Improving Oral Health and Modulating the Oral Microbiome to Reduce Bloodstream Infections from Oral Organisms in Pediatric and Young Adult Hematopoietic Stem Cell Transplantation Recipients: A Randomized Controlled Trial

Risk factors of bloodstream infection after allogeneic hematopoietic cell transplantation in children/adolescent and young adults

Allogeneic hematopoietic cell transplantation (HCT) is a crucial treatment for various diseases, including hematological malignancies, solid tumors, and genetic disorders. Despite its curative potential, HCT is associated with severe complications, notably infections, graft-versus-host disease, and organ damage. Infections, particularly bloodstream infections (BSIs), pose a significant threat in the initial weeks post-HCT, necessitating effective management strategies. This retrospective study aimed to clarify the incidence, pathogens, and risk factors associated with BSI within the first 30 days after allogeneic HCT in children/adolescents and young adults (AYAs). The study included 115 patients aged <31 years who underwent 121 allogeneic HCTs at the Department of Pediatrics, Nagoya University Hospital between January 1, 2018, and March 31, 2022. Data encompassed demographic characteristics, HCT details, and BSI information. Overall, 27 of 121 patients developed BSI with the cumulative incidence of 23.5% (95% confidence intervals [CI]: 17.0%-30.6%) at 30 days after HCT. The median onset time of BSI was 7 (range, 4-26 days) after HCT. Gram-positive bacteria accounted for 89% of pathogens isolated from blood cultures, with Streptococcus mitis/oralis being the most common. In multivariable analysis, tandem HCT (subdistribution hazard ratio [SHR]: 5.67, 95% CI: 2.74-11.7, p < 0.001) and peripherally inserted central catheters (SHR: 2.96, 95% CI: 1.34-6.55, p  =  0.007) were identified as independent risk factors for BSI. In patients receiving tandem HCT, the pathogens isolated from blood cultures were all gram-positive bacteria, with Streptococcus mitis/oralis accounting for up to 67% of the isolated pathogens. Tandem HCT and PICCs were identified as independent risk factors for BSI after allogeneic HCT in children/AYAs. The pathogens were commonly gram-positive, and Streptococcus mitis/oralis is important in patients who received tandem HCT. These data can provide valuable information for future studies to consider effective interventions to reduce the risk of BSI in high-risk patients.

Temporal variation in oral microbiome composition of patients undergoing autologous hematopoietic cell transplantation with keratinocyte growth factor

INTRODUCTION

Autologous hematopoietic cell transplantation (AHCT) is a well-established treatment for lymphoma. Unintended effects of this therapy include oral mucositis (OM) and gastrointestinal toxicities, resulting in poor clinical outcomes. The gut microbiome has been previously linked to transplant toxicities among allogeneic recipients, but little is known about the effects of AHCT on the oral microbiome.

METHODS

Seven patients with non-Hodgkin or Hodgkin lymphoma undergoing AHCT with palifermin (keratinocyte growth factor) were included. Buccal swab samples were collected at baseline and 14- and 28-days post-treatment. Oral microbial communities were characterized with 16 S rRNA amplicon sequencing. Temporal trends in community composition, alpha diversity, and beta diversity were investigated.

RESULTS

A significant reduction in the relative abundance of the genera Gemella and Actinomyces were observed from baseline. No significant temporal differences in alpha diversity were observed. Significant changes in beta diversity were recorded.

CONCLUSION

Results of this pilot study suggest treatment with AHCT and palifermin affects the oral microbiome, resulting in temporal shifts in oral microbial community composition. Future studies are warranted to confirm these trends and further investigate the effects of AHCT on the oral microbiome and how these shifts may affect health outcomes.

Children's Oncology Group's 2023 blueprint for research: Cancer control and supportive care

The objective of the Cancer Control and Supportive Care (CCL) Committee in the Children's Oncology Group (COG) is to reduce the overall morbidity and mortality of therapy-related toxicities in children, adolescents, and young adults with cancer. We have targeted five major domains that cause clinically important toxicity: (i) infections and inflammation; (ii) malnutrition and metabolic dysfunction; (iii) chemotherapy-induced nausea and vomiting; (iv) neuro- and oto-toxicty; and (v) patient-reported outcomes and health-related quality of life. Subcommittees for each domain prioritize randomized controlled trials and biology aims to determine which strategies best mitigate the toxicities. The findings of these trials are impactful, informing clinical practice guidelines (CPGs) and directly leading to changes in the standard of care for oncology practice. With the development of new therapies, there will be new toxicities, and the COG CCL Committee is dedicated to developing interventions to minimize acute and delayed toxicities, lessen morbidity and mortality, and improve quality of life in pediatric and young adult patients with cancer.

Oral microbial changes and oral disease management before and after the treatment of hematological malignancies: a narrative review

OBJECTIVES

Patients with hematological malignancies have dynamic changes in oral microbial communities before and after treatment. This narrative review describes the changes in oral microbial composition and diversity, and discusses an oral microbe-oriented strategy for oral disease management.

MATERIALS AND METHODS

A literature search was performed in PubMed/Medline, Web of Science, and Embase for articles published between 1980 and 2022. Any articles on the changes in oral microbial communities in patients with hematological malignancies and their effects on disease progression and prognosis were included.

RESULTS

Oral sample detection and oral microbial sequencing analysis of patients with hematological malignancies showed a correlation between changes in oral microbial composition and diversity and disease progression and prognosis. The possible pathogenic mechanism of oral microbial disorders is the impairment of mucosal barrier function and microbial translocation. Probiotic strategies, antibiotic strategies, and professional oral care strategies targeting the oral microbiota can effectively reduce the risk of oral complications and the grade of severity in patients with hematological malignancies.

CLINICAL RELEVANCE

This review provides dentists and hematologists with a comprehensive understanding of the host-microbe associated with hematologic malignancies and oral disease management advice.

Oral microbiome as a new research-target for supportive care and precision oncology

PURPOSE OF REVIEW

A growing number of studies demonstrate the oral bacterial shift in cancer patients and the enrichment of oral bacteria in distant tumours. During the oncological treatment, opportunistic oral bacteria correlate with oral toxicities. This review focused on the most recent studies to identify which genera are the most mentioned and deserved further investigation.

RECENT FINDINGS

This review evaluated bacterial changes in patients with head and neck, colorectal, lung and breast cancer. Greater composition of disease-related genera (e.g., Fusobacterium , Porphyromonas , Lactobacillus , Streptococcus , and Parvimonas ) are present in the oral cavity of these groups of patients. The tumour specimen characterisation of head and neck, pancreatic and colorectal cancer also describes the presence of oral taxa. No evidence indicates that commensal oral bacteria have protective roles in distant tumours. Regardless, oral care is critical to prevent the growth of oral pathogens and reduce infection foci.

SUMMARY

Recent evidence suggests that oral microbiota is a potential biomarker for oncological clinical outcomes and oral toxicities. Currently, the literature presents a remarkable methodological variety - from the sample collection site to the preference of the data analysis tools. For the oral microbiome to achieve the stage of being used as a clinical tool in the oncological context, more studies are necessary.

Bloodstream Infections in Infants and Children With Congenital Heart Disease Undergoing Cardiac Surgery

BACKGROUND

Children with congenital heart disease undergoing cardiac surgery are at risk for laboratory-confirmed bloodstream infections (LCBIs). These infections can lead to morbidity, mortality, and increased health care costs. The role of mucosal barrier injury in causing LCBIs is unknown.

OBJECTIVES

To describe characteristics of LCBIs in patients admitted to cardiac intensive care and step-down units and to assess frequencies of National Healthcare Safety Network infection types and associations with organism classification, patient clinical factors, and infection outcomes.

METHODS

A retrospective cohort analysis using manual electronic medical record data abstraction included children with congenital heart disease who developed an LCBI while receiving inpatient cardiac care between August 2011 and November 2018 at one institution. Demographic, clinical, laboratory, and outcome variables were collected and analyzed with descriptive and inferential statistics.

RESULTS

Eighty-seven patients with congenital heart disease developed 103 LCBIs during the study time frame. The most common causative microorganisms were gram-positive bacteria, including Enterococcus faecalis and Staphylococcus epidermidis. Sixty-three percent of causative organisms were characterized as originating from mucosal barrier injury, although no infections met National Healthcare Safety Network criteria for mucosal barrier injury LCBIs.

CONCLUSIONS

Translocation of bacteria through injured gut mucosa may cause bloodstream infections in children with congenital heart disease. Further investigation is warranted to understand microbiome changes that adversely select pathogenic gut organisms. Preventive care to maintain intact gut function and a healthy microbiome should be explored for this patient population.

Dvorak C, Den Besten P. Dental caries as a risk factor for bacterial blood stream infection (BSI) in children undergoing hematopoietic cell transplantation (HCT)

Background

Hematopoietic cell transplantation (HCT) is a potentially curative therapy for a wide range of pediatric malignant and nonmalignant diseases. However, complications, including blood stream infection (BSI) remain a major cause of morbidity and mortality. While certain bacteria that are abundant in the oral microbiome, such as S. mitis, can cause BSI, the role of the oral microbial community in the etiology of BSI is not well understood. The finding that the use of xylitol wipes, which specifically targets the cariogenic bacteria S. mutans is associated with reduced BSI in pediatric patients, lead us to investigate dental caries as a risk factor for BSI.

Methods

A total of 41 pediatric patients admitted for allogenic or autologous HCT, age 8 months to 25 years, were enrolled. Subjects with high dental caries risk were identified as those who had dental restorations completed within 2 months of admission for transplant, or who had untreated decay. Fisher's exact test was used to determine if there was a significant association between caries risk and BSI. Dental plaque and saliva were collected on a cotton swab from a subset of four high caries risk (HCR) and four low caries risk (LCR) children following pretransplant conditioning. 16SrRNA sequencing was used to compare the microbiome of HCR and LCR subjects and to identify microbes that were significantly different between the two groups.

Results

There was a statistically significant association between caries risk and BSI (p < 0.035) (Fisher's exact test). Multivariate logistic regression analysis showed children in the high dental caries risk group were 21 times more likely to have BSI, with no significant effect of age or mucositis severity. HCR subjects showed significantly reduced microbial alpha diversity as compared to LCR subjects. LEfse metagenomic analyses, showed the oral microbiome in HCR children enriched in order Lactobacillales. This order includes Streptococcus and Lactobacillus, both which contain bacteria primarily associated with dental caries.

Discussion

These findings support the possibility that the cariogenic microbiome can enhance the risk of BSI in pediatric populations. Future metagenomic analyses to measure microbial differences at, before, and after conditioning related to caries risk, may further unravel the complex relationship between the oral microbiome, and whether it affects health outcomes such as BSI.

The Impact of Human Microbiotas in Hematopoietic Stem Cell and Organ Transplantation

The human microbiota heavily influences most vital aspects of human physiology including organ transplantation outcomes and transplant rejection risk. A variety of organ transplantation scenarios such as lung and heart transplantation as well as hematopoietic stem cell transplantation is heavily influenced by the human microbiotas. The human microbiota refers to a rich, diverse, and complex ecosystem of bacteria, fungi, archaea, helminths, protozoans, parasites, and viruses. Research accumulating over the past decade has established the existence of complex cross-species, cross-kingdom interactions between the residents of the various human microbiotas and the human body. Since the gut microbiota is the densest, most popular, and most studied human microbiota, the impact of other human microbiotas such as the oral, lung, urinary, and genital microbiotas is often overshadowed. However, these microbiotas also provide critical and unique insights pertaining to transplantation success, rejection risk, and overall host health, across multiple different transplantation scenarios. Organ transplantation as well as the pre-, peri-, and post-transplant pharmacological regimens patients undergo is known to adversely impact the microbiotas, thereby increasing the risk of adverse patient outcomes. Over the past decade, holistic approaches to post-transplant patient care such as the administration of clinical and dietary interventions aiming at restoring deranged microbiota community structures have been gaining momentum. Examples of these include prebiotic and probiotic administration, fecal microbial transplantation, and bacteriophage-mediated multidrug-resistant bacterial decolonization. This review will discuss these perspectives and explore the role of different human microbiotas in the context of various transplantation scenarios.

Long-Term Analysis of Resilience of the Oral Microbiome in Allogeneic Stem Cell Transplant Recipients

Stem cell transplantation (SCT) is associated with oral microbial dysbiosis. However, long-term longitudinal data are lacking. Therefore, this study aimed to longitudinally assess the oral microbiome in SCT patients and to determine if changes are associated with oral mucositis and oral chronic graft-versus-host disease. Fifty allogeneic SCT recipients treated in two Dutch university hospitals were prospectively followed, starting at pre-SCT, weekly during hospitalization, and at 3, 6, 12, and 18 months after SCT. Oral rinsing samples were taken, and oral mucositis (WHO score) and oral chronic graft-versus-host disease (NIH score) were assessed. The oral microbiome diversity (Shannon index) and composition significantly changed after SCT and returned to pre-treatment levels from 3 months after SCT. Oral mucositis was associated with a more pronounced decrease in microbial diversity and with several disease-associated genera, such as Mycobacterium, Staphylococcus, and Enterococcus. On the other hand, microbiome diversity and composition were not associated with oral chronic graft-versus-host disease. To conclude, dysbiosis of the oral microbiome occurred directly after SCT but recovered after 3 months. Diversity and composition were related to oral mucositis but not to oral chronic graft-versus-host disease.