Background: Temporary implant-retained restorations are required to support function and esthetics of the masticatory system until the final restoration is completed and delivered. Acrylic resins are commonly used in prosthetic dentistry and lately they have been used in three-dimensional (3D) printing technology. Since this technology it is fairly new, the number of studies on their susceptibility to microbial adhesion is low. Restorations placed even for a short period of time may become the reservoir for microorganisms that may affect the peri-implant tissues and trigger inflammation endangering further procedures. The aim of the study was to test the biofilm formation on acrylamide resins used to fabricate temporary restorations in 3D printing technology and to assess if the post-processing impacts microbial adhesion. Methods: Disk-shaped samples were manufactured using the 3D printing technique from three commercially available UV-curable resins consisting of acrylate and methacrylate oligomers with various time and inhibitors of polymerization (NextDent MFH bleach, NextDent 3D Plus, MazicD Temp). The tested samples were raw, polished and glazed. The ability to create biofilm by oral streptococci (S. mutans, S. sanguinis, S. oralis, S. mitis) was tested, as well as species with higher pathogenic potential: Staphylococcus aureus, Staphylococcus epidermidis and Candida albicans. The roughness of the materials was measured by an atomic force microscope. Biofilm formation was assessed after 72 h of incubation by crystal violet staining with absorbance measurement, quantification of viable microorganisms, and imaging with a scanning electron microscope (SEM). Results: Each tested species formed the biofilm on the samples of all three resins. Post-production processing resulted in reduced roughness parameters and biofilm abundance. Polishing and glazing reduced roughness parameters significantly in the NextDent resin group, while glazing alone caused significant surface smoothing in Mazic Temp. A thin layer of microbial biofilm covered glazed resin surfaces with a small number of microorganisms for all tested strains except S. oralis and S. epidermidis, while raw and polished surfaces were covered with a dense biofilm, rich in microorganisms. Conclusions: UV-curing acrylic resins used for fabricating temporary restorations in the 3D technology are the interim solution, but are susceptible to adhesion and biofilm formation by oral streptococci, staphylococci and Candida. Post-processing and particularly glazing process significantly reduce bacterial biofilm formation and the risk of failure of final restoration.

Cattle is a reservoir of potentially pathogenic E. coli, bacteria that can represent a significant threat to public health, hence it is crucial to monitor the prevalence of the genetic determinants of virulence and antimicrobial resistance among the E. coli population. The aim of this study was the analysis of the phylogenetic structure, distribution of virulence factors (VFs) and prevalence of antimicrobial resistance among E. coli isolated from two groups of healthy cattle: 50 cows housed in the conventional barn (147 isolates) and 42 cows living on the ecological pasture (118 isolates). The phylogenetic analysis, identification of VFs and antimicrobial resistance genes were based on either multiplex or simplex PCR. The antimicrobial susceptibilities of E. coli were examined using the broth microdilution method. Two statistical approaches were used to analyse the results obtained for two groups of cattle. The relations between the dependent (VFs profiles, antibiotics) and the independent variables were described using the two models. The mixed logit model was used to characterise the prevalence of the analysed factors in the sets of isolates. The univariate logistic regression model was used to characterise the prevalence of these factors in particular animals. Given each model, the odds ratio (OR) and the 95% confidence interval for the population were estimated. The phylogroup B1 was predominant among isolates from beef cattle, while the phylogroups A, B1 and D occurred with equal frequency among isolates from dairy cattle. The frequency of VFs-positive isolates was significantly higher among isolates from beef cattle. E. coli from dairy cattle revealed significantly higher resistance to antibiotics. Some of the tested resistance genes were present among isolates from dairy cattle. Our study showed that the habitat and diet may affect the genetic diversity of commensal E. coli in the cattle. The results suggest that the ecological pasture habitat is related to the increased spreading rate of the VFs, while the barn habitat is characterised by the higher levels of antimicrobial resistance among E. coli.

Commensal Escherichia coli, naturally occurring in the intestinal tract, can be the origin of extraintestinal pathogenic E. coli (ExPEC) strains. ExPEC causes high mortality and significant economic losses in the swine industry in several countries and poses a serious threat to public health worldwide. The aim of this study was to analyze the extended phylogenetic structure and extraintestinal virulence potential in two groups of commensal E. coli isolates from post-weaning piglets and sows. The phylogenetic assignment to eight groups was determined using the revised Clermont phylogenetic typing method in quadruplex PCR. Identification of extraintestinal virulence genes (VGs) and adhesin operon genes was performed using multiplex or simplex PCR. The revised phylogenetic assignment allowed us to distinguish E. coli with significantly higher (groups C and F) or lower (group E) virulence potential in isolates from piglets. The majority of the tested VGs occurred more frequently in isolates from piglets than from sows, with statistically significant differences for seven genes: fimH, papAH, iutA, iroN, ompT, traT, and iss. Complete operons for type I and P fimbriae significantly prevailed among E. coli from piglets. This study provides insight into the extended phylogenetic structure of porcine commensal E. coli and showed that these strains, particularly from piglets, constitute a considerable reservoir of extraintestinal VGs and may increase the potential risk of extraintestinal infections.

The prevalence of trimethoprim (TMP) and sulfamethoxazole (SMX) resistance in commensal E. coli from pigs was tested in this study. E. coli was derived from three groups of piglets in successive stages of metaphylactic therapy and from two groups of sows 10 and 18 weeks after the treatment. MIC values of TMP and SMX were determined for a total of 352 strains. The presence of resistance genes (dfrA1, dfrA5, dfrA7, dfrA12, dfrA17, sul1, sul2, sul3) and class 1 and 2 integron-associated dfrA gene cassettes was tested. Resistance to TMP was very high during the administration of the antimicrobial (from 97 to 100%) and amounted to 86% and 69% in the post-exposure period; MIC > 32 mg/L. The isolates from all groups of pigs were resistant to sulfamethoxazole, with MIC > 1028 mg/L. The dfrA1 and sul1 genes (as part of integrons) dominated in E. coli from piglets, but the dfrA12 and sul1 genes were prevalent in E. coli from sows. Coexistence of the different dfrA genes was detected in 71 isolates from all groups of swine. Transcription analysis revealed that most of these genes were not transcribed, particularly gene cassettes of class 1 integrons. The research revealed a high level of resistance associated with the metaphylactic treatment, persistence and circulation of resistance in bacterial populations. Diverse genetic background with multiple and not transcribed resistance genes was observed.

Background: In the oral and maxillofacial surgery, fixation plates are commonly used for the stabilization of bone fragments. Additive manufacturing has enabled us to design and create personalized fixation devices that would ideally fit any given fracture. Aim: The aim of the present preliminary study was to assess the susceptibility of 3D-printed titanium fixation plates to biofilm formation. Methods: Plates were manufactured using selective laser melting (SLM) from Ti-6Al-4 V. Reference strains of Streptococcus mutans, Staphyloccocus epidermidis, Staphylococcus aureus, Lactobacillus rhamnosus, and Candida albicans, were tested to evaluate the material’s susceptibility to biofilm formation over 48 hours. Biofilm formations were quantified by a colorimetric method and colony-forming units (CFU) quantification. Scanning electron microscopy (SEM) visualized the structure of the biofilm. Results: Surface analysis revealed the average roughness of 102.75 nm and irregular topography of the tested plates. They were susceptible to biofilm formation by all tested strains. The average CFUs were as follows: S. mutans (11.91 x 10⁷) > S.epidermidis (4.45 x 10⁷) > S. aureus (2.3 x 10⁷) > C.albicans (1.22 x 10⁷) > L. rhamnosus (0.78 x 10⁷). Conclusions: The present preliminary study showed that rough surfaces of additively manufactured titanium plates are susceptible to microbial adhesion. The research should be continued in order to compare additively manufactured plates with other commercially available osteotomy plates. Therefore, we suggest caution when using this type of material.