# Potential Role of Plant Extracts and Phytochemicals Against Foodborne Pathogens
## 3 Plant Extracts and Phytochemicals against Bacteria Causing Foodborne Diseases
### Salmonella  
_Salmonella_ is a rod-shaped, Gram-negative, motile, non-spore-forming bacteria belonging to family Enterobacteriaceaeae. Members of this genus are facultative anaerobes, oxidase negative and catalase-positive bacteria [65]. _Salmonella_ species exist everywhere in nature, however, the gastrointestinal tracts of mammals, reptiles, birds and insects and environment polluted with humans or animals' excreta are the main reservoirs [66]. Their characteristic to survive and grow over a wide range of temperature (2-54 \({}^{\circ}\)C) and pH (3.6-9.6) makes them difficult to control [67]. Salmonellosis, which is an infection caused by _Salmonella_ species is one of the leading causes of foodborne diseases [68]. Transmission to humans occurs via consumption of contaminated food, mostly of animal origins such as milk, eggs and meat. The antibiotics ampicillin, chloramphenicol and co-trimoxazole were once considered as the mainstay treatments for _Salmonella_ infection but are largely replaced by fluoroquinolones due to bacterial resistance to antibiotics. Recently, resistance to fluoroquinolones has also emerged [69], thus necessitating the use of traditional medicines for _Salmonella_ infections. Extracts of _Acacia nilotica_ L. have been tested against _Salmonella_ species in which the extract disrupted the cell wall of bacteria with consequent release of electrolytes and cellular constituents [70]. Another study conducted by [PERSON] et al. in India has also confirmed the potential use of _A. nilotica_ against _Salmonella_. They recorded MIC as 9.75 \(\upmu\)g/mL in their study [71]. Sugarcane bagasse has also been tested for anti-_Salmonella_ activity. It was found to be bacteriostatic and caused leakage of electrolytes [72]. In South Africa, herbs are used as traditional medicine for the treatment of GIT disorders, e.g., stomach pain, diarrhea, etc. [PERSON] et al. conducted a comprehensive study to scientifically prove the effectiveness of traditional plants for treating Salmonella infection. These plants include _Aloe arborescens_ [PERSON], _Acacia mearnsii_ [PERSON], _Aloe striata_ [PERSON], _Eucomis autummalis_ ([PERSON].) [PERSON], _E. comosa_ ([PERSON].) [PERSON], _Caythula uncinulata_ ([PERSON]). [PERSON], _Hydrona africana_ [PERSON], _Hernbstaedith odorata_ ([PERSON].) [PERSON], _Hypoxia tafifolia_ [PERSON], _Psidium guajava_ [PERSON], _Pelargonium sidoides_ [PERSON], _Schizophcarbus nervosus_ ([PERSON]) [PERSON]. Although most of the studied plantswere active in the study, but _A. arborescens_, _A. striata_, _C. uncinulata_, _E. autnumalis_, _E. comosa_ and _P. guajava_ were particularly potent. The _Salmonella_ species used in this study was extended spectrum beta-lactamase positive (ESBL) [73]. In another study from South Africa, the potent antibacterial activity of medicinal was been reported which include _Hypericum roeperianum_ Schimp. ex [PERSON], _Cremaspora triflora_ ([PERSON].) [PERSON], _Heteromorpha arborescens_ ([PERSON].) [PERSON]. & [PERSON], _Pittsporum viridiflorum_ [PERSON], _Bolusanthus speciosus_ ([PERSON]) [PERSON], _Calpururia aurea_ ([PERSON]) [PERSON], _Masa lanccolata_ [PERSON], _Elaoedendron croceum_ ([PERSON].) [PERSON] and _Morus mesozygia_ [PERSON]. All the plant extracts used were active against _Salmonella_ isolates, but _Cremaspora triflora_ and _Maesa lanccolata_ were very potent having MIC of 0.12 and 0.13 mg/mL, respectively [74]. _Entada abyssinica_ A.Rich. is traditionally used in bacterial infections of the gastrointestinal tract (GIT). A total of 8 compounds were isolated from this plant including flavonoids and terpenoids and tested for anti-Salmonella activity. Entadanin was found to be the most potent compound having a MIC of 1.56 ug/mL [75]. _Leen indica_ (Burm. f.) [PERSON] from Saudi Arabia [76], _Leen indica_, _Sclerocarpa birrea_ (A.Rich.) [PERSON] from South Africa [77; 78], _Lawsonia internis_ L. from Pakistan [79], _Rlus succedane_ L. from India [80], _Achillea clavenmae_ L., _Achillea holosericea_ [PERSON], _Achillea lingulata_ [PERSON].