Dynamic Adhesive Behavior and Biofilm Formation of Staphylococcus aureus on Polylactic Acid Surfaces in Diabetic Environments.

Interest in biodegradable implants has focused attention on the resorbable polymer polylactic acid. However, the risk of these materials promoting infection, especially in patients with existing pathologies, needs to be monitored. The enrichment of a bacterial adhesion medium with compounds that are associated with human pathologies can help in understanding how these components affect the development of infectious processes. Specifically, this work evaluates the influence of glucose and ketone bodies (in a diabetic context) on the adhesion dynamics of S. aureus to the biomaterial polylactic acid, employing different approaches and discussing the results based on the physical properties of the bacterial surface and its metabolic activity. The combination of ketoacidosis and hyperglycemia (GK2) appears to be the worst scenario: this system promotes a state of continuous bacterial colonization over time, suppressing the stationary phase of adhesion and strengthening the attachment of bacteria to the surface. In addition, these supplements cause a significant increase in the metabolic activity of the bacteria. Compared to non-enriched media, biofilm formation doubles under ketoacidosis conditions, while in the planktonic state, it is glucose that triggers metabolic activity, which is practically suppressed when only ketone components are present. Both information must be complementary to understand what can happen in a real system, where planktonic bacteria are the ones that initially colonize a surface, and, subsequently, these attached bacteria end up forming a biofilm. This information highlights the need for good monitoring of diabetic patients, especially if they use an implanted device made of PLA.

Synergistic Activity of Ingulados Bacteria with Antibiotics against Multidrug-Resistant Pathogens.

Antimicrobial resistance is a critical challenge due to the overuse of conventional antimicrobials, and alternative solutions are urgently needed. This study investigates the efficacy of compounds derived from lactic acid bacteria (LAB) fermentation combined with antibiotics against multidrug-resistant pathogens isolated from clinical cases in a hospital setting. Strains of Escherichia coli, Klebsiella pneumoniae, and Enterococcus faecium and faecalis were isolated and selected from blood, respiratory, and urine samples. They were tested against the fermentation products from the Ingulados LAB collection (BAL5, BAL6, BAL8, BAL13, and BAL16), recognized for their antimicrobial efficacy against veterinary pathogens. The activity against multidrug-resistant (MDR) pathogens was evaluated initially, followed by synergy tests using checkerboard assays and subsequent analysis. Bioinformatic assessments and supernatant treatments were performed to characterize the nature of the compounds responsible for the antimicrobial activity. Notably, BAL16 exhibited significant growth inhibition against multidrug-resistant E. faecium. Synergy tests highlighted its combined activity with tetracycline through FICI and surface analysis and bioinformatic analysis unveiled the protein fraction containing bacteriocins as the underlying mechanism. This study highlights BAL16 fermentation products potential as valuable antimicrobial agents against MDR E. faecium infections, attributed to bacteriocins. Further in-depth studies are necessary for complete bacteriocin characterization.

Subclinical bowel inflammation increases healthcare resources utilization and steroid use before diagnosis of inflammatory bowel disease.

BACKGROUND: Previous data support that the inflammatory process underlying ulcerative colitis (UC) and Crohn's disease (CD) can start years before the diagnosis. The aim of this study was to determine if patients with an incidental diagnosis of UC or CD demonstrate an increase in healthcare utilization in the years preceding the symptomatic onset of the disease. METHODS: We performed a multicenter, retrospective, hospital-based, case-control study. Patients with an incidental diagnosis of UC or CD during the colorectal cancer screening program at 9 hospitals were included. Cases were matched 1:3 and compared separately with two control populations: one including healthy non-IBD subjects adjusted by gender, age, and date, excluding those with visits to Gastroenterology; and a second control cohort of UC/CD patients with symptomatic onset. RESULTS: A total of 124 patients with preclinical inflammatory bowel disease (IBD) were included (87 UC, 30 CD, 7 IBD unclassified; median age 56 years). Patients with preclinical IBD showed an increase in the number of visits to Primary Care up to 3 and 5 years before diagnosis (aIRR 1.59, 95% CI [1.37-1.86], p = 0.001; aIRR 1.43, 95% CI [1.24-1.67], p = 0.01) and more frequent use of steroids (aOR 2.84, 95% CI [1.21-6.69], p = 0.03; aOR 2.25, 95% CI [1.06-4.79], p = 0.04) compared to matched non-IBD healthy controls, respectively. In contrast, patients with a symptomatic onset visited Primary Care less frequently, but they had an increase in the number of visits to Emergency Department, specialist care, sick-leaves, CT/ultrasound examinations, and use of antibiotics or systemic steroids. CONCLUSIONS: There is an increased need for medical assistance and use of systemic steroids during the presymptomatic phase of IBD. These results will help in establishing new tools for early identification of IBD in the future.

Antibacterial and Antibiofilm Activity of Carvacrol against Oral Pathogenic Bacteria.

Faced with the current situation of high rates of microbial resistance, together with the scarcity of new antibiotics, it is necessary to search for and identify new antimicrobials, preferably natural, to alleviate this situation. The aim of this work was to evaluate the antibacterial activity of carvacrol (CAR), a phenolic compound of essential oils, against pathogenic microorganisms causing oral infections, such as Streptococcus mutans and S. sanguinis, never evaluated before. The minimum inhibitory and the minimum bactericidal concentration were 93.4 µg/mL and 373.6 µg/mL, respectively, for the two strains. The growth kinetics under different concentrations of CAR, as well as the bactericidal power were determined. The subinhibitory concentrations delayed and decreased bacterial growth. Its efficacy on mature biofilms was also tested. Finally, the possible hemolytic effect of CAR, not observable at the bactericidal concentrations under study, was evaluated. Findings obtained point to CAR as an excellent alternative agent to safely prevent periodontal diseases. In addition, it is important to highlight the use of an experimental methodology that includes dual-species biofilm and subinhibitory concentration models to determine optimal CAR treatment concentrations. Thus, CAR could be used preventively in mouthwashes or biomaterials, or in treatments to avoid existing antibiotic resistance.

In vitro Cholesterol Assimilation by Bifidobacterium animalis subsp. lactis (BPL1) Probiotic Bacteria Under Intestinal Conditions.

BACKGROUND: Hypercholesterolemia is one of the principal causes of the development of cardiovascular diseases. Recently, probiotics consumption has also been proposed as a non-pharmacological intervention to control cholesterol concentrations. OBJECTIVE: To evaluate in vitro assimilation of cholesterol by Bifidobacterium animalis subsp. lactis (BPL1) under simulated intestinal environment in anaerobic conditions and to review and discuss potential physiological mechanisms in this context. METHODS: Bacterial viability and cholesterol assimilation were evaluated in both standard MRS and Stimulated Intestinal Fluid (SIF) medium under anaerobic conditions and in the presence or absence of cholesterol. For assimilation assays, cholesterol concentrations in the different suspensions, containing the probiotic or not, were determined by chromatography coupled to mass spectrometry. RESULTS: The results showed that the growth of B. lactis BPL1 under intestinal conditions is favored when cholesterol is present in the culture medium. In addition, cholesterol assimilation of up to 44.4% under intestinal and anaerobic conditions was observed. CONCLUSION: Taking into account the revised literature and the experimental results presented herein, the administration of functional foodstuffs together with probiotic bacteria, such as B. lactis BPL1, could be a potentially effective option to decrease hypercholesterolemia, thus preventing the development of cardiovascular diseases. Nevertheless, further studies on mechanisms of effectiveness in animals and clinical trials are still needed.

Antifungal and anti-biofilm activity of a new Spanish extract of propolis against Candida glabrata.

BACKGROUND: Resistance to traditional antifungal agents is a considerable health problem nowadays, aggravated by infectious processes related to biofilm formation, usually on implantable devices. Therefore, it is necessary to identify new antimicrobial molecules, such as natural products, to develop new therapeutic strategies to prevent and eradicate these infections. One promising product is propolis, a natural resin produced by honeybees with substances from various botanical sources, beeswax and salivary enzymes. The aim of this work was to study the effect of a new Spanish ethanolic extract of propolis (SEEP) on growth, cell surface hydrophobicity, adherence and biofilm formation of Candida glabrata, a yeast capable of achieving high levels of resistance to available anti-fungal agents. METHODS: The antifungal activity of SEEP was evaluated in the planktonic cells of 12 clinical isolates of C. glabrata. The minimum inhibitory concentration (MIC) of propolis was determined by quantifying visible growth inhibition by serial plate dilutions. The minimum fungicide concentration (MFC) was evaluated as the lowest concentration of propolis that produced a 95% decrease in cfu/mL, and is presented as MFC50 and MFC90, which corresponds to the minimum concentrations at which 50 and 90% of the C. glabrata isolates were inhibited, respectively. Influence on cell surface hydrophobicity (CSH) was determined by the method of microbial adhesion to hydrocarbons (MATH). The propolis effect on adhesion and biofilm formation was determined in microtiter plates by measurement of optical density (OD) and metabolic activity (XTT-assay) in the presence of sub-MIC concentrations of SEEP. RESULTS: SEEP had antifungal capacity against C. glabrata isolates, with a MIC50 of 0.2% (v/v) and an MFC50 of 0.4%, even in azole-resistant strains. SEEP did not have a clear effect on surface hydrophobicity and adhesion, but an inhibitory effect on biofilm formation was observed at subinhibitory concentrations (0.1 and 0.05%) with a significant decrease in biofilm metabolism. CONCLUSIONS: The novel Spanish ethanolic extract of propolis shows antifungal activity against C. glabrata, and decreases biofilm formation. These results suggest its possible use in the control of fungal infections associated with biofilms.

A physico-chemical study of the interaction of ethanolic extracts of propolis with bacterial cells.

In the present study, an effort has been made to understand the interaction mode of propolis, a natural substance produced by honey bees, with gram-positive and gram-negative bacterial cells by measuring alterations in cell surface physico-chemical properties following the incubation of the cells with different sub-inhibitory concentrations of this antimicrobial agent. Electrophoretic mobility and surface hydrophobicity measurements revealed for the first time that propolis induced substantial changes in the volumetric charge density, electrophoretic softness and degree of hydrophobicity characterizing the outermost surface layer of cells. These changes, which appear to be dose-dependent, seem to be consistent with the increasing accumulation and penetration of the propolis antimicrobial components through the cells extracellular layer. Moreover, electron microscopy observation and the determination of the cell constituents' release demonstrated that propolis at sub-bactericidal concentrations already provoked (at least localized) cell wall damage and/or perturbations. These findings thus suggest that the initial mechanism of action of propolis is most likely structural, resulting from sufficient interaction between the different propolis components and bacterial cell wall structures.

Pan-enteric capsule for bleeding high-risk patients. Can we limit endoscopies?

INTRODUCTION: obscure gastrointestinal bleeding is defined as bleeding from a source that cannot be identified on upper or lower gastrointestinal endoscopy and capsule endoscopy is the next step in these patients. Some patients may be unsuitable for conventional endoscopy and performing a capsule panendoscopic test as a first line procedure might potentially reduce the number of endoscopies and their subsequent risk. AIM: to analyze our experience with capsule endoscopy in the bleeding setting. METHODS: the first 100 panendoscopic capsule procedures performed in our center from August 2011 until December 2016 were retrospectively reviewed. RESULTS: positive findings were observed in 61.2 % of patients; 46.26 % had a previous negative gastroscopy and the capsule detected small bowel lesions in 67.7 % and colonic findings in 80.64 %. Taking into consideration that our population were high-risk patients (mainly because of comorbidities) and that we used up to 45 ml of sodium phosphate, sodium, potassium and creatinine changes were analyzed before and after procedure. The mean "before" values were 140.68, 4.04 and 1.36, respectively. The mean "after" values were 140.28, 3.9 and 1.35 (p = n.s.). According to our findings, no other endoscopic studies would be needed in 64.5 % of patients with negative gastroscopy. According to capsule results, conventional endoscopy could have been avoided in 68.6 % of cases. CONCLUSION: panendoscopy with a capsule may be useful and safe in bleeding high-risk patients, by selecting those who need therapeutic endoscopy, avoiding up to 68.6 % of diagnostic endoscopies in our series.

Chemical Profile and Antibacterial Activity of a Novel Spanish Propolis with New Polyphenols also Found in Olive Oil and High Amounts of Flavonoids.

Propolis is a natural product obtained from hives. Its chemical composition varies depending on the flora of its surroundings, but nevertheless, common for all types of propolis, they all exhibit remarkable biological activities. The aim of this study was to investigate the chemical composition and antimicrobial activity of a novel Spanish Ethanolic Extract of Propolis (SEEP). It was found that this new SEEP contains high amounts of polyphenols (205 ± 34 mg GAE/g), with unusually more than half of this of the flavonoid class (127 ± 19 mg QE/g). Moreover, a detailed analysis of its chemical composition revealed the presence of olive oil compounds (Vanillic acid, 1-Acetoxypinoresinol, p-HPEA-EA and 3,4-DHPEA-EDA) never detected before in propolis samples. Additionally, relatively high amounts of ferulic acid and quercetin were distinguished, both known for their important therapeutic benefits. Regarding the antimicrobial properties of SEEP, the minimal inhibitory and bactericidal concentrations (MIC and MBC) against Staphylococcus epidermidis strains were found at the concentrations of 240 and 480 µg/mL, respectively. Importantly, subinhibitory concentrations were also found to significantly decrease bacterial growth. Therefore, the results presented here uncover a new type of propolis rich in flavonoids with promising potential uses in different areas of human health.

Early microscopic findings in preclinical inflammatory bowel disease.

BACKGROUND: The immune response involved in the pathogenesis of Inflammatory Bowel Disease (IBD) may be present years before the diagnosis, but the characteristics of the disease during the preclinical period have been scarcely investigated. AIM: To describe the microscopic findings of preclinical IBD and its relationship with the natural history of the disease. METHODS: Medical records from all patients with an incidental diagnosis of IBD during a screening colonoscopy were included in this multicentric and retrospective study. We assessed 15 histologic items in the biopsy samples at diagnosis, and the Geboes score was calculated in patients with Ulcerative Colitis (UC). The main outcome was the development of gastrointestinal symptoms during follow-up. RESULTS: We included 110 patients (79 UC, 24 Crohn's Disease (CD) and 7 with unclassified disease). In UC the most common histologic findings were acute or chronic inflammatory infiltrate and crypt epithelial polymorphs, while in CD we observed acute or chronic neutrophilic infiltrate and epithelial irregularity. Granuloma were only observed in 4% of CD patients. Crypt distortion and the infiltration of neutrophils in the epithelium were associated with a higher risk of developing symptomatic disease. CONCLUSIONS: Preclinical IBD shows specific microscopic findings and they are associated with the progression to symptomatic disease.

Relevance of Topographic Parameters on the Adhesion and Proliferation of Human Gingival Fibroblasts and Oral Bacterial Strains.

Dental implantology allows replacement of failing teeth providing the patient with a general improvement of health. Unfortunately not all reconstructions succeed, as a consequence of the development of infections of bacterial origin on the implant surface. Surface topography is known to modulate a differential response to bacterial and mammalian cells but topographical measurements are often limited to vertical parameters. In this work we have extended the topographical measurements also to lateral and hybrid parameters of the five most representative implant and prosthetic component surfaces and correlated the results with bacterial and mammalian cell adhesion and proliferation outcomes. Primary human oral gingival fibroblast (gum cells) and the bacterial strains: Streptococcus mutans, Streptococcus sanguinis and Aggregatibacter actinomycetemcomitans, implicated in infectious processes in the oral/implant environment were employed in the presence or absence of human saliva. The results confirm that even though not all the measured surface is available for bacteria to adhere, the overall race for the surface between cells and bacteria is more favourable to the smoother surfaces (nitrided, as machined or lightly acid etched) than to the rougher ones (strong acid etched or sandblasted/acid etched).

Candida tropicalis biofilm formation and expression levels of the CTRG ALS-like genes in sessile cells.

Candida tropicalis is an emergent pathogen with a high rate of mortality associated with it; however, less is known about its pathogenic capacity. Biofilm formation (BF) has important clinical repercussions, and it begins with adherence to a substrate. The adherence capacity depends principally on the cell surface hydrophobicity (CSH) and, at a later stage, on specific adherence due to adhesins. The ALS family in C. tropicalis, implicated in adhesion and BF, is represented in several CTRG genes. In this study, we determined the biofilm-forming ability, the primary adherence, and the CSH of C. tropicalis, including six isolates from blood and seven from urine cultures. We also compared the expression of four CTRG ALS-like genes (CTRG_01028, CTRG_02293, CTRG_03786, and CTRG_03797) in sessile versus planktonic cells, selected for their possible contribution to BF. All the C. tropicalis strains were biofilm producers, related to its filamentation capacity; all the strains displayed a high adherence ability correlated to the CSH, and all the strains expressed the CTRG genes in both types of growth. Urine isolates present, although not significantly, higher CSH, adherence, and biofilm formation than blood isolates. This study reveals that three CTRG ALS-like genes-except CTRG_03797-were more upregulated in biofilm cells, although with a considerable variation in expression across the strains studied and between the CTRG genes. C. tropicalis present a high biofilm capacity, and the overexpression of several CTRG ALS-like genes in the sessile cells suggests a role by the course of the biofilm formation.

Bacterial response to spatially organized microtopographic surface patterns with nanometer scale roughness.

In this study, the influence of nanometer scale roughness on bacterial adhesion and subsequent biofilm formation has been evaluated using spatially organized microtopographic surface patterns for four major opportunistic pathogens of the genus Staphylococcus (S. epidermidis and S. aureus) responsible for associated-biofilm infections on biomedical devices. The results presented demonstrated that regardless of the strain employed the initial adhesion events to these surfaces are directed by cell-surface contact points maximisation and thus, bacterial cells actively choose their position to settle based on that principle. Accordingly, bacterial cells were found to preferably adhere to the square corners and convex walls of recessed surface features rather than the flat or concave walls of equal protruding features. This finding reveals, for the first time, that the particular shape of the surfaces features employed potentially determined the initial location of the adhering cells on textured surfaces. It was further shown that all surfaces patterns investigated produce a significant reduction in bacterial adhesion (40-95%) and biofilm formation (22-58%). This important observation could not be related to physical constrains or increased solid surface hydrophobicity, as previously suggested by other authors using engineered topographies with microscale surface roughness. It is evident that other causes, such as nanoscale surface roughness-induced interaction energies, might be controlling the process of bacterial adhesion and biofilm formation on surfaces with well-defined nanoscale topography.

Balancing microbial and mammalian cell functions on calcium ion-modified implant surfaces.

Implant integration is a complex process mediated by the interaction of the implant surface with the surrounding ions, proteins, bacteria, and tissue cells. Although most implants achieve long-term bone-tissue integration, preventing pervasive implant-centered infections demands further advances, particularly in surfaces design. In this work, we analyzed classical microrough implant surfaces (only acid etched, AE; sandblasted then acid etching, SB + AE) and a new calcium-ion-modified implant surface (AE + Ca) in terms of soft- and hard-tissue integration, bacterial adhesion, and biofilm formation. We cultured on the surfaces primary oral cells from gingiva and alveolar bone, and three representative bacterial strains of the oral cavity, emulating oral conditions of natural saliva and blood plasma. With respect to gingiva and bone cells and in the presence of platelets and plasma proteins, AE + Ca surfaces yielded in average 86% higher adhesion, 44% more proliferation, and triggered 246% more synthesis of extracellular matrix biomolecules than AE-unmodified controls. Concomitantly, AE + Ca surfaces regardless of conditioning with saliva and/or blood plasma showed significantly less bacterial adhesion (67% reduction in average) and biofilm formation (40% reduction in average) than unmodified surfaces. These results highlight the importance of a calcium-rich hydrated interface to favor mammalian cell functions over microbial colonization at implant surfaces. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 421-432, 2018.

Characteristics and Progression of Preclinical Inflammatory Bowel Disease.

BACKGROUND & AIMS: Inflammatory bowel disease (IBD) is a chronic disease usually diagnosed after the appearance of gastrointestinal symptoms. Little is known about IBD progression during its early and even preclinical phases. We aimed to determine the number of new incidental diagnoses of IBD in an older population, and evaluate disease progression from its early stages. METHODS: We performed a retrospective analysis of 31,005 colonoscopies performed during colorectal cancer screening of patients with positive results from fecal immunochemical tests, at 11 centers in the Basque Country (Spain) from 2009 through 2014. We collected clinical and laboratory data from all asymptomatic individuals suspected to have IBD during screening colonoscopies, with histologic confirmation. RESULTS: Colonoscopy screening led to 79 new diagnoses of ulcerative colitis, 24 of Crohn's disease, and 7 of unclassified colitis (average patient age, 57 y; interquartile range, 52-62 y; 57% male). Eleven patients had symptoms before colonoscopy and were excluded from the analysis. Among those patients who were asymptomatic at diagnosis, 36% developed symptoms after a follow-up period of 25 months (interquartile range, 10.5-42 mo), mostly rectal bleeding and diarrhea. Treatment was prescribed for 81 patients (88%), and 2 cases required surgery. CONCLUSIONS: We analyzed data from a large cohort of patients with IBD diagnosed at early or even preclinical stages, from an older population. New incidental diagnoses of IBD were made in 0.35% of individuals undergoing a population-based screening colonoscopy-most were classified as ulcerative colitis. Approximately one third of patients developed symptoms during the follow-up period.

Direct Covalent Grafting of Phytate to Titanium Surfaces through Ti-O-P Bonding Shows Bone Stimulating Surface Properties and Decreased Bacterial Adhesion.

Myo-inositol hexaphosphate, also called phytic acid or phytate (IP6), is a natural molecule abundant in vegetable seeds and legumes. Among other functions, IP6 inhibits bone resorption. It is adsorbed on the surface of hydroxyapatite, inhibiting its dissolution and decreasing the progressive loss of bone mass. We present here a method to directly functionalize Ti surfaces covalently with IP6, without using a cross-linker molecule, through the reaction of the phosphate groups of IP6 with the TiO2 layer of Ti substrates. The grafting reaction consisted of an immersion in an IP6 solution to allow the physisorption of the molecules onto the substrate, followed by a heating step to obtain its chemisorption, in an adaptation of the T-Bag method. The reaction was highly dependent on the IP6 solution pH, only achieving a covalent Ti-O-P bond at pH 0. We evaluated two acidic pretreatments of the Ti surface, to increase its hydroxylic content, HNO3 30% and HF 0.2%. The structure of the coated surfaces was characterized by X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, and ellipsometry. The stability of the IP6 coating after three months of storage and after sterilization with γ-irradiation was also determined. Then, we evaluated the biological effect of Ti-IP6 surfaces in vitro on MC3T3-E1 osteoblastic cells, showing an osteogenic effect. Finally, the effect of the surfaces on the adhesion and biofilm viability of oral microorganisms S. mutans and S. sanguinis was also studied, and we found that Ti-IP6 surfaces decreased the adhesion of S. sanguinis. A surface that actively improves osseointegration while decreasing the bacterial adhesion could be suitable for use in bone implants.

Quercitrin-nanocoated titanium surfaces favour gingival cells against oral bacteria.

Many dental implants fail due to the infection and inflammation that walk hand in hand with poor healing and soft tissue integration. Titanium surfaces were nanocoated with quercitrin, a natural flavonoid, with the aim to improve soft tissue integration and increase dental implants success. Streptococcus mutans attachment and biofilm formation was analysed. Then, the anti-inflammatory properties and the potential of quercitrin-nanocoated surfaces to boost soft tissue regeneration were tested using human gingival fibroblasts. An inflammatory situation was mimicked using interleulin-1-beta. We found that quercitrin-nanocoated surfaces decreased initial bacterial adhesion while increasing human gingival fibroblasts attachment. Furthermore, quercitrin-nanocoated Ti increased collagen mRNA levels and decreased matrix metalloproteinase-1/tissue inhibitor of metalloproteinanse-1 mRNA ratio, which is related to a reduced metalloproteinase-mediated collagen degradation, while also decreasing the pro-inflammatory prostaglandin E2 release under basal and inflammatory conditions. These results suggest that quercitrin-nanocoated surfaces could enhance the soft tissue integration and increase dental implants success.

Surface Topographical Changes of a Failing Acid-Etched Long-Term in Function Retrieved Dental Implant.

The aim of the present study was to report the main topographical and chemical changes of a failing 18-year in function retrieved acid-etching implant in the micro- and nanoscales. A partially edentulous 45 year old rehabilitated with a dental implant at 18 years of age exhibited mobility. After careful examination, a 3.25 × 13-mm press-fit dental implant was retrieved. Scanning electron microscope (SEM) analysis was carried out to study topographical changes of the retrieved implant compared with an unused implant with similar topographical characteristics. Moreover, X-ray photoelectron spectroscopy (XPS) analysis was used to study the surface composition of the retrieved failing implant. Clear changes related to the dual dioxide layer are present as visible in ≥×500 magnification. In addition, it was found that, for the retrieved implant, the surface composition consisted mainly of Ti2p, O1s, C1s, and Al2p. Also, a meaningful decrease of N and C was noticed, whereas the peaks of Ti2p, Al2p, and O1s increased when analyzing deeper (up to ×2000s) in the sample. It was shown that the superficial surface of a retrieved press-fit dual acid-etched implant 18 years after placement is impaired. However, the causes and consequences for these changes cannot be determined.

Covalent immobilization of hLf1-11 peptide on a titanium surface reduces bacterial adhesion and biofilm formation.

Bacterial infection represents a major cause of implant failure in dentistry. A common approach to overcoming this issue and treating peri-implant infection consists in the use of antibiotics. However, the rise of multidrug-resistant bacteria poses serious concerns to this strategy. A promising alternative is the use of antimicrobial peptides due to their broad-spectrum activity against bacteria and reduced bacterial resistance responses. The aim of the present study was to determine the in vitro antibacterial activity of the human lactoferrin-derived peptide hLf1-11 anchored to titanium surfaces. To this end, titanium samples were functionalized with the hLf1-11 peptide either by silanization methods or physical adsorption. X-ray photoelectron spectroscopy analyses confirmed the successful covalent attachment of the hLf1-11 peptide onto titanium surfaces. Lactate dehydrogenase assay determined that hLf1-11 peptide did not affect fibroblast viability. An outstanding reduction in the adhesion and early stages of biofilm formation of Streptococcus sanguinis and Lactobacillus salivarius was observed on the biofunctionalized surfaces compared to control non-treated samples. Furthermore, samples coated with the hLf1-11 peptide inhibited the early stages of bacterial growth. Thus, this strategy holds great potential to develop antimicrobial biomaterials for dental applications.