Abstract

Background:
Galleria mellonella larvae (GML) are an alternative model for evaluating the in vivo antimicrobial activity of several medicinal plants. Tocosh, a traditional Peruvian food made from fermented potatoes, has been shown to have in vitro antibacterial properties; however, its in vivo effects remain unknown. Antibiotic-resistant Campylobacter coli is a bacterium implicated in gastrointestinal diseases in humans.

Aim:
In this study, GML were used as an in vivo model to evaluate the efficacy of ethanolic extract of tocosh (EET) against C. coli.

Methods:
Three trials were conducted on GML: (i) Evaluation of EET (3.50, 2.63, 1.75, and 0.88 mg/larva) safety. (ii) Determination of LD50 with different C. coli concentrations (1 to 8 Log CFU/mL). (iii) Effect of the safety dosage of EET on GML infected with the LD50. In all trials, larval mortality was evaluated over 96 hours.

Results:
Dosage of 1.75 and 0.88 mg/larva of EET from both brands was harmless to GML. The LD50 was 7 Log CFU/mL for the SM19 strain and 6 Log CFU/mL for the ATCC strain. GML inoculated with the SM19 strain and treated with the EET (0.88 mg/larva) showed a survival rate greater than 70%, while those inoculated with the ATCC strain and treated with the EET (1.75 and 0.88 mg/larva) showed a survival rate greater than 75%.

Conclusion:
The results obtained support the use of GMLs as an alternative experimental model for studies of the efficacy of tocosh against C. coli, with potential applications in veterinary medicine, clinical, and food microbiology.

Key words: Antimicrobial activity; Campylobacter coli; Galleria mellonella; Medicinal plants; Tocosh.