Parabacteroides distasonis: intriguing aerotolerant gut anaerobe with emerging antimicrobial resistance and pathogenic and probiotic roles in human health

Abstract

Parabacteroides distasonis is the type strain for the genus Parabacteroides, a group of gram-negative anaerobic bacteria that commonly colonize the gastrointestinal tract of numerous species. First isolated in the 1930s from a clinical specimen as Bacteroides distasonis, the strain was re-classified to form the new genus Parabacteroides in 2006. Currently, the genus consists of 15 species, 10 of which are listed as 'validly named' (P. acidifaciens, P. chartae, P. chinchillae, P. chongii, P. distasonis, P. faecis, P. goldsteinii, P. gordonii, P. johnsonii, and P. merdae) and 5 'not validly named' (P. bouchesdurhonensis, P. massiliensis, P. pacaensis, P. provencensis, and P. timonensis) by the List of Prokaryotic names with Standing in Nomenclature. The Parabacteroides genus has been associated with reports of both beneficial and pathogenic effects in human health. Herein, we review the literature on the history, ecology, diseases, antimicrobial resistance, and genetics of this bacterium, illustrating the effects of P. distasonis on human and animal health.

Classification of Parabacteroides distasonis and other Bacteroidetes using O- antigen virulence gene: RfbA -Typing and hypothesis for pathogenic vs. probiotic strain differentiation

“…From 15 possible Parabacteroides species (as complete genomes) available to date, 2 rfbA sequences were only available for 13 species ( P. distasonis, P.johnsonii, P. merdae, P. golsteinii, P. acidifaciens, P. faecis, P. bouchesdurhonensis, P. chartae, P. massiliensis, P. provencensis, P. timonensis, P. pacaensis, P. gordonii ). Sequences for the rfbA gene in P. chongii and P. chinchilla were not available.…”

“…While this bacterium has reported associations with IBD and other diseases, its specific mechanisms are not well understood. 2 The fact that P. distasonis had been found in extraintestinal lesions ( e.g ., abscesses) does not necessarily indicate that Pdis is a primary pathogen, but rather indicates that the dissemination of this bacterium from the gut lumen may make Pdis an opportunistic pro-inflammatory microorganism. To what extent this intestinal commensal promotes inflammation in the gut wall in humans and how this varies with human genetics and predisposition to IBD remains unclear, but strain isolation from pus-containing intramural microscopic lesions (CavFT-hAR46 and CavFT-hAR56) indicates that opportunistic inflammation may depend on the environment where Pdis is encountered.…”

“…Parabacteroides distasonis ( Pdis ), a gram-negative bacterium of the intestinal tract, 1 is the type strain for the genus Parabacteroides , for which there is emerging controversy regarding the role that they play in human and animal health. 2 Although Pdis has been recognized as an intestinal commensal since the mid-1930s, 3 there is a recent increase in reports describing contradictory pathogenic (detrimental) 4–9 and probiotic (beneficial) 10–17 effects on human and animal health. There is need to identify and characterize factors that could account for reported differences in potential Pdis strain pathogenicity, especially because there is an emerging interest in using Pdis as a human probiotic, which poses a major risk to public health.…”

CACONET: a novel classification framework for microbial correlation networks

“…It is also worth noting that Blautia was associated with several microbes in the Healthy network, including Enterococcus , Parabacteroides , Phascolarctobacterium and Sutterella but was abscent in the CRC network. The potential probiotic functions of Blautia have been recently reviewed in Liu et al , 2021 , whereas Parabacteroides has been associated with both probiotic and pathogenic roles in human health ( Ezeji et al , 2021 ).…”

Gut commensal bacteria enhance pathogenesis of a tumorigenic murine retrovirus

“…A major difference between the two Bacteroidales bacteria utilized in this study is the presence of an S-layer in P. goldsteinii (Fletcher et al, 2007). The S-layer is a bacterial cell structure composed of protein or glycoprotein thought to have evolved to provide protection against environmental factors (Fletcher et al ., 2007; Sleytr et al, 1993) and the host’s immune response (Ezeji et al, 2021). Thus, S-layer may prevent proinflammatory signaling (Cuffaro et al, 2020; Kverka et al, 2011).…”