Antibiotic Resistance

The best way to keep that tail wagging is by following your pet’s doctor’s instructions.

Drug resistance.

You hear about it on the television news. You read about it in the newspaper. How does it happen?

Drug-resistant bacteria are produced by many, many factors. People, and our misbehavior, are the cause of most resistance.

One of the ways people create drug-resistant strains of bacteria is by not following directions. For example, when physicians dispense antibiotics for a certain number of doses, they expect us to take the medicine until all is gone. Even though we have been instructed to do so many times, and we know we should, we still fail.

However, we begin to feel better, we get back into our daily routine, and life’s duties, distractions and responsibilities make us forget to take a dose, or two, or three, then we think, “Why bother starting it up again, I feel fine now.”

Or, in the case of our pets we might say, “There’s no blood in Fluffy’s urine anymore, she must be OK.”

In a grossly oversimplified analogy we will look at what happens next with the remaining infectious organisms.

Picture a war in a faraway country. We will call it Terroristan. Some of that country’s bad-guy army folks have engaged in a terrorist act and are known to be stockpiling a variety of weapons across the country.

World leaders call for the good old USA to step in. The Secretary of Defense calls for six Navy Seal teams to enter the country to vaporize the entire Terroristan army. Somewhere between his order of an all-out attack and the actual deployment, low-ranking, minimally-trained soldiers (we’ll call them Sad Sack and Beetle Bailey) arrive in country. They see two of Terroristan’s off-duty army guys, “eliminate” them, and head home.

Is Terroristan shut down? Of course not! With personnel insufficient to totally eliminate the enemy, Sad Sack and Beetle Bailey knock off the two weakest members of the opposing army, leaving the smartest and baddest to continue to wreak havoc worldwide.

That scenario represents an infection properly diagnosed by the doctor, an appropriate bacteria-killing medication dispensed, but with insufficient medication administered to completely eliminate the host’s infection. The weakest bacteria were killed at first, leaving behind the strongest and baddest organisms to continue the infection’s damaging attack on the host.

Now, in reality all of this is occurring at a DNA level in the bacteria, with the genetic code of the surviving bacteria, the ones that lived through the shortened duration of antibiotic administration, changing in ways that allow it to be no longer threatened by the medication.

Once a strain of bacteria is resistant to an antibiotic, that medicine will no longer kill that particular organism, which means the medicine you didn’t finish for the infection you had may not work if you try to take it again for the same infection.

Furthermore, bacterial resistance to one antibiotic often confers resistance to other bacteria related to it, thus rendering the antibiotic useless against those bacteria, also.

Now your infection, or your pet’s infection, will require an antibiotic costing more, possibly much more. The reason? Millions of dollars of research had to be performed to create an antibiotic with activity against the resistant organism someone created.

But the expense isn’t the worst news. This is not a story that goes on and on. There is an end point with some bacteria, and several species have reached it. MRSA and VRSA are two common ones we read about in the news daily. MRSA stands for Methicillin-Resistant-Staphylococcus-aureus. VRSA stands for Vancomycin-Resistant-Staphylococcus-aureus. These are common bacteria that have evolved the ability to survive the powerful antibiotic, methicillin. Experts believe that as much as 50% of the Staphylococcus aureus (Staph aureus or Staph a.) in the world is resistant to methicillin. Such resistant bacteria must be treated with the even more powerful antibiotic vancomycin. To date, no bacteria have been detected resistant to vancomycin, but worldwide research shows that some strains of Staph aureus are requiring higher and higher doses. Researchers are exploring modifications to the vancomycin molecule that may improve its performance when (not if) resistance occurs. That research is promising.

So, when your physician or your pet’s doctors instructs you to “take (give) the medicine until all is gone,” he is serious. It can be a matter of life-and-death.

See you next week, Dr. Randolph.

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