Description
Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium responsible for several difficult-to-treat infections in humans. It may also be referred to as multidrug-resistant Staphylococcus aureus or oxacillin-resistant Staphylococcus aureus (ORSA). MRSA is by definition any strain of Staphylococcus aureus bacteria that is resistant to a large group of antibiotics called the beta-lactams, which include the penicillins and the cephalosporins.

MRSA has adapted to survive treatment with beta-lactam antibiotics, including methicillin, dicloxacillin, nafcillin, and oxacillin. MRSA is especially troublesome in hospital-associated (nosocomial) infections. In hospitals, patients with open wounds, invasive devices, and weakened immune systems are at greater risk for infection than the general public. Hospital staff who do not follow proper sanitary procedures may transfer bacteria from patient to patient. Visitors to patients with MRSA infections or MRSA colonization are advised to follow hospital isolation protocol by using gloves, gowns, and masks when indicated. Visitors, including health care providers, who do not follow such protocols are capable of spreading the bacteria to areas such as cafeterias, bathrooms, elevators, or various other surfaces.

MRSA is often sub-categorized as community-acquired MRSA (CA-MRSA) or health care-associated MRSA (HA-MRSA) although this distinction is complex. Some have defined CA-MRSA by characteristics of patients who develop an MRSA infection while other authors have defined CA-MRSA by genetic characteristics of the bacteria themselves. The first reported cases of community-acquired MRSA began to appear in the mid-1990s from Australia, New Zealand, the United States, the United Kingdom, France, Finland, Canada, and Samoa, notable because they involved people who had not been exposed to a health-care setting. The new CA-MRSA strains have rapidly become the most common cause of cultured skin infections among individuals seeking emergency medical care in urban areas of the United States. These strains also commonly cause skin infections in athletes, prisoners and soldiers. However, in a 2002 report about CRSA, many cases were children who required hospitalization.

The Cannabis Science™

Antibacterial Cannabinoids from Cannabis Sativa: a structure-activity study.

Marijuana (Cannabis sativa) has long been known to contain antibacterial cannabinoids, whose potential to address antibiotic resistance has not yet been investigated. All five major cannabinoids (cannabidiol (1b), cannabichromene (2), cannabigerol (3b), Delta (9)-tetrahydrocannabinol (4b), and cannabinol (5)) showed potent activity against a variety of methicillin-resistant Staphylococcus aureus (MRSA) strains of current clinical relevance. Activity was remarkably tolerant to the nature of the prenyl moiety, to its relative position compared to the n-pentyl moiety (abnormal cannabinoids), and to carboxylation of the resorcinyl moiety (pre-cannabinoids). Conversely, methylation and acetylation of the phenolic hydroxyls, esterification of the carboxylic group of pre-cannabinoids, and introduction of a second prenyl moiety were all detrimental for antibacterial activity. Taken together, these observations suggest that the prenyl moiety of cannabinoids serves mainly as a modulator of lipid affinity for the olivetol core, a per se poorly active antibacterial pharmacophore, while their high potency definitely suggests a specific, but yet elusive, mechanism of activity.