International Journal of Applied Science and Technology Vol. 3 No. 3; March 2013 85 Antimicrobial Susceptibility Testing of Enterohaemorharrgic Escherichia coli Isolated from Rectal Swab of Cattle in Oko Oba Abattoir, Agege, Lagos. Opere, Bolanle Olaitan 1 Omonigbehin, Emmanuel Adedayo 2 Ezeh, Abimbola Rashidat 3 Mbacha, Margaret Ituen 2 Fowora, Muinah Adenike 2 Smith, Stella Ifeanyi 2 Anwoju, Fatmah Oluwabunmi 1 Abstract Fifty rectal swab samples were collected from healthy beef cattle at Oko – Oba Agege abattoir in Lagos Metropolis and were screened for the presence of enterohaemorrhagic Escherichia coli (EHEC), using standard media selective for Escherichia coli. Eight different antibiotics such as Gentamicin (Gen), Augmentin (Aug), Tetracycline (Tet), Ofloxacin (Ofl), Cotrimoxazole (Cot), Amoxicillin (Amx), Nalidixic acid (Nal) and Nitrofurantoin (Nitro) were used in this study. Sensitivity test was carried out by the Kirby-Bauer disc diffusion method and the efficacy of a drug was determined by measuring the diameter of the zone of inhibition that results from diffusion of the agent into the medium surrounding the disc. Antibiotic susceptibility patterns showed 44% of the isolates to be highly susceptible to the different antibiotics screened, with 56% showing multiple antibiotic resistance. Key words: E. coli, EHEC, efficacy, resistance, rectal swab, cattle, antibiotics 1. Introduction E. coli is the most common cause of food and waterborne human diarrhea worldwide in developing countries causing 800,000 deaths out of 650 million cases per year primarily in children under the age of five years (Turner et al., 2006).Enterohaemorrhagic Escherichia coli (EHEC) is a subset of pathogenic E. coli that can cause diarrhea or hemorrhagic colitis in humans. It is an important food and waterborne pathogen of humans that colonizes and is shed in the feces of many animal species (Elder et al., 2000). Human infections result from diverse exposures including contaminated foods of animal (especially bovine) origin, direct contact with shedding or contaminated animals, direct contact with environmental (water) contaminants, and ingestion of contaminated animal products and contaminated vegetables and fruit. Both cattle and sheep are well characterized hosts of EHEC O157:H7 but, while both have been repeatedly linked to human infection, cattle have received much more research attention (Grauke et al 2002). Numerous epidemiologic studies have described the bovine EHEC O157:H7 reservoir (Hancock et al. 2000; LeJeune and Wetzel 2007; Renter and Sargeant 2002; Sargeant et al. 2007). Other animals such as rabbits and pigs can also carry this organism. The infectious dose is very low, which increases the risk of disease. EHEC 0157:H7 infections occur worldwide (Griffin, 1995). EHEC are transmitted by the fecal–oral route. They can be spread between animals by direct contact or via water troughs, shared feed, contaminated pastures or other environmental sources. ________________ 1. Department of Microbiology, Lagos State University, Ojo, Lagos, Nigeria. 2. Nigerian Institute of Medical Research, Yaba, Lagos. 3. Department of Microbiology, University of Lagos, Akoka, Lagos, Nigeria.