Abstract
Introduction and objective: Phage therapy to treat chronic lung infections in patients with Cystic Fibrosis (CF) is attractive due to its safety, specificity, natural occurrence and ability to potentially be utilised as a targeted inhaled aerosol therapy. In vitro studies have also shown the ability of phages to penetrate bacterial biofilms and thus help eradicate them. This study was designed to evaluate the feasibility of isolating, propagating and purifying phages against bacterial isolates commonly seen in children with CF.
Methods: Nine clinical bacterial isolates of Staphylococcus aureus (n = 6), non-mucoid Pseudomonas aeruginosa (n = 2) and mucoid Pseudomonas aeruginosa (n = 1) were obtained from sputa of patients followed up in The Children’s Hospital at Westmead CF clinic. Phages for each strain were isolated from cocktails of environmental water samples. The lysates produced were extracted and subjected to phage propagation and purification using the Phage on Tap (PoT) protocol to produce high-titre homogenous phages.
Results: Fourteen morphologically distinct plaques were observed on the respective bacterial culture plates (S. aureus n = 8, P. aeruginosa n = 6). Five
phages (S. aureus n = 3 and P. aeruginosa n = 2) were selected and amplified to high titres (107 to 108 plaque-forming units [pfu]/mL). The 3 S. aureus phages showed highly isolate-specific lytic activity. Both P. aeruginosa phages that were isolated exhibited a wider host range against all of the P. aeruginosa clinical isolates tested, which included both mucoid and nonmucoid strains. The bactericidal activity was further demonstrated on a time-kill curve.
Conclusion: We were able to successfully isolate and purify phages with lytic activity against both mucoid and non-mucoid P. aeruginosa as well as S. aureus clinical isolates. This pilot study demonstrates the feasibility of isolating phages that may potentially be useful in the treatment of CF patients with chronic respiratory infections.
Methods: Nine clinical bacterial isolates of Staphylococcus aureus (n = 6), non-mucoid Pseudomonas aeruginosa (n = 2) and mucoid Pseudomonas aeruginosa (n = 1) were obtained from sputa of patients followed up in The Children’s Hospital at Westmead CF clinic. Phages for each strain were isolated from cocktails of environmental water samples. The lysates produced were extracted and subjected to phage propagation and purification using the Phage on Tap (PoT) protocol to produce high-titre homogenous phages.
Results: Fourteen morphologically distinct plaques were observed on the respective bacterial culture plates (S. aureus n = 8, P. aeruginosa n = 6). Five
phages (S. aureus n = 3 and P. aeruginosa n = 2) were selected and amplified to high titres (107 to 108 plaque-forming units [pfu]/mL). The 3 S. aureus phages showed highly isolate-specific lytic activity. Both P. aeruginosa phages that were isolated exhibited a wider host range against all of the P. aeruginosa clinical isolates tested, which included both mucoid and nonmucoid strains. The bactericidal activity was further demonstrated on a time-kill curve.
Conclusion: We were able to successfully isolate and purify phages with lytic activity against both mucoid and non-mucoid P. aeruginosa as well as S. aureus clinical isolates. This pilot study demonstrates the feasibility of isolating phages that may potentially be useful in the treatment of CF patients with chronic respiratory infections.
| Original language | English |
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| Number of pages | 2 |
| DOIs | |
| Publication status | Published - 1 Jun 2020 |