Antibiotic-resistant MRSA all too common

Aug 20 2006

Researchers in the U.S. say that methicillin-resistant Staphylococcus aureus or MRSA is the most common cause of skin and soft-tissue infections among patients presenting in emergency rooms across the country.

MRSA is now resistant to antibiotics such as cephalexin and dicloxacillin used for years to treat skin conditions.

Dr. Gregory J. Moran, the study's principal investigator is a clinical professor of medicine in the department of emergency medicine and the Division of Infectious Diseases at Olive View - UCLA Medical Center; he says that the rising prevalence of this type of MRSA demonstrates the need for clinicians to culture infections and make sure the proper antibiotic is administered to treat MRSA.

MRSA has been found in health care settings since the 1960s, most commonly amongst patients who have been hospitalized or are in nursing homes.

However in the last few years, a new type of MRSA has emerged, which is affecting people with no connection to health care settings.

Such outbreaks of these new strains of MRSA have been reported among athletes, correctional facility inmates and military recruits.

The bacteria live uneventfully in the nose of many people but sometimes lead to serious infection and symptoms can range from something as benign as an infected paper cut, to bloodstream infections, to infections of heart valves that can be fatal.

This study demonstrates that the infections appear to be common in people who are not connected to any particular risk group.

Professor David Talan, an author of the study and chief of the department of emergency medicine at the UCLA Medical Center, says the number of patients showing up in the emergency room with infections that turned out to be community-associated MRSA was noticeable and they were interested to see if this was the case nationwide.

Apparently community-associated MRSA usually manifests itself on the skin as a boil or pimple that can be swollen, red and painful, and have discharge.

Researchers cultured the acute skin or soft-tissue infections of 422 patients seen at 11 metropolitan emergency rooms in the United States during August 2004 and of those patients, 249, or 59 percent, were found to have MRSA.

The proportion of infections caused by MRSA in various cities ranged from 15 to 74 percent.

Further investigations by the Centers for Disease Control and Prevention, revealed that of the MRSA samples, one genetic type accounted for 97 percent of the samples.

Dr. Moran says this one genetic type of MRSA is appearing in metropolitan areas across the country, and more research should determine how prevalent it is in other parts of the nation.

When researchers tested the antibiotic resistance of the isolated MRSA samples they found that in 57 percent of cases, doctors had prescribed an antibiotic to which the bacteria were resistant.

Professor Talan says doctors need to change their tactics as traditional antibiotics do not work against MRSA, and they need to reconsider antibiotic choices for skin and soft-tissue infections in areas where MRSA is prevalent in the community.

Talan says though most MRSA cases are mild, and having the infection drained and keeping it clean resolves the problem, when antibiotics are needed, it's important to prescribe an effective medication.

Sometimes such infections demand hospitalization and in rare cases, may even be life-threatening and Dr. Moran says it is important for doctors to identify and properly treat MRSA in order to halt further progression of serious infections and to prevent recurrence.

When the researchers tested the effectiveness of different types of antibiotics on the MRSA samples they found that 95 percent were susceptible to clindamycin, 6 percent to erythromycin, 60 percent to fluoroquinolones, 100 percent to rifampin and trimethoprim-sulfamethoxazole, and 92 percent to tetracycline.

According to Moran, the next step is to compare the different antibiotics in real patients in order to identify an optimal treatment.

The study revealed several potential risk factors for community-associated MRSA.

It seems patients with MRSA were more likely to report a spider bite as the reason for the skin lesion, perhaps thinking it was a bite in absence of other skin problems and those with MRSA were more likely to have close contact with a person with a similar infection.

However, Moran says none of these risk factors were consistent enough to help doctors identify cases of MRSA and it appears that everyone is at risk.

He advises people who think they have a spider bite or other type of skin lesion that is not healing, to see a doctor to check it is not an infection such as MRSA.

Dr. Rachel J. Gorwitz, an author of the study and a medical epidemiologist at the Centers for Disease Control and Prevention, says it is important to educate patients in order to avoid transmission and she advises the following;-

• Wash hands often with soap and water to keep them clean, or use an alcohol-based hand sanitizer (if hands are not visibly soiled).
• Don't share towels, razors or other personal items.
• Avoid contact with other people's wounds or bandages.
• Keep breaks in your skin clean and covered and watch for signs of infection, such as redness, warmth and swelling.
• See your doctor if you notice signs of infection; don't try to drain a boil yourself at home.
• If you have a skin infection, keep the infected area covered with a clean, dry bandage until it is healed; wash your hands thoroughly after changing the bandage and put used bandages in the trash.

The study is published in the Aug. 17 issue of the New England Journal of Medicine.