Influence of Oral Anaerobic Bacteria on Hematopoietic Stem Cell Transplantation Patients: Oral Mucositis and General Condition

Safety, Feasibility, and Advantages of Oral Microbiota Transplantation: The First Clinical Case

The pilot clinical study presented demonstrates the possibility, safety, and effectiveness of oral microbiota transplantation from a healthy donor to a patient with neuroblastoma to prevent chemotherapy-induced oral mucositis. A 6-month-old patient with a diagnosis of retroperitoneal neuroblastoma was treated according to the NB 2004 protocol. Due to the development of severe oral mucositis, it was decided to perform oral microbiota transplantation. During the next 3 chemotherapy cycles and conditioning regimen before autologous hematopoietic cell transplantation (auto-HCT), the patient was repeatedly injected per os with donor saliva from her healthy mother. Oral microbiota transplantation was shown to effectively prevent the development of oral mucositis after chemotherapy, and only grade 1 oral mucositis developed after auto-HCT. In all loci of the oral cavity, there was a decreased abundance of bacteria from the Staphylococcaceae, Micrococcaceae, and Xanthomonadaceae families. Conversely, there was an increase in the relative abundance of Streptococcaceae and certain other bacterial taxa. In conclusion, the transplantation of maternal saliva in this patient prevented severe mucositis and was accompanied by a compositional change of the patient's oral microbiota. No adverse events due to the transplantation of maternal saliva were noted.

Effective Oral Indicators With Medical and Dental Collaboration in Open Heart Surgery: A Representative Survey

Purpose Postoperative infections pose an important problem for patients with cardiac disease. Moreover, oral health status is associated with the risk of longer hospital stays. Therefore, the oral health status of patients was assessed before open-heart surgery. This study aimed to determine the relationship between oral health status and postoperative status. Methods The study included 25 patients who underwent open-heart surgery at our university hospital in 2020. Upon admission, dentists conducted an oral examination and assessed the oral health status of the patients, also using the Japanese version of the Oral Health Assessment Tool (OHAT-J), Revised Oral Assessment Guide (ROAG), oral moisture level, oral bacteria, and other relevant factors. The study investigated the association with postoperative status. Findings Significant postoperative infections were found in patients aged ≥70 years, with an OHAT-J score of ≥5, OHAT-J lip score of ≥1, Streptococcus γ count of 1.0 × 10^6 or higher (CFU/mL), and increased Streptococcus γ before and after surgery. The duration of hospitalization correlated with the OHAT-J, OHAT-J gum and tissue, and ROAG scores. The duration of intensive care unit (ICU) stays correlated with the OHAT-J score. Conclusions The study demonstrates that OHAT-J scores are linked with predicting not just postoperative infection but also the length of hospitalization and ICU stay. As OHAT-J scores do not necessitate specialized dental instruments, they are straightforward and beneficial for healthcare professionals outside of dentistry.

Oral microbiome characterization in oral mucositis patients-A systematic review

BACKGROUND

Oral mucositis (OM) is a severe and common adverse effect of cancer treatment. The oral microbiome appears to play a role on the onset and severity of OM. Therefore, this systematic review aims to characterize the oral dysbiosis associated with OM.

METHODS

The PRISMA checklist was followed and PubMed, Web of Science, and Scopus were screened for clinical studies characterizing the oral microbiome alterations in patients with OM.

RESULTS

From a total of 2500 articles retrieved, we included nine articles in this systematic review. Certain types of bacteria, as Fusobacterium, were recognized as predictors of the onset of OM. In addition, it was reported that patients with severe OM presented a reduction in alpha-diversity, an increase in beta-diversity. The abundance of some taxa significantly changed with OM severity, with Bacillota phylum and genera Leptotrichia, Actinomyces, and Prevotella decreasing and Treponema increasing with disease progression. Additionally, during cancer treatment, changes in the oral microbiome have been observed in OM patients, with an increase in Candida and nosocomial pathogens, including Staphylococcus species.

CONCLUSION

Our review indicates that cancer treatment can significantly alter the oral microbiome, with more pronounced changes observed in patients with severe OM in all relevant oral phyla, but more pronounced in Bacillota phylum.

Application of hypoxia-mesenchymal stem cells in treatment of anaerobic bacterial wound infection: wound healing and infection recovery

Mesenchymal stromal cells, commonly referred to as MSCs, are a type of multipotent stem cells that are typically extracted from adipose tissue and bone marrow. In the field of tissue engineering and regenerative medicine, MSCs and their exosomes have emerged as revolutionary tools. Researchers are now devoting greater attention to MSCs because of their ability to generate skin cells like fibroblasts and keratinocytes, as well as their distinctive potential to decrease inflammation and emit pro-angiogenic molecules at the site of wounds. More recent investigations revealed that MSCs can exert numerous direct and indirect antimicrobial effects that are immunologically mediated. Collectively, these antimicrobial properties can remove bacterial infections when the MSCs are delivered in a therapeutic setting. Regardless of the positive therapeutic potential of MSCs for a multitude of conditions, transplanted MSC cell retention continues to be a major challenge. Since MSCs are typically administered into naturally hypoxic tissues, understanding the impact of hypoxia on the functioning of MSCs is crucial. Hypoxia has been postulated to be among the factors determining the differentiation of MSCs, resulting in the production of inflammatory cytokines throughout the process of tissue regeneration and wound repair. This has opened new horizons in developing MSC-based systems as a potent therapeutic tool in oxygen-deprived regions, including anaerobic wound infection sites. This review sheds light on the role of hypoxia-MSCs in the treatment of anaerobic bacterial wound infection in terms of both their regenerative and antimicrobial activities.

Dental consensus on HSCT - Part II: dental Care during HSCT

During the state of immune vulnerability in hematopoietic stem cell transplantation (HSCT), the patient has an increased risk of developing a vast number of complications, including severe problems in the oral cavity. These situations require professional oral care to act in the diagnosis and treatment of these conditions, as well as to develop prevention protocols to minimize patient's complications. Oral mucositis, opportunistic infections, bleeding, specific microbiota, taste, and salivary alterations are complications that can occur during HSCT and interfere with various aspects, such as pain control, oral intake, nutrition, bacteremia and sepsis, days of hospitalization and morbidity. Several guidelines have been published to address the role of professional oral care during the HSCT, we describe a consensus regarding these recommendations.

Oral microbiota dysbiosis accelerates the development and onset of mucositis and oral ulcers

With the rapid development of metagenomic high-throughput sequencing technology, more and more oral mucosal diseases have been proven to be associated with oral microbiota shifts or dysbiosis. The commensal oral microbiota can greatly influence the colonization and resistance of pathogenic microorganisms and induce primary immunity. Once dysbiosis occurs, it can lead to damage to oral mucosal epithelial defense, thus accelerating the pathological process. As common oral mucosal diseases, oral mucositis and ulcers seriously affect patients' prognosis and quality of life. However, from the microbiota perspective, the etiologies, specific alterations of oral flora, pathogenic changes, and therapy for microbiota are still lacking in a comprehensive overview. This review makes a retrospective summary of the above problems, dialectically based on oral microecology, to provide a new perspective on oral mucosal lesions management and aims at improving patients' quality of life.

Mucosal microbiotas and their role in stem cell transplantation

Mucosal microbiotas and their role in stem cell transplantation. Patients with hematological disorders such as leukemia often undergo allogeneic hematopoietic stem cell transplantation, and thereby receive stem cells from a donor for curation of disease. This procedure also involves immunosuppressive and antimicrobial treatments that disturb the important interactions between the microbiota and the immune system, especially at mucosal sites. After transplantation, bacterial diversity decreases together with a depletion of Clostridia, and shifts toward predominance of Proteobacteria. Infectious and inflammatory complications, such as graft-versus-host disease, also interfere with patient recovery. This review collects and contextualizes current knowledge of the role of mucosal microbiotas at different body sites in stem cell transplantation, proposes underlying mechanisms, and discusses potential clinical value of bacterial markers for improved treatment strategies.

Pitfalls and Challenges in Oral Plasma Cell Mucositis: A Systematic Review

Plasma cell mucositis (PCM) is an unusual idiopathic disorder characterized by dense infiltrates of plasma cells in submucosa. Clinical phenotypes of oral plasma cell mucositis (o-PMC) are heterogenous. A systematic review has been conducted, aiming to synthesize the available evidence on o-PCM. Literature search, study design, and data analysis were performed following PRISMA guidelines. The SPIDER and the PICO tools were used to structure the research question. In all, 79 case reports and 19 case series on a total of 158 patients (85 females and 73 males; average age: 44.1 years) were identified. Among oral sites involved, gingiva (65.82%) was the most frequent site. The main clinical phenotype was erythema (99.37%). In relation to symptoms, pain (60.76%) was the most reported. On histological examination, all samples showed a dense inflammatory infiltration with predominant plasma cells. The treatment regimens of o-PCM were summarized in six groups: irritant removal; topical/systemic corticosteroids; topical/systemic immunosuppressants/immunomodulators; surgery and similar treatments; radiotherapy and chemotherapy; other therapies, such as antifungals, antibiotics, and antivirals drugs. This is the first systematic review aimed to synthesize the findings of studies on o-PCM. The lack of universally shared information on etiological factors and the absence of international consensus of pharmacological protocols make o-PCM a diagnostic and therapeutic challenge.

Oral-Gut Microbiome Axis in the Pathogenesis of Cancer Treatment-Induced Oral Mucositis

Oral mucositis (OM) is one of the most common and debilitating oral complications of cancer treatments including chemotherapy, radiotherapy, and hematopoietic stem cell transplantation. It is associated with severe pain and difficulties in chewing, swallowing, and speech. This leads to impairment of basic oral functions and could result in unplanned treatment interruption or modification. As such, OM negatively impacts both patients' quality of life as well as tumor prognostic outcomes. Understanding pathways underlying OM pathogenesis help identify new targets for intervention or prevention. The pathophysiology of OM has been widely studied over past decades with several pathways related to oxidative stress, inflammation, and molecular and cellular signaling being implicated. In this mini-review, we will discuss the emerging role of the oral-gut microbiome axis in the development of OM. Particularly, we will elaborate on how the alterations in the oral and gut microbiota as well as intestinal dysfunction caused by cancer treatments could contribute to the pathogenesis of OM. Further, we will briefly discuss the potential methods for targeting the oral-gut microbiome axis to improve OM outcomes.

Intensive oral care can reduce bloodstream infection with coagulase-negative staphylococci after neutrophil engraftment in allogeneic hematopoietic stem-cell transplantation

PURPOSE

Bloodstream infection (BSI) is a major complication of allogeneic hematopoietic stem-cell transplantation (allo-SCT). There are several causes of BSI; in particular, severe oral mucositis (OM) can induce BSI due to coagulase-negative staphylococci (CoNS). The OM severity may be reduced with intensive oral care. Thus, we evaluated whether the type of oral care affects the BSI incidence eventually.

METHOD

We performed retrospective analysis on 206 recipients who underwent allo-SCT from 2006 to 2017 at our institute. Intensive oral care by a dental specialist was performed for 111 recipients (intensive-care group) and self-oral care was performed by 95 recipients (self-care group). Incidence of BSI was assessed by type of the oral care, before neutrophil engraftment (pre-E-BSI) and after neutrophil engraftment (post-E-BSI) period until 180 days after allo-SCT.

RESULT

A total of 112 BSI occurred in 90 of the 206 recipients and 120 bacteria were identified, with CoNS being the most prevalent. There was no significant difference in the incidence of pre-E-BSI between the self-care and intensive-care groups (30.8% and 30.6%, respectively; P = 0.508). Meanwhile, the incidence of post-E-BSI was significantly lower in the intensive-care group than in the self-care group (14.3% and 28.6%; P = 0.008). In addition, the intensive-care group had significantly lower incidence of post-E-BSI with CoNS than the self-care group (8.5% and 21.5%, respectively; P = 0.009).

CONCLUSION

Intensive oral care through the period of allo-HCT can significantly reduce the post-E-BSI occurrence, especially due to CoNS.

Microbiota long-term dynamics and prediction of acute graft-versus-host disease in pediatric allogeneic stem cell transplantation

BACKGROUND

Patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT) exhibit changes in their gut microbiota and are experiencing a range of complications, including acute graft-versus-host disease (aGvHD). It is unknown if, when, and under which conditions a re-establishment of microbial and immunological homeostasis occurs. It is also unclear whether microbiota long-term dynamics occur at other body sites than the gut such as the mouth or nose. Moreover, it is not known whether the patients' microbiota prior to HSCT holds clues to whether the patient would suffer from severe complications subsequent to HSCT. Here, we take a holobiont perspective and performed an integrated host-microbiota analysis of the gut, oral, and nasal microbiota in 29 children undergoing allo-HSCT.

RESULTS

The bacterial diversity decreased in the gut, nose, and mouth during the first month and reconstituted again 1-3 months after allo-HSCT. The microbial community composition traversed three phases over 1 year. Distinct taxa discriminated the microbiota temporally at all three body sides, including Enterococcus spp., Lactobacillus spp., and Blautia spp. in the gut. Of note, certain microbial taxa appeared already changed in the patients prior to allo-HSCT as compared with healthy children. Acute GvHD occurring after allo-HSCT could be predicted from the microbiota composition at all three body sites prior to HSCT. The reconstitution of CD4⁺ T cells, T_H17, and B cells was associated with distinct taxa of the gut, oral, and nasal microbiota.

CONCLUSIONS

This study reveals for the first time bacteria in the mouth and nose that may predict aGvHD. Monitoring of the microbiota at different body sites in HSCT patients and particularly through involvement of samples prior to transplantation may be of prognostic value and could assist in guiding personalized treatment strategies. The identification of distinct bacteria that have a potential to predict post-transplant aGvHD might provide opportunities for an improved preventive clinical management, including a modulation of microbiomes. The host-microbiota associations shared between several body sites might also support an implementation of more feasible oral and nasal swab sampling-based analyses. Altogether, the findings suggest that the microbiota and host factors together could provide actionable information to guiding precision medicine. Video Abstract.

Oral microorganisms and bloodstream infection in allogeneic hematopoietic stem cell transplantation

OBJECTIVES

We aimed to compare oral and pathogenic microorganisms in bloodstream infections (BSIs) in allogeneic hematopoietic stem cell transplantation (allo-HSCT). We also investigated the relationship between BSIs and oral mucositis to identify the ratio of BSIs caused by oral microorganisms and the pathogenic microorganisms involved.

MATERIALS AND METHODS

We collected data on BSIs in 96 patients who underwent allo-HSCT in our institute between April 2009 and December 2019, including BSI pathogens isolated from blood cultures (BBSIs) and microorganisms isolated from washing the oral cavity with sterile distilled water. Oral microorganisms obtained at the onset of BSI (OBSIs) and during allo-HSCT (OSCTs) were defined as isolates collected during the week of blood culturing. Study entry was limited to samples collected up to 1 month after allo-HSCT without BSI. When the BBSI and OBSI were the same, we considered the oral microorganism to have caused the BSI.

RESULTS

The incidence rate of BSIs was 27%, and the predominant microorganism was coagulase-negative Staphylococci. Normal bacterial flora were decreased to 15.8% in OBSIs and 25.5% in OSCTs. The distribution of microorganisms without normal bacterial flora showed significant difference between BBSIs and OSCTs (p < 0.05). Oral mucositis was found in 72.9%, and BSI caused by oral microorganisms occurred in 46.2% of BSIs in allo-HSCT patients.

CONCLUSION

The distribution of microorganisms obtained from blood in patients with BSI during allo-HSCT was found to be similar to that of microorganisms from oral cultures.

CLINICAL RELEVANCE

Oral microorganism monitoring may be able to predict BSI during allo-HSCT.

Impact of intensifying primary antibiotic prophylaxis in at-home autologous stem cell transplantation program for lymphoma patients

Despite the use of fluoroquinolone (FQ) prophylaxis, neutropenic fever (NF) is the most frequent cause of hospital readmission in ambulatory care programs for patients treated with autologous stem cell transplantation (ASCT). We analyzed the impact of intensifying primary prophylaxis with the addition of piperacillin/tazobactam (PT) to FQ. Between January 2002 and August 2018, 154 lymphoma patients conditioned with BEAM were included (40% received ceftriaxone (Ct) plus FQ and 60% PT plus FQ). NF and hospital readmission were required in 84 vs. 41% (p < .0001) and 12 vs. 1% (p = .007) of patients within the Ct and PT groups, respectively. The multivariate analysis showed that PT plus FQ retained its independent protective factor for NF (odds ratio (OR): 0.13; p < .001) and for hospital readmission (OR: 0.07; p = .01). The use of PT and FQ prophylaxis may effectively prevent episodes of NF and hospitalizations in lymphoma patients managed in our at-home ASCT care model.

Microbial changes in relation to oral mucositis in autologous hematopoietic stem cell transplantation recipients

The aim of this prospective, two center study was to investigate the dynamics of the microbial changes in relation to the development of ulcerative oral mucositis in autologous SCT (autoSCT) recipients. Fifty-one patients were diagnosed with multiple myeloma and treated with high-dose melphalan followed by autoSCT. They were evaluated before, three times weekly during hospitalization, and three months after autoSCT. At each time point an oral rinse was collected and the presence or absence of ulcerative oral mucositis (UOM) was scored (WHO scale). Oral microbiome was determined by using 16S rRNA amplicon sequencing and fungal load by qPCR. Twenty patients (39%) developed UOM. The oral microbiome changed significantly after autoSCT and returned to pre-autoSCT composition after three months. However, changes in microbial diversity and similarity were more pronounced and rapid in patients who developed UOM compared to patients who did not. Already before autoSCT, different taxa discriminated between the 2 groups, suggesting microbially-driven risk factors. Samples with high fungal load (>0.1%) had a significantly different microbial profile from samples without fungi. In conclusion, autoSCT induced significant and reversible changes in the oral microbiome, while patients who did not develop ulcerative oral mucositis had a more resilient microbial ecosystem.

The Dysbiosis and Inter-Kingdom Synergy Model in Oropharyngeal Candidiasis, a New Perspective in Pathogenesis

As more information emerges on oral microbiota using advanced sequencing methodologies, it is imperative to examine how organisms modulate the capacity of each other to colonize or trigger infection. Most mouse models of oral C. albicans infection have focused on interactions with single bacterial species. Thus, little is known about the microbiome-mediated interactions that control the switch of C. albicans from commensalism to infection. Evidence is accumulating that in immunosuppression where mucosal candidiasis is more prevalent, there is an altered oral bacterial microbiome with reduced diversity, but not an altered mycobiome. Oropharyngeal candidiasis in immunosuppressed humans and mice is associated with a further reduction in oral bacterial diversity and a dysbiotic shift with significant enrichment of streptococcal and enterococcal species. Our recent studies in a cancer chemotherapy mouse model supported the combined profound effect of immunosuppression and C. albicans in reducing oral bacterial diversity and provided the first direct evidence that these changes contribute to pathogenesis, representing dysbiosis. There is still a gap in understanding the relationship between Candida and the oral bacterial microbiome. We propose that certain oral commensal bacteria contribute to fungal pathogenesis and we identify gaps in our understanding of the mechanisms involved in this cooperative virulence.

Complications of Stem Cell Transplantation that Affect Infections in Stem Cell Transplant Recipients, with Analogies to Patients with Hematologic Malignancies

This article discusses the complications of hematopoietic stem cell transplantion (HSCT) that affect infections in HSCT recipients, with analogies to patients with hematologic malignancies. Mucositis, with mucosal barrier disruption, is common and increases the risk of gram-positive and anaerobic bacterial, and fungal infections, and can evolve to typhlitis. Engraftment syndrome; graft-versus-host disease, hepatic sinusoidal obstruction syndrome; and posterior reversible encephalopathy syndrome can affect the infectious potential either directly from organ dysfunction or indirectly from specific treatment. Pulmonary infections can predispose to life threatening complications including diffuse alveolar hemorrhage, idiopathic pulmonary syndrome, bronchiolitis obliterans syndrome, and bronchiolitis obliterans with organizing pneumonia.