Antibacterial activity of coatings based on metal and metal oxide nanoparticles (NPs) often depends on materials and biotic targets resulting in a material-specific killing activity of selected Gram-positive and Gram-negative bacteria, including drug-resistant strains. In this perspective, the NPs loading amount, the relative elemental concentration inside the nanogranular building blocks and the deposition method are of paramount importance when the goal is to widen the antimicrobial spectrum, but at the same time to avoid high levels of metal content to limit undesired toxic effects. Aim of the present study was evaluation of the antimicrobial properties of two multielement nanogranular coatings composed of Titanium-Silver and Copper and of Magnesium-Silver and Copper. Ti-Ag-Cu and Mg-Ag-Cu NPs were deposited on circular cover glasses (VWR) by Supersonic Cluster Beam Deposition. Biofilm-producer strains of Aim
Method
The analysis of synovial fluid has proved to be of crucial importance in the diagnostic process of prosthetic joint infections (PJI), suggesting the presence of an infection before the microbiological culture results. In this context, several studies illustrated the efficacy of synovial calprotectin in supporting the diagnosis of PJI [1, 2]. However, several testing methods have been explored to detect synovial calprotectin levels, emphasizing the need to use a standardized, rapid and rapid test. In this study, synovial calprotectin was analyzed by means of a commercial stool test [3] to explore whether the detected levels might predict PJIs and, therefore, being a promising tool for the fast and reliable diagnosis of this complication. The synovial fluid of 55 patients underwent to revision of the prosthetic implant were analyzed. The measurement of calprotectin was carried out by of commercial stool test, following the protocol for liquid samples. Calprotectin levels were then compared to other synovial biomarkers of PJI such as leucocyte esterase and count and percentage of polymorphonuclear cells. Data analysis were performed using R software v4.1.1 (R Core Team) and package “pROC” [4]. Receiver operator characteristics curves were designed using culture test as gold standard to evaluate the area under curve (AUC) of each method (with DeLong method for confidence-interval calculation). Thresholds were calculated to maximize Youden's index; sensitivity and specificity were reported. One-to-one Pearson's correlations coefficient were calculated for each pair of methods. P value <0.05 were considered statistically significant.Aim
Method
Despite the availability of numerous tests, the diagnosis of periprosthetic infection (PJI) continues to be complex. Although several studies have suggested that coagulation-related markers, such as D-dimer and fibrinogen, may be promising tools in the diagnosis of prosthetic infections, their role is still controversial. The aim of this study is to evaluate the diagnostic accuracy of serum D-dimer and fibrinogen in patients with painful total knee replacement. 83 patients with painful total knee replacement and suspected peri-prosthetic infection were included. All patients underwent pre-operative blood tests to evaluate inflammation indices (ESR and CRP) and serum D-Dimer and Fibrinogen levels. The diagnostic performance of the tests was assessed using the ICM definition as the gold standard. The diagnostic accuracy of the D-dimer and fibrinogen was measured by assessing sensitivity, specificity and by calculating the area under the ROC curve.Aim
Method
Bone and implant-associated infections caused by microorganisms that grow in biofilm are difficult to treat because of persistence and recurrence. Systemic administration of antibiotics is often inefficient because the poor vascularization of the site of infection. This issue has led to the development of biomaterials capable to locally deliver high doses of therapeutic agents to the injured bone with minimal systemic effects. In this context, calcium sulphate/hydroxyapatite (CS/HA) bone graft substitutes are widely used being safe, osteoconductive and resorbable biomaterials that can be easily enriched with consistent amounts of antibiotics. In this in vitro study, the capability of the eluted antibiotics to select the tested bacterial strains for antibiotic resistance was evaluated to confirm the safe use of the product. S. aureus, S. epidermidis and P. aeruginosa isolated in our Institute from bone and joint infection with different resistance phenotypes were used. 6 × 2.5 mm CS/HA discs were generated by pouring the antibiotic loaded formulations in a mold and were used as a modified disk diffusion test. The resistance selection was evaluated by subculturing cells growing on the edge of the zone of inhibition (ZOI) for seven days. Minimum inhibitory concentrations (MICs) of gentamicin and vancomycin were determined by broth microdilution method before and after the selection of resistance assay. In addition, MICs were assessed after seven day passage on antibiotic free agar plates to evaluate if eventual decrease of antibiotic susceptibility was stable or only transient.Aim
Method
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 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 and biofilm formation on sandblasted titanium surfaces.Aim
Method
Culture examination is still considered the gold standard for diagnosis of bone and joint infections, including prosthetic ones, even if in up to 20–30% of cases, particularly prosthetic joint infections, it fails to yield microbial growth. To overcome this limitation, determination of markers of inflammation and or infection directly in joint fluid has been proposed. Aim of this study was to evaluate the applicability of measurement of lecukocyte esterase (LE), C-reactive protein (CRP) and glucose in synovial fluid for diagnosis of bone and joint infections. Synovial fluids from 80 patients were aseptically collected and sent to laboratory for microbiological cultures. After centrifugation at 3000 rpm for 10 minutes, pellet was used for cultures, while the surnatant was used for determination of LE, CRP and glucose. LE and glucose were evaluated by means of enzymatic colorimetric strips developed for urinanalysis. One drop of synovial fluid was placed on the LE and on the glucose pads and the results were read after about 120 seconds. A LE test graded + or ++, and a glucose test equal to trace or negative were considered suggestive for infection. CRP was measured by an automated turbidimetric method. On the basis of clinical findings, microbiological, haematological and histological analyses patients were retrospectively divided into 2 groups. Group 1 comprised 19 infected patients (12 males, 7 females age: 70.6 ± 10.3 yrs, range: 47 – 88 yrs) while Group 2 included 61 aseptic patients (32 males and 29 females, age: 61.5 ± 16.3 yrs, range: 15 – 84). Sensitivity of the three tests was 89.5%. 84% and 73,7% for LE, CRP and glucose, respectively. Specificity was 98.4%, 88.5% and 70% for LE, CRP and glucose, respectively. Positive and negative predictive values were 94.4% and 96.8% for LE, 69.6% and 94.6% for CRP and 77.8% and 89.6% for glucose test. When LE was combined with CRP, sensitivity increased to 94.7%, while no differences were observed for LE combined with glucose. Leukocyte esterase has proven to be a rapid, simple and inexpensive test to rule in or out bone and joint infections. Combination of its measurement with that of CRP increased sensitivity. In conclusion, the combination of leukocyte esterase and CRP may represent a simple and useful tool for diagnosis of bone and joint infections.
Prosthetic implants, periprosthetic and osteoarticular tissues are specimens of choice for diagnosis of bone and joint infections including prosthetic joint infections (PJIs). However, it is widely known that cultures from prostheses and tissues may fail to yield microbial growth in up to one third of patients. In the recent past, treatment of prosthetic implants have been optimized in order to improve sensitivity of microbiological cultures, while less attention has been addressed to tissue samples. For these latter homogenization is considered the best procedure, but it is quite laborious, time-consuming and it is not always performed in all laboratories. Dithiothreitol (DTT) has been proposed as an alternative treatment to sonication for microbiological diagnosis of PJIs. In this study, we evaluated the applicability of MicroDTTect treatment, a closed system developed for transport and treatment of tissues and prosthetic implants with DTT. For evaluation of applicability of MicroDTTect to tissue specimens, samples (tissues and, in case of PJI, prosthetic implants) from 40 patients (12 PJIs and 5 osteomyelitis and 23 not-infected) were evaluated. MicroDTTect system consists of a sterile plastic bag containing a reservoir which allows for release of a 0.1% (v:v) DTT solution, once the sample is placed into the bag. Comparison of MicroDTTect treatment of prostheses with sonication included samples from 30 patients (14 with aseptic loosening of the prosthesis and 16 with PJIs). Of two tissue samples from the same region, one was placed into MicroDTTect bag and the other was collected in a sterile container with addition of sterile saline. After agitation and centrifugation of the eluate, aliquots of the pellets were plated on agar plates and inoculated into broths which were incubated for 48 hrs and 15 days, respectively. Treatment of prosthetic implants with MicroDTTect showed a higher specificity and sensitivity than sonication (specificity 92.8% vs 85.7%; sensitivity: 87.5% vs 75.0 % DTT vs sonication). When used for tissue treatment, MicroDTTect showed a sensitivity of 82.3% and a specificity of 97% which were higher than that observed when saline was used (sensitivity: 64.7%; specificity 91%). Treatment of tissues and prosthetic implants with MicroDTTect may be a practicable strategy to improve microbiological diagnosis of osteoarticular infections, reducing sample manipulation and therefore limiting sample contamination. Moreover, use of MicroDTTect does not require dedicated instrumentation, and is time and cost saving.
The role of biofilm in pathogenesis of several chronic human infections is widely accepted, as this structure leads pathogens to persist among the human body, being protected from the action of antibacterial molecules and drugs (1). It has been estimated that up to 65% of bacterial infections are caused by microorganisms growing in biofilms (2). Moreover, biofilm is involved in device-related orthopaedic bacterial infections, which are unaffected by vaccines and antibiotic therapies, constituting a serious problem for the human health care. The aim of the present work was to evaluate the anti-biofilm action of a selected and patented lactobacillus strain (MD1) supernatant, both on the in-formation- biofilm and on mature biofilm produced by pathogenic bacteria. MD1 was grown in BHI for 48 h at 37°C. After incubation, the sample was centrifuged for 5’ for 14,000 × g and the supernatant previously filtered and treated in order to obtain the anti-biofilm compounds (Special Supernatant – SS) was collected. Staphylococcus aureus and Pseudomonas aeruginosa strains were grown in BHI for 24h at 37°C. The anti-biofilm ability of the tested SS – lactobacillus strain was evaluated by a spectrophotometric method according to Christensen at al., following the incubation of pathogens and the “mature biofilm” with the lactobacillus supernatant. Confocal Laser Scanning Microscopy was used to confirm the data obtained from Crystal Violet Assay. After the incubation of the SS with pathogens and mature biofilm, the formation of biofilm was inhibited and a significant disruption of the mature biofilm was observed. Interestingly, the same properties were observed also when the SS pH was neutralized to pH 6.5. In particular, the reduction of biofilm production and the disruption of mature biofilm was about 50–70% for all microorganisms. The SS lactobacillus strain MD1 exhibited a relevant antibiofilm action against mature and in-formation-biofilm produced by S. aureus and P. aeruginosa strains tested in the study. Moreover, the antibiofilm action has been observed to be pH-independent, as when the supernatant was neutralized to pH 6.5, the reduction of pathogenic biofilm has been still observed. These promising results highlighted the possibility to use this SS-lactobacillus anti-biofilm property to develop a cost-effective and safety treatment able to reduce the impact of pathogenic biofilm on device-related orthopaedic bacterial infections.
