Pseudomonadota in the oral cavity: a glimpse into the environment-human nexus

The phylum Pseudomonadota is amongst the most represented in the environment, with a comparatively lower prevalence in the human oral cavity. The ubiquity of Pseudomonadota and the fact that the oral cavity is the most likely entry portal of bacteria from external sources underlie the need to better understand its occurrence in the interface environment-humans. Yet, the relevance oral Pseudomonadota is largely underexplored in the scientific literature, a gap that this review aims at addressing by making, for the first time, an overview of the diversity and ecology of Pseudomonadota in the oral cavity. The screening of scientific literature and human microbiome databases unveiled 1328 reports of Pseudomonadota in the oral cavity. Most of these belonged to the classes Beta- and Gammaproteobacteria, mainly to the families Neisseriaceae, Campylobacteriaceae, and Pasteurelaceae. Others also regularly reported include genera such as Enterobacter, Klebsiella, Acinetobacter, Escherichia, Burkholderia, or Citrobacter, whose members have high potential to acquire virulence and antibiotic resistance genes. This review provides evidence that clinically relevant environmental Pseudomonadota may colonize humans via oral cavity. The need for further investigation about Pseudomonadota at the environment-oral cavity interface and their role as vectors potentially involved in virulence and antibiotic resistance transmission is demonstrated.

Automated summary

Pseudomonadota is less prevalent in the human oral cavity despite being one of the most represented phyla in the environment. This review provides an overview of the diversity and ecology of Pseudomonadota in the oral cavity, which has been largely underexplored in scientific literature. The screening of scientific literature and human microbiome databases revealed more than 1300 reports of Pseudomonadota in the oral cavity, mainly belonging to Beta- and Gammaproteobacteria classes.