IncHI1A plasmids potentially facilitate a horizontal flow of antibiotic
resistance genes to pathogens in microbial communities of urban
Horizontal gene transfer via plasmids is important for the dissemination
of antibiotic resistance genes among medically relevant pathogens.
Specifically, the transfer of IncHI1A plasmids is believed to facilitate
the spread of antibiotic resistance genes, such as carbapenemases,
within the clinically important family Enterobacteriaceae. The
microbial community of urban wastewater treatment plants has been shown
to be highly permissive towards conjugal transfer of IncP1 plasmids.
Here, we tracked the transfer of the P1 plasmid pB10 and the clinically
relevant HI1A plasmid R27 in the microbial communities present in urban
residential sewage entering full-scale wastewater treatment plants. We
found that both plasmids readily transferred to these communities and
that strains in the sewage were able to further disseminate them.
Furthermore, that R27 has a broad potential host range, but a low host
divergence. Interestingly, although the majority of R27 transfer events
were to members of Enterobacteriaceae, we found a subset of
transfer to other families, even other phyla. Indicating, that HI1A
plasmids facilitate horizontal gene transfer both within
Enterobacteriaceae, but also across families of especially
Gammaproteobacteria, such as Moraxellaceae,
Pseudomonadaceae and Shewanellaceae. pB10 displayed a
similar potential host range as R27. In contrast to R27, pB10 had a high
host divergence. By culture enrichment of the transconjugant
communities, we show that sewage strains of Enterobacteriaceae
and Aeromonadaceae can stably maintain R27 and pB10,
respectively. Our results suggest that dissemination in the urban
residual water system of HI1A plasmids may result in an accelerated
acquisition of antibiotic resistance genes among pathogens.