Elizabeth Hofheinz, M.P.H., M.Ed.
With bacterial resistance an ongoing issue, surgeons need more tools to combat this scourge. A new pilot study performed at Loma Linda University set out to test the phenolic compound protocatechuic acid (PCA). The work, “Protocatechuic Acid as a Topical Antimicrobial for Surgical Skin Antisepsis: Preclinical Investigations,” was published in the July-September 2020 edition of JBJS Open Access.
Co-author Omid Jalali, M.D. is with the Keck School of Medicine of the University of Southern California. He commented to OSN, “The motivation for this study stemmed from a need for novel skin antiseptic agents to combat the rising health-care burden associated with surgical site infection (SSI). In conjunction with the rising number of orthopaedic surgeries being performed annually, microbial resistance and a lack of development of novel antimicrobials have contributed to the increasing prevalence of surgical site infections. To ensure orthopedic surgeries can continued to be performed safely and to combat the healthcare and economic burden associated with SSI, investigations into alternative skin antiseptic agents are of paramount importance, with the hope of identifying reagents with a broad spectrum of utility, adequate skin penetration, and without a history of overuse or resistance.”
Seeking broad-spectrum antimicrobial agents
“Natural substrates with antimicrobial properties have recently emerged as possible sources of novel antimicrobials,” said Dr. Jalali. There is mounting evidence that phenolic compounds in particular function as broad-spectrum antimicrobial agents, including activity against drug-resistant organisms, and demonstrate potent skin penetration properties when applied topically. However, most recent investigations involving these compounds have focused on plant extracts, of which the exact ingredients and dosages are not well described, limiting the feasibility for studies of potential clinical applications of the antimicrobial effects associated with these compounds.”
“Based on the results of our laboratory testing, we sought to explore the potential clinical application of PCA as a topical agent for deep, penetrating skin antisepsis using a mouse model of C. Acnes dermal infection. When administered topically, daily application of 78 mM of PCA resulted in a 13.8-fold (p=0.0295) reduction in C. Acnes bacterial loads per gram of mouse skin. Lower tested doses of PCA (39 and 19.5 mM) failed to show an effect.”
Down with bacterial loads
“Compared with other polyphenols,” said Dr. Jalali to OSN, “Protocatechuic Acid (PCA) demonstrated the broadest spectrum of antimicrobial activity in laboratory testing against pathogens implicated in surgical site infection, including drug-resistant organisms. Furthermore, topical PCA demonstrated a dose-dependent reduction in intradermal bacterial loads in a mouse model of skin infection. These findings lay the groundwork for studies exploring the antimicrobial efficacy of topical PCA in human skin and provide a theoretical basis for the application of PCA as a deep, penetrating topical skin antiseptic to combat surgical site infection. As a next step toward the potential clinical translation of these findings, our group performed a pilot study involving the human shoulder in which we explored the application of topical PCA for shoulder skin antisepsis in human subjects (separate study).”