Multidrug resistance pumps (MDR pumps) of bacteria confer protection against aggressive environmental factors. The genes coding for MDR pumps are thought to be variable. They belong to the group of the so-called contingency genes, i.e are necessary for bacterial adaptation to the changing environment. The aim of the present work was to establish how conserved are the sequences of genes coding for MDR pumps. We analyzed the sequences of AcrA, AcrB and TolC proteins of different Escherichia coli strains. Using sequence alignment tools, we demonstrated that strains originating in different countries and cultured in the labs for a long time are amazingly conserved in terms of AcrAB-TolC sequences. They resemble housekeeping genes, suggesting the involvement of the AcrAB-TolC pump into permanent “cleaning” of various biotic and abiotic agents.