Ethnopharmacological survey and antibacterial activity of medicinal plant extracts used against bacterial enteritis in rabbits

Bacterial enteritis is one of the diseases negatively affecting the rabbit farming industry. Communities across the globe are using medicinal plants as an alternative treatment against many diseases in rabbits. This study aimed at identifying medicinal plants used by local farmers in Cameroon and evaluate their antibacterial activity alone and in combination with oxytetracycline against some bacterial causative agents of diarrhoea in rabbits. The ethnopharmacological survey was performed in Cameroon’s Western and Central regions, where breeders were interviewed about their knowledge on the medicinal plants and plant parts often used to cure rabbit diseases, the methods of preparation and the route of administration. Plants were collected, and extracts were prepared by decoction, infusion and maceration using distilled water. The antibacterial activity of extracts and combinations was evaluated against enteropathogenic Escherichia coli, Salmonella enterica and Clostridium perfringens (WAL-14572 HM-310) using the microdilution and checkerboard methods. From the survey, fifteen medicinal plants belonging to nine families, with Asteraceae being the most represented, were identified as currently used to treat diarrhoea in rabbits. Bidens pilosa and Psidium guajava were the most mentioned medicinal plant species with 24 and 17 citations, respectively. Leaves were the most commonly used plant parts, and maceration in water was the primary preparation method of remedies administered orally. Out of the forty-five extracts prepared, only six from Tithonia diversifolia (TdlM, TdlI, TdlD) and Psidium guajava (PglM, PglI, PglD) exhibited potency with MIC values ranging from 1.25 to 5 mg/mL. The combination of infusion extract from leaves of Tithonia diversifolia (TdlI) and decoction extract from Psidium guajava (PglD) exhibited synergistic interaction (FICI = 0.312; 0.281; 0.265), while oxytetracycline in combination with decoction extract from leaves of Psidium guajava (PglD) exhibited a synergistic interaction (FICI = 0.5). The phytochemical screening of the six extracts revealed polyphenols, glycosides, saponins, terpenoids, anthraquinones, tannins and flavonoids. The antibacterial activity of extracts from medicinal plants P. guajava and T. diversifolia demonstrated in the present study supports the use of these plants by farmers of the targeted localities to treat diarrhoea in rabbits.