Potential antimicrobial effect of plant essential oils and virulence genes expression in methicillin-resistant Staphylococcus aureus isolates.

Mohammad H Gharaibeh,Esam M Zattout,Mohammad S Khalifeh,Luay F Abu-Qatouseh

doi:10.14202/vetworld.2020.669-675

Mohammad H Gharaibeh, Esam M Zattout + Show 2 more

Open Access

https://doi.org/10.14202/vetworld.2020.669-675

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Abstract

Aim:This study aimed to investigate the antibacterial efficacy of eight commercially available essential oil (EO) blends and characterize the effect on the expression of some virulence genes against methicillin-resistant Staphylococcus aureus (MRSA).Materials and Methods:In vitro evaluation of the antimicrobial effects of oils against MRSA was performed using the disk diffusion method and by measuring the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). The EOs (A-F) were contained (β-pinene, carvacrol, carvone, dimethyl trisulfide, linalool, limonene, menthol, monoterpene hydrocarbons, and thymol) in different amounts. In addition, a real-time polymerase chain reaction was also used to determine the gene expression of the virulence genes (intercellular adhesion cluster [ica]-9, ica-15, and RNA III) against MRSA (ATCC 43300) after treatment with selected oils.Results:Among the eight EOs evaluated, EO (D), (E), and (A) showed, in general, the greatest antimicrobial activity against MRSA. EO at 1/3 MIC has effectively down-regulated ica-9 and ica-15 of MRSA by 17.83 and 4.94 folds, respectively. Meanwhile, EO (A) has effectively down-regulated RNAIII by 3.74 folds. Our results indicated that some of the EOs exhibit promising antimicrobial effects against MRSA isolates. Moreover, the results of the analyzed virulence genes related to the pathogenicity of MRSA were down-regulated at the sub-MIC concentrations of EOs, indicated that EOs could be successfully used to suppress the virulence factors and, consequently, decreased the pathogenicity of MRSA.Conclusion:These encouraging results indicate that some of the EOs used in this study can be utilized as a natural antibiotic for the treatment of MRSA disease.

Highlights

Staphylococcus aureus is considered as the main pathogen among Gram-positive bacteria that cause nosocomial infections [1]
Our results indicated that some of the essential oil (EO) exhibit promising antimicrobial effects against methicillin-resistant S. aureus (MRSA) isolates
The results of the analyzed virulence genes related to the pathogenicity of MRSA were down-regulated at the sub-minimum inhibitory concentration (MIC) concentrations of EOs, indicated that EOs could be successfully used to suppress the virulence factors and, decreased the pathogenicity of MRSA

Summary

Introduction

Staphylococcus aureus is considered as the main pathogen among Gram-positive bacteria that cause nosocomial infections [1]. The first case of clinical methicillin-resistant S. aureus (MRSA) was reported 58 years ago [2]. S. aureus has become resistant to many commonly used antibiotics due to the improper use of antibiotics as well as to the genetic plasticity of MRSA [3]. The development of antibiotic resistance has started with penicillin; this resistance was overcome with the use of penicillinase-stable methicillin. The widespread use of methicillin and their derivatives (such as methicillin, oxacillin, cloxacillin, and flucloxacillin) has led to the re-emergence of MRSA, which is very difficult to treat [4].

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