Novel <i>Staphylococcus aureus</i> Secreted Protein Alters Keratinocyte Proliferation and Elicits a Proinflammatory Response <i>In Vitro</i> and <i>In Vivo</i>

Staphylococcus aureus is a leading cause of surgical site infections that results in increased hospital stays due to the development of chronic wounds. Little is known about factors involved in S. aureus’ ability to prevent wounds from healing. We discovered a novel secreted protein produced by a surgical site isolate of S. aureus that prevents keratinocyte proliferation. The protein has a molecular weight of 15.7 kDa and an isoelectric point of 8.9. The cloned and purified protein has cytotoxic and proinflammatory properties, as shown <i>in vitro</i> and <i>in vivo</i>. Potent biological effects on keratinocytes and rabbit skin suggest that this protein may play an important role in preventing re-epithelialization. Its lack of homology to known exotoxins suggests that this protein is novel, and this observation is likely to open a new field of research in S. aureus exotoxins. Due to its cytotoxic activities, we call this new protein ε-cytotoxin

Patient category and underlying conditions.

<p>*Other species include: <i>C. kefyr</i> (nine isolates), <i>C. famata</i> (four isolates), <i>C. rugosa</i> (three isolates), <i>C. utilis</i> (two isolates) and one isolate each of <i>C. fennica</i>, <i>C. fermentati</i>, <i>C. lipolytica</i>, and <i>Torulopsis</i> spp.</p>†<p>multiple species include <i>C. parapsilosis</i>+<i>C. glabrata</i> (n = 30), <i>C. tropicalis</i>+<i>C. glabrata</i> (n = 21), <i>C. krusei</i>+<i>C. glabrata</i> (n = 8), <i>C. dubliniensis</i>+<i>C. glabrata</i> (n = 3), <i>C. lusitaniae</i>+<i>C. glabrata</i> (n = 4), other <i>Candida</i> spp.+<i>C. glabrata</i> (n = 3), unknown <i>Candida</i> spp.+<i>C. glabrata</i> (n = 3), <i>C. guilliermondii</i>+<i>C. glabrata</i> (n = 2), <i>C. parapsilosis</i>+<i>C. krusei</i> (n = 5), <i>C. lusitaniae</i>+<i>C. krusei</i> (n = 2), <i>C. tropicalis</i>+<i>C. dubliniensis</i> (n = 1), <i>C. tropicalis</i>+<i>C. guilliermondii</i> (n = 1), <i>C. tropicalis</i>+<i>C. krusei</i> (n = 4), other <i>Candida</i> spp.+<i>C. guilliermondii</i> (n = 1), unknown <i>Candida</i> spp.+<i>C. dubliniensis</i> (n = 1), <i>C. glabrata</i>+<i>C. krusei</i>+<i>C. lusitaniae</i> (n = 1), <i>C. dubliniensis</i>+<i>C. glabrata</i>+<i>C. guilliermondii</i> (n = 1).</p><p>CMV = cytomegalovirus; GVHD = graft versus host disease; NICU = neonatal intensive care unit.</p

Prior antifungal therapy.

<p>*other species includes: <i>C. kefyr</i> (nine isolates), <i>C. famata</i> (four isolates), <i>C. rugosa</i> (three isolates), <i>C. utilis</i> (two isolates) and one isolate each of <i>C. fennica</i>, <i>C. fermentati</i>, <i>C. lipolytica</i>, and <i>Torulopsis</i> spp.</p>†<p>multiple species include <i>C. parapsilosis+C. glabrata</i> (n = 30), <i>C. tropicalis+C. glabrata</i> (n = 21), <i>C. krusei+C. glabrata</i> (n = 8), <i>C. dubliniensis+C. glabrata</i> (n = 3), <i>C. lusitaniae+C. glabrata</i> (n = 4), other <i>Candida</i> spp.<i>+C. glabrata</i> (n = 3), unknown <i>Candida spp.+C. glabrata</i> (n = 3), <i>C. guilliermondii+C. glabrata</i> (n = 2), <i>C. parapsilosis+C. krusei</i> (n = 5), <i>C. lusitaniae+C. krusei</i> (n = 2), <i>C. tropicalis+C. dubliniensis</i> (n = 1), <i>C. tropicalis+C. guilliermondii</i> (n = 1), <i>C. tropicalis+C. krusei</i> (n = 4), other <i>Candida</i> spp.+<i>C. guilliermondii.</i></p

Variation in frequency of non-<i>albicans</i> species of <i>Candida</i> by geographic region.

<p>*hospitals designated by the letter ‘H’; and a number: H1, H2 etc.</p>†<p>other species includes: <i>C. kefyr</i> (nine isolates), <i>C. famata</i> (four isolates), <i>C. rugosa</i> (three isolates), <i>C. utilis</i> (two isolates) and one isolate each of <i>C. fennica</i>, <i>C. fermentati</i>, <i>C. lipolytica</i>, and <i>Torulopsis</i> spp.</p>§<p>multiple species include <i>C. parapsilosis+C. glabrata</i> (n = 30), <i>C. tropicalis+C. glabrata</i> (n = 21), <i>C. krusei+C. glabrata</i> (n = 8), <i>C. dubliniensis+C. glabrata</i> (n = 3), <i>C. lusitaniae+C. glabrata</i> (n = 4), other <i>Candida</i> spp.<i>+C. glabrata</i> (n = 3), unknown <i>Candida spp.+C. glabrata</i> (n = 3), <i>C. guilliermondii+C. glabrata</i> (n = 2), <i>C. parapsilosis+C. krusei</i> (n = 5), <i>C. lusitaniae+C. krusei</i> (n = 2), <i>C. tropicalis+C. dubliniensis</i> (n = 1), <i>C. tropicalis+C. guilliermondii</i> (n = 1), <i>C. tropicalis+C. krusei</i> (n = 4), other <i>Candida</i> spp.+<i>C.</i> guilliermondii (n = 1), unknown <i>Candida</i> spp.+C. <i>dubliniensis</i> (n = 1), <i>C. glabrata+C. krusei+C. lusitaniae</i> (n = 1), <i>C. dubliniensis+C. glabrata+C. guilliermondii</i> (n = 1).</p

90-day survival stratified by non-<i>albicans Candida</i> species.

<p>90-day survival stratified by non-<i>albicans Candida</i> species.</p

Antifungal treatment administered by species on infection day 3.

<p>*Other species includes: <i>C. kefyr</i> (nine isolates), <i>C. famata</i> (four isolates), <i>C. rugosa</i> (three isolates), <i>C. utilis</i> (two isolates) and one isolate each of <i>C. fennica</i>, <i>C. fermentati</i>, <i>C. lipolytica</i>, and <i>Torulopsis</i> spp.</p>†<p>multiple species include <i>C. parapsilosis+C. glabrata</i> (n = 30), <i>C. tropicalis+C. glabrata</i> (n = 21), <i>C. krusei+C. glabrata</i> (n = 8), <i>C. dubliniensis+C. glabrata</i> (n = 3), <i>C. lusitaniae+C. glabrata</i> (n = 4), other <i>Candida</i> spp.<i>+C. glabrata</i> (n = 3), unknown <i>Candida spp.+C. glabrata</i> (n = 3), <i>C. guilliermondii+C. glabrata</i> (n = 2), <i>C. parapsilosis+C. krusei</i> (n = 5), <i>C. lusitaniae+C. krusei</i> (n = 2), <i>C. tropicalis+C. dubliniensis</i> (n = 1), <i>C. tropicalis+C. guilliermondii</i> (n = 1), <i>C. tropicalis+C. krusei</i> (n = 4), other <i>Candida</i> spp.+<i>C.</i> guilliermondii (n = 1), unknown <i>Candida</i> spp.+C. <i>dubliensis</i> (n = 1), <i>C. glabrata+C. krusei+C. lusitaniae</i> (n = 1), <i>C. dubliniensis+C.glabrata+C.guilliermondii</i> (n = 1).</p>§<p>patients in this category were in a blinded clinical trial.</p>‡<p>Other combination therapies included lipid amphotericin B +5-fluorocytosine (n = 7), lipid amphotericin B+fluconazole (n = 10), amphotericin B deoxycholate+lipid amphotericin B (n = 1), amphotericin B deoxycholate+fluconazole (n = 2), echinocandins +5-fluorocytosine (n = 1), echinocandins+amphotericin B deoxycholate (n = 9), echinocandins+fluconazole (n = 1), echinocandins+itraconazole (n = 1), fluconazole+blinded (n = 1), fluconazole+voriconazole (n = 8).</p

Baseline characteristics.

<p>*other species includes: <i>C. kefyr</i> (nine isolates), <i>C. famata</i> (four isolates), <i>C. rugosa</i> (three isolates), <i>C. utilis</i> (two isolates) and one isolate each of <i>C. fennica</i>, <i>C. fermentati</i>, <i>C. lipolytica</i>, and <i>Torulopsis</i> spp.</p>†<p>multiple species include <i>C. parapsilosis+C. glabrata</i> (n = 30), <i>C. tropicalis+C. glabrata</i> (n = 21), <i>C. krusei+C. glabrata</i> (n = 8), <i>C. dubliniensis+C. glabrata</i> (n = 3), <i>C. lusitaniae+C. glabrata</i> (n = 4), other <i>Candida</i> spp.<i>+C. glabrata</i> (n = 3), unknown <i>Candida spp.+C. glabrata</i> (n = 3), <i>C. guilliermondii+C. glabrata</i> (n = 2), <i>C. parapsilosis+C. krusei</i> (n = 5), <i>C. lusitaniae+C. krusei</i> (n = 2), <i>C. tropicalis+C. dubliniensis</i> (n = 1), <i>C. tropicalis+C. guilliermondii</i> (n = 1), <i>C. tropicalis+C. krusei</i> (n = 4), other <i>Candida</i> spp.+<i>C. guilliermondii</i>.</p

Figure 2

<p>A: PFGE of MRSA isolates from swine and swine workers; DNA digested with <i>Sma</i>I. B: PFGE of MRSA isolates from swine and swine workers; DNA digested with <i>Eag</i>I. Lane 1: molecular weight ladder. Lanes 2, 12, 25: NCTC 8325 (control strain). Lanes 3–11: isolates from swine workers. Lanes 13–24: isolates from swine.</p

Prevalence of MRSA in swine from production system A by age aroup.

<p>Prevalence of MRSA in swine from production system A by age aroup.</p