**5. Concluding remarks**

According to the theoretical bases discussed here, PDT deserves a more central position in the treatment of infectious diseases, since several studies report its enormous potential and applicability on several fronts.

Bacteriophages can act for delivering antimicrobial agents into bacteria, which consist in a potential and efficient alternative for the treatment of infectious diseases.

Delivery systems based on a phage-carrying PS exhibit increased effective killing by the concentrated fluence at the bacterial cell wall, and consequently, reduced side damage to the indigenous microbiota by the site singlet oxygen.

The discovery of new PSs and formulations based on nano structures, in addition to the use in conjunction with already established protocols, PDT shows itself as a strong alternative to conventional treatments.
