Purpose: The purpose of this study was to evaluate the effect of bioactive extracts from blueberry and blackberry pomaces and its major components against MRSA and rescue the inactive antibiotics supplemented with trace amount of bioactive berry pomaces extracts.
Methods: Two MRSA isolates, including one (C98) recovered from processed chicken meat and other one (COL, Sabath et al Ann N Y Acad. Sci. 1974, 236:435–43) as a reference strain, were used in this study. Antibiotic resistance of the MRSA was determined with agar dilution method as well as evaluated the presence or absence of specific antibiotic resistance genes by PCR. Synergistic or rescuing effect of bioactive extracts of berry pomace and antibiotics were checked in broth dilution methods.
Results: Bioactive pomace extracts of Blackberry (512 GAE µg/ml) and blueberry (256 GAE µg/ml) inhibited the growth of C98 and COL completely. Both MRSAs, C98 and COL, were resistant to a single or multiple antibiotics tested regardless the presence and absence of antibiotic resistance gene. The synergistic effect of bioactive berry pomace extracts and its major components with methicillin and erythromycin inhibited the growth of MRSA isolates and could reduce the MICs and make sensitive.
Significance: Bioactive extracts from berry pomace are potential alternative antimicrobials to treat MRSA infections and act synergistically with inactive antibiotics to reduce MIC significantly and make them further effective.