In Vitro time-course study to determine the effect of Nanocurcumin on Methicillin-resistant Staphylococcus aureus (MRSA) growth using optical density measurement

Background: Methicillin-resistant Staphylococcus aureus (MRSA) has been a significant clinical issue because of its resistance to common antimicrobial agents. Although nanocurcumin has been shown to have an antibacterial effect against MRSA, it is not yet well understood how it influences the dynamics of bacterial growth. This study aims to assess the impact of nanocurcumin on the kinetics of MRSA growth under continuous monitoring of optical density with particular dependence on the presence of mecA in the bacteria. Methods: Isolates of 50 S. aureus were obtained from clinical samples and tested on antimicrobial susceptibility. MRSA was confirmed molecularly by use of PCR which targeted the mecA gene. The efficacious concentrations of nanocurcumin were established by using predetermined MIC values to conduct an analysis on growth kinetics. MecA-positive MRSA isolates were subjected to 24-hour optical density to determine the growth dynamics in the presence of nanocurcumin. Results: The isolates were all identified as S. aureus, with 15 mecA-positive MRSA isolates exhibiting multidrug resistance but being sensitive to doxycycline and rifampicin. Nanocurcumin treatment led to a significant growth reduction starting from 4–6 hours. This resulted in a persistent negative growth rate of –0.012 ± 0.003 optical density/hour and a 90.6% reduction in total bacterial growth (AUC) compared to untreated controls. This implies a gradual decrease in bacterial viability, and not just growth inhibition. Conclusion: Nanocurcumin is fast and long-lasting in its ability to inhibit mecA-positive MRSA and highlights its strong potential in terms of addressing multidrug-resistant strains.