Potentially zoonotic shiga toxin-producing Escherichia coli serogroups in the faeces and meat of food-producing animals in Ibadan, Nigeria O.E. Ojo a, ⁎, A.T.P. Ajuwape b , E.B. Otesile c , A.A. Owoade d , M.A. Oyekunle a , A.I. Adetosoye b a Department of Veterinary Microbiology and Parasitology, College of Veterinary Medicine, University of Agriculture Abeokuta, Abeokuta, Nigeria b Department of Veterinary Microbiology and Parasitology, Faculty of Veterinary Medicine, University of Ibadan, Ibadan, Nigeria c Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Agriculture Abeokuta, Abeokuta, Nigeria d Department of Veterinary Medicine, Faculty of Veterinary Medicine, University of Ibadan, Ibadan, Nigeria abstract article info Article history: Received 18 February 2010 Received in revised form 25 June 2010 Accepted 28 June 2010 Keywords: STEC serogroups Virulence factors Antimicrobial resistance Food-producing animals Meat Nigeria Shiga toxin-producing Escherichia coli (STEC) are major food-borne pathogens associated with gastroenter- itis and sometimes fatal haemolytic uraemic syndrome complication. Farm animals are asymptomatic carriers of STEC and contaminated meat is an important vehicle for zoonotic transmission from animals to humans. This study investigated the presence, virulence traits and antimicrobial susceptibility of seven potentially human pathogenic STEC serogroups (O157, O26, O91, O103, O111, O128 and O145) in the faeces and meat of food-producing animals in Ibadan, Nigeria. One hundred and fifty-four (7.3%) of 2133 samples were positive for STEC serogroups. The pathogens were detected in the faeces of cattle (15.2%), sheep (10.7%), goats (7.5%) and pigs (5.6%) as well as in beef (3.8%), goat-meat (1.7%) and pork (4.0%). All seven investigated STEC serogroups were found in cattle, all except O145 were found in sheep, three serogroups (O157, O26 and O111) were found in goats and three (O157, O111 and O128) in pigs. The rate of detection of each of the serogroups in all 2133 samples was: O157 (5.0%), O26 (0.2%), O91 (0.3%), O103 (0.3%), O111 (1.0%), O128 (0.2%) and O145 (0.1%). Of all 154 isolates, 11.0% had shiga toxin type 1 gene (stx 1 ), 25.3% had stx 2 and 41.6% had stx 1 /stx 2 ; intimin gene (eaeA) was detected in 56.5% and enterohaemolysin gene (hlyA) in 75.3%. Among the O157 isolates, 24.5% were negative for stx genes but positive for eaeA and/or hlyA while 7.6% were negative for all four virulence genes. Fourteen different combinations of virulence genes were encountered but stx 1 /stx 2 /eaeA/hlyA combination was the most predominant. The percentage resistance of the isolates to the tested antimicrobial agents was: ampicillin (82.5%), chloramphenicol (42.9%), ciprofloxacin (22.1%), enrofloxacin (25.3%), nalidixic acid (37.7%), neomycin (24.0%), norfloxacin (20.8%), streptomycin (50.7%) and tetracycline (75.3%). One hundred and forty-eight (96.1%) of all 154 isolates were resistant to at least one of the tested antimicrobial agents while 69.5% were categorised as multi-drug resistant. Potentially pathogenic multi-drug resistant STEC isolates were recovered from the meat production chain in Nigeria. Unhygienic practices that predominate during slaughter and processing were observed to have contributed to faecal contamination and presence of STEC in meat. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Shiga toxin-producing Escherichia coli (STEC) strains are important food-borne pathogens that have been implicated in cases of gastrointestinal illnesses and potentially fatal haemolytic uraemic syndrome complication (Karmali, 1989). Clinical manifestations of STEC infections in humans range from mild, non-bloody diarrhoea to severe bloody diarrhoea referred to as haemorrhagic colitis (HC) (Nataro and Kaper, 1998; Paton and Paton, 1998a). Infection can develop into life-threatening haemolytic uraemic syndrome (HUS), a leading cause of acute renal failure in children (Karmali, 1989; Boyce et al., 1995; Andreoli et al., 2002; Razzaq, 2006). Shiga toxin- producing E. coli strains associated with severe gastroenteritis and life-threatening complications of HC and HUS are commonly referred to as Enterohaemorrhagic E. coli (EHEC) (Nataro and Kaper, 1998). Shiga toxin-producing E. coli strains are of many serotypes with varied combinations of somatic (O) and flagella (H) antigens (Blanco et al., 2004). Serotype O157:H7 is the most frequently encountered STEC in human infections (Griffin and Tauxe, 1991). Large outbreaks and sporadic cases of STEC O157 infection have been reported in different nations of the world (Isaäcson et al., 1993; Watanabe et al., 1999; Breuer et al., 2001; Rangel et al., 2005; Sugiyama et al., 2005; Greenland et al., 2009; Lathrop et al., 2009). However, non-O157 serogroups have been implicated in human STEC infections in different regions of the world (Beutin et al., 1998; Brooks et al., 2004; Vaz et al., 2004; Guth et al., 2005; Johnson et al., 2006). In the International Journal of Food Microbiology 142 (2010) 214–221 ⁎ Corresponding author. Tel.: + 234 803 5803 716. E-mail addresses: oeoefemi@yahoo.com, ojooe@unaab.edu.ng (O.E. Ojo). 0168-1605/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.ijfoodmicro.2010.06.030 Contents lists available at ScienceDirect International Journal of Food Microbiology journal homepage: www.elsevier.com/locate/ijfoodmicro