Susceptibility Pattern of Tetracycline-Resistant Salmonella Species to other Antibiotics and some Plant Extracts

Antibiotic resistance is a growing concern in the treatment of gastrointestinal diseases caused by Salmonella species. This study investigated the antibiotic susceptibility pattern of tetracycline-resistant Salmonella species and their response to selected medicinal plant extracts. Faecal isolates (n=450) from hospitals in Kano were screened, leading to the identification of Tetracycline-resistant Salmonella species (n=4). These isolates were assessed for susceptibility to various antibiotics and ethanolic extracts of Psidium guajava, Khaya senegalensis, and Bridelia ferruginea. Notably, the Tetracycline-resistant Salmonella species exhibited susceptibility to Amoxicillin, Chloramphenicol, Cefotaxime, Ciprofloxacin, Trimethoprim, and Gentamicin. The extracts of the plant parts contained carbohydrates, flavonoids, tannins, and saponins, while anthraquinone and steroids were absent. P. guajava had the highest antibacterial activity against (9.5±0.29mm) Salmonella sp., followed by K. senegalensis (8.75±0.36mm) and B. ferruginea (8.75±0.48mm) at a concentration of 500µg/mL for all extracts. Psidium guajava extract with Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of 50mg/mL and 100mg/mL, respectively, emerged as the most active extract. Tetracycline-resistant Salmonella species can best be treated using P. guajava among the plants.