This study addresses the presence and frequency of particular genetic variants and virulence factors found in staphylococcal bacteria causing periprosthetic joint infection (PJI) of the hip and knee to ascertain their clinical relevance as predictors of treatment failure. We characterized the genetic virulence traits of a large collection of clinical staphylococci isolated from patients with PJI and evaluated their association with the patient’s infection outcome.

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The widespread threat of antibiotic resistance requires new treatment options. Disrupting bacterial communication, quorum sensing (QS), has the potential to reduce pathogenesis by decreasing bacterial virulence. The aim of this study was to investigate the influence of sodium salicylate (NaSa) on Staphylococcus aureus QS, virulence production and biofilm formation. In S. aureus ATCC 25923 (agr III), with or without serum, NaSa (10 mM) downregulated the agr QS system and decreased the secretion levels of alpha-hemolysin, staphopain A and delta-hemolysin. Inhibition of agr expression caused a downregulation of delta-hemolysin, decreasing biofilm dispersal and increasing biofilm formation on polystyrene and titanium under static conditions. In contrast, NaSa did not increase biofilm biomass under flow but caused one log10 reduction in biofilm viability on polystyrene pegs, resulting in biofilms being twice as susceptible to rifampicin. A concentration-dependent effect of NaSa was further observed, where high concentrations (10 mM) decreased agr expression, while low concentrations (≤0.1 mM) increased agr expression. In S. aureus 8325-4 (agr I), a high concentration of NaSa (10 mM) decreased hla expression, and a low concentration of NaSa (≤1 mM) increased rnaIII and hla expression. The activity of NaSa on biofilm formation was dependent on agr type and material surface. Eight clinical strains isolated from prosthetic joint infection (PJI) or wound infection belonging to each of the four agr types were evaluated. The four PJI S. aureus strains did not change their biofilm phenotype with NaSa on the clinically relevant titanium surface. Half of the wound strains (agr III and IV) did not change the biofilm phenotype in the 3D collagen wound model. In addition, compared to the control, ATCC 25923 biofilms formed with 10 mM NaSa in the collagen model were more susceptible to silver. It is concluded that NaSa can inhibit QS in S. aureus, decreasing the levels of toxin production with certain modulation of biofilm formation. The effect on biofilm formation was dependent on the strain and material surface. It is suggested that the observed NaSa inhibition of bacterial communication is a potential alternative or adjuvant to traditional antibiotics.

Objectives: This study would like to investigate the in vitro antioxidant activity through 2,2-diphenyl-1-picrylhydrazyl assay and in vitro xanthine oxidase activity of the bulbs. This study performs in vivo assays to study the antihyperuricemic activity and antioxidant in the hyperuricemic rat through plasma malondialdehyde measurement. Method: The study was conducted by testing the fresh bulbs of bawang tiwai (Eleutherine palmifolia (L.) Merr. with chemical solvent of ethanol 70% to extract the bulbs. Allopurinol and Vitamin C were used as positive control for the antihyperuricemic assay and antioxidant assay, respectively. Other chemical substances were also used in this study. This study used chicken extract (Brands) 20 ml/kg/body weight to induce the level of uric acid in the blood serum, and potassium oxonate (Sigma 156124) to inhibit the uricase in rats. Results: The results show that the levels of uric acid were measured using spectrophotometer with dichloro-hydroxybenzen sulfonate (Biolabo) a as reagent. The ethanol extract of bawang tiwai (EBT) (E. palmifolia (L.) Merr) was potential to reduce uric acid level at 140, 280, and 560 mg/kg body weight, but possibly without inhibition against xanthine oxydase activity. Conclusion: All doses of EBT could inhibit lipid peroxidation in hyperuricemic condition caused by high purine diet in 14 days.

Objectives: This study would like to investigate the in vitro antioxidant activity through 2,2-diphenyl-1-picrylhydrazyl assay and in vitro xanthine oxidase activity of the bulbs. This study performs in vivo assays to study the antihyperuricemic activity and antioxidant in the hyperuricemic rat through plasma malondialdehyde measurement. Method: The study was conducted by testing the fresh bulbs of bawang tiwai (Eleutherine palmifolia (L.) Merr. with chemical solvent of ethanol 70% to extract the bulbs. Allopurinol and Vitamin C were used as positive control for the antihyperuricemic assay and antioxidant assay, respectively. Other chemical substances were also used in this study. This study used chicken extract (Brands) 20 ml/kg/body weight to induce the level of uric acid in the blood serum, and potassium oxonate (Sigma 156124) to inhibit the uricase in rats. Results: The results show that the levels of uric acid were measured using spectrophotometer with dichloro-hydroxybenzen sulfonate (Biolabo) a as reagent. The ethanol extract of bawang tiwai (EBT) (E. palmifolia (L.) Merr) was potential to reduce uric acid level at 140, 280, and 560 mg/kg body weight, but possibly without inhibition against xanthine oxydase activity. Conclusion: All doses of EBT could inhibit lipid peroxidation in hyperuricemic condition caused by high purine diet in 14 days.

Neisseria meningitidis is the most frequent cause of bacterial meningitis and is one of the few bacterial pathogens that can breach the blood-brain barrier (BBB). The 37/67 kDa laminin receptor (LamR) was previously identified as a receptor mediating meningococcal binding to rodent and human brain microvascular endothelial cells, which form part of the BBB. The meningococcal surface proteins PorA and PilQ were identified as ligands for this receptor. Subsequently, the fourth extracellular loop of PorA (PorA-Loop4) was identified as the LamR-binding moiety. Here, we show that PorA-Loop4 targets the 37 kDa laminin receptor precursor (37LRP) on the cell surface by demonstrating that deletion of this loop abrogates the recruitment of 37LRP under meningococcal colonies. Using a circularized peptide corresponding to PorA-Loop4, as well as defined meningococcal mutants, we demonstrate that host cell interaction with PorA-Loop4 results in perturbation of p-CDK4 and Cyclin D1. These changes in cell cycle control proteins are coincident with cellular responses including inhibition of cell migration and a G1 cell cycle arrest. Modulation of the cell cycle of host cells is likely to contribute to the pathogenesis of meningococcal disease.

Neisseria meningitidis (meningococcus) is a major meningitis-causing bacteria and is known for its ability to breach blood-brain barrier (BBB). Meningococcus binds to Laminin receptor (LAMR) on the surface of endothelium, which is part of the BBB. The meningococcal surface proteins PorA and PilQ were previously identified as bacterial ligands responsible for binding and, subsequently, the LAMR-binding moiety of PorA was localised to its fourth extracellular loop (PorA-Loop4). Using a circularised peptide corresponding to PorA-Loop 4 from N. meningitidis MC58, the PorA-LAMR interaction induced specific cellular responses in human brain microvascular endothelial cells (HBMECs) including G1 cell cycle arrest. Flow cytometric analysis indicated that the treatment of HBMECs with PorA-Loop4 for 24 h caused a significant reduction of cells (20 %) at S-phase and a corresponding increase (23 %) in G1 population. Immunoblotting and quantitative real time PCR (qRT-PCR) analysis suggested that a blockade in Akt signalling (key proteins including Akt, GSK-3β, CyclinD1, and CDK4) contributes to the G1 arrest. Immunoblotting showed that the expression of phosphorylated GSK-3β and CDK4 were significantly increased in treated HBMECs. In contrast, the expression of phosphorylated Akt and Cyclin D1 were decreased following treatment. Transcriptome analysis using qRT-PCR confirmed that treatment of HBMECs with PorA-Loop4 peptide for 2, 4, 8, or 24 h increased gene expression of CDK4, and decreased expression of Cyclin D1. Immunofluorescent imaging of Akt, GSK-3β, CyclinD1, and CDK4 in Loop4-treated HBMECs are consistent with qRT PCR and immunoblot results. The data confirm that PorA-Loop4 induce G1 arrest through the Akt signalling pathway via Akt/GSK-3β/CyclinD1/CDK4.

BACKGROUND: Rapid and accurate identification of Staphylococcus capitis is required to provide a better prognosis for endocarditis patients and tackle the emergence of multidrug resistant strains of the bacteria in hospitals. The current study was aimed to develop polymerase chain reaction (PCR) assay for specific identification of S. capitis using sodA and gap genes as markers.METHODS: Five sequences of sodA and sixteen sequences of gap registered in GeneBank were analysed using bioinformatic tools. PCR primers were designed based on the conserved and specific regions of sodA and gap. Four clinical isolates of S. capitis (named no. 56-59) and six reference strains of coagulase-negative staphylococci (CoNS) species including S. epidermidis ATCC 35984, S. epidermidis 48951I/09, S. lugdunensis 44987/09, S. sciuri 109645I/08, S. warneri 135612/09, S. hominis 114202/08 were used to validate the conventional PCR system.RESULTS: The current PCR system only amplified the DNA template of S. capitis. Current primers specifically targeted S. capitis as the agarose images only showed bands from S. capitis samples.CONCLUSION: The sodA and gap genes might serve as effective markers for identification of S. capitis using conventional PCR. The PCR assay in the current study was able to identify five clinical isolates of S. capitis accurately without mispriming, misamplification and misidentification. The PCR system was also able to discriminate other CoNS including S. epidermidis, S. lugdunensis, S. sciuri, S. warneri and S. hominis.KEYWORDS: Staphylococcus, S. capitis, sodA, gap, PCR