Synergistic effects of Psidium guajava and procaine penicillin on MRSA, MSSA and E. faecalis

Background: Antibiotic resistance is a significant public health challenge, exacerbated by resistant strains such as methicillin-resistant Staphylococcus aureus (MRSA). Aim: This study investigates the synergistic antibacterial effects of Psidium guajava aqueous extract combined with procaine penicillin against MRSA, methicillin-sensitive S. aureus (MSSA) and Enterococcus faecalis. Setting: In-vitro study conducted under controlled laboratory settings at the Mangosuthu University of Technology, Department of Biomedical Sciences, Kwa-Zulu Natal, South Africa. Methods: Psidium guajava leaves were collected and prepared according to the German Homeopathic Pharmacopoeia, while procaine penicillin was diluted for testing. The combination treatment was evaluated using the Kirby–Bauer Antimicrobial Sensitivity Test and Minimum Inhibitory Concentration (MIC) assays. Results: Results showed that the combination of P. guajava extract and procaine penicillin significantly enhanced the antibacterial activity against MRSA, as evidenced by larger zones of inhibition and lower MIC values compared to P. guajava extract and procaine penicillin on their own. However, no significant difference was observed against MSSA and E. faecalis. Conclusion: The findings suggest that P. guajava extract could potentiate the efficacy of procaine penicillin against MRSA, providing a potential alternative strategy to combat antibiotic-resistant bacteria. Contribution: The study revealed that P. guajava aqueous extract enhances the antibacterial efficacy of procaine penicillin specifically against MRSA, suggesting a potential alternative treatment strategy for antibiotic-resistant infections, validated through robust methods and highlighting the need for further research to understand the mechanisms and clinical applications.