In Vitro Newly Isolated Environmental Phage Activity against Biofilms Preformed by Pseudomonas aeruginosa from Patients with Cystic Fibrosis.

Ersilia Vita Fiscarelli,Arianna Pompilio,Veronica Lupetti,Paola Rosati,Nour Essa,Valentina Crocetta,Giovanni Di Bonaventura,Martina Rossitto,Andrea Di Giulio

doi:10.3390/microorganisms9030478

Abstract

As disease worsens in patients with cystic fibrosis (CF), Pseudomonas aeruginosa (PA) colonizes the lungs, causing pulmonary failure and mortality. Progressively, PA forms typical biofilms, and antibiotic treatments determine multidrug-resistant (MDR) PA strains. To advance new therapies against MDR PA, research has reappraised bacteriophages (phages), viruses naturally infecting bacteria. Because few in vitro studies have tested phages on CF PA biofilms, general reliability remains unclear. This study aimed to test in vitro newly isolated environmental phage activity against PA isolates from patients with CF at Bambino Gesù Children’s Hospital (OBG), Rome, Italy. After testing in vitro phage activities, we combined phages with amikacin, meropenem, and tobramycin against CF PA pre-formed biofilms. We also investigated new emerging morphotypes and bacterial regrowth. We obtained 22 newly isolated phages from various environments, including OBG. In about 94% of 32 CF PA isolates tested, these phages showed in vitro PA lysis. Despite poor efficacy against chronic CF PA, five selected-lytic-phages (Φ4_ZP1, Φ9_ZP2, Φ14_OBG, Φ17_OBG, and Φ19_OBG) showed wide host activity. The Φ4_ZP1-meropenem and Φ14_OBG-tobramycin combinations significantly reduced CF PA biofilms (p < 0.001). To advance potential combined phage-antibiotic therapy, we envisage further in vitro test combinations with newly isolated phages, including those from hospital environments, against CF PA biofilms from early and chronic infections.

Highlights

All phages isolated on MA4 were able to infect PAO1, MA1, and MA3 cystic fibrosis (CF)
When the PAO1 strain was used for the three infection cycles needed for isolating single phages, each of the 7-phage stock infected various CF Pseudomonas aeruginosa (PA)
Combination failed to reduce the PAO1 biofilm [18]. Our study brings this result into question by providing in vitro evidence that Φ4_ZP1-MPM and Φ14-TOB combinations compared with antibiotics alone against clinical CF PA isolates from various lung infection stages exhibit an improved effect in reducing PA biofilm biomasses (Figures 4 and 5)

Summary

Introduction

Colonizes the lungs, causing pulmonary failure and mortality. Because few in vitro studies have tested phages on CF PA biofilms, general reliability remains unclear. This study aimed to test in vitro newly isolated environmental phage activity against PA isolates from patients with CF at Bambino Gesù Children’s Hospital (OBG), Rome, Italy. After testing in vitro phage activities, we combined phages with amikacin, meropenem, and tobramycin against CF PA pre-formed biofilms. In about 94% of 32 CF PA isolates tested, these phages showed in vitro PA lysis. To advance potential combined phage-antibiotic therapy, we envisage further in vitro test combinations with newly isolated phages, including those from hospital environments, against CF PA biofilms from early and chronic infections. Cystic fibrosis (CF), a common genetic disease among Caucasian populations, has a typically poor prognosis related to recurrent bacterial lung infections.

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Conclusion