Assessment of the Stability of Pseudomonas aeruginosa-specific Myoviridae Bacteriophages in Mupirocin and Abukhalsa Burnt Ointments

Background and Aim: Antibiotic resistance in bacterial infections poses a global health crisis, leading to over 1.27 million annual global deaths in 2019. Pseudomonas aeruginosa is the major cause of healthcare-associated infections, particularly in severe burn cases. The use of lytic phages in a mono- or combination therapy with antibiotics, can be helpful to combat antimicrobial-resistant infections in burn wound patients. This study explores stability in mupirocin and Abukhalsa of three P. aeruginosa-specific characterized and annotated phages (PA45, PA32, PA6) belonging to the Myoviridae group. Materials and Methods: Each phage was mixed with the mupirocin and Abukhalsa and incubated for 2, 4, and 24 hours at 37°C, with quantification using the agar-overlay method. The results were measured with a one-way analysis of variance statistical method (ANOVA) followed by Holm-Sidak’s multiple comparisons test. Results: The study shows that all three phages were stable above the effective therapeutic titer (ETT) which is considered 107 pfu/mL, with mupirocin more affecting phage activity and retaining efficacy after 24 hours. Notably, Abukhalsa inhibited phage activity even though phages remained active above the ETT after 24 hours. Conclusion: This study highlights the suitability of mupirocin and Abukhalsa ointments for the studied phages, sustaining their activity beyond the ETT for 24 hours. PA6 and PA32 (jumbo phage) were more stable than PA45 in both ointments tested. These findings emphasize the potency of further investigations for an effective topical combination treatment option in burn wound infections.