When the CDC published a study showing MRSA is more lethal to Americans than HIV, the news came as no surprise to knowledgeable healthcare practitioners.

"This is a significant public health problem," said Scott K. Fridkin, a CDC medical epidemiologist. "We should be very worried."

The CDC names MRSA as the culprit in more than 94,000 serious infections and close to 19,000 deaths each year, according to a 2007 study published by JAMA. But Elizabeth Bancroft, MD, a medical epidemiologist with the Los Angeles Department of Public Health, noted these figures identify only the most serious infections.

"It's really just the tip of the iceberg," she said. "It is astounding."

No Longer An Acute Care Issue
Once solely associated with hospital-acquired infections, MRSA now is divided into two categories: hospital-acquired MRSA (HA-MRSA) and community-acquired MRSA (CA-MRSA).

Robert Stack, MD, an infectious disease specialist at Mercy San Juan Medical Center, Carmichael, CA, noted lab tests have determined 80-90 percent of MRSA infections come from the community, not the hospital setting. Since stepping up its infection control measures against MRSA 2 years ago, Mercy San Juan has seen a decrease in its MRSA rate. Active critical care surveillance, which involves screening all admissions for MRSA and isolating those who test positive, has been an important component of the campaign against CA-MRSA.

Eric Peters, MD, medical director of the PICU at Renown Regional Medical Center, Reno, NV, emphasized most CA-MRSA infections are relatively benign, involving the skin and soft tissue.

"The classic situation is one in which we admit babies with little boils on their bodies and grow out CA-MRSA from the boils," he said. "We treat them with one of the antibiotics effective against MRSA, and the infection rarely advances to invasive disease."

Habte Tecle, MS, MT(ASCP), CIC, infection control coordinator at Childrens Hospital Los Angeles, makes it his business to know where organisms are coming from and to track their spread.

"This particular form of MRSA is coming from the community, and we're seeing many patients presenting at the emergency department, almost all with skin and soft tissue infections," he said. "Many have incision and drainage (I and D) of the infection in the ED, but others need to be admitted for I and D in the operating room. They may be sent home on empiric antibiotics or if susceptibility is confirmed, antimicrobials like clindamycin or vancomycin."

Peggy Mercer, BS, RN, infection control nurse at Little Company of Mary Torrance Hospital, has seen babies as young as 10 days old with boils from CA-MRSA.

"While some parents bring their children to the ED with a chief complaint of boils, others will say spider bites or insect bites," she said. "The moment I see these word sets in the ED records, I strongly suspect MRSA."

Life-Threatening Infections
Fortunately, life-threatening, invasive CA-MRSA infections are much less common than the typical skin and soft tissue infections.

"The 10-day-old was admitted, but not for very long," Mercer said. "We also see a number of teenagers with boils and infection that's gone into their joints, but they tend to heal quickly and go home. Those youngsters who are immune-compromised develop more complications, and those can be life-threatening. We can't just send people home on cephalexin anymore, because MRSA is resistant to that antibiotic. So we give them a prescription for rifampin, Bactrim or vancomycin."

Tecle has seen an increase in the prevalence of serious forms of CA-MRSA infections, including empyema, osteomyelitis and sepsis.

"It's a virulent infection, and outcomes depend on the patient's immune status, how early the infection is detected and other factors," he said. "Most of them are treated with IV antibiotics and go home with their issues resolved within 2-3 weeks."