MRSA is a type of staph bacteria that causes a highly contagious infection that is resistant to many antibiotics. While it is often found in hospitals -- over five percent of admitted patients in the U.S. carry MRSA in their nose or on their skin -- people who live in crowded areas or those with activities that involve skin-to-skin contact or shared equipment and supplies are also at risk of infection. Most MRSA infections outside healthcare settings affect the skin, but it can also result in pneumonia and, in severe cases, sepsis -- the body's extreme response to infection. Infections in healthcare settings, in particular, can cause severe problems like bloodstream and surgical site infections. (Related: MRSA is NOT just in hospitals, new research discovers: The antibiotic-resistant superbug is spreading in the wild.)
For this study, the researchers investigated extracts obtained from rosemary and misty plume bush leaves, as well as pomegranate peels, to determine their efficacy against MRSA using multiple in vitro assays. They found that rosemary and misty plume bush -- a winter flowering plant native to riverbanks in Africa -- exhibited significant antibacterial activity against MRSA. While the team noted that pomegranate extract was moderately active against MRSA, it was still outperformed by the other plants. They also found that using the plant extracts together with penicillin resulted in a synergistic effect. As for the extracts' ability to inhibit the growth of biofilm, a complex formation of bacteria which have heightened resistance to antibiotic combinations, both rosemary and misty plume bush exhibited significant reductions in biofilm cells, based on data from scanning electron microscopy.
"The present results clearly show the anti-MRSA potential of R. officinalis, P. granatum, and T. riparia when considering the planktonic and biofilm modes of bacterial growth, which may contribute to the development of new strategies against S. aureus and infections caused by this pathogen," the researchers wrote in their report.
This study isn't the first to identify the antibacterial properties of these plants. In an earlier study in the Jordan Journal of Biological Sciences, researchers from Saudi Arabia's Mu'tah University found that rosemary, when used with Mediterranean sage, can potentially treat MRSA infections. The leaves of the two plants, in particular, exhibited significant bacteriostatic (inhibits bacterial growth and reproduction) and bactericidal properties based on in vitro tests.
Pomegranate rinds, on the other hand, can be developed to produce an ointment for treating MRSA and other infections in healthcare settings. Scientists from Kingston University in London used a series of tests to assess the efficacy of the rinds against various microbes taken from hospital patients including MRSA. They found that combining the rinds with metal salts and vitamin C increased their infection-fighting properties.
While limited studies are available on the antibacterial properties of misty plume bush, the Zulu people of southern Africa use the plant to treat chest complaints, stomachaches, and even malaria. The leaves, when crushed, can also relieve headaches.
Other plants that have been studied for their ability to combat MRSA infections include the Brazilian peppertree, which disrupts communication between MRSA bacteria and prevents biofilm formation. The plant, while native to South America, is abundant in Florida, where it's considered an invasive weed. Other additions include the California laurel and coffeeberry, two indigenous plants used in Native American medicine. In a study led by the Dominican University of California, researchers found that the two plants can be used as natural antibiotics against MRSA and other bacterial infections.