Skin infections caused by multidrug-resistant (MDR) Pseudomonas aeruginosa are difficult to treat because of high virulence and increasing resistance to conventional antibiotics. The authors investigated combined strategies that pair photodynamic therapy (PDT) with nanotechnology and conventional antibiotics. Specifically, curcumin was nanoencapsulated in bovine serum albumin nanoparticles (NanoBSA) with distinct surface charges (anionic and cationic) and evaluated in combination with the aminoglycoside amikacin in a murine model of cutaneous MDR P. aeruginosa infection.
This pilot in vivo study used 22 BALB/c mice infected with an MDR P. aeruginosa strain. Treatment arms included free curcumin or nanoencapsulated curcumin (anionic and cationic NanoBSA), administered with or without amikacin, followed by light activation for PDT. The trial structure and group allocation were those of a pilot study; detailed dosing schedules and exact group sizes beyond the total of 22 animals were not reported in the source abstract.
All procedures were performed under institutional and national guidelines for laboratory animal care. The experimental protocol received Ethics Committee on Animal Use (CEUA) approval under protocol number NA08/CEUA 2024.
Curcumin served as the photosensitizer and was administered either free or encapsulated within bovine serum albumin nanoparticles engineered to carry an anionic or cationic surface charge. After administration, infected sites were irradiated at 450 ± 10 nm to activate the curcumin-mediated photodynamic effect. The source abstract does not report further formulation details such as particle size, zeta potential values, curcumin loading efficiency, or specific amikacin dosing regimens.
To assess therapeutic effects, the investigators collected blood and skin samples from the infected areas. Analyses included measurement of lesion area change, leukocyte profiling, serum inflammatory cytokine quantification, and histopathological examination of tissue repair and structural preservation. Bacterial load quantification was not performed and is explicitly cited as a limitation.
Combination therapy comprising PDT with NanoBSA and amikacin led to a greater reduction in lesion area compared with other tested conditions. Among nanoparticle formulations, the anionic NanoBSA formulation produced the most pronounced decrease in lesion size. These macroscopic findings support a beneficial effect of pairing nanoencapsulated curcumin PDT with an antibiotic in this model of MDR P. aeruginosa skin infection.
Leukocyte analyses indicated that treatment regimens including amikacin were associated with modulation of the inflammatory response. A more balanced leukocyte profile was observed in groups treated with amikacin, notably when combined with the anionic NanoBSA formulation. Serum cytokine measurements also showed evidence of inflammatory modulation; this effect was most evident with the cationic NanoBSA combined with amikacin. Specific cytokines measured and their numeric results were not detailed in the abstract.
Histological assessment of infected skin revealed improved tissue reorganization and better structural preservation in groups receiving combination therapy. The anionic NanoBSA formulation stood out in histological comparisons for promoting tissue repair and maintaining structural integrity in the treated areas. The abstract does not provide quantitative histology scores or representative micrographs within the text provided.
A primary limitation stated by the authors is that bacterial load was not quantified in this study. Without direct measures of bacterial counts, antimicrobial efficacy cannot be conclusively established, and the mechanisms underlying the observed lesion reduction and tissue repair remain incompletely defined. The authors recommend that future studies incorporate bacterial quantification assays to confirm antimicrobial activity and to clarify how PDT, NanoBSA charge, and amikacin interact mechanistically. Additional experimental details such as precise dosing, nanoparticle physicochemical characterization, and group sizes were not reported in the abstract and should be detailed in subsequent work or the full text.
In this pilot murine study, PDT mediated by curcumin-loaded bovine serum albumin nanoparticles combined with amikacin improved macroscopic lesion outcomes, modulated inflammatory responses, and enhanced histological tissue repair in a model of MDR Pseudomonas aeruginosa skin infection. The anionic NanoBSA formulation produced the most consistent benefit for lesion reduction and histological preservation, while the cationic NanoBSA plus amikacin showed notable cytokine modulation. The absence of bacterial load data limits conclusions about direct antimicrobial effects; future experiments should include microbial quantification to validate and extend these findings.