MRSA emerging as cause of community-acquired infections, studies show.(Clinical Rounds)

BOSTON -- Methicillin-resistant Staphylococcus aureus is rearing its ugly head outside of the hospital, causing record numbers of skin infections in children, necrotizing fasciitis in otherwise healthy adults, and severe pneumonia among some flu sufferers with no known factors that would put them at risk for the infection, three studies have shown.

Until recently, infections caused by methicillin-resistant S. aureus (MRSA) were highly unusual in healthy people outside of the hospital. The new data exacerbate already growing concerns that increases in MRSA-related infections might contribute to the evolution of additional drug-resistant mutations for which "there simply are not enough new drugs in the pharmaceutical pipeline to keep pace," Joseph R. Dalovisio, M.D., president of the Infectious Diseases Society of America, said at the organization's annual meeting.

"S. aureus is a bad bug to begin with, and this resistant form also is more potent, making it easier for people to become infected," Kevin Purcell, M.D., said in reporting on a study of MRSA-caused skin infections at Driscoll Children's Hospital in Corpus Christi, Tex.

Dr. Purcell and his colleagues investigated the incidence, severity, and treatment of community-acquired MRSA noninvasive and invasive infections at Driscoll during 1990-2003 and determined that the infection rate has reached "epidemic" proportions. Between 1990 and 1999, there were fewer than 10 cases of community-acquired MRSA infections per year. In the 5-year period of 1999-2003, the yearly infection rate increased from 9 to 459. In total, 928 children presented with MRSA infections between 1999 and 2003, and nearly 90% of them were otherwise healthy and had no risk factors that would predispose them to the infection. Most of the infections (94%) were abscesses, although there were reports of some life-threatening conditions, including pneumonia, endocarditis, and toxic shock.

Although MRSA-caused abscesses are rarely fatal, their rising incidence means physicians should be on the lookout for them. "Doctors must be able to recognize that skin boils in their patients may be caused by MRSA, necessitating treatment with stronger than usual antibiotics," Dr. Purcell said.

The infection, which is usually a consequence of broken skin or an insect bite, first shows up as a redness or swelling, or as a pustule. It can be easily stopped if detected and treated early with an appropriate antibiotic, such as clindamycin, Dr. Purcell said. Left untreated, however, the infection could lead to more serious consequences and treatment difficulty, he warned, including:

* Necrotizing fasciitis. Among the more serious infections newly associated with the community form of MRSA is necrotizing ...