Patients with AD differ in the ability to clear S. aureus from the skin during anti-inflammatory treatment, which appears to be related to the abnormalities in immunological parameters. Local antibiotic therapy should be considered only in patients with persistent S. aureus colonization.

Staphylococcus aureus strains isolated from the colonized skin lesions of 26 patients with acute-phase atopic dermatitis were reported to produce various extracellular proteolytic enzymes. Using the skim-milk-agar culture plating method, it was shown that 97% of the strains (65 of 67 examined) produced proteolytic activity, with 61% (42 strains) producing activity comparable to that of the proteolytically hyperactive reference strain Staphylococcus aureus V8. This observation was confirmed by azocasein degradation with culture supernatants, which indicated that 91% of the strains produced extracellular proteinases and 43% exceeded the 2% activity threshold of the reference strain. Control strains were isolated from the nose vestibules of 18 healthy carriers; the proteolytic activity of these strains never exceeded 2.5% of the activity of the reference strain. In 54% of the patients examined ( n=14), the activity of the strains was higher than that determined for the isolates from the control group. The combined use of assays incorporating azocasein and a synthetic chromogenic substrate, N-CBZ-Phe-Leu-Glu- pNA, showed that two staphylococcal enzymes, Staphylococcus aureus metalloproteinase (SAMP) and Staphylococcus aureus serine proteinase (SASP), contributed to the total proteolytic activity released by the strains examined. The contribution of each of the two enzymes varied greatly between different isolates. The undamaged skin of the patients was not colonized with Staphylococcus aureus. The presence of several strains with atypical proteinase characteristics was also reported, suggesting the possible involvement of enzymes other than serine- and metallo-proteinases in the proteolytic activity of Staphylococcus aureus. Taken together, the results of the study imply that staphylococcal proteinases may contribute to the pathogenicity of atopic dermatitis.

Staphylococcus pseudintermedius is a veterinary pathogen that has seldom been described as an agent of human disease. Features of this probably underreported coagulase-positive Staphylococcus species are depicted here through the description of a graftversus-host disease-related wound infection caused by a multidrug-resistant strain. CASE REPORTA 65-year-old male patient who had received (3 years previously) an allogeneic bone marrow transplant (BMT) for chronic lymphoblastic leukemia was admitted to the Pescara Civic Hospital (Italy) because of a wound infection, located in the periumbilical region and showing two different purulent discharges. The lesion was due to chronic graft-versus-host disease (GvHD) that complicated the BMT. The patient affirmed that he lived in proximity to a pet dog and farm cows.Pus staining revealed Gram-positive cocci within leukocytes, while cultures yielded a massive growth of mannitol-nonfermenting coagulase-positive staphylococci (CPS). Based on colony aspect (brightness of the white-gray color), two different isolates (named S32 and S33) were recognized, sharing a double-zone hemolysis on the sheep blood agar plate (Fig. 1). They were identified as Staphylococcus intermedius by both the Vitek2 and the API system (bioMérieux, Marcy l'Etoile, France). However, S. intermedius is the only species belonging to the so-called Staphylococcus intermedius group included in these systems' databases. The S. intermedius group includes S. intermedius, cultured from a wide variety of animals, Staphylococcus pseudintermedius, which recent studies indicate is the prevalent S. intermedius group species harbored by dogs and cats, and Staphylococcus delphini, first isolated from dolphins but later collected from several terrestrial animals (1, 2). Thus, we did not consider this identification as conclusive. Moreover, since the absence of mannitol fermentation, along with the double-zone hemolysis, was highly suggestive for S. intermedius/S. pseudintermedius, the patient was screened for S. intermedius group nasal and skin colonization. Five phenotypically similar organisms were grown from the nasal and the hand skin swabs. Again, they were identified as S. intermedius by the Vitek2 and the API system. Different tests (both phenotypic and genotypic) were performed to confirm the identification. Phenotypically, all the strains were colistin resistant and showed a slow positivity to the Voges-Proskauer reaction (suggesting that the isolates were S. pseudintermedius rather than S. intermedius). Among genotypic assays, 16S rRNA sequencing did not provide a definitive discrimination among S. intermedius, S. pseudintermedius, and S. delphini. The isolates were then analyzed through automated ribotyping (RiboPrinter; Qualicon DuPont, USA). The instrument provided identical fingerprints for all of the strains and identified them as S. intermedius. A specific multiplex PCR was performed, as previously described (3). The isolates were identified as S. pseudintermedius, since a clear band was obtained at 926 ...

Proteinases of Staphylococcus aureus are emerging as potential virulence factors which may be involved in the pathogenecity of staphylococcal diseases. We describe here the structure of the gene encoding the metalloproteinase referred to as aureolysin. This gene occurs in two allelic forms and is strongly conserved among S. aureus strains, implying the possibility that the proteinase may have important housekeeping functions.Staphylococcus aureus is a major human pathogen of increasing importance because of its rapid development of antibiotic resistance. Due to the possession of a broad array of potential virulence factors, including several toxins, adhesins, and exoenzymes, this organism is able to colonize a broad range of tissues in the host and, as a result, cause many grave infections (9). Recently, a renewed interest has been focused on proteinases from S. aureus which are under the control of agr (accessory gene regulator) and sar (staphylococcal accessory regulator), the main regulators of S. aureus virulence determinant genes (3,4,8). In this case, the expression of a specific serine glutamyl endopeptidase (V8 protease) was found to be important for the full display of bacterial virulence in animal models of staphylococcal infection (5).In addition to the glutamyl endopeptidase, S. aureus secretes at least one papain-like cysteine proteinase as well as a typical metalloproteinase that is commonly referred to as aureolysin. The primary and tertiary structures of the latter enzyme have been determined (1), revealing a polypeptide chain of 301 amino acids which is folded into a ␤-pleated N-terminal domain and an ␣-helical C-terminal domain, a typical fold for the thermolysin family of metalloproteinases. This diverse family of proteinases also encompasses several enzymes which are acknowledged virulence factors, including Pseudomonas aeruginosa elastase, Legionella pneumophila and Listeria monocytogenes metalloproteinases, Vibrio cholerae hemagglutinin protease, Staphylococcus epidermidis elastase, and the lambda toxin of Clostridium perfringens. In contrast to these proteinases, however, little is known about the exact role of aureolysin in the pathogenicity of S. aureus. In vitro, aureolysin has been shown to cleave the plasma proteinase inhibitors, ␣ 1 -antichymotrypsin and ␣ 1 -proteinase inhibitor (13,14), and to activate prothrombin in human plasma (20). It may also affect the stimulation of T and B lymphocytes by polyclonal activators and display inhibitory activity against immunoglobulin production by lymphocytes (15). In addition, aureolysin activates the precursor of the glutamyl endopeptidase (V8 protease) secreted by this same microorganism (6).In order to cast more light on the potential importance of staphylococcal proteinases in pathogenicity, we have focused the present study on the genetic analysis of aureolysin, including distribution, copy number, and genetic variability of the aureolysin gene in both clinical isolates and laboratory strains of S. aureus.The PCR technique was first appli...

Since PA is considered to be an etiological agent in acne and ROS are closely correlated with the pathogenesis of inflammatory skin diseases, the reported data suggest that TauBr may be a good candidate for the topical therapy for acne vulgaris.