Antimicrobial potential of Rhus coriaria, Hibiscus sabdariffa, Syzygium aromaticum and Punica granatum plant extracts against Streptococcus pneumoniae: An in vitro study

For a long time, traditional treatment has gained approbation of ancient people, elders and people under poverty. The antibiotic-resistant, Gram-positive, virulent bacterium Streptococcus pneumoniae is one of the most significant pathogens responsible for a wide range of nasopharyngeal infections. These infections are often persistent and difficult to treat due to the organism’s Gram-positive nature and multiple virulence factors, including a polysaccharide capsule that protects the bacterium from host defenses. In addition, S. pneumoniae rapidly develops mechanisms of antibiotic resistance, further complicating effective treatment. Finding a sustainable alternative treatment, particularly from plant sources, has gained traction due to the bacterium's increasing antibiotic resistance. Aqueous and alcoholic extracts of Rhus coriaria L., Hibiscus sabdariffa L., Syzygium aromaticum (L.) Merr. & L.M.Perry and Punica granatum L., were assayed on S. pneumoniae, which was diagnosed by biochemical tests. Sensitivity test was carried out in comparison with standard antibiotic disc. Cytotoxicity test on blood cells were also performed. The antimicrobial susceptibility assays showed that S. pneumoniae was moderately sensitive for R. coriaria, H. sabdariffa, S. aromaticum and P. granatum. These plant extracts can be suggested as a traditional treatment alternative to antibiotics.