Microbiology of wound infection after oral cancer surgery

Porphyromonas gingivalis-OMVs promote the epithelial-mesenchymal transition of oral squamous cell carcinoma by inhibiting ferroptosis through the NF-κB pathway

Background

Recent studies reported the role of Porphyromonas gingivalis (P. g) in promoting oral squamous cell carcinoma (OSCC) progression. However, the molecular mechanism remains unclear.

Materials and methods

P. g-OMVs were isolated using ultracentrifugation method and characterized by transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA). CCK-8, migration, invasion, Quantitative real-time Polymerase Chain Reaction (qRT-PCR) and immunocytochemistry assays were performed to evaluate the effect of P. g-OMVs on tumor cells' proliferation, migration, invasion, epithelial-mesenchymal transition (EMT), and ferroptosis in vitro. Western blot was performed to study the phosphorylation of transcription factor nuclear factor kappa B (NF-κB). In vivo, the effect of P. g-OMVs on the growth of OSCC was evaluated using a xenograft tumor model, followed by hematoxylin and eosin and immunohistochemistry staining.

Results

TEM and NTA demonstrated that P. g-OMVs have a vesicular structure with a particle size of around 118 nm. Compared to the control group, P. g-OMVs significantly enhance the proliferation, migration, and invasion of tumor cells. In addition, P. g-OMVs promote the EMT of OSCC cells, which can be attenuated by ferroptosis activator erastin. Moreover, P. g-OMVs inhibit feroptosis of OSCC by activating NF-κB signaling. In vivo, P. g-OMVs significantly enhance tumor growth of OSCC. Inhibition of NF-κB could significnatly reduce the growth of OSCC, which can be further rescued using ferroptosis inhibitor Ferrostain-1.

Conclusions

P. g-OMVs promote OSCC progression by modulating the ferroptosis-related EMT through NF-κB signaling.

Cydonia oblonga extract mediated biosynthesis of gold nanoparticles: Analysis of its anti-oral cancer and antioxidant properties

Here, using natural and biological macromolecules derived from Cydonia oblonga extract, we have developed a green protocol for the biogenic made Au NPs. Under ultrasonic activated conditions, the Cydonia oblonga phytomolecules were employed as an efficient green reducing agent for the Au3+ ions to the Au0 NPs. Additionally, by encapsulating or capping, they allowed the Au NPs to stabilize on their own. Several physicochemical techniques, such as elemental mapping, TEM, FE-SEM, UV-Vis spectroscopy, EDS, and ICP-OES, were used to analyze the structure of the Au NPs/Cydonia oblonga bio-nanocomposite. The field of medicinal therapeutics pertaining to human health includes cancer treatment as a major component. Subsequently, the as prepared Au NPs/Cydonia oblonga bio-nanocomposite was investigated for antioxidant and human anti-oral cancer assays. In such studies a number of cell lines, viz., HSC-3, HSC-2, and Ca9-22 were used in determining the cytotoxicity. Notably, Au NPs/Cydonia oblonga exhibit significant anti-oral cancer properties against HSC-3, HSC-2, and Ca9-22 cancer cell lines following time and dose-dependent manner. The corresponding IC50 values were determined as 201, 192, and 246 µg/mL respectively. DPPH radical scavenging method was used to determine the antioxidant activity of Au NPs/Cydonia oblonga bio-nanocomposite. The significant IC50 value suggested the material having very good antioxidant potential. The anti-human oral cancer effect of our material is believed to be due to its antioxidant effects.

Establishing a role for the oral microbiome in infectious complications following major oral cavity cancer surgery

Surgery forms the backbone of treatment for most locoregional or advanced oral cavity squamous cell carcinoma. Unfortunately, infectious complications (including orocutaneous fistulas) are common following such extensive surgery and can afflict over half of patients. These complications can lead to delays in adjuvant treatment, prolonged hospitalization, reconstructive failure, and decreased quality of life. The frequency and morbidity associated with infectious complications has led to the search for pre-disposing risk factors; and, several have been identified, including both patient (e.g. diabetes) and surgical (e.g. operative time) factors. However, these findings are inconsistently reproduced, and risk factor modification has had a limited impact on rates of infectious complications. This is striking given that the likely contaminant-the oral microbiome-is a well-studied microbial reservoir. Because many oral cavity cancer surgeries involve violation of oral mucosa and the spillage of the oral microbiome into normally sterile areas (e.g. the neck), variance in oral microbiome composition and function could underly differences in infectious complications. The goal of this perspective is to highlight 1) this knowledge gap and 2) opportunities for studies in this domain. The implication of this line of thought is that the identification of oral microbial dysbiosis in patients undergoing surgery for oral cavity cancer could lead to targeted pre-operative therapeutic interventions, decreased infectious complications, and improved patient outcomes.

Molecular Genetic Analysis of Perioperative Colonization by Infection-Related Microorganisms in Patients Receiving Intraoral Microvascular Grafts

Background/Objectives: In oral and maxillofacial surgery, the reconstruction of defects often involves the transfer of skin tissue into the oral cavity utilizing microvascular grafts. This study investigates postoperative changes in microbial colonization following intraoral microvascular transplantation, as well as potential influencing factors. Methods: In 37 patients undergoing intraoral reconstructions, pre- and postoperative swabs were taken from the donor and recipient regions to quantify the seven selected marker bacteria using TaqMan PCRs. Patient-specific factors and clinical data were also recorded. Results: The infection-associated Acinetobacter baumannii tended to decrease postoperatively, while the infectious pathogens Pseudomonas aeruginosa, Enterococcus faecalis and the family of Enterobacteriaceae showed a postoperative increase without being directly associated with a clinical infection. Streptococcus mitis showed a significant postoperative decrease on buccal mucosa and increase on the graft surface (oral dysbiosis) and was significantly reduced or displaced by other bacteria (e.g., Mycoplasma salivarium, positive selection) when treated with ampicillin/sulbactam. Conclusions: The cutaneous microbiome of the graft adapts to the local intraoral environment. Postoperative shifts in oral bacterial colonization and an increase in infection-relevant bacteria were observed. These perioperative changes in colonization are also influenced by the administration of ampicillin/sulbactam. Consequently, single doses of antibiotics appear to be more beneficial compared to longer-term preventive use.

Variations in oral microbiome and its predictive functions between tumorous and healthy individuals

Introduction. The oral cavity is one of the largest reservoirs of microorganisms and many pathogenic bacteria have been shown to be associated with the aetiology of oral cancers.Gap Statement. Owing to the complexity of oral microbial communities and their unclear relationship with oral cancer, identification of specific bacteria which contribute to oral cancer is a key imperative.Aim. To compare and investigate the variations in the composition of the bacterial microbiome and its functions between patients with oral tumorous lesions and healthy subjects.Methodology. Twenty-seven samples from individuals with oral tumours (five oral benign tumours and 22 oral squamous cell carcinomas) and 15 samples from healthy subjects were collected. Genomic DNA was extracted and the V3-V5 region of the 16S rRNA gene was sequenced. Subsequently, bioinformatic assessment was conducted using QIIME2, PICRUSt and linear discriminant analysis effect size analyses (LEfSe).Results. The oral microbiota was composed mainly of the phyla Proteobacteria (31.76 %, 35.00 %), Bacteroidetes (30.13 %, 25.13 %) and Firmicutes (23.92 %, 17.07 %) in tumorous and healthy individuals, respectively. Neisseria, Prevotella, Fusobacterium, Streptococcus, Capnocytophaga, Veillonella, Haemophilus, Prevotella, Porphyromonas and Leptotrichia were the most abundant genera. Alpha diversity in the tumour group was significantly greater than that in the healthy group (P<0.05). Differential analysis of microbes between groups demonstrated a significantly higher number of Neisseria, Veillonella, Streptococcus, Leptotrichia, Lautropia, Sphingopyxis, Sphingobium, Tannerella, Actinomyces and Rothia in healthy controls compared with the tumour group. However, the genera Treponema, Micrococcus, Pseudomonas, Janthinobacterium, Parvimos, Loktanella, Staphylococcus, Acinetobacter, Catonella, Aggregatibacter and Propionibacterium were significantly higher in the tumour group. Pathways related to cancers, cell motility, environmental adaptation, metabolism and signal transduction were enhanced in the tumour group, while functions associated with immune system diseases, replication, repair and translation were significantly enhanced in the healthy group.Conclusion. Variations in the oral microbiota and its functions showed a correlation with oral tumours. The tumour group showed an increased abundance of some multi-drug-resistant and periodontitis-related pathogens. The significantly altered microbiotas may serve as potential biomarkers or inform combination therapy for oral tumours.

The function of small RNA in Pseudomonas aeruginosa

Pseudomonas aeruginosa, the main conditional pathogen causing nosocomial infection, is a gram-negative bacterium with the largest genome among the known bacteria. The main reasons why Pseudomonas aeruginosa is prone to drug-resistant strains in clinic are: the drug-resistant genes in its genome and the drug resistance easily induced by single antibiotic treatment. With the development of high-throughput sequencing technology and bioinformatics, the functions of various small RNAs (sRNA) in Pseudomonas aeruginosa are being revealed. Different sRNAs regulate gene expression by binding to protein or mRNA to play an important role in the complex regulatory network. In this article, first, the importance and biological functions of different sRNAs in Pseudomonas aeruginosa are explored, and then the evidence and possibilities that sRNAs served as drug therapeutic targets are discussed, which may introduce new directions to develop novel disease treatment strategies.

Gold nanomaterials for oral cancer diagnosis and therapy: Advances, challenges, and prospects

Early diagnosis and treatment of oral cancer are vital for patient survival. Since the oral cavity accommodates the second largest and most diverse microbiome community after the gut, the diagnostic and therapeutic approaches with low invasiveness and minimal damage to surrounding tissues are keys to preventing clinical intervention-related infections. Gold nanoparticles (AuNPs) are widely used in the research of cancer diagnosis and therapy due to their excellent properties such as surface-enhanced Raman spectroscopy, surface plasma resonance, controlled synthesis, the plasticity of surface morphology, biological safety, and stability. AuNPs had been used in oral cancer detection reagents, tumor-targeted therapy, photothermal therapy, photodynamic therapy, and other combination therapies for oral cancer. AuNPs-based noninvasive diagnosis and precise treatments further reduce the clinical intervention-related infections. This review is focused on the recent advances in research and application of AuNPs for early screening, diagnostic typing, drug delivery, photothermal therapy, radiotherapy sensitivity treatment, and combination therapy of oral cancer. Distinctive reports from the literature are summarized to highlight the latest advances in the development and application of AuNPs in oral cancer diagnosis and therapy. Finally, this review points out the challenges and prospects of possible applications of AuNPs in oral cancer diagnosis and therapy.

Surgical and remote site infections after reconstructive surgery of the head and neck: A risk factor analysis

The aim of this study was to identify risk factors for surgical (SSI) and remote site (RSI) infections, pathogens and antibiotic resistances in patients after pedicled and free flap reconstruction in the head and neck area. SSI criteria implicated infections affecting superficial or deep tissue in the flap area with purulent discharge, fistula, abscess formation and local infections signs. RSI criteria were defined as infections remote from the surgical site presenting with systemic symptoms like fever, leucocytosis, increase in C-reactive protein, purulent tracheobronchial secretion or deterioration of blood gases. Focus adequate specimen sampling and aerobic and anaerobic incubation and cultivation was performed. Epidemiological data, factors directly related to surgery or reconstruction, perioperative antibiotic regimen, length of stay, autologous blood transfusion and microbiological aspects were retrospectively analysed in 157 patients. 10.8% of patients presented SSI, 12.7% RSI. Cultivated bacteria were sampled from flap sites, blood cultures, central catheters and sputum including mainly gram-negative bacteria (70.3%) being frequently resistant against penicillin (85%) and third generation cephalosporine derivates (48%). Autologous blood transfusion (p = 0.018) and perioperative clindamycin use (p = 0.002) were independent risk factors for overall (SSI and RSI combined) infections. Prior radiation (p = 0.05), autologous blood transfusion (p = 0.034) and perioperative clindamycin use (p = 0.004) were predictors for SSIs. ASA >2 (p = 0.05) was a risk factor for remote site infections and prolonged ICU stay (p = 0.002) was associated with overall infections, especially in irradiated patients. Efforts need to be made in improving patient blood management, antibiotic stewardship and accurate postoperative care to avoid postoperative infections after head and neck reconstructive surgery.