Staphylococcal Purpura Fulminans: A Toxin-Mediated Disease?

Clinical Infectious Diseases, Apr 2005

Henry F. Chambers

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Staphylococcal Purpura Fulminans: A Toxin-Mediated Disease?

Henry F. Chambers 0 0 Medical Service, San Francisco General Hospital, Department of Medicine, University of California-San Francisco - Dramatic disease presentations create strong impressions. Kravitz et al. [1] describe 5 cases of purpura fulminansa syndrome of sepsis, disseminated intravascular coagulation, and purpuric skin lesions [2]in association with Staphylococcus aureus isolated from blood in 3 patients and from respiratory cultures in the other 2 patients. All 5 patients had either frank septic shock or severe sepsis [3], at least 4 required pressor support, and 3 died as a direct consequence of their infections. These cases occurred within a 4-year period in the MinneapolisSt. Paul, Minnesota, metropolitan area. The clinical isolates produced 1 of 3 staphylococcal superantigen toxins: staphylococcal enterotoxin B (SEB; 1 strain), staphylococcal enterotoxin C (SEC; 3 strains), and toxic shock syndrome toxin1 (TSST-1; 1 strain). The 1 methicillin-resistant strain, in addition to producing SEC, also had the genes for Panton-Valentine leukocidin, a hallmark of community strains of methicillin-resistant S. aureus [4, 5]. The rarity of S. aureusassociated purpura fulminansplus the fact that all 5 strains produced a superantigen that can cause a septic or toxic shock by an inappropriately massive release of cytokines from macrophages and T cellsled the authors to speculate that purpura fulminans may represent a new and emerging manifestation of severe staphylococcal disease. Purpura fulminans is not a specific diagnosis, but a syndrome. It is probably caused by an inherited or acquired abnormality of the protein C anticoagulant pathway [2]. Most commonly, it is a complication of severe bacterial infection (typically meningococcemia), although numerous noninfectious and infectious agents also have been associated with it [614]. Purpura fulminans complicating staphylococcal sepsis has been reported previously, and several case reports are cited by Kravitz et al. [1]. In a study from Finland of 12 cases of sepsis-associated purpura fulminans, S. aureus was responsible for 1 of the 10 cases in which a bacterial infection was documented, with Neisseria meningitides (5 cases), Streptococcus pneumoniae (2 cases), and Capnocytophaga canimorsus (2 cases) responsible for the other 9 cases [15]. Thus, S. aureus as a cause of purpura fulminans is new, and it may be as common a cause as other nonmeningococcal organisms. Whether staphylococcal purpura fulminans is emergingor, to be more precise, increasing in prevalence or incidenceis more difficult to assess, because neither entity is reportable, and surveillance data are unavailable. The absence of this complication among 235 cases of staphylococcal bacteremia reported in 2 publications [16, 17] cited by the authors indicates that it is not common. But does the occurrence of 5 cases over a 4-year period represent an increase? It may not. On the basis of the estimated 100,000 bacteremia cases per year, the incidence of S. aureus bacteremia is 360 cases per 1,000,000 persons per year in the United States. The MinneapolisSt. Paul metropolitan area, with its population of 3,000,000, would be expected to have slightly more than 4000 cases of staphylococcal bacteremia in the 4-year period during which these 5 cases were observed, or 1 case of purpura fulminans per 800 cases of S. aureus bacteremia. Given this case rate, it is not surprising that this complication was not reported in case studies that were both too small by an order of magnitude to have detected it. Regardless of whether staphylococcal purpura fulminans is a new or emerging problem, these 5 cases raise the intriguing possibility that superantigen production is the cause. Superantigen toxins certainly can cause illness of a severity observed in these cases, and the fact that, in each case, a toxin-producing strain was isolated seems compelling. However, this apparent Genea Vandenesch et al.b [5] Von Eiff et al. [18] Nashev et al. [19] Mehrotra et al. [20] Peacock et al. [21] Larsen et al. [22] NOTE. Data are percentage of isolates containing gene, unless otherwise indicated. a seb, sec, tst, and lukFS-PV are genes encoding staphylococcal enterotoxin B, staphylococcal enterotoxin C, toxic shock syndrome toxin1, and Panton-Valentine leukocidin, respectively. b Community methicillin-resistant S. aureus strains. association between superantigens and purpura fulminans must be viewed in the context of the prevalence of genes encoding these toxins among S. aureus isolates. Virulence factors and toxin-encoding genes are ubiquitous among S. aureus clinical isolates (table 1) [5, 1822]. Approximately one-half to three-quarters of human carriage isolates contain superantigen genes, and finding these in the 5 isolates recovered from patients with purpura fulminans could be the result of chance alone. With respect to specific toxins, 10% (and perhaps up to 25%) of S. aureus strains contain seb, the gene (...truncated)


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Henry F. Chambers. Staphylococcal Purpura Fulminans: A Toxin-Mediated Disease?, Clinical Infectious Diseases, 2005, pp. 948-950, 40/7, DOI: 10.1086/428584