On the Horizon: The Antibiotic Potential of Cannabis
A Potential Weapon Against Antibiotic-Resistant Superbugs.
The World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) recognize antibiotic resistance as one of the biggest global public health threats of the 21st century. According to the CDC, antibiotic-resistant bacterial infections affect at least 2.8 million Americans each year; at least 35,000 patients die as a result, which translates to one death roughly every 15 minutes. According to WHO, deaths from antibiotic-resistant infections were estimated at 700,000 worldwide in 2016, and are predicted to increase to up to several million annually within the next few decades. The emergence and persistence of “superbugs”—bacteria that have evolved to be multidrug-resistant—are especially troubling, given that no new classes of antibiotics have been developed in more than 50 years.
Staphyolococcus aureus—one of the most common pathogens in health care settings—is responsible for skin infections. But the bacteria can migrate through the body, infecting other organs, including the heart, and causing bloodstream infection (sepsis). Methicillin-resistant S aureus (MRSA) is especially difficult to eradicate due to its antibiotic resistance, and fatal MRSA infections have recently increased in prevalence, according to the CDC.
The persistence of MRSA and other bacteria is due to their ability to form a biofilm—a complex and dense formation of cells surrounded by secreted polymers that allow the bacteria to coat surfaces; biofilms increase the bacteria’s resistance to antibiotics. S aureus biofilms have been found on implanted medical devices, such as heart valves, joint replacements, pacemakers, and catheters. A new antibacterial agent that’s effective against MRSA and other bacterial biofilms would be key in fighting antibiotic-resistant “superbugs.”
The antibiotic properties of cannabis have been known for millennia. Ancient Egyptian, Chinese, Arabic, Indian, and Greek civilizations documented its topical use as an antiseptic for wounds, leprosy, and other skin conditions, as well as its ingestion to treat lung and gastrointestinal infections.1 Unfortunately, the intoxicating properties of THC ultimately led to its use being criminalized, which was a primary cause of most other medicinal applications of cannabis languishing. Modern medical researchers investigated antibiotic properties in the 1950s and 1960s1 and again in 2008, when researchers found that several cannabinoid ingredients of cannabis demonstrated antibiotic activity against MRSA.2
CBD is being investigated as a potential new antibacterial agent. Research into its potential medical benefits has been vigorous, with hundreds of studies published in the last 10 years focusing primarily on relieving pain, inflammation, and anxiety. Studies of CBD as an antibiotic, however, have been few and far between since 2008. Now, some researchers are revisiting the use of CBD as an antibiotic, with the hope of finding a new antibacterial weapon to use against antibiotic-resistant bacteria.
In June 2019, the antibiotic potential of CBD made science and health news headlines when a group of Australian researchers presented laboratory research results at the American Society for Microbiology annual meeting. The researchers found that a synthetically produced CBD had a potency similar to that of common antibiotics (eg, vancomycin, daptomycin) against gram-positive bacteria, including Streptococcus pneumoniae and MRSA, but not gram-negative bacteria. CBD appeared to disrupt the bacterial biofilm, though an exact mechanism of CBD’s bactericidal action was not determined in this study. The researchers concluded that CBD is a promising new antibiotic, especially given its reported anti-inflammatory action that could also address inflammation associated with infection.3 Results of this study have not yet been published.
Then, in September 2019, a group of United Kingdom (UK) researchers published a groundbreaking study demonstrating a novel pathway on how naturally derived CBD acts against bacteria and increases the effectiveness of antibiotics.4 The study evaluated Escherichia coli and S aureus bacteria, and several commonly used antibiotics, including erythromycin, vancomycin, rifampicin, kanamycin, and colistin. Various species of bacteria have evolved resistance to these antibiotics.
Sigrun Lange, PhD, a senior lecturer in the School of Life Sciences at the University of Westminster in the UK, who designed and led the research study, says, “CBD in combination with different antibiotics was found to have more bacterial killing effects than the antibiotics alone.” She notes that this study is the first of its kind to identify and assess the effects of CBD on the release of bacterial membrane vesicles, essential cell components that help transfer material for bacterial communication, produce biofilm, and function as “traps” for antibiotics. In the study, CBD application to bacterial cultures affected the structure, composition, and number of membrane vesicles released from the bacteria, in particular from gram-negative types, such as E coli, the most common gram-negative pathogen in humans. “This indicates that CBD, in combination with specific antibiotics, may be used to selectively target bacteria to make them less antibiotic resistant via such membrane vesicle release alterations,” Lange says. “These findings reveal a significant new pathway of CBD-mediated antibiotic effects, and highlights that CBD added to antibiotic treatment may lead to the development of a novel adjunct treatment to help reduce antibiotic resistance.”
Research into the antibiotic potential of CBD is still in the laboratory setting. The timeframe for studies in humans remains uncertain at this time. Given this new understanding of CBD’s action against bacterial biofilm and reduced resistance to antibiotics via altered vesicle release, human studies are likely not far off, Lange says. Several companies are developing natural and synthetic CBD pharmaceuticals to treat various medical conditions, but no clinical trials for antibiotics have been registered yet. One company is planning a clinical trial to investigate topical CBD applied to the skin of preoperative patients to prevent postsurgical S aureus infections.
The development of CBD as a new type of antibiotic or as an enhancer of existing antibiotics and the introduction of CBD-based antibacterial products would represent a significant advance in the important global fight against antibiotic-resistant superbugs.
— Jennifer Van Pelt, MA, is a health care researcher and freelance writer in the Lancaster, Pennsylvania, area.
1. Kabelik J, Krejci Z, Santavy F. Cannabis as a medicament. United Nations Office on Drugs and Crime website. https://www.unodc.org/unodc/en/data-and-analysis/bulletin/bulletin_1960-01-01_3_page003.html. Published January 1, 1960.
2. Appendino G, Gibbons S, Giana A, et al. Antibacterial cannabinoids from cannabis sativa: a structure-activity study. J Nat Prod. 2008;71(8):1427-1430.
3. Blaskovich MAT, Kavanagh A, Ramu S, Levy S, Callahan M, Thurn M. Cannabidiol is a remarkably active gram-positive antibiotic. Paper presented at: American Society for Microbiology Microbe; June 23, 2019; San Francisco, CA.
4. Kosgodage US, Matewele P, Awamaria B, et al. Cannabidiol is a novel modulator of bacterial membrane vesicles. Front Cell Infect Microbiol. 2019;9:324.