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Recent research spearheaded by infectious disease specialists points to a growing danger from antibiotic-resistant bacteria that fights off the body’s immune system and destroys tissues. Methicillin resistant staphylococcus aureus, or MRSA-previously seen chiefly in health care settings-is now showing up with alarming frequency in the general population.
Since 2000, community-acquired infections have spread quickly throughout the country.
Since 2000, community-acquired infections have spread quickly throughout the country.
A study in the Aug. 17, 2006, issue of the New England Journal of Medicine (NEJM)- conducted by the Centers for Disease Control and Prevention, the University of California at Los Angeles and several other institutions-shows the extent to which community-acquired MRSA has spread. In data gathered from 422 patients visiting the emergency rooms of 11 major metropolitan hospitals, the bacterium accounted for 59 percent of the skin infections doctors treated. Prevalence ranged from 15 percent in New York City to 74 percent in Kansas City, Mo.
MRSA skin infections are usually spread from person to person by direct contact, either by touching a draining lesion or by contact with an asymptomatic carrier. Transmission can also occur by touching contaminated surfaces or clothing. Several cases have been reported among tattoo customers in Kentucky, Ohio and Vermont. Most of the infections were linked to unlicensed tattooists who did not follow proper infection control precautions.
The bacteria usually enter the body through an opening in the skin, from something as minor as a paper cut to major trauma. It can also enter through weakened skin, such as a bruise, blister or abrasion. In some cases there appears to be no identifiable point of entry. MRSA was first discovered in the 1960s when it began showing up in health care settings. Then, just six years ago, infections were found in the community among prison inmates, intravenous-drug users, professional athletes, military trainees and sexually active gay men. Since that time, community-acquired infections have spread quickly throughout the country.
Earlier this year, the CDC published the first reliable evidence documenting the extent of MRSA in the community. As many as two million people carry the bacteria in their noses, according to a Jan. 15, 2006, article in The Journal of Infectious Diseases. Prevalence appears to be highest among men and 6- to 11-year-old children. Although those who harbor the bacterium may be asymptomatic, they are at higher risk for developing an infection.
Most cases of community-acquired MRSA are characterized by skin and soft tissue infections. But the bacterium can cause potentially fatal, once-rare conditions such as necrotizing fasciitis, commonly known as flesh-eating bacteria, and toxic-shock syndrome. The hospital strain, on the other hand, is more commonly associated with surgical site infections, vascular catheter-associated infections and even ventilator-associated pneumonia.
In the NEJM study, most of the patients with community-acquired MRSA infections came to emergency rooms with painful skin lesions that resembled spider bites. As a result, the study authors wrote, physicians should be alerted to test for MRSA if a patient has such a lesion.
In the past, community-acquired soft-tissue infections were treated with antibiotics like cephalexin, macrolides or methicillin, and clinicians didn’t routinely obtain cultures. However, new, more virulent strains have developed that are resistant to these commonly used antibiotics. Scientists have identified the USA300 strain as the fastest spreading MRSA infection.
Many MRSA-caused skin abscesses can be treated with drainage alone. But when antibiotics are necessary, choosing the correct one is imperative. The CDC/UCLA researchers found that in almost all cases they studied, community-acquired MRSA was treatable with antibiotics such as clindamycin, trimethoprin-sulfamethoxazole, doxycycline and rifampin.
“The high prevalence of MRSA among patients with community-associated skin and soft-tissue infections has implications for hospital policies regarding infection control," they wrote. "Clinicians should consider obtaining cultures from patients with skin and soft-tissue infections and modifying standard empirical therapy to provide MRSA coverage when antibiotics are indicated.”
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We already have an international epidemic of community-acquired MRSA. It's very important to recognize the threat and educate the public. These bacteria have been present long before the human race, and they'>re going to be here long after we’re gone. They're two steps ahead of the game because they are survivors. They develop patterns of survival in the face of threats like antibiotics.
In the last few years, the organism that has been introduced into the population is a new strain of staph. It differs in genetic makeup from what we used to see only in health-care settings.
“75% of the community-acquired MRSA infections are usually skin and soft tissue infection.”
In 2003, these bacteria received a lot of attention when they were identified in young, healthy people-football players who shared bath towels or hand soap and in prison populations where the hygiene area wasn't well kept. Eighteen to 25 people out of every 100,000 in the U.S. develop the hospital- or community-acquired strains of MRSA. That’s a big increase. The main reason for the increase is that a new strain of the bacterium has been introduced into the community.
In 2003, these bacteria received a lot of attention when they were identified in young, healthy people-football players who shared bath towels or hand soap and in prison populations where the hygiene area wasn't well kept. Eighteen to 25 people out of every 100,000 in the U.S. develop the hospital- or community-acquired strains of MRSA. That's a big increase. The main reason for the increase is that a new strain of the bacterium has been introduced into the community.
There are many ways in which this organism can enter a person’s body and cause an infection. Any time you violate the integrity of the skin, such as with tattoos and piercings, and you don’t pay attention to strict antisepsis during procedures, you put yourself at risk.
Fortunately, 75 percent of the community-acquired MRSA infections are usually skin and soft tissue infection. Occasionally they can cause serious, or deep skin infections, similar to flesh-eating bacteria, as well as pneumonia and bloodstream or bone infections. Toxic shock syndrome is also possible.
The important thing for the consumer is recognizing the early manifestations of the skin and soft tissue infection. It usually starts as a red, raised welt, almost like a spider bite, and can also be very painful. If it is as much as 5 centimeters in size, it should be drained by a surgeon. "Spider bite" should be a buzz word to alert clinicians to consider soft-tissue infection with community-acquired MRSA.
The community strain and the hospital strain of MRSA have different antibiotic susceptibility patterns. The community strain is much more sensitive to more drugs; however, it also has the ability to produce various toxins much more effectively, which is part of the reason it causes infections.
These organisms can adapt quickly to new environmental conditions. They mutate and evolve rapidly. A mutation that helps the bacteria survive exposure to an antibiotic will quickly become dominant.
The inappropriate use of antibiotics serves only to increase their resistance. Physicians sometimes inappropriately prescribe antibiotics to treat a patient who has a virus. Also, when a patient does not finish taking a prescription for antibiotics, some bacteria may remain. These bacterial survivors are more likely to develop resistance and spread. Judicious use of antibiotics is extremely important.
It should be noted that if the organism is resistant to erythromycin, the microbiology laboratory should verify that it is not able to inactivate clindamycin before this drug is selected for therapy.
It takes a concerted effort to get rid of these infections in the long term because the bacteria can colonize your body. The infected person should:
• Wear cotton clothing that can be washed in hot water.
• Change sheets and towels daily and not share with others in the household.
• Clip fingernails and toenails short.
Clorox is an excellent disinfectant, and liquid, alcohol-based soaps should be used rather than bar soap.
Infection control is just good common sense. For example, if you’re going to get a tattoo or body piercing, ask questions about equipment and antiseptic procedures. Find out if the tattooist is licensed.
The Centers for Disease Control and Prevention recommends the following:
Dr. McCormick is an associate professor of medicine at the UK College of Medicine and UK Chandler Hospital epidemiologist.
Each issue of Advances & Insights summarizes an important piece of medical news, accompanied by commentary from a UK expert.
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