Community-Acquired Methicillin-Resistant Staphylococcus aureus Emerging as an Important Cause of Necrotizing Fasciitis
ABSTRACT Necrotizing fasciitis (NF) is an uncommon fulminant soft tissue infection characterized by extensive fascial necrosis. Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) isolates producing the Panton-Valentine leukocidin (PVL) cytotoxin have been associated with serious necrotizing infections, but NF caused by CA-MRSA has been described only recently. We reviewed our NF experience at Denver Health Medical Center, where CA-MRSA accounts for more than 50% of community S. aureus clinical isolates.
Patients treated for NF from January 2004 to February 2006 were identified by review of pathology records and diagnostic codes, and their medical records were reviewed. Isolates of MRSA from monomicrobial NF underwent testing for the PVL gene and pulsed-field gel electrophoresis to determine relatedness to CA-MRSA strains.
Five of 30 NF cases during the study period, all involving the extremities, were caused by MRSA. Monomicrobial MRSA NF accounted for three cases, with all of the patients reporting a distinct "spider bite" lesion 2-3 days prior to admission. The median age was 32 years (range 28-55 years). Resistance to erythromycin and levofloxacin was present in four isolates. None of the isolates displayed inducible clindamycin resistance. Within 12 hours of admission, all patients received empiric antibiotics to which their isolate was susceptible. Patients required a median of six surgical procedures (range 2-7 operations). All patients survived. The MRSA isolates tested positive for PVL and had the USA 300 CA-MRSA deoxyribonucleic acid banding pattern.
Community-acquired MRSA is an important cause of NF in our region, accounting for > 15% of NF cases. This infection was associated with significant morbidity necessitating multiple surgical interventions. Given the propensity of PVL-positive CA-MRSA to cause severe necrotizing infections, it is reasonable to administer empiric MRSA coverage for NF in endemic locations.
SourceAvailable from: Ching Wen Tseng[Show abstract] [Hide abstract]
ABSTRACT: Elderly humans show increased susceptibility to invasive staphylococcal disease after skin and soft tissue infection. However, it is not understood how host immunity changes with aging, and how that predisposes to invasive disease. In a model of severe skin infection, we showed that aged mice (16- to 20-month-old) exhibit dramatic bacterial dissemination compared with young adult mice (2-month-old). Bacterial dissemination was associated with significant reductions of CXCL1 (KC), polymorphonuclear cells (PMNs), and extracellular DNA traps (NETs) at the infection site. PMNs and primary skin fibroblasts isolated from aged mice showed decreased secretion of CXCL2 (MIP-2) and KC in response to MRSA, and in vitro analyses of mitochondrial functions revealed that the mitochondrial electron transport chain complex I plays a significant role in induction of chemokines in the cells isolated from young but not old mice. Additionally, PMNs isolated from aged mice have reduced ability to form NETs and to kill MRSA. Expression of nuclease by S. aureus led to increased bacterial systemic dissemination in young but not old mice, suggesting that defective NETs formation in elderly mice permitted nuclease and non-nuclease expressing S. aureus to disseminate equally well. Overall, these findings suggest that gross impairment of both skin barrier function and innate immunity contributes to the propensity for MRSA to disseminate in aged mice. Furthermore, the study indicates that contribution of bacterial factors to pathogenicity may vary with host age.PLoS ONE 07/2012; 7(7):e41454. DOI:10.1371/journal.pone.0041454 · 3.53 Impact Factor
Revue Francophone des Laboratoires 12/2008; 2008(407):71-80. DOI:10.1016/S1773-035X(08)74869-X
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ABSTRACT: Necrotizing fasciitis represents a group of highly lethal infections characterized by rapidly progressing inflammation and necrosis. The aim of the study was to analyze the clinical profile, microbial flora, and predisposing risk factors in patients with necrotizing fasciitis. Lastly, we aimed to formulate a protocol for management of necrotizing fasciitis. Forty-eight cases of necrotizing fasciitis patients who reported to our hospital between April 2007 and September 2009 were included in the study. The commonest predisposing factors were age greater than 50 years (58 % cases) and diabetes mellitus (52 % cases). The commonest site involved was extremity (70.8 %). Majority of infections were polymicrobial (87.5 %). Repeated aggressive debridement was the commonest surgical procedure performed. Early and aggressive surgical debridement, often in multiple sittings, supplemented by appropriate antibiotics and supportive therapy, forms the key to a successful outcome in necrotizing fasciitis.Indian Journal of Surgery 01/2013; DOI:10.1007/s12262-013-0835-2 · 0.27 Impact Factor