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Biochemical characterization of clinical strains of Staphylococcus spp. and their sensitivity to polyphenols-rich extracts from pistachio (Pistacia vera L.).

La Camera, E., C. Bisignano, G. Crisafi, A. Smeriglio, M. Denaro, D. Trombetta, G. Mandalari, 2018. Biochemical characterization of clinical strains of Staphylococcus spp. and their sensitivity to polyphenols-rich extracts from pistachio (Pistacia vera L.). Pathogens. 7(4). pii: E82. doi: 10.3390/pathogens7040082.

We characterized a number of clinical strains of Staphylococcus spp. and investigated their sensitivity against polyphenols-rich extracts from natural raw and roasted pistachios (NPRE and RPRE, respectively). Out of 31 clinical isolates of Staphylococcus spp., 23 were coagulase-positive and identified as S. aureus, of which 21 were MRSA. Polyphenols-rich extracts from natural pistachios and roasted pistachios were prepared: the total phenols content, expressed as gallic acid equivalent (GAE)/100 g fresh weight (FW), was higher in natural pistachios (359.04 ± 8.124 mg) than roasted pistachios (225.18 ± 5.055 mg). The higher total phenols content in natural pistachios also correlated to the higher free-radical scavenging activity found by DPPH assay: NPRE and RPRE showed IC50 values of 0.85 (C.L. 0.725⁻0.976 mg mL-1) and 1.15 (C.L. 0.920⁻1.275 mg mL-1), respectively. Both NPRE and RPRE were active against S. aureus 6538P and Staph. spp. clinical isolates, with RPRE being the most active (MIC values ranging between 31.25 and 2000 μg mL-1). The antimicrobial potential of pistachios could be used to identify novel treatments for S. aureus skin infections.