Antibacterial Effects of Eucalyptus camaldulensis and Myrtus communis Methanolic Extracts on Methicillin-Resistant Staphylococcus aureus and Streptococcus mutans

Sogol  Nejadkarimi; Leila  Azimi; Kiarash  Ghasri; Soudabeh  Taheri; Narges  Panahandeh

doi:10.18502/jimc.v9i2.21189

Sogol Nejadkarimi Department of Restorative Dentistry, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran
Leila Azimi Pediatric Infections Research Center, Research Institute for Children’s Health, Tehran, Iran
Kiarash Ghasri School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran
Soudabeh Taheri Department of Microbiology, Medical Faculty, Shahid Beheshti University of Medical Sciences, Tehran, Iran
Narges Panahandeh Dental Research Center, Research Institute of Dental Sciences, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran

DOI: https://doi.org/10.18502/jimc.v9i2.21189

Keywords: Augar, Anti-bacterial agents, Eucalyptus, Methicillin-Resistant Staphylococcus aureus, Microbial sensitivity tests, Myrtus, Plant extracts, Streptococcus mutans

Abstract

Background: Considering the emergence of resistant microbial species, there is need for safe and effective alternatives to antibiotics. This study evaluated the antibacterial effects of Eucalyptus camaldulensis (E. camaldulensis) and Myrtus communis (M. communis) methanolic extracts on methicillin-resistant Staphylococcus aureus (MRSA) and Streptococcus mutans (S. mutans).

Methods: This in vitro study evaluated standard strains and clinical isolates of MRSA and S. mutans. The E. camaldulensis and M. communis methanolic extracts were obtained by the maceration technique, and their antibacterial activity against the aforementioned micro-organisms was evaluated by the agar well diffusion technique and measurement of growth inhibition zone diameter. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of the extracts were also determined against the tested micro-organisms by the broth microdilution technique.

Results: The M. communis extract had a MIC of 3.12 mg/mL and MBC of 6.25 mg/mL against most S. mutans isolates, and a MIC=MBC of 6.25 mg/mL against most MRSA isolates. The E. camaldulensis extract had a MIC=MBC of 12.5 mg/mL against most MRSA isolates and a MIC=MBC of 6.25 mg/mL against most S. mutans isolates. The two extracts had different effects on the two micro-organisms, and the M. communis extract caused a significantly larger growth inhibition zone in S. mutans culture than MRSA culture (p=0.046); however, the difference in this regard was not significant in use of E. camaldulensis (p=0.76).

Conclusion: The M. communis extract had significantly superior antibacterial effects on S. mutans and MRSA isolates than the E. camaldulensis extract.