Attack of the Killer Superbugs

June 1, 2001
Concerns about drug-resistant microbes have raised questions about the necessity of antibiotic prophylaxis. Do the benefits outweigh the risks?

The premedication of some medically compromised patients to prevent bacteremia has been a recommended procedure prior to invasive dental treatments for many years. But new concerns about drug-resistant microbes have raised questions about the necessity of this procedure. Do the benefits outweigh the risks?

It sounds like something from one of those 1950s sci-fi flicks. Common microbes invade human flesh and cause disease. Microbiologists create antibiotic concoctions to stop the growing menace. They are soon dancing gleefully around agar plates of dying microbes. The public breathes a collective sign of relief, then demand these drugs for every sniffle and cough. Suddenly, the microbes aren't dying so easily. They change. They mutate. And like a Saturday morning swap meet, the microbes are sharing the genetic codes needed to break the antibiotic stronghold. These resistant "superbugs" re-engage the population and tear in with a vengeance. Too late, the scientists discover it is the overuse of antibiotics that caused the microbes to develop their super resistance. In the battle of the bacteria, entire populations are wiped out. Millions succumb, still clutching the amber bottles of drugs they thought would save them.

A scary premise, but is it possible? Unfortunately, this scenario may be closer to reality than we think. Our current patterns for employing antibiotics are creating resistant superbugs that can withstand the most effective antimicrobial drugs science can produce.

The World Health Organization (WHO), the Institute of Medicine, and the American Society of Microbiology, as well as mainstream medical journals such as The Journal of the American Medical Association, are sounding the alarm about microbe resistance. These organizations suggest antibiotic resistance will continue to develop and intensify if action isn't taken.

In June 2000, WHO published a report, "Overcoming Antimicrobial Resistance." It warned, "The level of resistance to drugs used to treat common infectious diseases is reaching a crisis point. If governments around the world do not make great efforts to control disease and stem the spread of resistance there will be a return to the pre-antibiotic era and entire populations could be wiped out by superbugs for which no effective treatment exists."

The U.S. government appears to be taking microbe resistance seriously as well. The Interagency Task Force on Antimicrobial Resistance, formed in 1999, published the "Public Health Action Plan to Combat Antimicrobial Resistance." This task force is a cooperative effort of several government agencies, including the Centers for Disease Control and Prevention (CDC), the National Institutes of Health, and the Food and Drug Administration (FDA). The Department of Agriculture, the Department of Defense, the Environmental Protection Agency, the Department of Veterans Affairs, and others have provided input into the task force. The plan outlines specific, coordinated federal actions to address the "emerging threat of antimicrobial resistance," both domestically and globally.

The experts report that the spread of these resistant bacteria, parasites, and viruses is due both to the overuse and underuse of drugs. Either people are not completing the full course of drugs, which allow the most resistant microbes to survive, multiply, and spread to others, or drugs are being overprescribed to meet patient demands. The food industry also uses antimicrobials, which can cause resistant microbes as well as pass low doses of antibiotics within the product on to consumers. For example, low doses of antibiotics are used to increase growth in pigs and cattle.

One of the main factors cited in this increased resistance is the explosive growth of antibiotic use. The first antibiotic was discovered in 1928, and by the 1940s, antibiotics became widely available. Scientists have known from the beginning that the more an antibiotic is used, the faster it becomes useless.

Today, the CDC reports that 150 million prescriptions are written for antibiotics each year, a 28 percent increase from 1980. Seventy-five percent of antibiotic prescriptions written in outpatient settings are for respiratory infections; about 50 million of these prescriptions are for colds and flu - illnesses that antibiotics do not help treat. Nearly 190 million doses of antibiotics are administered in hospitals every day. The rate of antibiotic usage among children has increased 48 percent since 1980. In some countries, antibiotics are available without a prescription. The CDC recently issued a recommendation that antibiotics be used only when necessary, expressing concern - but not pessimism - with the resistance issue.

This incredible reliance on antibiotics has occurred for several reasons. Society has the expectation that antibiotics can cure any illness. Consumers have been lulled into complacency about medications, not finishing prescriptions and then liberally using leftover drugs to self-medicate. Many doctors report feeling pressured by patients to hand out prescriptions - even when they know it won't help. Often dual-income parents are pushing to get their child back into daycare so they can get back to work. Busy, overbooked physicians express concern about failing to prescribe an antibiotic to a patient who really needs one.

Another reason for the higher levels of microbe resistance is due to the nature of the bug: What doesn't kill them makes them stronger. The huge numbers of bacteria have short generation times, and they can actually swap biochemistry with each other. They travel the world quickly, and great defense systems protect them. Research is ongoing to prove that the very bacteria that helped create the antibiotics of the past are passing biomolecular "resistance genes" to other species - sort of a swap meet for bacteria.

New drugs are in the works, including several that are awaiting FDA approval. But even more drugs will be needed to overcome the resistance problem. These new drugs will be given out much more selectively than in the past to protect their effectiveness for a longer period of time.

The dental connection

The drug resistance issue is causing some researchers to question antibiotic prophylaxis, including those prescribed prior to dental treatment. For patients with cardiac defects or artificial joints, just how likely are they to develop a bacteremia and then endocarditis or prosthetic joint infection after invasive dental treatment? According to the American Heart Association, it depends on the patient and the procedure.

Endocarditis is a relatively rare, but often deadly, occurrence. Definitive research has not conclusively attributed it to invasive dental procedures, but enough evidence exists that the American Heart Association recommends antibiotics for patients with certain heart conditions.

A statement from the American Heart Association about the prevention of bacterial endocarditis asserts, "No randomized and carefully controlled human trials of patients with underlying structural heart disease definitively establishes that antibiotic prophylaxis provides protection against development of endocarditis during bacteremia-inducing procedures." It also states that most cases of endocarditis are "not attributable to an invasive procedure." However, primary prevention of endocarditis is important because - although occurrence is rare - it does have "substantial morbidity and mortality."

Dr. Ann Bolger, an associate professor of medicine at the University of California, San Francisco, said that the AHA releases these recommendations because "we are a public advocacy organization, concerned about the heart health of the American public. We are extraordinarily concerned about bacteria developing increasing resistance, because to us the worse thing that could happen is for someone to have a case of endocarditis and no antibiotic that it is sensitive to.

"But the other issue to consider is that endocarditis can be fatal. There are many cases we can't avoid which are due to lifestyle choices or unpredictable bacteremias."

Dr. Bolger, who is also director of echocardiography at San Francisco General Hospital and a spokesperson for the American Heart Association, emphasized that predictable bacteremias can be avoided.

"We are constantly refining the criteria for avoidance of predictable bacteremias," she said. "There are some bacteremias that are not likely to cause endocarditis, but unfortunately the mouth is full of the exact type of bacteria that stick to heart valves and can cause endocarditis. We take dental procedures very seriously." She added that not enough is known about exactly how and why these bacteria stick to heart valves. With future research, hopefully it will become less of a mystery.

Dr. Bolger explained that even a person with a healthy heart can develop endocarditis, and a healthy heart has a good chance of recovering quickly. But a person with congenital heart disease with complicated blood flow is very prone to endocarditis and the consequences can be severe, even fatal. She explained that a person with a prosthetic heart valve who develops endocarditis may die from the infection, or may have to have their heart surgery redone at tremendous risk and cost.

"Endocarditis is a terrible disease," Dr. Bolger said. "Our main concern has to be the public well-being. Admittedly, we don't have all the data on this. We will continue to refine who needs antibiotics, how much, and how often as new data is discovered. Hopefully this will minimize unnecessary antibiotic use."

The American Heart Association, in conjunction with cardiac experts, released revised guidelines in 1997 regarding antibiotic prophylaxis. The guidelines suggest one dose of antibiotics prior to treatment instead of multiple doses over time.

"The recommendations are just that - recommendations. It doesn't claim you are in malpractice if you don't premedicate," Dr. Bolger said.

It isn't just the threat of endocarditis that may require premeds. The ADA and the American Academy of Orthopaedic Surgeons developed recommendations (in July 1997) for antibiotic prophylaxis for patients with total joint replacements. Their conclusion was that antibiotic prophylaxis was not routinely indicated for most dental patients with total joint replacements, or those with pins, screws, and plates. Only a limited group of immunosuppressed or immunocompromised patients may be at a higher risk for infection, or those with insulin-dependent diabetes, previous prosthetic joint infections, malnourishment, hemophilia, or during the first two years of joint replacement. The report stressed bacteremias that can lead to infected prosthetic joints can happen with or without invasive procedures. The report also says instrument processing. Bench space should be assigned in a linear fashion to receiving, waste disposal, cleaning, rinsing, drying/rust inhibition, and packaging. Consider adding compressed air and a vacuum line in the decontamination area for cleaning/lubricating handpieces. During this process, the spray should be directed into a vacuum line to avoid air contamination.

Do not arrange tasks or storage space that will require one to move back and forth between the two designated areas. Don't work in the sterilization area with contaminated gloves, and don't place contaminated instruments, packs, or cassettes in the sterilization area. The goal is to eliminate any intermingling of sterilized and unsterilized instruments, instrument packs, or instrument cassettes.

The sterilizer(s) in the sterilizing area should be arranged so that ample space is available to open the door. Steam and unsaturated chemical vapor sterilizers need space above the unit for pouring in water or the chemical solution. Steam from autoclaves will escape and rise from the front of the door when opened. Thus, do not store moisture-sensitive items (for example, sterilized packages) above the autoclave.

In summary, organizing the instrument-processing area into a decontamination area and a sterilizing area - and identifying these areas with appropriate signage - can help assure patient safety and facilitate efficiency.

The right way to be sick

  • Avoid using antibiotics unnecessarily. In general, antibiotics do not work against colds, flu, mild coughs, and other viral infections. Taking one will not help.
  • When prescribed any drug for an illness, finish all of the medication even if you feel better or unless specifically instructed by your doctor to stop.
  • Never take medication left over from a previous illness. See your doctor to discover if a new prescription is needed for the specific illness you have now.
  • Take the drug exactly the way your doctor prescribes. Don't skip or double up on dosage. If you have any questions, call your doctor or pharmacist.
  • Don't expect a visit to the doctor to mean a prescription in your hand. Studies show that most doctors feel pressured by patients to write out prescriptions, even when it won't help. Antibiotics are not a cure-all.
  • If you need a drug, let your doctor choose the best one. Don't ask for the drug that you think is best, even if one worked well the last time you were sick. Most drugs are targeted to kill specific bacteria, which can be better than a broad-spectrum drug. Do ask what you are getting and why that particular drug is selected.
  • Don't expect your doctor to call in a prescription for you without a visit, even when you think you know what is wrong. It's always best to see the physician in person when illness strikes.

For more information about antibiotics American Heart Association Alliance for the Prudent Use of Antibiotics Centers for Disease Control & Prevention (CDC) In addition, RDH has published the American Heart Association's guidelines on "cardiac conditions associated with endocarditis" and "regimen for prophylactic antibiotics," which are also available on the association's Web site. To review the RDH version, simply access and initiate a search for "antibiotics." Select the article titled, "Danger: Overuse of antibiotics" by Cindy Biron, RDH.