key: cord-1049301-i90bpl6s
authors: Patel, Jay; Sampson, Victoria
title: The role of oral bacteria in COVID-19
date: 2020-07-03
journal: Lancet Microbe
DOI: 10.1016/s2666-5247(20)30057-4
sha: 2d9440ba65195b7530e44f7a6b9fe824a5706d68
doc_id: 1049301
cord_uid: i90bpl6s

nan

www.thelancet.com/microbe Vol 1 July 2020 e105

The role of oral bacteria in COVID-19

We read with interest the Corre spondence by Michael J Cox and colleagues, 1 highlighting the relevance of coinfections in the clinical outcomes and mortality of patients with coronavirus disease 2019 (COVID19). We believe the role of oral bacteria in facilitating coinfections in COVID19 is pertinent, yet overlooked. We concur with the need for wholegenome metagenomics to capture the data relevant to coinfections, but this should also warrant consideration for the bacterial species comprising the oral microbiome.

Poor oral hygiene is considered to be a major ecological pressure that steers complex microbial communities in the mouth into dysbiosis. Ecological shifts in a dysbiotic ecosystem favour an increased prevalence of pathogenic oral bacteria. Daily activities such as mastication, flossing, and tooth brushing can induce bacteraemia, which facilitate haematogenous dissemination of oral bacteria and inflammatory mediators, inducing systemic inflammation in some patients. Individuals with periodontal disease show microulcerated sulcular epithelia and damaged periodontal tissues, and thus seem more susceptible to bacteraemia. Good oral hygiene is therefore essential for controlling the total bacterial load in the mouth, maintaining or reestablishing the oral symbiotic equilibrium, and preventing the dissemination of oral bacteria to other sites in the body. 2 Metagenomic analyses of patients infected with severe acute respiratory syndrome coronavirus 2 have frequently reported high reads of cariogenic and periodontopathic bacteria, 3 endorsing the notion of a connection between the oral micro biome and COVID19 comp lications. Evidence suggests that period ontopathic bacteria are involved in the pathogenesis of respiratory diseases, such as those implicated in COVID19, and are associated with chronic inflammatory systemic diseases including type 2 diabetes, hypertension, and cardiovascular disease. These diseases are frequently reported comorbidities associated with an increased risk of severe complications and death from COVID19. Suggested mechanisms that might explain the role of oral bacteria in the pathogenesis of respiratory infections are via the aspiration of oral pathogens into respiratory organs, the alteration of the respiratory epithelium by periodontal associated cytokines, and oral mucosal surfaces rendered to promote the adhesion of respiratory pathogens. 4 Numerous studies 5, 6 report that oral hygiene interventions in patients with pneumonia have substantially improved clinical outcomes and reduced mortality. One in ten pneumoniarelated deaths of older nursing home residents (≥65 years) are considered preventable by improving oral hygiene. 7 Improved oral care has been shown to significantly reduce the incidence of ventilatorassociated pneumonia in patients in an intensive care unit. 8 Further metagenomic studies and clinical trials are required for the characterisation of coinfections in COVID19 and the potential connection between the role of the oral microbiome and complications arising from the virus.

These data are vital to ascertain whether poor oral hygiene is a modifiable risk factor for COVID19 complications and if there is a place for the promotion of good oral hygiene as a preventive public health intervention during the pandemic.

Coinfections: potentially lethal and unexplored in COVID19

The oral microbiome -an update for oral healthcare professionals

Metagenome of SARSCov2 patients in Shenzhen with travel to Wuhan shows a wide range of species Lautropia, Cutibacterium, Haemophilus being most abundant and Campylobacter explaining diarrhea

Role of oral bacteria in respiratory infection

Evidence summary: the relationship between oral health and pulmonary disease

Systematic review of the association between respiratory diseases and oral health

A systematic review of the preventive effect of oral hygiene on pneumonia and respiratory tract infection in elderly people in hospitals and nursing homes: effect estimates and methodological quality of randomized controlled trials

Oral care reduces incidence of ventilatorassociated pneumonia in ICU populations