Resistance unspecific mechanisms

Two mechanisms are operating alone or in concert to minimize the antibiotic concentration at the intracellular target site Downregulation of the expression of the pore proteins, also called porins, and upregulation of one or a set of several unspecific efflux pumps. However, the impact of these mechanisms on the resistance is low, since due to the essential function of porins for uptake of nutrients their reduction is limited and to avoid disturbances of membrane integrity due to extensive oveiproduction of mdr efflux pumps these are subjected a strict regulation. 

The biocidal spectrum of these compounds is generally broader compared to compounds with a specific mechanism. The unspecific action leads in general to a significant decrease in possible resistance (except resistance caused by reduced uptake and detoxification). The selectivity toward different organisms of these intrinsically unspecific compounds results from different transport-mechanisms and differences in the metabolism. The disadvantage is sometimes a higher toxicity toward warm-blooded animals and an increase in the possibility of other toxic effects like sensitization. 

---