Interaction of beauvericin in combination with antibiotics against methicillin-resistant Staphylococcus aureus and Salmonella typhimurium

Multidrug resistance in bacteria is a major challenge worldwide, increasing both mortality by infections and costs for the health systems. Therefore, it is of utmost importance to find new drugs against resistant bacteria. Beauvericin (BEA) is a mycotoxin produced by entomopathogenic and other fungi of the genus Fusarium . Our work determines the effect of BEA combined with antibiotics, which has not been previously explored. The combination analysis included different antibiotics against non-methicillin-resistant Staphylococcus aureus (NTMRSA), methicillin-resistant Staphylococcus aureus (MRSA), and Salmonella typhimurium . BEA showed a synergy effect with oxacillin with a fractional inhibitory concentration index (FICI) = 0.373 and an additive effect in combination with lincomycin (FICI = 0.507) against MRSA. In contrast, it was an antagonist when combined with ciprofloxacin against S. typhimurium. We propose BEA as a molecule with the potential for the development of new therapies in combination with current antibiotics against multidrug-resistant bacteria.