**11.5 The antibacterial activity of antibiotics**

322 Salmonella – A Dangerous Foodborne Pathogen

**Sesquiterpènes oxygénés 0.2**  Spathulénol 1561 2059 0.2 Caryophyllène oxyde 1567 1920 0.1 Globulol 1571 - tr **Autres 2.4**  Octen-3-ol 964 1357 1.3 Octen-3-one 980 1225 0.2 Carvacryl acetate 1345 1690 Tr Acetovanillone 1516 - 0.9

Table 3. Percentage and chemical composition of the HE part of the leaf of *T. maroccanus*

As has been reported in the literature, we considered that an essential oil has bacteriostatic action if the diameter of inhibition is greater than 12 mm (Baudoux, 2001; Sağdac ° 2003) or 15mm (Rossi, 2003). The diameters of inhibition zones obtained with the essential oils of *T. broussonetii* and *T. maroccanus*, from the region of Marrakech (Morocco), are 19 mm and 23 mm respectively. The essential oils acted actively on the growth of *Salmonella sp* responsible

*Salmonella sp.* 19±0.9 23±0.4 25±0.1 15±0.3

Table 4**.** Antibacterial activity of the essential oils of *Thymus broussonetii* (T.b.) and *Thymus* 

These values are reported as means ± standard deviations of three separate determinations.

The major activity of essential oils of *Thyme broussonetii* and *Thyme maroccanus* is due to their richness in phenolic compounds (thymol and carvacrol). Most antimicrobial compounds are phenols (carvacrol, thymol, eugenol), followed by alcohol (cineole, linalool ...) and to a lesser extent alkenes (p-cymene, pinene, terpinene ...) (Burt, 2004, Ultee et al., 2002). Indeed, several studies have shown that high antimicrobial power of essential oils of several species of thyme is attributed to their high phenolic compounds (carvacrol and thymol) (Marino et al. 1999; Mirmostafa and Rasool, 2002; Dafer and Ziogas , 2000; Baranauskiene et al. 2003; Di

Most of the work that had for its object the study of the mechanism of action of phenolic compounds suggests that their main site of action is the bacterial plasma membrane

*maroccanus* (T.m.) and from antibiotic expressed by diameter of inhibition zone.

Disc diameter. 6mm (Romane et al, 2010).

Pasqua et al. 2005; Di Pasqua et al. 2007; Cristan et al., 2007).

**11.4 In vitro effect of essential oils of** *T. broussonetii* **and** *T. maroccanus* 

for salmonellosis. They have an inhibitory effect on the growth of Salmonella sp.

IRa: Index of retention in non-polar chromatographic column HP-1

IRb: Index of retention in the polar chromatographic column HP-20, tr: trace

IRa IRb %

Inhibition Zone (mm) *Essential oil* Standard antibiotics *T.b. T.m.* Gentamicine Tetracycline The study by (Imelouane & ElBachiri, 2010) of the antibiotic susceptibility shows that the strain used is relatively sensitive to Florenfinicol, Spectinomycin, Enrofloxacin, Cotrimoxazole, Flumequine Tiafen, Tetracycline and Gentamycin. This sensitivity varies from one antibiotic to another and from one strain to another



Kf: Cephalothin; AMP: Ampiciline; AML:Amoxycilline; TPC:Tiafen; E:Erythromycine UB: Fluméquine ,SXT: Cotrimoxazole; MY:Lyncomycine ; ENR:Enrofloxacine ; SH : Spectinomycine; FFC: Florenfinicol

Table 5. Inhibitory effect of different antibiotic discs: Diameter of inhibition zones in mm among Salmonella sp.

The study of antibiotic susceptibility shows that the strain used is sensitive to Florenfinicol, Spectinomycin, Enrofloxacin, Flumequine, Tetracycline and Gentamycin. This sensitivity varies from one antibiotic to another (Table), while the strain is resistant to Cephalothin, Ampicillin, Amoxicillin and Lyncomycine.

Quantitative comparison of the results of EO to antibiotics is difficult because the nature of the activity and composition of the molecules are not comparable. Unlike EO, complex mixtures of volatile compounds that evaporate, but also that diffuse into the agar at different speeds, antibiotics are large non-volatile molecules. There Dissemination takes place probably at the surface and / or volume in the mass of the agar.


Table 6. Antibioaromatogramme of the essential oil of *Thymus pubenscens*. Diameter of inhibition zone of *Salmonella sp* determined using the diffusion method on solid medium.

Use Thyme Essential Oils for the Prevention of Salmonellosis 325

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