**10. Conclusions**

In the preantibiotic era [81], it was showed that from 30 lyophilized strains before 1950, four were multidrug resistant. The study of bacterial resistance can contribute to the discovery of the potential sources and novel alleles of antibiotic resistance genes. Considering that antibiotic treatment is our primary, and in many cases only, method of treating infectious diseases. We conclude that studies of environmental reservoirs of resistance are crucial to our future ability to fight infection. It is important to establish measures and politics to control the use of antibiotics, but an immediate modification of resistant profile in bacteria is not expected. Patients may follow procedures and use the antibiotics according prescription. The usual techniques of hand wash and use of barriers to prevent bacterial spread is important.

In the experiments, the FDU-12/silver nanoparticles showed the greatest inhibition in the growth of *E. coli*, as was observed fewer colonies or even their absence. Based on these results, we can infer that the best nanoparticle, among tested to inhibit the growth of *E. coli* is described above. The second nanocomposites with proven efficiency in inhibiting the growth of *E. coli* were nanoparticles containing only FDU-12, with an intermediate efficiency. The last nanoparticle studied, FDU-12/lignin/silver, showed the lowest efficiency in inhibiting the growth of *E. coli*, allowing a greater number of colonies to grow in the culture medium.
