AUTHOR=Di Pierro Francesco , Sagheddu Valeria , Galletti Serena , Forti Mara , Elli Marina , Bertuccioli Alexander , Gaeta Simone 

TITLE=Antibacterial Activity of a Fractionated Pistacia lentiscus Oil Against Pharyngeal and Ear Pathogens, Alone or in Combination With Antibiotics

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.686942

DOI=10.3389/fmicb.2021.686942

ISSN=1664-302X

ABSTRACT=<p>Previous studies have clearly demonstrated that the addition of lentisk oil (LO) to streptococcal cultures makes it possible to differentiate <italic>Streptococcus</italic> spp. into three categories with <italic>Streptococcus mitis</italic> and <italic>Streptococcus intermedius</italic> sensitive, <italic>Streptococcus pyogenes</italic>, <italic>Streptococcus agalactiae</italic>, and <italic>Streptococcus mutans</italic> partially sensitive, and <italic>Streptococcus salivarius</italic> insensitive to the product. We have investigated here whether the winterization of LO, an easy and cheap procedure that removes some of the fatty substances contained within, resulted in a better antimicrobial effect on human pathogens affecting the pharyngeal mucosa and middle ear such as <italic>S</italic>. <italic>pyogenes</italic>, <italic>S</italic>. <italic>pneumoniae</italic>, <italic>Moraxella catarrhalis</italic>, and <italic>Haemophilus influenzae</italic>, without affecting, or minimally affecting, <italic>S</italic>. <italic>salivarius</italic> strains, oral probiotics commonly used to reduce oral and middle ear infection recurrence, especially in children. Our results not only demonstrated a stronger antimicrobial action of winterized LO (WLO) on <italic>S</italic>. <italic>pyogenes</italic>, compared to what was seen with LO, but also demonstrated a strong antimicrobial action vs. <italic>S</italic>. <italic>pneumoniae</italic> and <italic>M</italic>. <italic>catarrhalis</italic> and a very limited effect on <italic>S</italic>. <italic>salivarius</italic> (strains K12 and M18). Moreover, WLO demonstrated a co-acting action when tested along with the antibiotics amoxicillin (A) and amoxicillin clavulanate (AC), effects clearly visible also on <italic>H</italic>. <italic>influenzae</italic>. Our results also showed that at least part of the antimicrobial effect observed was due to the presence of anacardic acids (AAs). Finally, WLO, when tested with human peripheral blood mononuclear cells (h-PBMCs), reduced the release of IL-6 and TNF-α and, in the case of cells stimulated by LPS, the release of IFN-γ. In conclusion, our study highlights an enhanced antimicrobial role for LO when winterized, suggests a co-acting effect of this when given with antibiotics, identifies AAs as possible active ingredients, and proposes a possible anti-inflammatory role for it.</p>