Vitamin E Phosphate Coating Stimulates Bone Deposition in Implant-related Infections in a Rat Model.

BACKGROUND: Implant-related infections are associated with impaired bone healing and osseointegration. In vitro antiadhesive and antibacterial properties and in vivo antiinflammatory effects protecting against bone loss of various formulations of vitamin E have been demonstrated in animal models. However, to the best of our knowledge, no in vivo studies have demonstrated the synergistic activity of vitamin E in preventing bacterial adhesion to orthopaedic implants, thus supporting the bone-implant integration. QUESTIONS/PURPOSES: The purpose of this study was to test whether a vitamin E phosphate coating on titanium implants may be able to reduce (1) the bacterial colonization of prosthetic implants and (2) bone resorption and osteomyelitis in a rat model of Staphylococcus aureus-induced implant-related infection. METHODS: Twelve rats were bilaterally injected in the femurs with S aureus UAMS-1-Xen40 and implanted with uncoated or vitamin E phosphate-coated titanium Kirschner wires without local or systemic antibiotic prophylaxis. Eight rats represented the uninfected control group. A few hours after surgery, two control and three infected animals died as a result of unexpected complications. With the remaining rats, we assessed the presence of bacterial contamination with qualitative bioluminescence imaging and Gram-positive staining and with quantitative bacterial count. Bone changes in terms of resorption and osteomyelitis were quantitatively analyzed through micro-CT (bone mineral density) and semiquantitatively through histologic scoring systems. RESULTS: Six weeks after implantation, we found only a mild decrease in bacterial count in coated versus uncoated implants (Ti versus controls: mean difference [MD], -3.705; 95% confidence interval [CI], -4.416 to -2.994; p < 0.001; TiVE versus controls: MD, -3.063; 95% CI, -3.672 to -2.454; p < 0.001), whereas micro-CT analysis showed a higher bone mineral density at the knee and femoral metaphysis in the vitamin E-treated group compared with uncoated implants (knee joint: MD, -11.88; 95% CI, -16.100 to -7.664; p < 0.001 and femoral metaphysis: MD, -19.87; 95% CI, -28.82 to -10.93; p < 0.001). We found decreased osteonecrosis (difference between medians, 1.5; 95% CI, 1-2; p < 0.002) in the infected group receiving the vitamin E-coated nails compared with the uncoated nails. CONCLUSIONS: These preliminary findings indicate that vitamin E phosphate implant coatings can exert a protective effect on bone deposition in a highly contaminated animal model of implant-related infection. CLINICAL RELEVANCE: The use of vitamin E coatings may open new perspectives for developing coatings that can limit septic loosening of infected implants with bacterial contamination. However, a deeper insight into the mechanism of action and the local release of vitamin E as a coating for orthopaedic implants is required to be used in clinics in the near future. Although this study cannot support the antimicrobial properties of vitamin E, promising results were obtained for bone-implant osseointegration. These preliminary results will require further in vivo investigations to optimize the host response in the presence of antibiotic prophylaxis.

BAG-S53P4 as bone graft extender and antimicrobial activity against gentamicin- and vancomycin-resistant bacteria.

AIM: To evaluate the suitability of bioactive glass (BAG)-S53P4 as a bone-graft extender for large bony defect filling in bone and joint infection. MATERIALS & METHODS: Antimicrobial activity of BAG-S53P4 against clinically relevant strains isolated from bone and joint infections was evaluated by means of time-kill curves in presence of bone graft. Furthermore, the susceptibility to BAG of strains resistant to vancomycin and gentamicin was assessed. RESULTS: Though attenuated, BAG maintains a good in vitro antimicrobial activity in presence of human body fluids and tissues contained in bone graft, with the exception of Enterococcus faecalis. CONCLUSION: BAG-S53P4 is a suitable bone substitute that can be used as an extender with autologous bone graft to promote better fusion and healing.

In vitro comparison between α-tocopheryl acetate and α-tocopheryl phosphate against bacteria responsible of prosthetic and joint infections.

Biofilm-related infections represent a recurrent problem in the orthopaedic setting. In recent years, great interest was directed towards the identification of novel molecules capable to interfere with pathogens adhesion and biofilm formation on implant surfaces. In this study, two stable forms of α-tocopherol, the hydrophobic acetate ester and the water-soluble phosphate ester, were tested in vitro as coating for titanium prosthesis. Antimicrobial activity against microorganisms responsible of prosthetic and joints infections was assessed by broth microdilution method. In addition, α-tocopherol esters were evaluated for both their ability to hamper bacterial adhesion to and biofilm formation on sandblasted titanium surfaces. Results showed that only α-tocopheryl phosphate displayed antimicrobial activity against the tested strains. Both esters were able to significantly interfere with bacterial adhesion and to prevent biofilm formation, especially by Staphylococcus aureus and Staphylococcus epidermidis. The activity of α-tocopheryl phosphate was greater than that of α-tocopheryl acetate. Alterations at membrane levels have been reported in literature and may be likely responsible for the interference on bacterial adhesion and biofilm formation shown by α-tocopherol esters. Although further studies are needed to better investigate the mechanisms of action and the spectrum of activity of α-tocopherol esters, these characteristics together with the positive effect on wound healing and immune response, make these molecules promising candidate for coating in order to prevent implant-associated infections.

Reliability of a multiplex PCR system for diagnosis of early and late prosthetic joint infections before and after broth enrichment.

Early microbiological diagnosis of prosthetic joint infection (PJI) is essential for successful antimicrobial treatment; however, culture has limited sensitivity, particularly in patients who had received antibiotic therapy, and the utility of molecular methods for diagnosing PJIs remains debated. We investigated the reliability of a multiplex PCR system for the microbiological diagnosis of early and late PJIs. Samples of periprosthetic tissues, synovial fluid, and prosthetic implants from 47 patients with early (n=13) or late (n=34) PJI were analyzed by conventional culture and with the multiplex-PCR Unyvero ITI® (U-ITI) cartridge system. Samples treated with dithiothreitol (DTT) and synovial fluids were spread directly on agar plates and inoculated into enrichment broths. The synovial fluids, DTT eluates and enrichment broths were processed according to the U-ITI protocol. When compared against culture as the reference method, U-ITI analysis of DTT eluates had a sensitivity of 34.2%; sensitivity of U-ITI analysis increased up to 81.6% when enrichment broths were analyzed. In particular, sensitivity was 44.4% for synovial fluids, and 41.7%, and 23.5% for DTT eluates from early and late infections, respectively. Sensitivity of analysis of enrichment broths was 83.3% for early infections, 82.3% for late infections and 77.8% for synovial fluids. Our findings seem to suggest that, when coupled with the use of broth culture, U-ITI analysis may allow for more rapid microbial identification than biochemical methods, while no advantages in time to detect microbial growth were observed. Improvements, particularly in sensitivity, are needed to make it more suitable for diagnosis of early and late PJIs.

In vitro Antimicrobial Activity of Chlorquinaldol against Microorganisms Responsible for Skin and Soft Tissue Infections: Comparative Evaluation with Gentamicin and Fusidic Acid.

Skin and soft tissue infections (SSTIs) are a major therapeutic challenge for clinicians. The emergence of pathogens with decreased susceptibility to available therapies has become an emerging problem often associated with treatment failure. Hence, there is an urgent need for novel broad-spectrum antimicrobial agents. The purpose of this study was to assess the feasibility of chlorquinaldol as an alternative approach to currently used topical antibiotics for the treatment of skin and soft tissue infections. The activity of chlorquinaldol was investigated against a collection of bacterial isolates responsible for skin infections, including strains resistant to fusidic acid and gentamicin. After determination of MIC and MBC, time-kill experiments were carried out by counting colonies grown after 0, 3, 6, 9, 24, and 48 h of incubation with concentrations equal to »×, ½×, 1×, 2×, and 4× MIC of chlorquinaldol, gentamicin, or fusidic acid. Staphylococci resulted the Gram-positives most sensitive to chlorquinaldol, with MIC-values ranging from 0.016 to 0.5 mg/L. A lower activity was observed against Gram-negative bacteria, with 77% of the isolates being inhibited at concentrations ranging from 128 to 512 mg/L. Generally, in time-kill studies, chlorquinaldol showed a bactericidal activity at the higher concentrations (2×, 4× MIC) after 24-48 h of incubation. In conclusion, chlorquinaldol may represent a valuable alternative to conventional topical antibiotics for the treatment of skin and soft tissue infections.

Epidemiology and Antibiotic Resistance of Late Prosthetic Knee and Hip Infections.

BACKGROUND: Prosthetic joint infections (PJI) are still a major complication of hip and knee arthroplasties. Identification of the causative pathogens and knowledge of their antibiotic susceptibilities are essential for the management of these infections. The main purpose of the study was to identify and compare the causative bacteria of prosthetic knee and hip joint infections in a reference Italian orthopedic center and to characterize antibiotic resistance profiles of bacteria involved. METHODS: Data from 429 patients with diagnosis of PJI were collected from January 2013 to June 2015: 229 presented a hip and 200 a knee prosthesis infection. Prostheses and periprosthetic tissues were treated with dithiothreitol before plating onto different media and broths. Identification and antimicrobial susceptibility testing were carried out by VITEK2 Compact (bioMerieux). RESULTS: There was not a substantial difference in the etiology of hip and knee PJI: staphylococci were the most frequently isolated bacteria in both groups, followed by Enterobacteriaceae and Propionibacterium acnes. Staphylococci showed a high rate of methicillin resistance (144 of 341) and a worrying frequency of isolates were resistant to teicoplanin (9%). Only 8.3% of Enterobacteriaceae produced extended-spectrum beta-lactamases, whereas the rate of carbapenemase-producing bacteria was not significant. CONCLUSION: We observed similar etiology of hip and knee PJIs. Nevertheless, bacteria isolated from knee showed higher resistance rates to glycopeptides and fluoroquinolones when compared with those isolated from the hip. The reason for this difference remains to be elucidated in future studies.

Terminal sterilization of equine-derived decellularized tendons for clinical use.

In the last few years, the demand for tissue substitutes has increased and decellularized matrices has been widely proposed in the medical field to restore severe damages thanks to high biocompatibility and biomechanical properties similar to the native tissues. However, biological grafts represent a potential source of contamination and disease transmission; thus, there is the need to achieve acceptable levels of sterility. Several sterilization methods have been investigated with no consensus on the outcomes in terms of minimizing structural damages and preserving functional features of the decellularized matrix for transplantation in humans. With the aim of making decellularized tendons safe for clinical use, we evaluated the cytocompatibility, and biochemical, structural and biomechanical variations of decellularized equine tendons sterilized with peracetic acid or ß-irradiation and differently wet- or dry- stored at 4°C or -80°C, respectively. Considering that both sterilization and long-term storage are crucial steps that could not be avoided, our results pointed at ionizing ß-rays as terminal sterilization method for decellularized grafts followed by frozen dry storage. Indeed, this approach can maintain the integrity of collagen-based structures and can avoid biomechanical changes, thus making xenogeneic decellularized tendons a promising candidate for clinical use.

Improving the Bacterial Recovery by Using Dithiothreitol with Aerobic and Anaerobic Broth in Biofilm-Related Prosthetic and Joint Infections.

Biofilm-related infections are serious complications in the orthopaedic prosthetic field and an accurate, quick microbiological diagnosis is required to set up a specific antimicrobial therapy. It is well known that the diagnosis of these infections remains difficult due to the bacterial embedding within the biofilm matrix on the implant surfaces. Recently, the use of DL-dithiothreitol (DTT) has been proved effective in biofilm detachment from orthopaedic devices.The purpose of the study is to evaluate the efficacy of two DTT solutions enriched with specific broths for aerobic or anaerobic bacteria to dislodge pathogens from the biofilm, while supporting the bacterial recovery and viability. To do this, different experimental solutions were tested for efficacy and stability on strong biofilm producers: S. aureus and P. acnes. Mainly, we evaluate the capability of DTT dissolved in saline solution, brain heart infusion or thioglycollate broth to support the bacterial detachment from prosthetic materials and bacterial growth at different time points and storage conditions.We demonstrated that the use of DTT enriched with specific bacterial broths could be a suitable approach to optimize the bacterial detachment, recovery, growth and viability in the diagnosis of biofilm-related infections developed on orthopaedic prosthetic devices.

Erythritol/chlorhexidine combination reduces microbial biofilm and prevents its formation on titanium surfaces in vitro.

BACKGROUND: The purpose of this in vitro study was to evaluate the antibiofilm activity of a novel air-polishing powder consisting of erythritol and chlorhexidine, assessing its ability to reduce previously grown microbial biofilm and to prevent biofilm formation on titanium surfaces. METHODS: Clinical strains of Staphylococcus aureus, Pseudomonas aeruginosa, Bacteroides fragilis and Candida albicans isolated from peri-implantitis lesions were used. Biofilm was grown on sandblasted titanium discs and treated with erythritol/chlorhexidine. The antimicrobial activity was evaluated by determining the minimum inhibitory concentration and the minimum microbicidal concentration. The antibiofilm activity was assessed by semiquantitative spectrophotometric assay and by confocal laser scanning microscopy. RESULTS: Erythritol/chlorhexidine displayed an inhibitory and a microbicidal activity against all the tested strains. The spectrophotometric analysis showed that the treatment was effective in both reducing the previously developed biofilm and decreasing biofilm formation on titanium surfaces. Confocal laser scanning microscopy analysis showed a significant reduction of the total biofilm volume, with an increase of the percentage of dead cells of all the microorganisms tested. CONCLUSIONS: Erythritol/chlorhexidine displayed significant antimicrobial and antibiofilm activity against microorganisms isolated from peri-implantitis lesions. Due to its properties, it might represent a promising approach for the prevention and treatment of peri-implant diseases associated to microbial biofilm infections.

Treatment With Dithiothreitol Improves Bacterial Recovery From Tissue Samples in Osteoarticular and Joint Infections.

BACKGROUND: Prosthetic implants, periprosthetic and osteoarticular tissues are specimens of choice for diagnosis of bone and joint infections. Homogenization is considered the best procedure for treatment of tissues samples, but, it is not always performed in all laboratories. Dithiothreitol (DTT) has been proposed as an alternative treatment to sonication for microbiological diagnosis of prosthetic joint infections. In this study, the applicability of DTT treatment for processing of periprosthetic and osteoarticular tissues for diagnosis of bone and joint infections was evaluated and compared with normal saline solution treatment. METHODS: Periprosthetic tissue samples were collected from 70 consecutive patients (25 infected and 45 not infected). For each patient, samples from the same site were randomly allocated to DTT or saline treatment. Treated samples were centrifuged at 3000 rpm for 10 minutes. Aliquots from the concentrated samples were plated on agar plates and inoculated in broths. Sensitivity and specificity were calculated for each treatment. RESULTS: Microbial growth was observed in samples from 14 and 11 infected patients after DTT and saline treatments, respectively. Concordance between the 2 methods was observed in the 85.7% of cases. Sensitivity was 88.0% for DTT and 72.0% for saline. Specificity was 97.8% and 91.1% for DTT and saline, respectively. Treatment with DTT showed higher sensitivity and specificity with respect to the method routinely used in our laboratory. CONCLUSION: DTT treatment may be considered a practicable strategy for microbiological analysis of tissues for diagnosis of bone and joint infections.

Antibiofilm activity of sandblasted and laser-modified titanium against microorganisms isolated from peri-implantitis lesions.

Infections due to biofilm-producing microorganisms are one of the main causes for the failure of dental implants. Increasing efforts have been made in order to develop new strategies to prevent biofilm formation. In this study, the biofilm development on a newly designed laser-modified titanium implant surface was evaluated and compared to that on conventional sandblasted titanium used in implant dentistry. The amount of biofilm produced by Staphylococcus aureus, Pseudomonas aeruginosa and Porphyromonas gingivalis isolated from peri-implantitis was assessed by a semi-quantitative spectrophotometric method and by confocal laser scanning microscopy. Results showed a lower biofilm production on laser-modified surface compared to the sandblasted one. In particular, a significantly lower total volume of the biomass was observed on laser-modified surface, while no significant changes in live/dead bacteria percentages were noticed between materials. Modifying the topography of the conventional implant surface with laser ablation could represent a promising approach for inhibiting biofilm formation.

How to Study Biofilms after Microbial Colonization of Materials Used in Orthopaedic Implants.

Over the years, various techniques have been proposed for the quantitative evaluation of microbial biofilms. Spectrophotometry after crystal violet staining is a widespread method for biofilm evaluation, but several data indicate that it does not guarantee a good specificity, although it is rather easy to use and cost saving. Confocal laser microscopy is one of the most sensitive and specific tools to study biofilms, and it is largely used for research. However, in some cases, no quantitative measurement of the matrix thickness or of the amount of embedded microorganisms has been performed, due to limitation in availability of dedicated software. For this reason, we have developed a protocol to evaluate the microbial biofilm formed on sandblasted titanium used for orthopaedic implants, that allows measurement of biomass volume and the amount of included cells. Results indicate good reproducibility in terms of measurement of biomass and microbial cells. Moreover, this protocol has proved to be applicable for evaluation of the efficacy of different anti-biofilm treatments used in the orthopaedic setting. Summing up, the protocol here described is a valid and inexpensive method for the study of microbial biofilm on prosthetic implant materials.

Antimicrobial properties of platelet-rich preparations. A systematic review of the current pre-clinical evidence.

In recent years autologous platelet concentrates (APCs) have become popular in several medicine fields, representing a valuable adjunct to regenerative surgical procedures. Beneficial effects in the control of postsurgical discomfort and infection have also been frequently reported, suggesting that APC may possess anti-inflammatory and antimicrobial properties. The aim of the present review was to summarize the current evidence regarding the antimicrobial effects of platelet concentrates, investigated by in vitro and animal studies. This review was conducted following a systematic approach. An electronic search was performed on MEDLINE, EMBASE and Scopus databases using appropriate search terms, without language or time restrictions. Preclinical studies assessing the antimicrobial activity of APC were included and divided according to the experimental design. Twenty in vitro studies and four animal studies, investigating APC effects on a broad range of microorganisms, were included. In in vitro studies APC reduced the growth of microorganisms during the first hours of incubation, while they could not completely break down the microbial load. In fact, over time a recovery of bacterial growth was always observed, suggesting that APCs display a bacteriostatic rather than a microbicidal activity. All animal studies showed that APC administered by local injections were able to reduce the infection caused by different microorganisms, although to a lesser extent compared to antibiotics. In conclusion, although the exact action mechanisms of interaction with microbial pathogens need further investigation, platelet concentrates proved to have antimicrobial properties, and therefore could represent a useful natural substance for controlling postoperative infections at surgical sites.

Antibiofilm agents against MDR bacterial strains: is bioactive glass BAG-S53P4 also effective?

OBJECTIVES: The treatment of bone and joint infections is challenging due to the presence of bacterial biofilm and the increasing emergence of multiresistant strains. BAG-S53P4 is a bone substitute that is characterized by osteoconductive and antimicrobial properties. The aim of this study was to assess the effectiveness of BAG-S53P4 against biofilm produced in vitro by multiresistant bacterial strains. METHODS: Multiresistant Staphylococcus epidermidis, Acinetobacter baumannii and Klebsiella pneumoniae isolated from bone and joint infections were used in this study. Titanium discs covered by bacterial biofilm were incubated with BAG-S53P4 or inert glass as a control. The amount of biofilm on each titanium disc was evaluated after 48 h of incubation by means of confocal laser scanning microscopy. RESULTS: Significantly lower total biomass volumes were observed for all strains after treatment with BAG-S53P4 when compared with controls. Moreover, the percentage of dead cells was significantly higher in treated samples than in controls for all the tested strains. CONCLUSIONS: BAG-S53P4 is able to reduce the biofilm produced by multiresistant S. epidermidis, A. baumannii and K. pneumoniae on titanium substrates in vitro, probably by interfering with cell viability. Owing to its osteoconductive, antibacterial and antibiofilm properties, the use of BAG-S53P4 may be a successful strategy for the treatment of bone and prosthetic joint infections.

Antimicrobial activity and resistance selection of different bioglass S53P4 formulations against multidrug resistant strains.

AIMS: This study aimed to evaluate the antimicrobial activity of two different formulations of bioglass BAG-S53P4 against multiresistant microorganisms involved in bone infections, and the capability of bioglass to select for resistance. METHODS: Antibacterial activity was evaluated by means of killing curves. The ability to select for resistant bacteria was evaluated by subculturing microorganisms in serial dilutions of bioglass. Scanning electron microscope acquisitions were conducted to evaluate bioglass-induced morphology changes. RESULTS: BAG-S53P4 formulations display a high antimicrobial activity and do not seem to select for resistance. Scanning electron microscopy analysis showed cell shrinkage and membrane damage after exposure to bioglass. CONCLUSIONS: BAG-S53P4 has a significant potential as bone substitute for the treatment of infections caused by multiresistant microorganisms.

Plasma components and platelet activation are essential for the antimicrobial properties of autologous platelet-rich plasma: an in vitro study.

Autologous platelet concentrates are successfully adopted in a variety of medical fields to stimulate bone and soft tissue regeneration. The rationale for their use consists in the delivery of a wide range of platelet-derived bioactive molecules that promotes wound healing. In addition, antimicrobial properties of platelet concentrates have been pointed out. In this study, the effect of the platelet concentration, of the activation step and of the presence of plasmatic components on the antimicrobial activity of pure platelet-rich plasma was investigated against gram positive bacteria isolated from oral cavity. The antibacterial activity, evaluated as the minimum inhibitory concentration, was determined through the microdilution two-fold serial method. Results seem to suggest that the antimicrobial activity of platelet-rich plasma against Enterococcus faecalis, Streptococcus agalactiae, Streptococcus oralis and Staphylococcus aureus is sustained by a co-operation between plasma components and platelet-derived factors and that the activation of coagulation is a fundamental step. The findings of this study may have practical implications in the modality of application of platelet concentrates.

Biofilm removal and antimicrobial activity of two different air-polishing powders: an in vitro study.

BACKGROUND: Biofilm removal plays a central role in the prevention of periodontal and peri-implant diseases associated with microbial infections. Plaque debridement may be accomplished by air polishing using abrasive powders. In this study, a new formulation consisting of erythritol and chlorhexidine is compared with the standard glycine powder used in air-polishing devices. Their in vitro antimicrobial and antibiofilm effects on Staphylococcus aureus, Bacteroides fragilis, and Candida albicans are investigated. METHODS: Biofilm was allowed to grow on sandblasted titanium disks and air polished with glycine or erythritol-chlorhexidine powders. A semiquantitative analysis of biofilm by spectrophotometric assay was performed. A qualitative analysis was also carried out by confocal laser scanning microscopy. Minimum inhibitory concentrations and minimum microbicidal concentrations were evaluated, together with the microbial recovery from the residual biofilm after air-polishing treatment. RESULTS: The combination of erythritol and chlorhexidine displayed stronger antimicrobial and antibiofilm activity than glycine against all microbial strains tested. CONCLUSION: Air polishing with erythritol-chlorhexidine seems to be a viable alternative to the traditional glycine treatment for biofilm removal.

Poly(amido-amine)-based hydrogels with tailored mechanical properties and degradation rates for tissue engineering.

Poly(amido-amine) (PAA) hydrogels containing the 2,2-bisacrylamidoacetic acid-4-amminobutyl guanidine monomeric unit have a known ability to enhance cellular adhesion by interacting with the arginin-glycin-aspartic acid (RGD)-binding αVß3 integrin, expressed by a wide number of cell types. Scientific interest in this class of materials has traditionally been hampered by their poor mechanical properties and restricted range of degradation rate. Here we present the design of novel biocompatible, RGD-mimic PAA-based hydrogels with wide and tunable degradation rates as well as improved mechanical and biological properties for biomedical applications. This is achieved by radical polymerization of acrylamide-terminated PAA oligomers in both the presence and absence of 2-hydroxyethylmethacrylate. The degradation rate is found to be precisely tunable by adjusting the PAA oligomer molecular weight and acrylic co-monomer concentration in the starting reaction mixture. Cell adhesion and proliferation tests on Madin-Darby canine kidney epithelial cells show that PAA-based hydrogels have the capacity to promote cell adhesion up to 200% compared to the control. Mechanical tests show higher compressive strength of acrylic chain containing hydrogels compared to traditional PAA hydrogels.

Magnifying loupes versus surgical microscope in endodontic surgery: a four-year retrospective study.

The purpose of this retrospective study was to evaluate the 4-year outcome of endodontic microsurgery using two different magnification devices. One-hundred and two teeth in 65 patients were included according to specific selection criteria. Endodontic surgery was performed under surgical microscope as magnification device in 63 teeth in 36 patients, while 39 teeth in 29 patients were treated under magnifying loupes. Thirteen patients did not attend the 4-year follow up. The overall success rate on a patient basis was 91.7% at the 1-year and 90.5% at the 4-year follow up for the group using loupes, while for the group using microscope it was 91.4% at the 1-year and 93.3% at the 4-year follow up. The relative risk was 2.07 (95% confidence interval: 0.31, 13.95) in favour of the group in which microscope was used. No statistically significant difference was found in the treatment outcomes relating to the type of magnification device.

Antimicrobial activity of pure platelet-rich plasma against microorganisms isolated from oral cavity.

BACKGROUND: Autologous platelet concentrates (PCs) have been extensively used in a variety of medical fields to promote soft and hard tissue regeneration. The significance behind their use lies in the abundance of growth factors in platelets α-granules that promotes wound healing. In addition, antibacterial properties of PCs against various bacteria have been recently pointed out. In this study, the antimicrobial effect of pure platelet-rich plasma (P-PRP) was evaluated against oral cavity microorganisms such as Enterococcus faecalis, Candida albicans, Streptococcus agalactiae, Streptococcus oralis and Pseudomonas aeruginosa. Blood samples were obtained from 17 patients who underwent oral surgery procedures involving the use of P-PRP. The antibacterial activity of P-PRP, evaluated as the minimum inhibitory concentration (MIC), was determined through the microdilution twofold serial method. RESULTS: P-PRP inhibited the growth of Enterococcus faecalis, Candida albicans, Streptococcus agalactiae and Streptococcus oralis, but not of Pseudomonas aeruginosa strains. CONCLUSIONS: P-PRP is a potentially useful substance in the fight against postoperative infections. This might represent a valuable property in adjunct to the enhancement of tissue regeneration.