Antimicrobial Activity of Roselle Hibiscus Sabdariffa Calyx Extracts on Culture Media and Carrots Against Multidrug-Resistant Salmonella Strains Isolated from Raw Carrots

Presence of antibiotic-resistant Salmonella strains on raw carrots was evaluated, as was the antibacterial activity of roselle calyx extracts against any identified resistant Salmonella strains. One hundred samples of carrots were collected from markets in Pachuca, Mexico. Salmonella was isolated from the carrot samples by culture procedure. Susceptibilities to sixteen antibiotics were determined for the isolated Salmonella strains by standard test. Antibacterial activity versus the isolated strains was measured for roselle extracts produced with water, methanol, acetone and ethyl acetate. Finally, the antibacterial effect of roselle extracts, sodium hypochlorite, acetic acid and colloidal silver against Salmonella strains isolated from carrots was evaluated on contaminated carrots. Thirteen Salmonella strains were isolated from 11% of the carrot samples. All strains exhibited resistance to at least two of the tested antibiotics. Roselle extracts caused a greater reduction in concentration of Salmonella than the sodium hypochlorite, acetic acid and colloidal silver on contaminated carrots.