Search

Temperate bacteriophages play an important role in the pathogenicity of Staphylococcus aureus, for instance, by mediating the horizontal gene transfer of virulence factors. Here we established a classification scheme for staphylococcal prophages of the major Siphoviridae family based on integrase gene polymorphism. Seventy-one published genome sequences of staphylococcal phages were clustered into distinct integrase groups which were related to the chromosomal integration site and to the encoded virulence gene content. Analysis of three marker modules (lysogeny, tail, and lysis) for phage functional units revealed that these phages exhibit different degrees of genome mosaicism. The prevalence of prophages in a representative S. aureus strain collection consisting of 386 isolates of diverse origin was determined. By linking the phage content to dominant S. aureus clonal complexes we could show that the distribution of bacteriophages varied remarkably between lineages, indicating restriction-based barriers. A comparison of colonizing and invasive S. aureus strain populations revealed that hlb-converting phages were significantly more frequent in colonizing strains.

On the basis of a large outbreak of vancomycin-resistant Enterococcus faecium in a German university hospital, we estimated costs ([approximately equal to] 1 million Euros) that could have been avoided [...]

Although Staphylococcus aureus is not a classical intracellular pathogen, it can survive within phagocytes and many other cell types. However, the pathogen is also able to escape from cells by mechanisms that are only partially understood. We analysed a series of isogenic S. aureus mutants of the USA300 derivative JE2 for their capacity to destroy human macrophages from within. Intracellular S. aureus JE2 caused severe cell damage in human macrophages and could efficiently escape from within the cells. To obtain this full escape phenotype including an intermittent residency in the cytoplasm, the combined action of the regulatory systems Sae and Agr is required. Mutants in Sae or mutants deficient in the Sae target genes lukAB and pvl remained in high numbers within the macrophages causing reduced cell damage. Mutants in the regulatory system Agr or in the Agr target gene psmα were largely similar to wild-type bacteria concerning cell damage and escape efficiency. However, these strains were rarely detectable in the cytoplasm, emphasizing the role of phenol-soluble modulins (PSMs) for phagosomal escape. Thus, Sae-regulated toxins largely determine damage and escape from within macrophages, whereas PSMs are mainly responsible for the escape from the phagosome into the cytoplasm. Damage of macrophages induced by intracellular bacteria was linked neither to activation of apoptosis-related caspase 3, 7 or 8 nor to NLRP3-dependent inflammasome activation. [ABSTRACT FROM AUTHOR]

Background: Intraocular inflammation of the posterior segment may be associated with neoplastic, infectious, and inflammatory diseases. Biopsy of vitreous and additional ocular tissue might be required for a definitive diagnosis. We therefore aimed to investigate the safety and usefulness of diagnostic vitrectomy in intraocular inflammation. Method: We performed an observational retrospective study of patients who underwent vitreous biopsy due to atypical intraocular inflammation, experienced failed resolution to empirical therapy, or for whom there was suspicion of an underlying neoplastic process. Results: Seventy consecutive patients were included due to idiopathic uveitis of the posterior segment unresponsive to systemic corticosteroids ( n = 33, 47%), suspected vitreoretinal or choroidal lymphoma ( n = 18, 26%), viral retinitis ( n = 17, 24%), and suspected endogenous endophthalmitis ( n = 2, 3%). Suspected viral retinitis was most often confirmed (13/17, 76%), followed by lymphoma (6/18, 33%). Remarkably, a proportion of suspected idiopathic uveitis was infectious (7/33, 21%). The most prevalent adverse event following diagnostic vitrectomy was cataract surgery in phakic patients ( n = 16/41, 39% of phakic patients). Retinal detachments were observed chiefly in infectious or neoplastic disease ( n = 5, 7%) after a median time of 105 days. Conclusion: Diagnostic vitrectomy was helpful in substantiating the clinical suspected diagnosis of posterior segment inflammation. Potential secondary adverse events should be kept in mind. [ABSTRACT FROM AUTHOR]

Background. Antibiotic-resistant Staphylococcus aureus is a globally emerging pathogen. Exchangeable virulence factors, such as Panton-Valentine leukocidin (PVL), have been proposed to drive this epidemic. We investigated whether skin infections and nasal colonization in travelers contribute to the global spread of such strains Methods. We conducted a case-control study of 38 returnees from the tropics and subtropics with S. aureus- positive skin and soft tissue infections (SSTIs) and 124 control patients with other travel-associated disorders. We collected information on travel characteristics, clinical outcomes of SSTIs, antibiotic sensitivity patterns, and genotypes of S. aureus strains isolated from skin lesions and the nares. Results. S. aureus-positive SSTIs were associated with travel duration and purpose and were most common in returnees from Africa (odds ratio, 4.2; P = .005). PVL-positive (PVL+) S. aureus was frequent in the lesional and nasal isolates from travelers with SSTIs but could not be found in the nares of the control patients. The presence of PVL in S. aureus in travelers was associated with complicated disease, reduced antibiotic susceptibility, and secondary spread. The genotypes of PVL+)S. aureus in returnees were reported to be endemic to the visited destination but rarely observed in Europe. Conclusions. Geographic variation in the risk of SSTIs in travelers supports a globally heterogeneous distribution of virulent S. aureus. Complicated SSTIs in returnees from nontemperate climates are associated with PVL+ S. aureus and promote the emergence and spread of virulent and antibiotic-resistant strains. We propose a network for the surveillance of imported S. aureus [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "Panton-Valentine leukocidinpositive Staphylococcus aureus skin infections," by M.J. Mimica in a previous 2012 issue.