Occurrence of extended-spectrum β-lactamases among isolates of Salmonella enterica subsp. enterica from food-producing animals and food products, in Portugal Lurdes Clemente a , Vera Manageiro b,c , Eugénia Ferreira b,c , Daniela Jones-Dias b,c , Ivone Correia a , Patrícia Themudo a , Teresa Albuquerque a , Manuela Caniça b,c, ⁎ a INIAV — Instituto Nacional de Investigação Agrária e Veterinária, Estrada de Benfica, 701, 1549-011 Lisboa, Portugal b National Reference Laboratory of Antimicrobial Resistances, Department of Infectious Diseases, National Institute of Health Dr Ricardo Jorge, Av. Padre Cruz, 1649-016 Lisboa, Portugal c Centre for the Study of Animal Sciences (ICETA), University of Oporto, Rua D. Manuel II, Apartado 55412, 4051-401 Porto, Portugal abstract article info Article history: Received 28 December 2012 Received in revised form 2 August 2013 Accepted 10 August 2013 Available online 18 August 2013 Keywords: Salmonella enterica Food-producing animals ESBL CTX-M group Multidrug resistance A total of 1120 Salmonella spp. isolates, recovered from poultry, swine and food products of animal origin (bovine, swine and poultry) over the period of 2009–2011, were investigated in order to determine their serotype, suscep- tibility to a panel of eleven antimicrobials (A, ampicillin; Ct, cefotaxime; Cp, ciprofloxacin; Tm, trimethoprim; Su, sulfamethoxazole; C, chloramphenicol; S, streptomycin; G, gentamicin; T, tetracycline; NA, nalidixic acid; Fl, florfenicol), and the presence of resistance determinants of extended-spectrum cephalosporins. Overall, Salmo- nella Enteritidis was the most common serotype in all three animal species. In 618 isolates of poultry, 32.8% com- prised S. Enteritidis, 18.3% Salmonella Havana and 16.5% Salmonella Mbandaka; in 101 isolates of pigs, 21.8% comprised Salmonella Rissen and Salmonella Typhimurium, 10.9% Salmonella Derby and Salmonella London. Sal- monella I 4,[5],12:i:- was the most common serotype recovered from pork and beef food products comprising 32.6% and 30% of isolates respectively, followed by S. Rissen (26% and 24%) and S. Typhimurium (18.2% and 19%), respectively. In poultry products, S. Enteritidis was the most frequent serotype (62.7%), followed by S. Mbandaka (10.2%) and S. Derby (8.5%). Susceptibility profiles differed according to the origin of the isolates. Five multidrug resistant isolates (0.45%) were further characterized as extended-spectrum β-lactamase (ESBL) producers. Polymerase chain reaction and sequencing of the amplicons confirmed the presence of bla CTX-M-1 (n= 2), bla CTX-M-14 (n= 1), bla CTX-M-15 (n= 1) and bla CTX-M-32 (n= 1); bla SHV-12 and bla TEM-1 genes were also detected in two isolates of S. I 4,[5],12:i:-. Four isolates, two S. Havana and two S. I 4,[5],12:i:-, carried class 1 integrons and in three, two S. I 4,[5],12:i:- and one S. Havana, ISEcp1 was identified associated to bla CTX-M-1 , bla CTX-M-32 and bla CTX-M-14 genes. Additionally, in one S. I 4,[5],12:i:- isolate, orf477 was identified linked to bla CTX-M-32 . No plasmid mediated quinolone resistance-encoding genes were detected. Here, we report for the first time the presence of bla CTX-M genes in Salmonella enterica subsp enterica isolates recovered from poultry and food products of swine origin, in Portugal. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Infections with Salmonella enterica are one of the most important causes of food-borne diseases worldwide and the great majority are as- sociated with the consumption of products such as meat, poultry, eggs, milk, seafood and other fresh products (Pui et al., 2011). S. enterica in- fection is the second most frequent cause of gastrointestinal infection in humans in the European Union (EU), with a total of 99,020 confirmed cases in 2010, although fewer cases had been observed in the previous years (EFSA, 2012c). Salmonella Enteritidis and Salmonella Typhimurium were the most frequently reported serotypes accounting for 45% and 22.4% of all isolates, respectively (EFSA, 2012c). Serotype I 4,[5],12:i:- is considered a monophasic variant of S. Typhimurium and one of the first reports of its occurrence in Europe was in Portugal from a chicken carcass (Machado and Bernardo, 1990). A survey conducted in 2010 in animals and animal products showed that this serovar was the second most common in swine (9.3% of all iso- lates), the third most common in pork (7.4%), cattle (4.7%) and beef products (10%) and was also present in turkey (2.4%) and chicken meat (0.4%) (EFSA, 2012c). This serotype is considered to be a new pan- demic strain of Salmonella in Europe, typically possessing resistance to four antimicrobials comprising ampicillin, streptomycin, sulphonamides and tetracycline, ASSuT (Hopkins et al., 2010). Salmonella Havana is a potential pathogenic serotype for humans (Bekal et al., 2012; Boisrame-Gastrin et al., 2011; Backer et al., 2000; International Journal of Food Microbiology 167 (2013) 221–228 ⁎ Corresponding author at: National Reference Laboratory of Antimicrobial Resistances, Department of Infectious Diseases, National Institute of Health Dr. Ricardo Jorge, Av. Padre Cruz, 1649-016 Lisboa, Portugal. Tel./fax: +351 217519246. E-mail address: manuela.canica@insa.min-saude.pt (M. Caniça). 0168-1605/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.ijfoodmicro.2013.08.009 Contents lists available at ScienceDirect International Journal of Food Microbiology journal homepage: www.elsevier.com/locate/ijfoodmicro