quickly because of the ways the disease is spread. Now the FDA and the CDC are developing a group of strategies to fight back against antibiotic resistance.

There are four core actions:
  1. Preventing infections. Avoiding infections in the first place prevent infection and the spread of antibiotic resistant bacteria. There are many ways that drug-resistant infections can be prevented: immunization, safe food preparation, hand washing, and using antibiotics as directed and only when necessary. Streptococcus pneumoniae (pneumococcus) can cause serious and sometimes life-threatening infections and can persist in a medical facility for years, so preventing infection in the first place is essential.
  2. Tracking. The CDC gathers data on antibiotic-resistant infections, the causes of infections and whether there are particular risk factors that caused some people to get a resistant infection. With more information, scientists can develop specific strategies to prevent those infections and prevent the resistant bacteria from spreading.
  3. Improving the way we use antibiotics. The most important action needed to greatly slow down the development and spread of antibiotic-resistant infections is to change the way antibiotics are used. Most antibiotic use is unnecessary and inappropriate and makes everyone less safe. Stopping the inappropriate and unnecessary use of antibiotics in people and animals would help greatly in slowing down the spread of resistant bacteria. This requires a commitment from all of us to only use antibiotics when necessary and appropriate and also to reserve the broad spectrum antibiotics (the big guns) for the most dire bacterial infections.
  4. Finally, new diagnostic tests and new antibiotics must be developed. Antibiotic resistance occurs as part of the natural process in which bacteria continually evolve. The process of developing resistance can be slowed but not stopped. Therefore, we will always need new antibiotics to fight resistant bacteria as well as new diagnostic tests to determine the most effective treatment and track the development of resistance.

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