Development of an in vitro model of peri-implantitis

Introduction Peri-implantitis is a bacterially induced inflammatory reaction surrounding dental implants leading to loss of supporting bone. Microbial biofilm development seems to play an important role in altering the biocompatibility of the implant surface leading to loss of the implant. Aims The aim of this study was to develop an in vitro model of peri-implantitis. Material and Methods Microcosm biofilms were grown on titanium discs in a constant depth film fermentor (CDFF). Artificial saliva and peri-implant sulcular fluid (PISF) were delivered to simulate three communities associated with dental implants (health, peri-implant mucositis and peri-implantitis). The intact biofilms were visualised by confocal laser scanning microscope (CLSM) at different time points. Biofilms were cultured on non-selective and selective media. PCR-cloning and comparative sequencing of the 16S rRNA gene was carried out to determine bacterial richness. To quantify bacterial species, multiplex qPCR was used for a range of important oral species; qPCR probes were designed, tested and used to quantify Capnocytophaga in the communities. Evaluation of current and novel treatment modalities, to eliminate the microcosm biofilm, on commercial titanium surfaces (polished, SLA and SLActive surfaces) was carried out. Furthermore, novel antimicrobial surfaces were prepared and initial biofilm formation assessed by cultural analysis and CLSM. Results The biofilms shifted from coccid dense communities, to those dominated by rods and long filaments. The clones shifted from healthy to mixed pathogens. The qPCR revealed significant differences between a healthy and disease conditions. The combined treatment (mechanical and chemical) revealed the greatest reduction of biofilm on all surfaces tested. The antibacterial surfaces showed promotion towards a healthy community on old mature biofilm. Discussion/Conclusion The CDFF allowed successful growth of microbial communities and the ability to monitor the bacterial shifts between three communities associated with dental implants. In addition, it has allowed the testing of a range of titanium surfaces and treatment modalities. This model will allow further understanding of the microbiology of peri-implantitis and provide appropriate biofilm communities for testing surfaces infection and treatments

Preoperative nasopharyngeal swab testing and postoperative pulmonary complications in patients undergoing elective surgery during the SARS-CoV-2 pandemic.

BACKGROUND: Surgical services are preparing to scale up in areas affected by COVID-19. This study aimed to evaluate the association between preoperative SARS-CoV-2 testing and postoperative pulmonary complications in patients undergoing elective cancer surgery. METHODS: This international cohort study included adult patients undergoing elective surgery for cancer in areas affected by SARS-CoV-2 up to 19 April 2020. Patients suspected of SARS-CoV-2 infection before operation were excluded. The primary outcome measure was postoperative pulmonary complications at 30 days after surgery. Preoperative testing strategies were adjusted for confounding using mixed-effects models. RESULTS: Of 8784 patients (432 hospitals, 53 countries), 2303 patients (26.2 per cent) underwent preoperative testing: 1458 (16.6 per cent) had a swab test, 521 (5.9 per cent) CT only, and 324 (3.7 per cent) swab and CT. Pulmonary complications occurred in 3.9 per cent, whereas SARS-CoV-2 infection was confirmed in 2.6 per cent. After risk adjustment, having at least one negative preoperative nasopharyngeal swab test (adjusted odds ratio 0.68, 95 per cent confidence interval 0.68 to 0.98; P = 0.040) was associated with a lower rate of pulmonary complications. Swab testing was beneficial before major surgery and in areas with a high 14-day SARS-CoV-2 case notification rate, but not before minor surgery or in low-risk areas. To prevent one pulmonary complication, the number needed to swab test before major or minor surgery was 18 and 48 respectively in high-risk areas, and 73 and 387 in low-risk areas. CONCLUSION: Preoperative nasopharyngeal swab testing was beneficial before major surgery and in high SARS-CoV-2 risk areas. There was no proven benefit of swab testing before minor surgery in low-risk areas