Polyoxometalate Induces Susceptibility of Methicillin-Resistant Staphylococcus Aureus to Oxacillin

Transition metal inorganic compounds, also known as polyoxometalates (POM), have many biological applications, such as antiviral, antitumor, and antibacterial therapies. The objective of this study was to determine if the POM α-K₆P₂W₁₈O₆₂ · 14H₂O could overcome the resistance of methicillin-resistant Staphylococcus aureus (MRSA). To determine the minimal inhibitory concentration (MIC) and possible synergistic effects, multiple dilutions of oxacillin and POM were combined with inoculums of MRSA. Susceptibility (MIC ≤ 0.25 µg/mL oxacillin) was achieved at a concentration of 5 µM of α-K₆P₂W₁₈O₆₂ · 14H₂O. The POM enhanced the efficacy of oxacillin and additionally showed low toxicity to mammalian cell cultures in vitro. The effect of the POM on mecA gene transcription was assessed using reverse transcriptase–quantitative polymerase chain reaction and showed a reduction in messenger RNA transcription at effective POM doses; however, increased transcription was observed at higher POM oxacillin doses. This pilot study illustrates that α-K₆P₂W₁₈O₆₂ · 14H₂O could be used in conjunction with oxacillin. However, further testing needs to be completed.