Investigation of Phage Activity in Combination with Thyme Oil Against Methicillin-Resistant Staphylococcus aureus (MRSA)

Introduction Methicillin-Resistant Staphylococcus aureus (MRSA) is an opportunistic pathogen that can cause resistant infections due to mecA gene that synthesizes Penicillin-binding protein 2a (PBP2a) which confers resistance against cephalosporin drugs. So, bacteriophages can serve as an alternative to developing antibacterial therapies alone, as well as in combination with essential oils that are isolated from several medicinal plants such as thyme oil. Thyme oil is an essential oil that is obtained mostly from garden thyme i.e., Thymus vulgaris. Hypothesis or Gap Statement The study was based on a hypothesis that the bacteriophage-thyme oil combination will produce a synergistic effect that will lead to improved antimicrobial and antibiofilm activity against Methicillin-Resistant Staphylococcus aureus. Aim This study aims to investigate the potential of bacteriophages in combination with Thyme oil against Methicillin-Resistant Staphylococcus aureus. Methodology Sewage water collected from sewage sites of hospitals was processed for the isolation of MRSA strain and bacteriophages. MRSA was confirmed by the detection of mecA gene through PCR and then Methicillin (5 µg), Oxacillin (1 µg), and Cefoxitin (30 µg) discs were used to check their activity according to Clinical Laboratory Standard Institute (CLSI) standards. Bacteriophage isolation was confirmed via spot assay and plaque assay was used to determine the phage titer. Also, phage lysate showed the activity against Staphylococcus capitis, but no activity was observed against Pseudomonas aeruginosa. Antibacterial activity of thyme oil was assessed via agar well diffusion assay. Phage suspension was assessed in combination with thyme oil against the MRSA biofilm. Results The phage lysate exhibited good lytic activity against MRSA biofilm and when used in combination with thyme oil (10% v/v), it showed more activity against MRSA biofilm. Conclusion The overall results of this study concluded that phages could work best against MRSA when used in combination with thyme oil due to improved activity.