Antibacterial and synergistic activity of a new 8-hydroxyquinoline derivative against methicillin-resistant Staphylococcus aureus

Aim: To evaluate the antibacterial and synergistic effect of a new 8-hydroxyquinoline derivative (PH176) against MRSA. Materials & methods: PH176 activity was determined by broth microdilution against 38 Staphylococcus aureus clinical isolates. The antibacterial and synergistic effects with oxacillin and nitroxoline were evaluated by time-kill assays to five MRSA isolates. Toxicity was evaluated by in vitro and ex vivo models. Results: The MIC50 and MIC90 of PH176 were 16 and 32 mu g/ml, respectively. The PH176 and nitroxoline led to a reduction in colony count for four isolates and the combination of PH176 and oxacillin acted synergically for three isolates. Furthermore, PH176 was determined to be noncytotoxic/nonirritant. Conclusion: These results demonstrate that PH176 has revealed promising results to be a potential candidate to treat MRSA infections.