The novel conceptual disease model, the oral–gut axis, which represents the immunomodulatory mutual relationship between oral and gut microbial compartments, has been attracting attention in relation to systemic health issues. We investigated whether this unique crosstalk influences the systemic condition of patients with COVID-19 infections who received extracorporeal membrane oxygenation (ECMO) in the intensive care unit (ICU) during April and December 2020. In this case-control study, patients were divided into two groups according to their survival (total entry size, n = 21; survivors, n = 13; non-survivors, n = 8). Patients were evaluated using the oral assessment guide from Fukuoka University (OAG-F) and the Bristol Stool Form Scale (BSFS) to examine the oral and fecal conditions. A blood-based inflammatory factor, the neutrophil-to-lymphocyte ratio (NLR), was used as an indicator of systemic immunity. The high total OAG-F scores were associated with both elevated BSFS and NLR values, and a mutually positive correlation between BSFS and NLR was observed. This indicated an interplay between oral deterioration, gut dysbiosis, and the impairment of immunity. Furthermore, oral deterioration was more frequently observed in non-survivors on day 14 of ICU admission. In addition, on days 7 and 21 of ICU admission, impaired immunity, reflected by an elevated NLR, was observed in non-survivors. However, the distribution of the gut microbiome—reflected by increased BSFS values—with the time it was examined was not directly observed in non-survivors. Taken together, these findings suggested that oral–gut health may be specifically associated with mortality in COVID-19 patients receiving ECMO in the ICU.

The oral health of coronavirus disease 2019 (COVID-19) patients in the intensive care unit (ICU) is an important issue in treatment of respiratory failure. We retrospectively investigated the oral health history of severe COVID-19 patients who received extracorporeal membrane oxygenation (ECMO) from April 2020 to December 2020 using the oral assessment guide from Fukuoka University (OAG-F). Nineteen consecutive patients (median age: 62 years) were divided into two groups according to survival (survivors, n = 12; non-survivors, n = 7). A univariate analysis revealed no significant differences between the groups in sex, age, body mass index (BMI), or the number of remaining teeth, whereas the ECMO assistance of non-survivors (median: 34 days) was prolonged in comparison to survivors (median: 8 days; p < 0.05). Among the factors of OAG-F, significant differences were observed between the groups in the conditions of the saliva, mucous membrane, and gingiva. The total scores in non-survivors (median: 19) were significantly higher in comparison to survivors (Median: 15.5), suggesting that the frequency of oral health deterioration was higher in non-survivors (p < 0.05). Taken together, these findings suggest that poor oral health is associated with mortality in COVID-19 patients receiving ECMO in the ICU.

To evaluate the prevalence of oral complications in patients with severe COVID-19; investigate the association between their oral health, organ status, and immunity; and determine whether the resazurin disc test is an effective substitute for the Oral Assessment Guide. A single-centre observational study. Intensive care unit with restricted access specialising in extracorporeal membrane oxygenation for COVID-19 treatment. We investigated the oral health of 13 patients with COVID-19 receiving extracorporeal membrane oxygenation therapy between April and December 2021 using the Oral Assessment Guide and colour reactive resazurin disc test. The Sequential Organ Failure Assessment and Prognostic Nutritional Index were used to assess organ status and immunity, respectively. The correlation of oral health status with organ status and immunity was investigated. High bacterial levels, revealed by the resazurin disc test, were associated with elevated Oral Assessment Guide scores, indicating oral health deterioration, particularly in terms of teeth and dentures. Increased Sequential Organ Failure Assessment scores and decreased Prognostic Nutritional Index were correlated with poor oral health, revealed by the Oral Assessment Guide and resazurin disc test. Poor oral health is an important risk factor for severe COVID-19 complications in patients admitted to an intensive care unit. The Oral Assessment Guide and resazurin disc test can evaluate oral conditions; however, the resazurin disc test is quantitative and does not require salivary specimens to be transferred outside the patient ward for evaluation. The resazurin disc test can be a useful substitute for the Oral Assessment Guide in intensive care units with restricted access. The resazurin disc test can be used for quantitative assessment of patients' oral condition in isolation wards. Multidisciplinary management of patients with COVID-19 should be promoted and involve oral healthcare providers such as dentists and dental hygienists.

Primary oral diffuse large B cell lymphoma (DLBCL) is rare and the differential diagnosis is difficult due to its low incidence and nonspecific symptoms, which resemble those of common oral diseases in the initial clinical setting. We aimed to discuss the value of making an accurate diagnosis using liquid-based cytology (LBC) and cell block (CB) for not only the morphological interpretation but also cytohistological assessment of oral DLBCL. LBC and CBs made from oral brushing materials were prepared on the first medical examination and a morphological analysis and immunohistochemical analysis of specific biomarkers were performed. The analysis of LBC preparations showed the presence of large-size lymphocytes with large irregular nuclei and prominent nucleoli, suggesting the existence of large B-cell lymphoma. A more detailed histological subclassification of the CB specimen was performed, which was classified as the activated B-cell (ABC) phenotype of DLBCL, by confirming the immunohistochemical expression of CD10−/ B-cell lymphoma 6 (BCL6)+/ multiple myeloma oncogene 1(MUM1)+, which is a significant risk factor in DLBCL. Our findings suggest that the combination of LBC and CB is a useful and informative tool for making an accurate molecular diagnosis of oral DLBCL in cases in which lymphomas are clinically suspected.