In Vitro Screening of the Antibacterial Activity of Bidens pilosa Flower Extract against Methicillin-Resistant Staphylococcus aureus Isolated from Wounds of Patients at National Polytechnic University Institute Laboratory

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of wound infections worldwide, associated with delayed healing, prolonged hospital stays, and increased treatment costs. The growing resistance of MRSA to conventional antibiotics highlights the urgent need for alternative therapies. This study evaluated the in vitro antibacterial activity of Bidens pilosa flower extracts against MRSA isolates from wound infections. A laboratory-based experimental design was employed at the National Polytechnic University Institute Laboratory. The fresh plant was collected, washed and dried away from sunlight. It was then crushed and blended to powder form and extraction was done. Extracts were prepared using aqueous, 50% ethanol, and 80% ethanol solvents, and their antibacterial activity was assessed through agar well diffusion and disk diffusion methods, inhibition zone measurements, and minimum inhibitory concentration (MIC) determination. Data was analyzed using SPSS version 23 and presented in tables and figures. Inferential statistics was computed using the t-test and the ANOVA test to assess for differences in mean values. Statistical significance was considered when p value was less than or equal to 0.05. Results showed that the 80% ethanol extract exhibited the strongest antimicrobial activity, producing a mean inhibition zone of 9.8 ± 1.7 mm, significantly higher than the 50% ethanol extract (6.8 ± 1.2 mm) and the aqueous extract (3.7 ± 0.5 mm) (F = 18.5, p = 0.003). Antibacterial activity decreased progressively with dilution, confirming a dose-dependent relationship. At ½ dilution, only the 80% ethanol extract retained activity (3.6 ± 0.6 mm), while aqueous and 50% ethanol extracts lost activity completely (0.0 ± 0.0 mm) (F = 54.3, p < 0.001). At ¼ dilution, the 80% ethanol extract still showed inhibition (2.1 ± 0.3 mm), and at ⅛ dilution, activity persisted (1.1 ± 0.1 mm) (F = 121.6, p < 0.001). MIC testing confirmed that the 80% ethanol extract had a measurable MIC of 12.5 mg/mL, while aqueous and 50% ethanol extracts showed no detectable MIC. Ethanol extracts of Bidens pilosa, particularly at 80% concentration, demonstrate significant antibacterial activity against MRSA, validating its traditional use in wound care. These findings provide preliminary scientific evidence supporting the potential of Bidens pilosa as a locally available, affordable alternative for managing resistant wound infections in resource-limited settings.