Receptor-Targeted Sequential Phage Dosing against Pseudomonas aeruginosa PAO1: An In Vitro Proof-of-Concept Study.

Abstract

PURPOSE: Antibiotic resistance has intensified the need for alternative therapies, such as bacteriophage administration. However, the optimal delivery strategy-specifically simultaneous versus sequential dosing-remains poorly defined for ensuring sustainable efficacy. This single-strain, in vitro proof-of-concept study evaluated receptor-targeted sequential dosing using phages Dobby, targeting lipopolysaccharide, and MPK7, targeting type IV pili, against P. aeruginosa PAO1. METHODS: Time-kill assays were conducted at various multiplicities of infection (MOI: 0.01, 1, and 100) to compare simultaneous and sequential dosing regimens. Resistance profiling was performed to assess the fitness costs of resulting isolates, while atomic force microscopy infrared spectroscopy (AFM-IR) was utilized to identify chemical signatures and underlying resistance mechanisms in phage-resistant mutants. RESULTS: Sequential treatment, particularly initiating therapy with the LPS-specific phage Dobby followed by MPK7, was more effective than simultaneous dosing, achieving bacterial reductions exceeding 3-log10 within 48 h. Notably, low MOI (0.01) sequential treatments maintained sustained population suppression, whereas high MOI (100) treatments triggered rapid bacterial rebound. Resistance profiling confirmed that Dobby-resistant isolates exhibited lower fitness costs, rendering them more susceptible to subsequent MPK7 treatment. AFM-IR revealed unique chemical alterations in resistant mutants, specifically linked to LPS truncation and TFP dysfunction. CONCLUSIONS: In the Dobby-MPK7-PAO1 model, receptor-specific sequential dosing produced more sustained bacterial suppression than simultaneous treatment. This proof-of-concept supports further evaluation of temporal phage dosing across diverse P. aeruginosa strains and phage combinations.

Abstract as supplied by the indexing source. © the authors / publisher.