Platelets augment respiratory burst in neutrophils activated by selected species of gram-positive or gram-negative bacteria.

Neutrophils and platelets circulate in blood system and play important physiological roles as part of immunological system. Neutrophils are the first line of host defense against various intruders, and platelets are satellite cells cooperating with other components of defense system. Recent studies report about the cooperation among these types of cells. We analyzed the effect of platelets on oxygen burst in neutrophils triggered by Staphylococcus aureus and Escherichia coli bacteria in vitro. The effect of platelets on oxygen burst in neutrophils was measured by luminol enhanced chemiluminescence. Opsonized and non-opsonized bacteria were used as activators. Activation of neutrophils with live non-opsonized and opsonized bacteria in the presence of platelets increased the oxygen burst as compared to the same system without platelets. The gram-positive bacteria (Staphylococcus aureus) were causing higher activation than gram-negative bacteria (Escherichia coli). This work demonstrate that platelets potentate the response of neutrophils augmenting their respiratory burst in vitro when triggered by bacteria

Joint genomic and proteomic analysis identifies meta-trait characteristics of virulent and non-virulent Staphylococcus aureus strains

Staphylococcus aureus is an opportunistic pathogen of humans and warm-blooded animals and presents a growing threat in terms of multi-drug resistance. Despite numerous studies, the basis of staphylococcal virulence and switching between commensal and pathogenic phenotypes is not fully understood. Using genomics, we show here that S. aureus strains exhibiting virulent (VIR) and non-virulent (NVIR) phenotypes in a chicken embryo infection model genetically fall into two separate groups, with the VIR group being much more cohesive than the NVIR group. Significantly, the genes encoding known staphylococcal virulence factors, such as clumping factors, are either found in different allelic variants in the genomes of NVIR strains (compared to VIR strains) or are inactive pseudogenes. Moreover, the pyruvate carboxylase and gamma-aminobutyrate permease genes, which were previously linked with virulence, are pseudogenized in NVIR strain ch22. Further, we use comprehensive proteomics tools to characterize strains that show opposing phenotypes in a chicken embryo virulence model. VIR strain CH21 had an elevated level of diapolycopene oxygenase involved in staphyloxanthin production (protection against free radicals) and expressed a higher level of immunoglobulin-binding protein Sbi on its surface compared to NVIR strain ch22. Furthermore, joint genomic and proteomic approaches linked the elevated production of superoxide dismutase and DNA-binding protein by NVIR strain ch22 with gene duplications

Development of a reference data set for assigning Streptococcus and Enterococcus species based on next generation sequencing of the 16S-23S rRNA region

Background: Many members of Streptococcus and Enterococcus genera are clinically relevant opportunistic pathogens warranting accurate and rapid identification for targeted therapy. Currently, the developed method based on next generation sequencing (NGS) of the 16S-23S rRNA region proved to be a rapid, reliable and precise approach for species identification directly from polymicrobial and challenging clinical samples. The introduction of this new method to routine diagnostics is hindered by a lack of the reference sequences for the 16S-23S rRNA region for many bacterial species. The aim of this study was to develop a careful assignment for streptococcal and enterococcal species based on NGS of the 16S-23S rRNA region. Methods: Thirty two strains recovered from clinical samples and 19 reference strains representing 42 streptococcal species and nine enterococcal species were subjected to bacterial identification by four Sanger-based sequencing methods targeting the genes encoding (i) 16S rRNA, (ii) sodA, (iii) tuf and (iv) rpoB; and NGS of the 16S-23S rRNA region. Results: This study allowed obtainment and deposition of reference sequences of the 16S-23S rRNA region for 15 streptococcal and 3 enterococcal species followed by enrichment for 27 and 6 species, respectively, for which reference sequences were available in the databases. For Streptococcus, NGS of the 16S-23S rRNA region was as discriminative as Sanger sequencing of the tuf and rpoB genes allowing for an unambiguous identification of 93% of analyzed species. For Enterococcus, sodA, tuf and rpoB genes sequencing allowed for identification of all species, while the NGS-based method did not allow for identification of only one enterococcal species. For both genera, the sequence analysis of the 16S rRNA gene was endowed with a low identification potential and was inferior to that of other tested identification methods. Moreover, in case of phylogenetically related species the sequence analysis of only the intergenic spacer region was not sufficient enough to precisely identify Streptococcus strains at the species level. Conclusions: Based on the developed reference dataset, clinically relevant streptococcal and enterococcal species can now be reliably identified by 16S-23S rRNA sequences in samples. This study will be useful for introduction of a novel diagnostic tool, NGS of the 16S-23S rRNA region, which undoubtedly is an improvement for reliable culture-independent species identification directly from polymicrobially constituted clinical samples

Comparison of PCR-Based Methods for Typing Staphylococcus aureus Isolates

In this study, we compared the potentials of (i) a multiplex PCR-based multilocus variable-number tandem repeat (VNTR) assay; (ii) a triplex PCR coamplifying fragments of spa, coa, and the hypervariable region adjacent to the mecA gene; (iii) restriction profile analysis of the STAR repetitive element; (iv) randomly amplified polymorphic DNA analysis; (v) inter-IS256 PCR; and (vi) rep-MP3 PCR. Multilocus VNTR typing and triplex PCR (coa, spa, and hypervariable region) approaches showed excellent reproducibility and high discriminatory power; however, only multilocus VNTR typing could distinguish all pulsed-field gel electrophoresis and spa types. Multilocus VNTR typing appears to be the most useful PCR-based method for the rapid genotyping of Staphylococcus aureus strains

[Influence of treating atopic dermatitis with oral antihistamine and topical steroids on selected parameters of cell and humoral immunity]

Pathogenesis of atopic dermatitis (AD) is multifactorial, therefore despite many different treatment protocols none of the available methods is effective enough. In the present study we analysed the effects of oral antihistamines and topical steroids on selected parameters of humoral (immunoglobulin levels) and cellular (lymphocyte proliferation index, granulocyte oxidative burst, lymphocyte phenotype CD4:CD8) immunity. These parameters were analysed in 34 AD subjects during the exacerbation of the disease and after 4 and 12 weeks of the treatment. RESULTS Along with the clinical status improvement (change form 3.17 +/- 0.1 to 1.3 +/- 0.2; 0-4 scale; p < 0.001), total serum IgE levels decreased significantly from 1563 +/- 459 to 1266 +/- +/- 364 IU/ml (p < 0.05). Other immunoglobulin levels did not change. Total blood chemiluminescence in response to latex stimulation was relatively higher during exacerbation than during remission, but this difference was not significant (p = 0.1). Mean spontaneous or PMA stimulated chemiluminescence did not differ either. CD4:CD8 index decreased significantly during the treatment (from 2.7 +/- 0.3 to 1.8 +/- 0.2; p = 0.03). Lymphocyte proliferation in response to PHA was significantly lower during exacerbation than during remission (10.4 +/- 2.8 vs. 27.1 +/- +/- 5.2; p < 0.03) and the improvement was observed after first 4 weeks of the treatment reaching the levels found in healthy controls. Proliferation index in response to anti-CD3 mAb (OKT-3) was in turn significantly higher during exacerbation (19.1 +/- 3.4 vs. 11.2 +/- 2.0; p = 0.04). CONCLUSIONS Oral antihistamine in combination with topical steroids leads to several significant changes in the immune parameters (IgE levels, CD4:CD8 and proliferation indexes) which may explain its high effectiveness in majority of patients with AD

Platelets augment respiratory burst in neutrophils activated by selected species of gram-positive or gram-negative bacteria.

Neutrophils and platelets circulate in blood system and play important physiological roles as part of immunological system. Neutrophils are the first line of host defense against various intruders, and platelets are satellite cells cooperating with other components of defense system. Recent studies report about the cooperation among these types of cells. We analyzed the effect of platelets on oxygen burst in neutrophils triggered by Staphylococcus aureus and Escherichia coli bacteria in vitro. The effect of platelets on oxygen burst in neutrophils was measured by luminol enhanced chemiluminescence. Opsonized and non-opsonized bacteria were used as activators. Activation of neutrophils with live non-opsonized and opsonized bacteria in the presence of platelets increased the oxygen burst as compared to the same system without platelets. The gram-positive bacteria (Staphylococcus aureus) were causing higher activation than gram-negative bacteria (Escherichia coli). This work demonstrate that platelets potentate the response of neutrophils augmenting their respiratory burst in vitro when triggered by bacteria

Comparison of Multiple-Locus Variable-Number Tandem-Repeat Analysis with Pulsed-Field Gel Electrophoresis, spa Typing, and Multilocus Sequence Typing for Clonal Characterization of Staphylococcus aureus Isolates

Multiple-locus variable-number tandem-repeat analysis (MLVA), a new PCR-based method of typing Staphylococcus aureus, was compared to pulsed-field gel electrophoresis (PFGE), spa typing, and multilocus sequence typing (MLST) on a group of 59 S. aureus (mostly methicillin-resistant) clinical isolates. The aim of the study was to establish possible criteria of clustering MLVA patterns and to check concordance levels between the results produced by MLVA and the three other typing methods. As in our earlier study, MLVA turned out to have discriminatory power similar to that of PFGE. Comparison of data obtained by the two approaches allowed us to propose a 70% or ca. 80% cutoff value of the similarity between two MLVA patterns, depending on a cutoff level applied to interpret the PFGE results, 75% or ca. 90%, respectively. The cutoff values corresponded to the difference of up to six or four bands, respectively, among maximum 14 bands in total produced by two isolates in the analysis. The MLVA clusters matched well those obtained by PFGE, and they were also consistent in general with clusters generated by spa typing and MLST, these latter methods characterized lower resolution. Our results suggest that MLVA may be reliable in shorter-term S. aureus epidemiological studies, including analyses of outbreaks and hospital-to-hospital strain transmission events. Well-known advantages of typing methods based on PCR (low cost, short time, and easiness of performance) make MLVA a method that may be useful in a variety of laboratories, including those performing routine microbiological analyses within medical centers

Genome-wide analysis reveals two novel mosaic regions containing an ACME with an identical DNA sequence in the MRSA ST398-t011 and MSSA ST8-t008 isolates

OBJECTIVES: The presence of the arginine catabolic mobile element (ACME) in Staphylococcus aureus has been reported to enhance the colonization of the human host. The aim of this study was to determine the genetic organization of composite islands harbouring ACME. METHODS: Two ACME-positive S. aureus isolates obtained during two different surveys conducted in the Netherlands and Poland were characterized in this study. The isolates were analysed by spa typing, DNA microarrays and whole-genome sequencing. RESULTS: The two isolates harboured a truncated yet fully functional ACME type II with an identical nucleotide sequence, but differed in their adjacent mobile genetic elements. The first strain was a livestock-associated ST398-t011 MRSA, which had a staphylococcal cassette chromosome mec (SCCmec) composite island composed of SCCpls adjacent to orfX followed by ACME type II and SCCmec type IVa. The second ACME-positive isolate was an ST8-t008 MSSA. Its composite island showed an SCC-like element carrying the ccrC gene followed by ACME II. CONCLUSIONS: This is the first report of an ACME in a livestock-associated MRSA ST398. It is also the first presentation of an ACME composite island structure in an MSSA isolate. Our findings indicate an extensive mosaicism of composite islands in S. aureus, which has implications for the transmissibility among humans and thus for public health