Efficacy of phage vB_Ps_ZCPS13 in controlling Pan-drug-resistant Pseudomonas aeruginosa from urinary tract infections (UTIs) and eradicating biofilms from urinary catheters.

Abstract

Background: Pan-drug resistance (PDR) is a ticking time bomb, as it causes high human hospitalizations and mortality rates. For instance, Pseudomonas aeruginosa is associated with significant rates of urinary tract infections (UTIs) due to several reasons including antibiotic resistance, biofilm formation and the presence of various virulence factors. Consequently, there is an urgent need for safe and effective alternative antibacterials. Phage therapy is a promising alternative that uses naturally occurring bacteriophages (phages). Therefore, our present study investigated the isolation and characterization of a novel virulent phage (vB_Ps_ZCPS13) against the PDR Pseudomonas aeruginosa strain (Ps13).

Methods: Phage vB_Ps_ZCPS13 was isolated from raw sewage water in Egypt during the springtime. The isolated phage was purified and amplified, followed by estimating its purity and genome size using pulsed-field gel electrophoresis (PFGE), morphology using transmission electron microscopy (TEM), antibacterial activity against other P. aeruginosa hosts, physiochemical stability studies, whole genome sequencing, antibiofilm activity on urinary catheters using scanning electron microscopy (SEM), and cytotoxicity assays against normal human skin fibroblast (HSF) cell lines.

Results: Based on vB_Ps_ZCPS13 morphology under TEM, the phage has been classified as a myovirus. In consistent with the PFGE results, DNA sequencing revealed a phage genome size of 92,443 bp, with lytic-associated genes and no antimicrobial resistance or virulence factors. Phage vB_Ps_ZCPS13 presented a wide host range of over 93% of tested clinical isolates having different multiple antibiotic resistance (MAR) indices. Furthermore, phage vB_Ps_ZCPS13 exhibited high efficiency in plaque formation (EOP ≥ 1) against 13% of the strains and exhibited low frequencies of bacteriophage insensitive mutants (BIM). The physical stability test against harsh environmental conditions revealed phage stability within a pH range of 3.0-11.0 and stable at temperatures below 70 °C. Phage vB_Ps_ZCPS13 also exposed a significant antibacterial activity in vitro across different MOIs, with the highest reduction in bacterial growth observed at lower MOIs. Furthermore, vB_Ps_ZCPS13 demonstrated potent biofilm inhibition and clearance capabilities, effectively eradicating P. aeruginosa from the urinary catheter surface. Moreover, the phage presented no cytotoxicity against normal human skin fibroblast (HSF) cell lines at high titer.

Conclusions: Our study offers an effective phage as a therapeutic candidate against PDR Gram-negative P. aeruginosa infections, including catheter-associated urinary tract infections.