A novel combination of a fluoroquinolone antibiotic and a widely used non-steroidal anti-inflammatory drug (NSAID) may offer a promising new approach to treating bacterial keratitis – particularly in the context of rising antimicrobial resistance.
In a recent preclinical study published in Scientific Reports, researchers evaluated the efficacy of combining topical levofloxacin 0.5% with ibuprofen 0.3% in a rat model of Staphylococcus aureus-induced keratitis. The rationale was twofold: to enhance antimicrobial activity and to address the inflammatory cascade that contributes significantly to corneal damage.
In the study, keratitis was induced in Sprague-Dawley rats, which were then treated with either levofloxacin alone, ibuprofen alone, or the combination therapy over a two-week period. The results were notable: the combination therapy consistently outperformed monotherapy across microbiological, molecular, and histological endpoints.
In vitro testing demonstrated a clear synergistic effect. The addition of ibuprofen reduced the minimum inhibitory concentration (MIC) of levofloxacin by up to eightfold, suggesting enhanced antibacterial potency. Moreover, ibuprofen independently exhibited anti-biofilm activity, significantly reducing Staphylococcus aureus biofilm formation – a key contributor to persistent infection.
At the tissue level, combination-treated corneas showed the lowest expression of inflammatory cytokines, as well as reduced activation of toll-like receptor 4 (TLR4), a central mediator of innate immune responses in the cornea. Matrix metalloproteinases (MMP-2 and MMP-9), which are implicated in stromal degradation and corneal ulceration, were also significantly downregulated.
Importantly, the therapy appeared to mitigate downstream pathological processes. Expression of VEGF-A was reduced, while pro-apoptotic signaling was attenuated. Histological analysis supported these findings, with near-normal corneal architecture observed in the combination group, compared with persistent inflammation and structural disruption in untreated and monotherapy groups.
While the findings are encouraging, the study authors emphasize that the data remain exploratory. The study is limited by its small sample size, short treatment duration, and reliance on transcriptional rather than protein-level analyses. Furthermore, only Staphylococcus aureus was evaluated, leaving questions about broader applicability to other pathogens such as Pseudomonas aeruginosa.
As antimicrobial resistance continues to challenge standard therapies, adjunctive strategies that combine anti-infective and anti-inflammatory mechanisms could represent a valuable evolution in keratitis management. However, safety considerations – particularly the known risk of corneal complications with topical NSAIDs – will require careful evaluation in future studies.
