Abstract Phytomedicines are becoming more popular in treatment of infectious diseases worldwide. Cinnamomum verum essential oil (EO) has been used as a therapeutic alternative for various diseases. This study aimed to evaluate the antibacterial and antibiofilm activity of the C. verum leaf EO against Pseudomonas aeruginosa, Staphylococcus aureus and Klebsiella pneumoniae. Effect of EO vapor on planktonic cells was determined using microatmosphere technique. CLSI M7-A10 method was employed in Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) experiments. Effect of EO on established biofilms was quantified and visualized using XTT and Scanning Electron Microscope (SEM). In-vitro toxicity was evaluated using Human Keratinocytes (HaCaT). Chemical analysis of EO was done using Gas Chromatography- Mass Spectrometry (GC-MS). All tested strains were sensitive to cinnamon oil vapor. EO exhibited 0.5 and 1.0 mg/mL MIC and MBC against all test strains. Minimum Biofilm Inhibitory and Biofilm Eradication Concentrations (MBIC50 and MBEC) were 1.0 and 4.0 mg/mL. SEM indicated cellular shrinkages, cell wall damages, and decreased biofilm densities. Cinnamon oil didn’t show any toxicity on HaCaT cell at any concentration tested. Eugenol was the most abundant compound in C. verum oil. C. verum EO shows an antibacterial and antibiofilm activity with minimal toxicity on host.

As there are sparse data on the impact of growth media on the phenomenon of biofilm development for Candida we evaluated the efficacy of three culture media on growth, adhesion and biofilm formation of two pathogenic yeasts, Candida albicans and Candida tropicalis. The planktonic phase yeast growth, either as monocultures or mixed cultures, in sabouraud dextrose broth (SDB), yeast nitrogen base (YNB), and RPMI 1640 was compared, and adhesion as well as biofilm formation were monitored using MTT and crystal violet (CV) assays and scanning electron microscopy. Planktonic cells of C. albicans, C. tropicalis and their 1:1 co-culture showed maximal growth in SDB. C. albicans/C. tropicalis adhesion was significantly facilitated in RPMI 1640 although the YNB elicited the maximum growth for C. tropicalis. Similarly, the biofilm growth was uniformly higher for both species in RPMI 1640, and C. tropicalis was the slower biofilm former in all three media. Scanning electron microscopy images tended to confirm the results of MTT and CV assay. Taken together, our data indicate that researchers should pay heed to the choice of laboratory culture media when comparing relative planktonic/biofilm growth of Candida. There is also a need for standardisation of biofilm development media so as to facilitate cross comparisons between laboratories.