Study examines antibiotic resistance in mouth microbiome

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New study examines antibiotic resistance in mouth microbiome

According to researchers, it is imperative to expand human resistome studies to include body areas other than the gut in order to understand the spread and persistence of antimicrobial resistance. (Image: Yuliia Gornostaieva/Shutterstock)

Tue. 18. February 2020


LONDON, UK: Antimicrobial resistance (AMR) influences the success of medical treatment and allows for unhindered diffusion of bacteria. Although antibiotic resistance and its effect in the human gut microbiota and the associated genes have been widely researched, there is currently little information on the resistance genes in the oral cavity, which is the first point of entry for various medications. Researchers from King’s College London have recently shed light on the issue and reported that AMR genes in the gut and the oral resistome differ greatly in abundance and diversity.

In the study, the research group assessed saliva, dental plaque and other oral data in 788 participants and analysed the data using the Comprehensive Antibiotic Resistance Database. The findings suggested that there are unique resistome profiles in the mouth compared with the gut. Additionally, while the researchers recorded less diversity of AMR genes in the mouth, those genes that were present were more pervasive across the populations studied.

“The oral resistome is distinct from the gut resistome—it shows less diversity among antimicrobial resistance genes than the gut, but those genes that are there are present in a greater number of microbes,” Dr David Moyes, lecturer in host–microbiome interactions at King’s College London, told Dental Tribune International. “There is more similarity between oral resistomes from two different individuals regardless of where they’re from than there is between the oral resistome and the gut resistome in the same individual,” he continued.

According to Moyes, the findings indicate that researchers cannot base their assumptions on AMR based purely on the gut, especially if they are specifically studying the mouth. “It also points out that there is significant resistance in the mouth, and that certain AMR genes are particularly prevalent in the mouth, indicating that these are not good antibiotics to use in the treatment of mouth infections,” he added.

“As such, it makes the point that we need to be more selective and careful in antibiotic usage for oral infections, limiting their use to when essential, rather than using them prophylactically,” Moyes concluded.

In the next phase of the study, the researchers will analyse the mobile genetic elements, such as bacteriophages and plasmids, within the oral cavity microbiome. They will use functional metagenomics to measure antibiotic susceptibility or resistance to antimicrobials in the mouth, especially to antibiotics such as amoxicillin and tetracyclines that are used frequently in the dental practice.

Additionally, the researchers will try to establish which genes can act as a diagnostic for resistance potential. This would help dentists choose more appropriate antibiotics and determine whether resistance in the mouth leads to resistant infections, colonisation and/or spread to other body sites via the bloodstream, as happens in the case of infective endocarditis.

The study, titled “Abundance and diversity of resistomes differ between healthy human oral cavities and gut”, was published online on 4 February 2019 in Nature Communications.

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