A Review on Antibacterial Effects of Iranian Herbal Medicine on Methicillin-Resistant Staphylococcus aureus

Staphylococcus aureus (S. aureus) is an opportunistic pathogen that is able to cause different types of life-threatening infections from acute bacteremia to often chronic osteomyelitis, endocarditis, infections of indwelling devices and wound infections. These chronic infections are highly recalcitrant to antibiotic treatment. Owing to the increasing incidence of S. aureus infections and resistance with long-term treatment with available antibiotics, S. aureus is notorious. Research for new drugs, especially from natural sources is ongoing. Plants were commonly used in the treatment of diseases by a primary human from ancient times. Exhibiting minimum side effects, ease of use, availability, and commonly cost-effective are the advantages of plants. So in the last few decades, research on herbal medicine is getting popularized.

In this systematic review, we aimed to review antimicrobial potential of essential oil and different extracts (methanolic, ethanolic, ethyl acetate, ether or aqueous extracts) from 31 genera of medical plants, including 83 species against S. aureus and its most frequent resistant strain, methicillin-resistant S. aureus (MRSA) for introducing themas potent therapeutic agents. To find intended articles, we searched in several databases using a list of suitable keywords.

The essential oil of T. caucasicus has the best inhibitory effect on S. aureus. However, extract of 8 plant species has also the acceptable inhibitory effect. Surprisingly, essential oil of some plants showed better anti-staphylococcal effect than standard antibiotics. Moreover, twelve plant species have effective inhibitory effect against MRSA.

Some of the evaluated Iranian plants such as T. parthenium, T. vulgaris, T. eriocalyx, T. persicus, A. millefollum, P. harmala, H. scabrum, and S. urmiensis with acceptable MIC or inhibition zone have the potency of antimicrobial activity, especially against S. aureus and MRSA. According to the comparison, essential oil of Thymus caucasicus with the MIC value of 0.31 g/mL for S. aureus and 2.5 g/mL for MRSA has the best inhibitory effect. So the mentioned natural extract, especially essential oil of T. caucasicus can be a candidate for drug design with the goal of the treatment of S. aureus infections.