What's particularly worrisome, one researcher told Reuters Health, is that these infections are being acquired in the community - not the hospital, as has been the usual case until now.

In Corpus Christi, Texas, the occurrence of community-acquired MRSA infections in children, which started occurring in the 1990s, "has now reached epidemic proportions," Dr. Kevin Purcell and colleagues warned.

In 1999, there were 9 cases of community-acquired MRSA documented at Driscoll Children's Hospital. The number jumped to 36 in 2000, 105 in 2001, 278 in 2002, and 459 in 2003.

Purcell told Reuters Health that among 1002 cases of MRSA skin infections seen in Corpus Christi children between 1990-2003, 93 percent occurred outside the hospital, and 98 percent of these children had no risk factors that would increase their likelihood of catching MRSA.

"Ninety-four percent of the community-acquired MRSA cases were localized infections of the skin and soft tissues, meaning that 6 percent were invasive and potentially life-threatening infections (e.g. sepsis, pneumonia, toxic shock syndrome)," he said.

Nearly all of the MRSA infections were susceptible to other antibiotics.

In related research, Dr. Jeffrey C. Hageman, an epidemiologist from the Centers for Disease Control and Prevention, detailed 17 cases of community-acquired pneumonia caused by MRSA that were documented in 9 different states during last year's influenza season.

The majority of these individuals had flu and progressed to MRSA pneumonia, the researcher said. Only 1 of the 17 cases had had a flu shot.

"Most of these individuals were otherwise healthy - only five had an underlying condition that would put them at risk for the infection," Hageman said. "This was surprising but parallels what we are seeing with the community-acquired MRSA disease causing skin infections, which also tends to occur in otherwise healthy individuals," he noted.

The average age of the people coming down with community-acquired MRSA pneumonia - 21 years - is also noteworthy, Hageman told Reuters Health, explaining that "community-acquired pneumonia is generally a disease of older populations, greater than age 65."

Of the 17 community-acquired MRSA pneumonia cases, 16 required hospitalization for an average of 22 days, 12 had to treated in an ICU, and five died.