**3. Treatment**

One of the most important challenges for physicians is the adequate treatment of infections due to Gram-negative pathogens because of the increasing antimicrobial resistance in the healthcare setting [10].

Among infections caused by Gram-negative rods, *P. aeruginosa* has a leading role [11], especially in critically ill and immunocompromised patients. Antimicrobial resistance has led to a serious restriction in treatment options for *P. aeruginosa* infections.

An anti-pseudomonal cephalosporin, or a carbapenem, or an anti-pseudomonal β-lactam/BLI represents potential options for definitive therapy. Aminoglycosides should not be used as monotherapy because success rates for aminoglycosides are low [8]. This may be due to the poor penetration of aminoglycosides into the lung, which require high peak serum concentrations to obtain adequate lung concentrations, thus increasing the risk of nephrotoxicity or ototoxicity [12, 13]. However, because in Europe fluoroquinolone resistance rate in P. aeuruginosa exceeds 30% [14], it is appropriate to use combination therapy including aminoglycosides for empirical therapy of serious VAP. A based approach is recommended of the prescription of an anti-pseudomonal β-lactam (piperacillin/tazobactam, ceftolozane/ tazobactam, ceftazidime, cefepime, or a carbapenem) plus a second anti-pseudomonal agent (aminoglycoside or a fluoroquinolones). As for aerosol therapy, there is not routinely recommended the use of inhaled antibiotics for the treatment of *P. aeruginosa* VAP. However, they may be considered as an adjunctive to intravenous therapy in cases of infections due to MDR (Multi-drug resistance) strains [15].
