Methicillin-resistant Staphylococcus aureus (MRSA) represent a major public health problem worldwide. This bacterium is associated with increased morbidity and mortality when compared with other pathogenic bacteria. The increase of its colonization rate affords the incrimination of infection rates in the population and hospitals leading significant rise in treatment cost. This situation become more complex when MRSA is acquiring resistance towards ciprofloxacin (Cipro), a broad-spectrum antibiotic commonly prescribed for treating bacterial infections. Recently, it was discovered that the 2-hexadecynoic acid (2-HDA) effectively inhibited the antibacterial activity of Gram-positive and Gram-negative bacteria as well as clinical isolates of MRSA (CIMRSA). In the present study, it was investigated whether 2-HDA, in combination with Cipro, improves the antibacterial activity of Cipro in CIMRSA strains. To perform this study, antibacterial activity of either 2-HDA or Cipro in six CIMRSA strains were tested by using broth-dilution susceptibility tests. Subsequently, Cipro-resistant CIMRSA strains were identified in those strains that displayed MIC values higher than 2 µg/mL. Once Cipro-resistant CIMRSA strains were identified, these bacteria were treated with equimolar concentrations of 2-HDA and Cipro. Preliminary results reveal that the combination of 2-HDA and Cipro were 2- to 16-fold more effective than Cipro in inhibiting the growth of five Cipro-resistant CIMRSA strains. In addition, results from S. aureus DNA gyrase inhibitory tests suggest that the combination of 2-HDA and Cipro increase the inhibitory effect on the DNA gyrase supercoiling activity when compared with Cipro alone. Results from this study will impact broadly the field by providing the first combinatorial study between Cipro and 2-HDA.

First investigation of the antibacterial activity of the combination of 2-hexadecynoic acid and ciprofloxacin against multi-drug resistant Staphylococcus aureus

2019 Spring National Meeting

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