Fig. 1: Co-selection mechanisms of cross-resistance, co-resistance and co-regulation.
From: Co-selection for antibiotic resistance by environmental contaminants
Cross-resistance occurs when a mechanism provides resistance to two or more agents (e.g., a multi-drug efflux pump). In this figure, the AcrAB-TolC efflux pump gene is shown, which can pump out of the cell multiple antibiotics and biocides137, non-antibiotic drugs86,138, and plant protection products32,139. Co-resistance occurs when two genes are physically linked on a piece of DNA so are inherited together e.g., an antibiotic and metal resistance gene located on a plasmid. In this figure, the metal resistance gene arsB and the antibiotic resistance gene blaTEM-1 are both present on a plasmid and can be inherited together139. Co-regulation occurs when the translational or transcriptional responses to one agent leads to a co-ordinated response to more than one agent (e.g., an antibiotic or biocide could lead to expression of a multi-drug efflux pump). In this figure, the transcriptional pathways of the mex operon and the czc operon are linked so that expression of either leads to the expression of both the czc and oprD efflux pumps140. Created with Biorender.
