TORONTO—Early, empiric antimicrobial therapy for possible necrotizing fasciitis should include coverage for methicillin-resistant Staphylococcus aureus in regions of the United States where the bacteria are endemic, according to Dr. Lisa S. Young of the University of Colorado Health Sciences Center, Denver.
Although the severe soft tissue infection continues to be rare, “community-acquired MRSA is on the rise and clinicians need to be aware of the potential association [with necrotizing fasciitis], especially in areas with high or increasing rates of community-acquired MSRA,” Dr. Young said at the annual meeting of the Infectious Diseases Society of America.
In the wake of a 2005 report linking community-acquired MRSA to 14 cases of necrotizing fasciitis in the Los Angeles area, Dr. Young and her colleagues retrospectively evaluated the prevalence of MRSA in patients treated for necrotizing fasciitis over a 2-year period at the Denver Health Medical Center, where community-acquired MRSA accounts for more than half of the community S. aureus clinical isolates.
The investigators reviewed the pathologic records and diagnostic codes of patients treated at the medical center for necrotizing fasciitis between January 2004 and February 2006 and determined that 5 of the 30 cases diagnosed were caused by MRSA. All five cases involved the extremities, and in all five cases, the patients' MRSA isolates were susceptible within 12 hours to the empiric antibiotics that were given. The patients required a median of six surgeries (range 2–7) to remove infected tissue. “None of them needed an amputation, and all five survived,” Dr. Young said.
Three of the five patients, whose ages ranged from 28 to 55 years, experienced “a spider bite lesion” 2 or 3 days prior to admission. One patient was an alcoholic, one was a diabetic, and the remaining three were healthy.
Pathology results showed that the MRSA isolates had the USA300 DNA banding pattern. This strain of community-acquired MRSA produces the Panton Valentine leukocidin cytotoxin, which has been associated with serious necrotizing infections, Dr. Young explained. The increasing prevalence in recent years of these isolates, which differ from other S. aureus clones, might be a result of antibiotic overuse, she noted.
With respect to clinical management of suspected necrotizing fasciitis, “in areas of high prevalence [of MRSA], do not wait for cultures before beginning empiric treatment with antibiotic therapy that is effective against MRSA,” Dr. Young advised. The organism is highly aggressive and virulent, so treatment delays or the use of ineffective therapies “could lead to severe tissue damage or amputation,” she said.
Dr. Young reported having no financial disclosures related to her presentation.