Community-acquired MRSA threat continues to grow

Key Points

Gothenberg, Sweden - Dermatologists worldwide must remain vigilant against community acquired methicillin-resistant Staphylococcus aureus (CA-MRSA). And for potentially serious CA-MRSA infections, dermatologists should enlist help from infectious disease experts.

"What's happening in Europe is similar to what's happening in the United States," says Erwin Tschachler, M.D., professor of dermatology and venereology, department of dermatology, Medical University of Vienna, Austria. "Dermatologists in particular must be aware that CA-MRSA represents an increasing threat, because most of these infections occur on the skin."

Dr. Tschachler spoke at the 19th Congress of the European Academy of Dermatology and Venereology in October 2010.

Ultimately, investigators isolated S. aureus from 130 patients, and 18 of these isolates were MRSA. Additionally, investigators determined that four of the 130 S. aureus isolates were CA-MRSA (Jappe U, Heuck D, Strommenger B, et al. J Invest Dermatol. 2008;128(11):2655-2664. Epub 2008 Jul 3).

Furthermore, they determined one of these four CA-MRSA cases to be the first documentation in Germany of the second most prevalent CA-MRSA strain in the United States (ST001).

PVL presence

Study investigators also analyzed S. aureus strains for the presence of the Panton-Valentine leukocidin (PVL) gene. Although there is no definite proof that this gene is the ultimate cause of deep skin infections, study authors write, "It seems to be a highly informative epidemiological marker for severe infections and, in some cases, CA-MRSA."

Researchers also investigated carriers of CA-MRSA and hospital-acquired MRSA for risk factors. In this analysis, visits to foreign countries and/or professional or private contacts with foreigners emerged as a significant factor for acquiring CA-MRSA.

MRSA history

First described in the 1960s, MRSA began appearing in hospitalized patients within two years of methicillin's commercial introduction, Dr. Tschachler says. Typically, he says, these patients already suffered from problems that predisposed them to infections, such as immune suppression or kidney failure requiring dialysis. The bacterial strains causing infections in such scenarios are now referred to as healthcare-associated (HA)-MRSA.

The first report of CA-MRSA emerged in 1991 from Australia, he says.

"In microbiology terms, MRSA and CA-MRSA are quite similar but have some distinct differences in that CA-MRSA is more virulent and aggressive," he says.