Antimicrobial and synergistic effects of lemongrass and geranium essential oils against Streptococcus mutans, Staphylococcus aureus, and Candida spp.

Figure 1 Reduction of Streptococcus mutans monotipic biofilm (in %) calculated using the MTT test after treatment with experimental groups. Data are presented as the mean ± standard deviation. Statistical analysis was performed using one-way analysis of variance with Tukey’s post-hoc test (n = 10, α = 0.05). Statistical significance is indicated as follows: ^aP ≤ 0.0001 vs the control group, ^bP < 0.0025 vs Cymbopogon schoenanthus 32%, and ^cP < 0.0001 vs C. schoenanthus 64%. A: Streptococcus mutans biofilm treated for 5 min with C. schoenanthus at various concentrations; B: S. mutans biofilm treated for 24 h with C. schoenanthus at various concentrations; C: S. mutans biofilm treated for 5 min with Pelargonium graveolens at various concentrations; D: S. mutans biofilm treated for 24 h with P. graveolens at various concentrations.

Figure 2 Reduction of Staphylococcus aureus monotipic biofilm (in %) calculated using the MTT test after treatment with experimental groups. Data are presented as the mean ± standard deviation. Statistical analysis was performed using one-way analysis of variance with Tukey’s post-hoc test (n = 10, α = 0.05). Statistical significance is indicated as follows: ^aP ≤ 0.0001 vs the control group, ^bP < 0.0025 vs Pelargonium graveolens 4%, and ^cP < 0.0001 vs all synergistic groups. A: Staphylococcus aureus biofilm treated for 5 min with Cymbopogon schoenanthus at various concentrations; B: S. aureus biofilm treated for 24 h with C. schoenanthus at various concentrations; C: S. aureus biofilm treated for 5 min with P. graveolens at various concentrations; D: S. aureus biofilm treated for 24 h with P. graveolens at various concentrations; E: S. aureus biofilm treated for 5 min with C. schoenanthus (C) and P. graveolens (P), combined, at various concentrations; F: S. aureus biofilm treated for 24 h with C. schoenanthus (C) and P. graveolens (P) combined, at various concentrations.

Figure 3 Reduction of Candida albicans monotipic biofilm (in %) calculated using the MTT test after treatment with experimental groups. Data are presented as the mean ± standard deviation. Statistical analysis was performed using one-way analysis of variance with Tukey’s post-hoc test (n = 10, α = 0.05). Statistical significance is indicated as follows: ^aP ≤ 0.0004 vs the control group, ^bP ≤ 0.0001 vs the control group and ^cP ≤ 0.0001 vs nystatin. A: Candida albicans biofilm treated for 5 min with Cymbopogon schoenanthus at various concentrations; B: C. albicans biofilm treated for 24 h with Cy. schoenanthus at various concentrations; C: C. albicans biofilm treated for 5 min with Pelargonium graveolens at various concentrations; D: C. albicans biofilm treated for 24 h with P. graveolens at various concentrations.

Figure 4 Reduction of Candida krusei monotipic biofilm (in %) calculated using the MTT test after treatment with experimental groups. Data are presented as the mean ± standard deviation. Statistical analysis was performed using one-way analysis of variance with Tukey’s post-hoc test (n = 10, α = 0.05). Statistical significance is indicated as follows: ^aP ≤ 0.04 vs the control group and ^bP ≤ 0.0001 vs the control group. A: Candida krusei biofilm treated for 5 min with Cymbopogon schoenanthus at various concentrations; B: C. krusei biofilm treated for 24 h with Cy. schoenanthus at various concentrations; C: C. krusei biofilm treated for 5 min with Pelargonium graveolens at various concentrations; D: C. krusei biofilm treated for 24 h with P. graveolens at various concentrations.

Figure 5 Reduction of Candida dubliniensis monotipic biofilm (in %) calculated using the MTT test after treatment with experimental groups. Data are presented as the mean ± standard deviation. Statistical analysis was performed using one-way analysis of variance with Tukey’s post-hoc test (n = 10, α = 0.05). Statistical significance is indicated as follows: ^aP ≤ 0.007 vs the control group, ^bP ≤ 0.0005 vs the control group, and ^cP ≤ 0.01 vs the control group. A: Candida dubliniensis biofilm treated for 5 min with Cymbopogon schoenanthus at various concentrations; B: C. dubliniensis biofilm treated for 24 h with Cy. schoenanthus at various concentrations; C: C. dubliniensis biofilm treated for 5 min with Pelargonium graveolens at various concentrations; D: C. dubliniensis biofilm treated for 24 h with P. graveolens at various concentrations.