Potentiation of the in vitro antistaphylococcal effect of oxacillin and tetracycline by the anti-inflammatory drug diacetyl rhein

Susceptibility of Staphylococcus aureus to Anti-Inflammatory Drugs with a Focus on the Combinatory Effect of Celecoxib with Oxacillin In Vitro

Musculoskeletal infections (MIs) are among the most difficult-to-treat staphylococcal diseases due to antibiotic resistance. This has encouraged the development of innovative strategies, such as combination therapy, to combat MI. The aim of this study was to investigate the in vitro antistaphylococcal activity of anti-inflammatory drugs and the combined antimicrobial effect of celecoxib and oxacillin. The minimum inhibitory concentrations (MICs) of 17 anti-inflammatory drugs against standard strains and clinical isolates of S. aureus, including methicillin-resistant strains (MRSAs), were determined using the broth microdilution method. The fractional inhibitory concentration indices (FICIs) were evaluated using checkerboard assays. Celecoxib produced the most potent antistaphylococcal effect against all tested strains (MICs ranging from 32 to 64 mg/L), followed by that of diacerein against MRSA3 and MRSA ATCC 33592 (MIC 64 mg/L). Several synergistic effects were observed against the tested S. aureus strains, including MRSA (FICI ranging from 0.087 to 0.471). The strongest synergistic interaction (FICI 0.087) was against MRSA ATCC 33592 at a celecoxib concentration of 2 mg/L, with a 19-fold oxacillin MIC reduction (from 512 to 26.888 mg/L). This is the first report on the combined antistaphylococcal effect of celecoxib and oxacillin. These findings suggest celecoxib and its combination with oxacillin as perspective agents for research focused on the development of novel therapies for MI caused by S. aureus. This study further indicates that celecoxib could resensitize certain MRSA strains, in some cases, to be susceptible to β-lactams (e.g., oxacillin) that were not previously tested. It is essential to mention that the in vitro concentrations of anti-inflammatory drugs are higher than those typically obtained in patients. Therefore, an alternative option for its administration could be the use of a drug delivery system for the controlled slow release from an implant at the infection site.

Anti-inflammatory Effects and Mechanisms of Rhein, an Anthraquinone Compound, and Its Applications in Treating Arthritis: A Review

Inflammation is a defensive response of living tissues to damaging agents, which exists in two forms, acute inflammation and chronic inflammation, and chronic inflammation is closely related to arthritis. Currently, the commonly prescribed anti-inflammatory medications are greatly limited by high incidence of gastrointestinal erosions in the clinical applications. Rhein, a bioactive constituent of anthraquinone, exhibits excellent anti-inflammatory activities and therapeutic effects on arthritis with less gastrointestinal damages. Although there are numbers of studies on anti-inflammatory effects and mechanisms of rhein in the last few decades, to the best of our knowledge, only a few review articles pay attention to the interactive relationships of rhein on multiple inflammatory signaling pathways and cellular processes from a comprehensive perspective. Herein, we summarized anti-inflammatory effects and mechanisms of rhein and its practical applications in the treatment of arthritis, thereby providing a reference for its basic researches and clinical applications.

In Vitro Antimicrobial Activity of Diacerein on 76 Isolates of Gram-Positive Cocci from Bacterial Keratitis Patients and In Vivo Study of Diacerein Eye Drops on Staphylococcus aureus Keratitis in Mice

Bacterial keratitis is an aggressive infectious corneal disease. With the continuing rise in antibiotic resistance and a decline in the discovery of new antibiotics, new antimicrobial drugs are now required. In the present study, we determined the antibacterial activity of diacerein, an anti-inflammatory drug, against 76 Gram-positive cocci isolated from bacterial keratitis patients in vitro and anti-Staphylococcus aureus activity in a mouse bacterial keratitis model in vivo The MICs of diacerein were tested using the broth microdilution method in vitro A BALB/c Staphylococcus aureus keratitis animal model was selected and the corneal clinical observation, viable bacteria, and hematoxylin-eosin and Gram staining of infected corneas were measured to evaluate the antibacterial efficacy of diacerein eye drops in vivo An in vivo eye irritation study was carried out by a modified Draize test in rabbits. Our in vitro results showed that diacerein possesses satisfactory antibacterial activity against the majority of Gram-positive cocci (60/76), including all 57 tested Staphylococcus spp. and 3 Enterococcus spp. The in vivo experiment showed that diacerein eye drops reduced bacterial load and improved ocular clinical scores after topical administration of diacerein drops on infected corneas. The ocular irritation test revealed that diacerein eye drop had excellent ocular tolerance. These results indicated that diacerein possesses in vivo anti-Staphylococcus aureus activity. We suggest that diacerein is a possible topically administered drug for Staphylococcus aureus-infected patients, especially those with ocular surface inflammatory disorders.