Detection of highly resistant strains of methicillin-resistant Staphylococcus aureus using polyoxotungstates

It was found that polyoxotungstates (POTs) such as undecatungstocobaltosilicate ([SiW11O39Co](6-)) greatly sensitize strains of methicillin-resistant Staphylococcus aureus (MRSA) to beta-lactam antibiotics by reducing the expression of penicillin-binding proteins. In this report, it is shown that MRSA strains with an extremely high resistance to beta-lactams were easily detected by adding a POT to the growth medium. When such a compound was mixed with the culture medium, the growth inhibition zone formed around a paper disk containing a beta-lactam antibiotic was significantly enlarged. However, colonies appeared inside the inhibition zone if the MRSA strain was highly resistant to the antibiotic.