MRSA - methicillin resistant Staph Aureus
Deadly Bacteria Found to Be More Common
By Kevin Sack : NY Times Article : October 17, 2007
Nearly 19,000 people died in the United States in 2005 after being infected with virulent drug-resistant bacteria that have spread rampantly through hospitals and nursing homes, according to the most thorough study of the disease’s prevalence ever conducted.
The government study, which is being published Wednesday in The Journal of the American Medical Association, suggests that such infections may be twice as common as previously thought, according to its lead author, Dr. R. Monina Klevens.
If the mortality estimates are correct, the number of deaths associated with the germ, methicillin-resistant Staphylococcus aureus, or MRSA, would exceed those attributed to H.I.V.-AIDS, Parkinson’s disease, emphysema or homicide each year.
By extrapolating data collected in nine places, the researchers estimated that 94,360 patients developed an invasive infection from the pathogen in 2005 and that nearly one of every five, or 18,650 of them, died. The study points out that it is not always possible to determine whether a death is caused by MRSA or merely accelerated by it.
The authors, who work for the Centers for Disease Control and Prevention, cautioned that their methodology differed significantly from previous studies and that direct comparisons were therefore risky. But they said they were surprised by the prevalence of serious infections, which they calculated as 32 cases per 100,000 people.
In an accompanying editorial in the medical journal, Dr. Elizabeth A. Bancroft, an epidemiologist with the Los Angeles County Department of Public Health, characterized that finding as “astounding.”
The prevalence of invasive MRSA — when the bacteria has not merely colonized on the skin, but has attacked a normally sterile part of the body, like the organs — is greater, Dr. Bancroft wrote, than the combined rates for other conditions caused by invasive bacteria, including bloodstream infections, meningitis and flesh-eating disease.
The study also concluded that 85 percent of invasive MRSA infections are associated with health care treatment. Previous research had indicated that many hospitals and long-term care centers had become breeding grounds for MRSA because bacteria could be transported from patient to patient by doctors, nurses and unsterilized equipment.
“This confirms in a very rigorous way that this is a huge health problem,” said Dr. John A. Jernigan, the deputy chief of prevention and response in the division of healthcare quality promotion at the disease control agency. “And it drives home that what we do in health care will have a lot to do with how we control it.”
The findings are likely to stimulate further an already active debate about whether hospitals and other medical centers should test all patients for MRSA upon admission. Some hospitals have had notable success in reducing their infection rates by isolating infected patients and then taking extra precautions, like requiring workers to wear gloves and gowns for every contact.
But other research has suggested that such techniques may be excessive, and may have the unintended consequence of diminishing medical care for quarantined patients. The disease control agency, in guidelines released last year, recommended that hospitals try to reduce infection rates by first improving hygiene and resort to screening high-risk patients only if other methods fail.
Dr. Lance R. Peterson, an epidemiologist with Evanston Northwestern Healthcare, said his hospital system in the Chicago area reduced its rate of invasive MRSA infections by 60 percent after it began screening all patients in 2005.
“This study puts more onus on organizations that don’t do active surveillance to demonstrate that they’re reducing their MRSA infections,” Dr. Peterson said. “Other things can work, but nothing else has been demonstrated to have this kind of impact. MRSA is theoretically a totally preventable disease.”
Numerous studies have shown that busy hospital workers disregard basic standards of hand-washing more than half the time. This week, Consumers Union, the nonprofit publisher of Consumer Reports, called for hospitals to begin publishing their compliance rates for hand-washing.
Lisa A. McGiffert, manager of the “Stop Hospital Infections” campaign at Consumers Union, said, “This study just accentuates that the hospital is ground zero, that this is where dangerous infections are occurring that are killing people every day.”
MRSA, which was first isolated in the United States in 1968, causes 10 percent to 20 percent of all infections acquired in health care settings, according to the disease control agency. Resistant to a number of front-line antibiotics, it can cause infections of surgical sites, the urinary tract, the bloodstream and lungs. Treatment often involves the intravenous delivery of other drugs, causing health officials to worry that overuse will breed further resistance.
The bacteria can be brought unknowingly into hospitals and nursing homes by patients who show no symptoms, and can be transmitted by contact as casual as the brush of a doctor’s lab coat. Highly opportunistic, they can enter the bloodstream through incisions and wounds and then quickly overwhelm a weakened immune system.
On Monday, a Virginia teenager died after a weeklong hospitalization for an MRSA infection that spread quickly to his kidneys, liver, lungs and the muscle around his heart. Local officials promptly closed 21 schools for a thorough cleaning.
A major difference between the new study and its predecessors is that it compiled confirmed cases of MRSA infection, rather than relying on coded patient records that sometimes lack precision. The study found higher prevalence rates and death rates for the elderly, African-Americans and men. The figures also varied by geography, with Baltimore’s incidence rates far exceeding those of the eight other locations: Connecticut; Atlanta; San Francisco; Denver; Portland, Ore.; Monroe County, N.Y.; Davidson County, Tenn.; and Ramsey County, Minn.
Dr. Klevens said further research would be needed to understand the racial and geographic disparities.
MRSA infection
Introduction
Methicillin-resistant Staphylococcus aureus (MRSA) infection is caused by Staphylococcus aureus bacteria — often called "staph." Decades ago, a strain of staph emerged in hospitals that was resistant to the broad-spectrum antibiotics commonly used to treat it. Dubbed methicillin-resistant Staphylococcus aureus (MRSA), it was one of the first germs to outwit all but the most powerful drugs. MRSA infection can be fatal.
Staph bacteria are normally found on the skin or in the nose of about one-third of the population. If you have staph on your skin or in your nose but aren't sick, you are said to be "colonized" but not infected with MRSA. Healthy people can be colonized with MRSA and have no ill effects, however, they can pass the germ to others.
Staph bacteria are generally harmless unless they enter the body through a cut or other wound, and even then they often cause only minor skin problems in healthy people. But in older adults and people who are ill or have weakened immune systems, ordinary staph infections can cause serious illness called methicillin-resistant Staphylococcus aureus or MRSA.
In the 1990s, a type of MRSA began showing up in the wider community. Today, that form of staph, known as community-associated MRSA, or CA-MRSA, is responsible for many serious skin and soft tissue infections and for a serious form of pneumonia.
Vancomycin is one of the few antibiotics still effective against hospital strains of MRSA infection, although the drug is no longer effective in every case. Several drugs continue to work against CA-MRSA, but CA-MRSA is a rapidly evolving bacterium, and it may be a matter of time before it, too, becomes resistant to most antibiotics.
Signs and symptoms
Staph infections, including MRSA, generally start as small red bumps that resemble pimples, boils or spider bites. These can quickly turn into deep, painful abscesses that require surgical draining. Sometimes the bacteria remain confined to the skin. But they can also burrow deep into the body, causing potentially life-threatening infections in bones, joints, surgical wounds, the bloodstream, heart valves and lungs.
Causes
Although the survival tactics of bacteria contribute to antibiotic resistance, humans bear most of the responsibility for the problem. Leading causes of antibiotic resistance include:
- Unnecessary antibiotic use in humans. Like other superbugs, MRSA is the result of decades of excessive and unnecessary antibiotic use. For years, antibiotics have been prescribed for colds, flu and other viral infections that don't respond to these drugs, as well as for simple bacterial infections that normally clear on their own.
- Antibiotics in food and water. Prescription drugs aren't the only source of antibiotics. In the United States, antibiotics can be found in beef cattle, pigs and chickens. The same antibiotics then find their way into municipal water systems when the runoff from feedlots contaminates streams and groundwater. Routine feeding of antibiotics to animals is banned in the European Union and many other industrialized countries. Antibiotics given in the proper doses to animals who are sick don't appear to produce resistant bacteria.
- Germ mutation. Even when antibiotics are used appropriately, they contribute to the rise of drug-resistant bacteria because they don't destroy every germ they target. Bacteria live on an evolutionary fast track, so germs that survive treatment with one antibiotic soon learn to resist others. And because bacteria mutate much more quickly than new drugs can be produced, some germs end up resistant to just about everything. That's why only a handful of drugs are now effective against most forms of staph.
Because hospital and community strains of MRSA generally occur in different settings, the risk factors for the two strains differ.
Risk factors for hospital-acquired (HA) MRSA include:
- A current or recent hospitalization. MRSA remains a concern in hospitals, where it can attack those most vulnerable — older adults and people with weakened immune systems, burns, surgical wounds or serious underlying health problems. A 2007 report from the Association for Professionals in Infection Control and Epidemiology estimates that 1.2 million hospital patients are infected with MRSA each year in the United States. They also estimate another 423,000 are colonized with it.
- Residing in a long-term care facility. MRSA is far more prevalent in these facilities than it is in hospitals. Carriers of MRSA have the ability to spread it, even if they're not sick themselves.
- Invasive devices. People who are on dialysis, are catheterized, or have feeding tubes or other invasive devices are at higher risk.
- Recent antibiotic use. Treatment with fluoroquinolones (ciprofloxacin, ofloxacin or levofloxacin) or cephalosporin antibiotics can increase the risk of HA-MRSA.
- Young age. CA-MRSA can be particularly dangerous in children. Often entering the body through a cut or scrape, MRSA can quickly cause a wide spread infection. Children may be susceptible because their immune systems aren't fully developed or they don't yet have antibodies to common germs. Children and young adults are also much more likely to develop dangerous forms of pneumonia than older people are.
- Participating in contact sports. CA-MRSA has crept into both amateur and professional sports teams. The bacteria spread easily through cuts and abrasions and skin-to-skin contact.
- Sharing towels or athletic equipment. Although few outbreaks have been reported in public gyms, CA-MRSA has spread among athletes sharing razors, towels, uniforms or equipment.
- Having a weakened immune system. People with weakened immune systems, including those living with HIV/AIDS, are more likely to have severe CA-MRSA infections.
- Living in crowded or unsanitary conditions. Outbreaks of CA-MRSA have occurred in military training camps and in American and European prisons.
- Association with health care workers. People who are in close contact with health care workers are at increased risk of serious staph infections.
Keep an eye on minor skin problems — pimples, insect bites, cuts and scrapes — especially in children. If wounds become infected, see your doctor. Ask to have any skin infection tested for MRSA before starting antibiotic therapy. Drugs that treat ordinary staph aren't effective against MRSA, and their use could lead to serious illness and more resistant bacteria.
Screening and diagnosis
Doctors diagnose MRSA by checking a tissue sample or nasal secretions for signs of drug-resistant bacteria. The sample is sent to a lab where it's placed in a dish of nutrients that encourage bacterial growth (culture). But because it takes about 48 hours for the bacteria to grow, newer tests that can detect staph DNA in a matter of hours are now becoming more widely available.
In the hospital, you may be tested for MRSA if you show signs of infection or if you are transferred into a hospital from another healthcare setting where MRSA is known to be present. You may also be tested if you have had a previous history of MRSA.
Treatment
Both hospital and community associated strains of MRSA still respond to certain medications. In hospitals and care facilities, doctors generally rely on the antibiotic vancomycin to treat resistant germs. CA-MRSA may be treated with vancomycin or other antibiotics that have proved effective against particular strains. Although vancomycin saves lives, it may grow resistant as well; some hospitals are already seeing outbreaks of vancomycin-resistant MRSA. To help reduce that threat, doctors may drain an abscess caused by MRSA rather than treat the infection with drugs.
Prevention
Hospitals are fighting back against MRSA infection by using surveillance systems that track bacterial outbreaks and by investing in products such as antibiotic-coated catheters and gloves that release disinfectants.
Still, the best way to prevent the spread of germs is for health care workers to wash their hands frequently, to properly disinfect hospital surfaces and to take other precautions such as wearing a mask when working with people with weakened immune systems.
In the hospital, people who are infected or colonized with MRSA are placed in isolation to prevent the spread of MRSA to other patients and healthcare workers.Visitors and healthcare workers caring for isolated patients may be required to wear protective garments and must follow strict handwashing procedures.
What you can do
Here's what you can do to protect yourself, family members or friends from hospital-acquired infections.
- Ask all hospital staff to wash their hands before touching you — every time.
- Wash your own hands frequently.
- Ask to be bathed with disposable cloths treated with a disinfectant rather than with soap and water.
- Make sure that intravenous tubes and catheters are inserted and removed under sterile conditions; some hospitals have dramatically reduced MRSA blood infections simply by sterilizing patients' skin before using catheters.
Protecting yourself from CA-MRSA — which might be just about anywhere — may seem daunting, but these common-sense precautions can help reduce your risk:
- Keep personal items personal. Avoid sharing personal items such as towels, sheets, razors, clothing and athletic equipment. MRSA spreads on contaminated objects as well as through direct contact.
- Keep wounds covered. Keep cuts and abrasions clean and covered with sterile, dry bandages until they heal. The pus from infected sores often contains MRSA, and keeping wounds covered will help keep the bacteria from spreading.
- Sanitize linens. If you have a cut or sore, wash towels and bed linens in hot water with added bleach and dry them in a hot dryer. Wash gym and athletic clothes after each wearing.
- Wash your hands. In or out of the hospital, careful hand washing remains your best defense against germs. Scrub hands briskly for at least 15 seconds, then dry them with a disposable towel and use another towel to turn off the faucet. Carry a small bottle of hand sanitizer containing at least 62 percent alcohol for times when you don't have access to soap and water.
- Get tested. If you have a skin infection that requires treatment, ask your doctor if you should be tested for MRSA. Many doctors prescribe drugs that aren't effective against antibiotic-resistant staph, which delays treatment and creates more resistant germs.
Here are answers to common questions about community-acquired staph infections, or CA-MRSA.
What does CA-MRSA look like?
CA-MRSA is primarily a skin infection. It often resembles a pimple, boil or spider bite, but it quickly worsens into an abscess or puss-filled blister or sore. Patients who have sores that won’t heal or are filled with pus should see a doctor and ask to be tested for staph infection. They should not squeeze the sore or try to drain it — that can spread the infection to other parts of the skin or deeper into the body.
Who is at risk?
The vast majority of MRSA cases happen in hospital settings, but 10 percent to 15 percent occur in the community at large among otherwise healthy people. Infections often occur among people who are prone to cuts and scrapes, such as children and athletes. MRSA typically spreads by skin-to-skin contact, crowded conditions and the sharing of contaminated personal items. Others who should be watchful: people who have regular contact with health care workers, those who have recently taken such antibiotics as fluoroquinolones or cephalosporin, homosexual men, military recruits and prisoners. Clusters of infections have appeared in certain ethnic groups, including Pacific Islanders, Alaskan Natives and Native Americans.
What can I do to lower my risk of contracting MRSA?
Bathing regularly and washing hands before meals is just a start. Wash your hands often or use an antibacterial sanitizer after you’ve been in public places or have touched handrails and other highly trafficked surfaces. Make sure cuts and scrapes are bandaged until they heal. Wash towels and sheets regularly, preferably in hot water, and leave clothes in the dryer until they are completely dry. “Staph is a pretty hardy organism,’’ said Dr. Gerba.
Remind kids and teenagers that personal items shouldn’t be shared with their friends, he added. This includes brushes, combs, razors, towels, makeup and cell phones. A teenager in Dr. Gerba’s own family once contracted MRSA, he said, and he eventually traced the bacteria to her cell phone. She had shared it with a friend whose mother worked in a nursing home. Dr. Gerba went on to discover MRSA on the friend’s cell phone and makeup compact and on a countertop in her home.
Where does MRSA lurk?
The bacteria may be found on the skin and in the noses of nearly 30 percent of the population without causing harm. Experts believe it survives on surfaces in 2 percent to 3 percent of homes, cars and public places.
But the bacteria are evolving, and the statistics may already underestimate the prevalence of MRSA. Be especially vigilant in health clubs and gyms — staph grows rapidly in warm, moist environments. The risks of infection and necessary precautions should be explained to student athletes, particularly those in contact sports who often suffer cuts and spend time in locker rooms. When working out at the gym, make sure you wipe down equipment before you use it. Many people clean just the sweaty benches, but Dr. Gerba notes that MRSA also has been found on the grips of workout machines. And if you have a scrape or sore, keep it clean and bandaged until it heals. Minor cuts and scrapes are the way MRSA takes hold.
What is the single best thing I can do to protect myself from MRSA?
Without question, people need to show far more respect for antibiotics. Misuse of antibiotics allows bacteria to evolve and develop resistance to drugs. But parents often pressure pediatricians to prescribe antibiotics even when they don’t help the vast majority of childhood infections. When you do take an antibiotic, finish the dose. Antibiotic resistance is bad for everyone, but your body can also become particularly vulnerable to resistant bacteria if you are careless with the drugs.
How do I find out more?
One of the most useful Web sites is a MRSA primer from Mayoclinic.com. The Centers for Disease Control and Prevention offers a useful Q&A about MRSA in schools.
CDC officials stress that the number of such infections is still relatively low, and children ages 5 to 17 years have the lowest rate of MRSA infection of any age group. The overall physical environment, moreover, hasn't played a significant role in the transmission of MRSA. Transmission occurs with direct contact with an infected person or contaminated items, such as sporting equipment or clothing. So scrubbing down locker-room walls as if they were a biohazard hot zone isn't going to protect kids as well as making sure that they keep their hands clean, cover open wounds with clean, dry bandages, and avoid sharing personal items such as towels, razors or uniforms.
In team sports it is also important to exclude players who have potentially infected skin lesions if their wounds can't be covered. Other measures include washing clothes, especially uniforms and exercise gear, in hot water and laundry detergent and drying them in a hot dryer. (For more information on infection prevention techniques, check cdc.gov.)
Such common-sense measures apply to protecting yourself and your children from other kinds of infections as well. In most places where people share facilities or water, bacteria can spread. That resort hot tub may look inviting, but there is always a risk that the others sharing it don't have pristine personal hygiene; so-called recreational water illnesses can cause skin, ear, respiratory, eye, neurologic and wound infections. If you are getting a salon pedicure, don't shave your legs beforehand, because any bacteria in a salon's foot baths, including MRSA, can enter the skin or bloodstream through minor nicks. Ensure that the foot bath basin is thoroughly sanitized, and bring your ownequipment, such as clippers.
