Antimicrobial Evaluation of Crude Methanolic Leaf Extracts from Selected Medicinal Plants Against Escherichia coli Hibert Rachuonyo Opinde 1* , Gatheri GW 2 and Nyamache AK 1 1 Department of Microbiology, Kenyatta University, Nairobi, Kenya 2 Department of Plant Sciences, Kenyatta University, Nairobi, Kenya * Corresponding author: Hibert Rachuonyo Opinde, Department of Microbiology, Kenyatta University, P.O Box 43844-00100, Nairobi, Kenya, Tel:+254728128031; E- mail: hibertrachuonyo@gmail.com Received date: March 22, 2016; Accepted date: April 28, 2016; Published date: May 03, 2016 Copyright: © 2016 Opinde HR, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract This study was aimed at determining the antibacterial effects of the selected plant leaf extracts of Tagetes minuta, Aloe secundiflora, Vernonia lasiopus and Bulbine frutescens against clinical isolate of Escherichia coli. The plants materials were obtained from Kenyatta University arboretum and identified by University taxonomist and voucher specimen deposited in the University. Methanol was used as the solvent for the extraction process and the antimicrobial activity test carried out using the disc diffusion method. All the plants extracts analysed had antimicrobial activity against Escherichia coli with Tagetes minuta extract being the most active at low concentrations (8.7 mg/ml). The standard antibiotic used for positive control was ciprofloxacin (5 µg/ml) while distilled water and dimethyl sulphoxide were used as negative control. Screening of phytochemical showed the presence of four phytochemicals; saponins, tannins, alkaloids and flavonoids. Keywords: Disc difusion method; Phytochemicals; Escherichia coli; Ciprofoxacin; Dimethyl sulphoxide Introduction Medicinal plants are used by almost 80% of the world’s population for their basic health care because of their low cost and ease in availability [1]. Herbal drugs made from medicinal plants have been used from ancient times to treat various diseases and their antimicrobial properties make them a rich source of many potent drugs [2]. Te use of herbal medicinal plants has always played a positive role in the control or prevention of diseases such as diabetes, heart disorders and various cancers [3]. Te genus Tagetes belongs to the Asteraceae family which presently comprises of 56 species, 27 biennials and 29 perennials [4]. Tagetes species and chemo-types from its genus have been largely examined for biological active metabolites that can be used in industry and medicine [5]. Compounds that have antimicrobial activity in the Tagetes minuta plant are said to be accumulated in the organs of the plant and their essential oils have not only antimicrobial efect but also insecticidal properties [6]. Extracts from Tagetes minuta leaf fowers and stem extracted using methanol have shown to contain secondary metabolites including terpenes which are thought to be responsible for antibacterial activities [7]. Te genus Aloe is common in Kenya; with about 60 taxa recognized [8]. Aloe species have antibacterial, antifungal, anticancer, antiviral and immunomodulatory properties [9]. Aloe secundifora other synonyms are; Aloe foramaculata, Aloe engleri and Aloe marsabitensis [10]. Aloe secundifora leaf components have been credited for antibacterial, antifungal and antiviral and antihelmintic medicinal properties [10]. Herbalists from the Lake Victoria region have traditionally used Aloe secundifora to treat ailments including chest problems, polio, malaria and stomach ache [11]. Vernonieae is a tribe of about 1300 species of plant in the Asteraceae (compositae) family which mostly contains herbaceous plants [12]. Vernonia laisopus decoctions from the stems and leaves have been traditionally been used by herbalist in East Africa to treat, malaria, worms and gastrointestinal problems [11]. Its extracts have also been used in treating some of the sexually transmitted diseases in southern parts of Africa [13]. Bulbine is a genus of plants in the family xanthorrhoeaceae and sub family asphodeloideae and its members are well known for their medicinal value [14]. Bulbine plant has been used for medicinal purposes in the early stages of the eighteen century by Dutch and British settlers of South Africa in treating various ailments [15]. Te leaves of the plant have been used in the treatment of wound thought to be infected with bacterial pathogens and it has shown antibacterial properties [16]. Some of the species of the plant found in South Africa have been used for blood cleansing, treatment of ringworms and gravel rush by some local communities such as the Xhosa [15]. A decoction of bulbs and roots of some of the species has been used in the treatment of some of the venereal diseases in women and stomach upsets [17]. Escherichia coli are normal fora in the body of human beings and they can be non- pathogenic, commensal or pathogenic [18]. When pathogenic they usually cause urinary tract infections, systematic infections and enteric infections [19]. Te development of resistance by Escherichia coli due to increase in use of antimicrobial agents has led to the use of medicinal plants extracts against it [20]. Medicinal plant extracts have shown to have antimicrobial activity against enteropathogenic Escherichia coli found in food material [21]. Tis study aided in determining whether the plant extracts can be used as an efective antimicrobial agent against Escherichia coli. Materials & Methods Plant material collection Te fresh plant material of Aloe secundifora, Bulbine frutescens, Vernonia lasiopus and Tagetes minuta were collected at Kenyatta University Arboretum. Voucher specimens were prepared and Bacteriology & Parasitology Opinde et al., J Bacteriol Parasitol 2016, 7:3 http://dx.doi.org/10.4172/2155-9597.1000272 Research Article Open Access J Bacteriol Parasitol ISSN:2155-9597 JBP, an open access journal Volume 7 • Issue 3 • 1000272