Polyoxometalate Induces Susceptibility of Methicillin-Resistant Staphylococcus aureus to Oxacillin

Abstract

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 · 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, the POM showed low toxicity to mammalian cell cultures in vitro. The effect of the POM on mecA gene transcription was assessed using reverse transcriptase quantitative PCR (RT-qPCR) and showed a reduction in mRNA transcription at effective POM doses, but 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 would need to be completed.