Phytocompounds present in essential oils used as alternative antimicrobial agents against Escherichia coli O157:H7

Escherichia coli O157:H7 is an enterohemorrhagic pathogen responsible for severe gastrointestinal illness, including hemorrhagic colitis and hemolytic uremic syndrome (HUS), with disease severity primarily driven by Shiga toxin production and other virulence determinants.
Conventional antibiotic therapy is often contraindicated due to toxin induction, intensifying the interest in traditional medicinal plants and their bioactive constituents as alternative therapeutic options.

In this study, we investigated the antibacterial activity of three essential oil-derived phytocompounds widely used in ethnomedicine: geraniol from Cymbopogon martini, cinnamaldehyde from Cinnamomum verum bark oil, and citral from Cymbopogon flexuosus. These compounds are traditionally valued for their antimicrobial and gastrointestinal protective properties. Antibacterial efficacy against E. coli O157:H7 was evaluated using growth inhibition assays and time-kill analyses.

All three phytocompounds demonstrated concentration-dependent inhibition of bacterial growth. Time-kill assays revealed significant reductions in viable bacterial counts at sub-minimal inhibitory concentrations, indicating predominantly bacteriostatic activity. Ongoing real-time PCR studies aim to assess the influence of these compounds on the expression of key virulence-associated genes.

The present findings support the ethnopharmacological relevance of Cymbopogon spp. and C. verum-derived phytochemicals and highlight their potential as natural antibacterial agents against enterohemorrhagic E. coli. These results provide a scientific basis for further exploration of traditionally used essential oil components in the development of alternative strategies for managing enteric infections.