INTRODUCTION
Infections caused by extremely resistant Pseudomonas aeruginosa (XDR) are a clinical challenge due to the lack of effective and safe therapeutic options. In this scenario, Ceftolozane-Tazobactam (CFT-TZB), a new drug with high bactericidal activity against P.aeruginosa (including XDR strains) which has been recently approved for the treatment of complicated intra-abdominal and urinary tract infections could be useful.

PURPOSE
To describe our experience in the use of CFT-TZB in patients with nosocomial pneumonia due to XDR-P.aeruginosa developed in the postoperative period during their admission to ICU.

METHODS
A retrospective analysis (January 2016-February 2017) of patients with nosocomial pneumonia by XDR-P.aeruginosa admitted to ICU and treated with CFT-TZB was carried out. The main variables analyzed were: type of sample, antibiotic sensitivity, treatment regimen (dose, duration, combination of drugs), side effects, efficacy and development of antibiotic resistance during treatment.

RESULTS AND DISCUSSION
We have analyzed 6 patients diagnosed with nosocomial pneumonia in the post-surgery period. Respiratory samples were cultured (5BAS / 1 sputum) and in all of them XDR P.aeruginosa was isolated. Antibiograms showed similar patterns of microbial resistance: the pathogen was sensitive to colistin ev (MIC <0.5-2mg / dL) and presented variable sensitivity to amikacin (MIC <8-> 32mg / dL) and meropenem (MIC 8-> 32mg / dL).
In all cases, rescue treatment with CFT-TZB was started due to poor clinical evolution after treatment with colistin ev and after checking that the germs were sensitive to the antibiotic. CFT-TZB was administered ev in 30 minute boluses. The dose was 1g/8h in most patients (4), and 2g/8h in the rest of them, for at least 2 weeks. Combination therapy was performed in the majority of cases (4): CFT-TZB + nebulized colistin, CFT-TZB + colistin ev + nebulized colistin, CFT-TZB + meropenem ev; only in 2 patients was the drug administered as monotherapy.
No side effects or resistances were reported during the treatment. All patients achieved clinical cure. The cultures of respiratory samples were negative in 5 cases while one patient presented persistent colonization by XDR P.aeruginosa.

CONCLUSION
CFT-TZB could be an effective option for the treatment of respiratory infections by XDR P.aeruginosa, however, further studies are needed. 


06 / “Ceftolozane-Tazobactam for the treatment of nosocomial pneumonia caused by extremely resistant Pseudomonas aeruginosa”.