Journal Review: Another flesh eater: MRSA and necrotizing fasciitis

Another flesh eater: MRSA and necrotizing fasciitis

Lack of deaths suggests reduced virulence

Miller LG, Perdreau-Remington F, Reig G, et al. Fourteen patients with necrotizing fasciitis caused by community-associated methicillin-resistant Staphylococcus aureus in Los Angeles. N Engl J Med 2005; 352:1,445-1,453.

Staphylococcus aureus has been an uncommon cause of necrotizing fasciitis, but the authors of this report found an alarming number of this type of infections caused by community-associated methicillin-resistant S. aureus (MRSA).

"Necrotizing fasciitis caused by community-associated MRSA is an emerging clinical entity," the authors report. "In areas in which community-associated MRSA infection is endemic, empirical treatment of suspected necrotizing fasciitis should include antibiotics predictably active against this pathogen."

They reviewed the records of 843 patients whose wound cultures grew MRSA at their center from Jan. 15, 2003, to April 15, 2004. Among this cohort, 14 were identified as patients presenting from the community with clinical and intraoperative findings of necrotizing fasciitis, necrotizing myositis, or both.

The median age of the patients was 46 years (range, 28 to 68), and 71% were men. Coexisting conditions or risk factors included current or past injection-drug use (43%); previous MRSA infection, diabetes, and chronic hepatitis C (21% each); and cancer and human immunodeficiency virus infection or acquired immunodeficiency syndrome (7 % each). Four patients (29%) had no serious coexisting conditions or risk factors. All patients received combined medical and surgical therapy, and none died, but they had serious complications, including the need for reconstructive surgery and prolonged stay in the intensive care unit. Wound cultures were monomicrobial for MRSA in 86%, and 40% of patients (4 of 10) for whom blood cultures were obtained had positive results. All MRSA isolates were susceptible in vitro to clindamycin, trimethoprim-sulfamethoxazole, and rifampin. All recovered isolates belonged to the same genotype (multilocus sequence type ST8, pulsed-field type USA300).

It was surprising that all patients survived, because the typical mortality rate of necrotizing fasciitis has been reported to be about 33%.

"The absence of deaths in our series suggests that necrotizing fasciitis caused by community-associated MRSA may be less virulent than similar infections caused by other organisms," the authors surmise. "Indeed, the onset of disease in our series was often subacute, with symptoms present an average of six days before admission (range, 3 to 21). Nevertheless, in some patients in our series, infection spread rapidly over a period of several hours. This finding suggests that necrotizing fasciitis caused by community-associated MRSA has the potential to cause rapidly progressive disease that is clinically indistinguishable from necrotizing fasciitis caused by pathogens such as group A streptococcus."