**10. Conclusion**

In many healthcare facilities around the world, bacterial pathogens that express multiple resistance mechanisms are becoming the norm, complicating treatment and increasing both human morbidity and financial costs. Until now, no antibiotic therapy has been reported to eliminate most intracellular bacteria such us *Brucella* or *Mycobaterium* too. Furthermore, a prolonged exposure to combined antibiotics is required to reduce the disease relapses down to 5-15%. In this sense, drug delivery scientists are searching for the ideal nanovehicle for the ideal nanodrug delivery system; one that would dramatically reduce drug dosage, improve in the drug absorption so that the patient can take a smaller dose, and yet have the same benefit, deliver the drug to the right place in the living system, increase the local concentration of the drug at the favorite site and limit or eliminate side effects. Compared with other colloidal carriers, polymeric particles, mainly nanoparticles, have appeared more recently as attractive carriers for the delivery of drugs to infected cells. Synthetic biodegradable and biocompatible polymers have been shown to be effective for encapsulating a great variety of antibiotics. In addition, these polymeric particles powerfully enhance phagocytosis and are suitable for intracellular delivery of antibacterial agents. With the continuous attempts in this field, there is no doubt that nanoparticle-based drug delivery systems will continue to improve treatment to bacterial infections, particularly in life-threatening diseases such as tuberculosis infections. Today the application of nanotechnology in drug delivery is widely expected to change the scenery of pharmaceutical and biotechnology industries for the foreseeable future. Targetspecific drug therapy and methods for early diagnosis of pathologies are the precedency research areas where nanotechnology would play a prominent role.
