Mobile genetic elements of the human gastrointestinal tract: potential for spread of antibiotic resistance genes

Abstract

The human intestine is an important location for horizontal gene transfer (HGT) due to the presence of a densely populated community of microorganisms which are essential to the health of the human superorganism. HGT in this niche has the potential to influence the evolution of members of this microbial community and to mediate the spread of antibiotic resistance genes from commensal organisms to potential pathogens. Recent culture-independent techniques and metagenomic studies have provided an insight into the distribution of mobile genetic elements (MGEs) and the extent of HGT in the human gastrointestinal tract. In this mini-review, we explore the current knowledge of mobile genetic elements in the gastrointestinal tract, the progress of research into the distribution of antibiotic resistance genes in the gut and the potential role of MGEs in the spread of antibiotic resistance. In the face of reduced treatment options for many clinical infections, understanding environmental and commensal antibiotic resistance and spread is critical to the future development of meaningful and long lasting anti-microbial therapies.

Keywords: antibiotics resistance; gene transfer; gut; microbiome; mobile genetic elements.

Figure 1. Distribution of most abundant resistance plasmids across HMP stool data sets. E.coli NR79 (Chloramphenicol), Enterobacteriaceae R387 (Chloramphenicol), E. faecium pIP816 (vanY) were represented in all of the 146 stool data sets. Lactobacillus sp P121BS (ermT) and L. reuteri pGT633 (ERM) were noted in 90% or more of the stool data sets. S. aureus pT48 (MLSB), S. aureus pE5 (ermC) and B. subtilis pIM13 (MLSB) S. epidermidis pNE131 (MLSB) were detected in over 80% of the data sets.

Figure 2. Plasmids of highest weighted relative abundance in HMP stool data sets. The resistance plasmid with the most weighted relative abundance in the HMP stool data sets was found to be S.aureus pT48 (MLSB) and this was followed by L. reuteri pGT633 (ERM), S. aureus pE5 (ermC), Lactobacillus sp p121BS (ermT), S. epidermidis pNE131 (MLSB), B. subtilis pIM13 (MLSB), E.coli NR79 (Chloramphenicol), C. coli pIP1433 (Kanamycin), Enterobacteriaceae R387 (Chloramphenicol), E. faecium pIP816 (vanY).