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Like characters in a bad horror movie, we had our backs turned when bacteria that we thought we'd beaten rose up with new powers and began to fight back. We had grown confident in the power of our weapons — antibiotics — and neglected to prepare for a counterattack. These mighty bacteria that are able to fight off antibiotics have certainly earned their popular name: superbugs.
Because bacteria are prevalent in places where sick people share close quarters with staff and other patients, hospitals are on the front lines of the war against superbugs.
Both normal and mutant bacteria replicate at incredible rates. Potent antibiotics easily wipe out most normal bacteria. But their mutant siblings, whose abnormalities often allow them to survive an antibiotic attack, then flourish with no competition for nutrients. Superbugs actually adapt their cellular structure to become invulnerable to future attacks by the same drug. Scarier still, superbugs may exchange their survival secrets with other bacteria — even different species — allowing additional resistant legions to grow.
On a global scale, modern medicine has inadvertently dealt a big hand to the superbugs through overuse of antibiotics. According to a 1998 report by the Institute of Medicine, up to 50 percent of antibiotics are prescribed unnecessarily. Many patients compound the problem. A recent survey showed that half of patients do not finish their prescribed course of antibiotics. Most respondents said they stopped taking their drugs when they felt better. Here's the problem with such habits: An abbreviated course of antibiotics often wipes out only the most vulnerable bacteria while allowing resistant bacteria to survive and prosper.
Penicillin was discovered in the 1940s. It was followed in quick succession by hundreds of other antibiotics, creating an arsenal of drugs that offered unprecedented control over bacterial infections. However, within just a few years of the introduction and use of antibiotics, a troubling pattern emerged. Bacteria frequently treated with the same antibiotic would eventually develop resistance to the drug. Another antibiotic would then have to be used — until the bug learned to resist that drug, too. For years, the potent antibiotic vancomycin offered a reliable last defense against the most virulent bacteria. However, in the last decade, some superbugs have figured out how to elude even vancomycin.
Hospitals are particularly fertile breeding grounds for superbugs. Confined populations of sick people, many with weakened immune systems, create bacteria-friendly environments. The Centers for Disease Control and Prevention (CDC) estimates that more than 2 million Americans develop hospital-acquired (nosocomial) infections each year, and between 60,000 and 80,000 of those people die. However, if you have surgery or other treatment in a hospital, your risk is still low. Only about 5 percent of hospital patients develop nosocomial infections.
"The risk to individual patients depends on their level of illness, the duration of their stay in the hospital, their need for broad-spectrum antibiotics, and their need for intensive care," says Rodney L. Thompson, M.D., an infectious disease specialist at Mayo Clinic, Rochester, Minn. "Patients with suppressed immune systems have a higher risk. The relatively well person undergoing less complicated treatment has a low risk."
Of those who do develop a hospital-acquired infection, a very small percentage is infected by bacteria that are resistant to multiple antibiotics. When resistant infections do occur, they usually can be conquered with higher doses or a potent combination of available drugs.
But if the global use of antibiotics isn't radically altered, superbugs have the potential to greatly increase the risks associated with even minor surgery and treatments received in hospitals.
The most worrisome antibiotic-resistant bacteria in hospitals today are strains of Enterococcus and Staphylococcus aureus.
A strain of vancomycin-resistant Enterococcus, known as VRE, first appeared in the late 1980s and has thrived ever since. Scientists worry that VRE will not only continue to proliferate but will share its genetic secrets for survival with bacteria such as Staphylococcus aureus.
Many strains of staph are resistant to multiple antibiotics. But until recently, vancomycin could always be depended on as a last resort. However, in 1997, a Japanese infant developed the first known case of staph that showed moderate resistance to vancomycin. Scientists fear that this strain of staph, called vancomycin intermediate-resistant staphylococcus aureus (VISA), may start infecting more patients and become even more resistant. The emergence of a staph strain able to fully resist vancomycin would present a serious crisis.
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