Background: Antibiotic resistance is today one of the most serious threats to global health, food
security and development. Due to the growing number of infections, treatment becomes more difficult, if
not impossible, because of the loss of antibiotic efficacy.
Objectives: In the present investigation, the chemical composition of essential oils of Ammoides verticillata
and Satureja candidissima and their synergistic effects on antimicrobial activities were investigated.
Methods: The chemical composition of the essential oil was analyzed by Gas Chromatography (GC) and
Gas Chromatography-Mass Spectroscopy (GC/MS). The antimicrobial activity of the essential oils was investigated
using dilution-agar method against nine bacterial strains three Gram-negative Escherichia coli
(ATCC 25922), Pseudomonas aeruginosa (ATCC 27853) and Salmonella typhi (ATCC 14028), and six
Gram-positive: Staphylococcus aureus (ATCC 43300,) Clostridium sporogenes (ATCC 19404), Bacillus
subtilis (ATCC 6633), Enterococcus faecalis (ATCC 7314), Lactobacillus rhamnosus (ATCC 53103) and
Bacillus cereus (ATCC 14579).
Results: The essential oil of A. verticillata was characterized principally by carvacrol (44,3%), Limonene
(19,3%) and p-cymene (19,2%). The constituents identified of S. candidissima essential oil were principally
oxygenated monoterpenes represented by pulegone (70,4%). The essential oil of A. verticillata had a
good antimicrobial activity against four bacterial strains (Escherichia coli, Salmonella typhi, Lactobacillus
rhamnosus and Bacillus cereus) with MIC and MBC values between 0.2-0.4 µl/ml and 0.2-6.2 µl/ml, respectively.
While, S. candidissima essential oil had moderate antimicrobial activities against all strains
with MIC and MBC values between 1.5-6.2 µl/ml and 6.2-12.5 µl/ml, respectively. The results of antimicrobial
activity of essential oils blend presented higher antimicrobial activity against all tested bacteria
with MIC and MBC values between 0.3-1.5 µl/ml and 0.4-6.2 µl/ml, respectively.
Conclusion: The essential oils blend presented high antimicrobial activity compared to virgin oils. This
activity can be due to the association of active compounds such as carvacrol and pulegone. These findings
provide a new source of drugs that may help in therapy to lead to the development of a new treatment
based on a combination of these essential oils against gram-negative and gram-positive bacteria that continue
to pose a threat to public health.