Antibacterial, Antibiofilm, and Antioxidant Activity of Polysaccharides Obtained from Fresh Sarcotesta of Ginkgo biloba: Bioactive Polysaccharide that Can Be Exploited as a Novel Biocontrol Agent

Staphylococcus aureus (S. aureus) biofilm plays an important role in the persistence of chronic infection due to its resistance to antibiotics. Because of their functional diversity, active polysaccharide is increasingly being applied as a biocontrol agent to inhibit the formation of biofilm by pathogens. In this study, a new polysaccharide, GBSPII-1, isolated from the fresh sarcotesta of Ginkgo biloba L. (G. biloba) was characterized and its effect on antibiofilm formation of S. aureus was examined in vitro. High-Performance Liquid Chromatography (HPLC) analysis showed that GBSPII-1 is an acidic heteropolysaccharide composed of mannose, rhamnose, glucose, glucuronic acid, and galacturonic acid. GBSPII-1 demonstrated a molecular weight of 34 kDa and may affect the accumulation of polysaccharide intercellular adhesion (PIA) by inhibiting icaA, icaB, icaC, and icaD gene expression at subinhibitory concentrations. Under 10 g/L, GBSPII-1 showed an antioxidant effect on the inhibition rate of H2O2-induced erythrocyte hemolysis and the scavenging rate of DPPH radicals was 76.5 ± 0.5% and 89.2 ± 0.26%, respectively. The findings obtained in this study indicate that GBSPII-1 has antibacterial effect, is a possible source of natural antioxidants, and may be a potential biocontrol agent for the design of new therapeutic strategies for biofilm-related S. aureus infections.

Diclofenac May Induce PIA-Independent Biofilm Formation in Staphylococcus aureus Strains

Staphylococcus aureus is a pathogen commonly resistant to antibiotics. Biofilm formation is one of the important factors related to its virulence. Non-antibiotics drugs, such as nonsteroidal anti-inflammatory agents (NSAIDs), have been studied as an alternative for treating infections by multiresistant pathogens and biofilm-associated infections. In this study, the effects of NSAID sodium diclofenac on growth inhibition and biofilm formation of S. aureus were evaluated. The minimum inhibitory concentration (MIC) of diclofenac for fifty isolates ranged from 200 to 400 μg/mL. Diclofenac sub-MICs induced biofilm in 32.3% of biofilm-negative strains in tryptic soy broth. All biofilms induced by the drug showed a PIA- (polysaccharide intercellular adhesion-) independent composition, and the scanning electron microscopy showed that the induced biofilm presented a very discrete matrix. The combination of diclofenac with rifampicin sub-MICs induced strong production of PIA-dependent biofilm in three of four strains, while combination of NSAID with NaCl induced the formation of partially polysaccharide biofilm in two strains and PIA-independent biofilm in another strain. The combination of NSAID with glucose resulted in PIA-independent biofilms in all four strains tested. The results showed that diclofenac can commonly induce biofilm production by a PIA-independent pathway. However, when this NSAID is combined with other types of inducing agents, the composition of the biofilm produced may vary.

IgY Targeting Bacterial Quorum-Sensing Molecules in Implant-Associated Infections

Background: Implant-associated infections are still a major complication in the field of orthopedics. Bacteria can form biofilms on implant surfaces, making them more difficult to detect and treat. Since standard antibiotic therapy is often impaired in biofilm infections, particular interest is directed towards finding treatment alternatives. Biofilm-formation is a well-organized process during which bacteria communicate via quorum-sensing molecules (QSM). The aim of this study was to inhibit bacterial communication by directing avian IgY against specific QSM. Methods: Chicken were immunized against the following QSM: (1) AtlE, a member of the autolysin family which mediates attachment to a surface in Staphylococcus epidermidis; (2) GroEL, the bacterial heat shock protein; (3) PIA (polysaccharide intercellular adhesion), which is essential for cell–cell adhesion in biofilms. Staphylococcus epidermidis biofilms were grown and inhibition of biofilm-formation by IgYs was evaluated. Additionally, human osteoblasts were cultivated and biocompatibility of IgYs was tested. Results: We were able to demonstrate that all IgYs reduced biofilm-formation, also without prior immunization. Therefore, the response was probably not specific with regard to the QSM. Osteoblasts were activated by all IgYs which was demonstrated by microscopy and an increased release of IL-8. Conclusions: In conclusion, avian IgY inhibits biofilm-formation, though the underlying mechanism is not yet clear. However, adverse effects on local tissue cells (osteoblasts) were also observed.

Evaluation of polysaccharide intercellular adhesion (PIA) and glycerol teichoic acid (Gly-TA) arisen antibodies to prevention of biofilm formation in Staphylococcus aureus and Staphylococcus epidermidis strains

Objective Staphylococcus aureus and S. epidermidis as opportunistic pathogens, notable for their frequency and severity of infections are recognized as the most usual reasons for medical device-associated infections that strike hospitalized patients and also immunocompromised individuals. In this study, the polysaccharide intercellular adhesion (PIA) and Glycerol teichoic acid) Gly-TA) as two major macromolecules in the biofilm formation process were purified under the native condition and their structure was analyzed by using colorimetric assays and Fourier Transform Infrared spectroscopy (FTIR). Afterward, the immune response of macromolecules and the mixture of them were assessed by measuring total IgG titers. Subsequently, biofilm inhibitory effects of raising antibodies to biofilm former S. aureus and S. epidermidis were evaluated. Results Obtained data were shown a significant rise in levels of antibodies in immunized mice with mentioned antibodies in comparison with the control group. According to the obtained findings, mentioned antibodies could eliminate S. aureus and S. epidermidis biofilm formation in vitro assays. This survey confirms the proposal that immunization of mice with a mixture of Gly-TA and PIA vaccine could be secure and protected against S. epidermidis and S. aureus infection.

Comparative analysis of PIA and rSesC mixture, arisen antibodies against the biofilm forming Staphylococcus aureus.

Background: Staphylococcus aureus as a causative agent of hospital-acquired infections, has been considered as the primary concern in biomaterial-related infections (BAIs). Following the purification of polysaccharide intercellular adhesion (PIA) as an efficient macromolecule in biofilm formation in the native condition, recombinant S . epidermidis surface exposed rSesC protein, with the most homology to clumping factor A (ClfA) in S. aureus was cloned and expressed in a prokaryotic host as well. Fourier transform infrared spectrometry (FTIR) and Western blotting procedure analyzed purified PIA and protein, respectively. Then, the immune response was evaluated by measuring total IgG titers. Moreover, the capacity of Anti-biofilm forming activity of arisen antibodies to a biofilm forming S. aureus strains was assessed by semi-quantitative micro-plate procedure. Results: Data showed that the total IgGs was boosted in mice immunized sera. By performing inhibition assay, biofilm inhibitory effect of secreted antibodies to test strain was observed. Arisen antibodies against the mixture significantly were more potent than PIA and rSesC, when comparing them in a biofilm inhibition assay. Conclusion: Immunization of mice with mentioned antigens especially a mixture of them, could eliminate the biofilm formation process in S. aureus . Hopefully, this study corresponds the suggestion that, the immunization of mice with PIA and rSesC candidate vaccine could protect against S. aureus infection.

Comparative analysis of PIA and rSesC mixture, as vaccine candidate against the biofilm forming Staphylococcus aureus.

Background: Staphylococcus aureus as a causative agent of hospital-acquired infections, has been considered as the primary concern in biomaterial-related infections (BAIs). Methods: Following the purification of polysaccharide intercellular adhesion (PIA) as an efficient macromolecule in biofilm formation in the native condition, recombinant S. epidermidis surface exposed rSesC protein, with the most homology to clumping factor A (ClfA) in S. aureus was cloned and expressed in a prokaryotic host as well. Fourier transform infrared spectrometry (FTIR) and Western blotting procedure analyzed purified PIA and protein, respectively. Then, the immune response was evaluated by measuring total IgG titers. Moreover, the capacity of Anti-biofilm forming activity of arisen antibodies to a biofilm forming S. aureus strains was assessed by semi-quantitative micro-plate procedure. Results: Data showed that the total IgGs was boosted in mice immunized sera. By performing inhibition assay, biofilm inhibitory effect of secreted antibodies to test strain was observed. Arisen antibodies against the mixture significantly were more potent than PIA and rSesC, when comparing them in a biofilm inhibition assay.