Reviewing MRSA , vaccine advances, resistance

April 1, 2006

San Francisco ? Dermatologists are seeing more community-acquired strains of methicillin-resistant Staphylococcus aureus (MRSA), according to John H. Epstein, M.D.

San Francisco - Dermatologists are seeing more community-acquired strains of methicillin-resistant Staphylococcus aureus (MRSA), according to John H. Epstein, M.D.

These strains differ from hospital-acquired strains in that they are more manageable and may respond to treatments to which they would appear to be resistant, according to their sensitivity cultures.

Therefore, the prudent dermatologist will start treatment of such infections while waiting for the cultures to come in, rather than the other way around, says Dr. Epstein, a clinical professor of dermatology at the University of California, San Francisco.

What is the most common infection seen in the dermatologist's office?

"We're seeing community-acquired MRSA all over the place," he tells Dermatology Times. "In my office, it may be the most common infection we see." While hospital-acquired MRSA only responds to vancomycin, the community-acquired strains respond to tetracycline and quinolone antibiotics, as well as vancomycin. "We don't know why community-acquired MRSA responds to antibiotics to which it is supposedly resistant, according to sensitivity testing," he says. "But because of that tendency, dermatologists should start treating before they get the sensitivities back."

Because community-acquired MRSA is so common, cutaneous infections should be routinely cultured, he advises.

Varicella vaccines

As dermatologists know, the varicella vaccine intended to prevent chickenpox has proven effective, with an 85 percent reduction in the prevalence of chickenpox between 1995 and 2003, Dr. Epstein notes.

"In one study on people over 60 years of age, investigators saw a 60 percent reduction in herpes zoster and in postherpetic neuralgia," Dr. Epstein says.

He says that the vaccine that targets shingles is more concentrated than the one targeting chicken pox, with 18,500 plaque-forming units compared to 1,350 in the chickenpox vaccine.

HPV vaccine

Another promising vaccine has been developed to prevent human papillomavirus (HPV) strains 16 and 18. These are the primary HPV strains implicated in cervical cancer and dysplasia, Dr. Epstein explains.

Right diagnosis is critical

Other research shows the importance of making sure that an illness is properly diagnosed, and that treatment of one condition does not exacerbate another.

Patients with hepatitis C should be screened for comorbid sarcoidosis, Dr. Epstein says, noting that interferon, the mainstay treatment for hepatitis C, can stimulate the formation of sarcoidosis, as investigators recently reported.

Melanoma still on the rise

The American Cancer Society has noted that there were 59,580 new cases of melanoma in the United States in 2005, compared to 55,100 such cases in 2004. Interestingly, one recent study showed that people with melanoma who have continued sun exposure are less likely to die from melanoma than those who avoid the sun. "We generally assume the other way around," Dr. Epstein says.