# Antibiofilm Potential of Natural Essential Oils
## 4 ABF Activity of EOs and Their Components
### EOs as Antimicrobial Agents (Mechanisms of Action)
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Essential Oil Source** & **Pathogenic Microorganism** & **MIC** & **Reference** \\ \hline \multirow{2}{*}{_Croton condulpicatatus [PERSON] (Euphoriaceae)_} & _S. aureus_ ATCC 25923 (MSSA) & 256 \(\upmu\)g/mL & [33] \\  & _S. aureus_ ATCC 33591 (MRSA) & 512 \(\upmu\)g/mL & [33] \\ \hline \multirow{2}{*}{_Foenticulum vulgare Mill. (Apiaceae)_} & _S. aureus_ ATCC 29213 (MSSA) & 71.3 \(\pm\) 1.90 mg/mL & [34] \\  & _S. aureus_ ATCC 43300 (MRSA) & 60.30 \(\pm\) 0.00 mg/mL & [34] \\  & _S. aureus_ ATCC 6538 (MSSA) & 100.4 \(\pm\) 34.80 mg/mL & [34] \\ \hline \multirow{2}{*}{_Hysospus officinalis_ L. (Lamiaceae)_} & _C. albicans_ & 0.9 \(\pm\) 0.3 mg/mL & [32] \\  & _C. albicans_ * & 0.4 mg/mL & [32] \\  & _S. aureus_ * & 5 \(\upmu\)L/mL & [35] \\  & _S. aureus_ ** & 10 \(\upmu\)L/mL & [35] \\ \hline \multirow{2}{*}{_Rosmarirus officinalis_ L. (Lamiaceae)_} & _S. aureus_ * & 0.04\% (\(\upnu\)/\(\upnu\)) & [36] \\  & _S. aureus_ ATCC 9144 & 1.25-2.5 \(\upmu\)L/mL & [37] \\  & _S. epidermidis_ S61 & 0.312-0.625 \(\upmu\)L/mL & [37] \\ \hline \multirow{2}{*}{_Tagetes minuta_ L. (Asteraceae)_} & _P. aeruginosa_ PAO1 & 312.5 \(\upmu\)g/mL & [29] \\ \hline \multirow{2}{*}{_Tetraclinis articulata_ ([PERSON])_} & _S. aureus_ ATCC 25923 & 0.38 nL/mL & [38] \\  & _S. aureus_ ATCC 25923 & 0.38 nL/mL & [38] \\ \hline \multirow{2}{*}{_Thymbra capitata_ L. (Lamiaceae)_} & _P. aeruginosa_ (BL) & 1.11\% & [39] \\  & _P. aeruginosa_ 10145 & 1.11\% & [39] \\ \hline \multirow{6}{*}{_Thymus vulgaris_ L. (Lamiaceae)_} & _P. fluorescens_ KM121 & 20.0 \(\upmu\)L/mL & [31] \\  & _S. aureus_ * & 0.02\% (\(\upnu\)/\(\upnu\)) & [36] \\  & _S. aureus_ ** & 0.63\% (\(\upnu\)/\(\upnu\)) & [36] \\  & _Candidia albicans_ * & 0.4 mg/mL & [32] \\  & _Haemophilus influenzae_ & 0.156 mg/mL & [30] \\  & _H. paraninfluenzae_ & 0.156 mg/mL & [30] \\  & _P. aeruginosa_ & 1.50 mg/mL & [30] \\ \hline \multirow{2}{*}{_Zataria multiiflora_ [PERSON]. (Lamiaceae)_} & _P. aeruginosa_ ** & 4 \(\upmu\)L/mL & [40] \\ \hline \multirow{2}{*}{_Zingiber officinal_ Roscoe (Zingiberaceae)_} & _S. mutans_ & 21.25 \(\upmu\)L/mL & [41] \\ \hline \hline \end{tabular}  
* MIC—Minimum Inhibitory Concentration; MSSA—methicillin-sensitive _S. aureus_; MRSA—methicillin-resistant _S. aureus_; BL—beta lactamase producing.
* planktonic cells; *
* biofilm cells.  
\end{table} 
Table 1: Antimicrobial and antibifilim activity of essential oils (selected examples). The efficacy of EOs in combating BF-related infections in chronic wounds is often assessed using standard microbiological media and conditions that do not reflect the actual chronic wound environment. To address this problem, [PERSON] et al. [36] cultured _S. aureus_ BF in the In Vitro Wound Milieu (IVWM) medium, which closely resembles the chronic wound environment. The BF cultured in a standard Tryptic Soy Broth (TSB) medium served as a control. The cultured bacterial strains were exposed to TEO and _Rosmarinus officinalis_ EO (REO), and a larval model (_Galieria mellonella_ L.) was deployed to assess TEO cytotoxicity and AM activity in vivo. The conducted analyses showed that the key characteristics of BF-forming cells (biomass, metabolic activity, cell number, and live/dead cell ratio) were poorer in BF from the IV medium than in that from the TS medium. Conversely, BF thickness was greater (up to 25%) when the BF was cultured in the IV medium. These differences resulted in various BF responses to EO exposure. The use of TEO led to a greater (up to 2-fold) reduction of 67% of the BF-forming strains in the IV medium compared to the TS medium, while biofilm exposure to REO caused a greater reduction (up to 2.6-fold) of 83% of the BF-forming strains in TS than in the IV medium. TEO was not only non-toxic to _G. mellonella_ larvae, but also increased the survival rate of larvae infected with staphylococci (from 48 to 85%). These results suggest that EOs are promising agents for the treatment of BF-related wound infections. [PERSON] et al.