Detection of Genotipically Related Multi-resistant Escherichia coli Isolates in Pig Feces and Carcasses


  • Caroline Pissetti Bolsista de Doutorado, Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES). Setor de Medicina Veterinária Preventiva, Faculdade de Veterinára, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil.
  • Gabriela Orosco Werlang Bolsista de Mestrado, CAPES. Setor de Medicina Veterinária Preventiva, Faculdade de Veterinára, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil.
  • Jalusa Deon Kich Embrapa Suínos e Aves, Concórdia, SC, Brazil.
  • Marisa Cardoso Setor de Medicina Veterinária Preventiva, Faculdade de Veterinára, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil.



Escherichia coli, swine, pork, antimicrobial resistance.


Background: Antimicrobial resistant bacteria are considered a hazard not only for the treatment of animal diseases but also for public health. Commensal bacteria, such as Escherichia coli are considered a good indicator of antimicrobial resistance in the population, because it is a gut inhabitant and thus undergoes constant pressure of selection by the administration of antimicrobials. Regarding the public health, it is important to evaluate if resistant bacteria carried in the intestinal content of slaughter pigs can be found on the surface of pre chill carcasses. Therefore, the aims of this study were to evaluate the frequency of antimicrobial resistance in E. coli isolated from feces and pig carcasses; and to assess if multi-resistant isolates from both sources were phenotypically and genotypically related.

Materials, Methods & Results: Two sampling cycles were conducted in three pig slaughterhouses (A, B and C). In each cycle, samples were collected form: i. feces deposited on the pen floor of the lairage; ii. surface of carcasses at the prechill step. Samples were submitted to a protocol of isolation and confirmation of Escherichia coli. Isolates were grouped according to the origin: feces (n = 355); carcasses (n = 319); and evaluated for antimicrobial resistance by agar diffusion test. Ninety two isolates presenting multidrug resistance profile were analyzed by pulsed-field gel eletrophoresis (PFGE). Among the 674 isolates of E. coli, 7.4% were susceptible to all tested antibiotics while 79.5% (536/674) were multi-resistant. The most frequent resistance patterns were displayed to tetracycline (Tet, 85.9%), ampicillin (Amp, 73.0%), sulfonamide (Sul, 70.0%), florfenicol (Flo, 65.0%) and nalidixic acid (Nal, 58.9%). The most frequent multi-resistance profile among isolates from both origins was [AmpFloNalSulTet]. Multiresistant isolates originated from feces and carcasses displaying genotypically related pulsotypes (≥70% similarity) were found in all three slaughterhouses.

Discussion: In agreement with other studies, E. coli isolated from pig feces and carcasses demonstrated a high frequency of antimicrobial resistance and multi-resistance. The most frequent resistance profiles included antimicrobials frequently used on farm as well as drugs that have been banned as feed additives some years ago in Brazil. The selection of resistant strains may be related to the selection pressiondue to the use of antimicrobials in the pig production chain as well as the co-selection of resistance mediated by genes located in common genetic elements. Therefore, the ban of an individual drug is not always associated with the immediate disappearance of the resistance phenotype in the bacteria population. The fact that most multi-resistant E. coli isolates from carcasses belonged to pulsotypes related to those originated from feces samples indicates that resistant E. coli isolates selected on farm may be able to survive the slaughter process and be found on the carcass. In this case, the possibility of those strains being able to reach the population through the consumption of pork products may have to be considered. This hazard has motivated the ban of antimicrobial use in animals in some countries. However, the ban of antimicrobials use on farm is a controversial issue, due to the economical losses that may result from this measure. Therefore, the prudent use of antimicrobials on farm should be encouraged and its influence in the multi-resistance profile of the enteric microbiota should be further studied.


Download data is not yet available.


Agência Nacional de Vigilância Sanitária (ANVISA). 2001. RDC nº 12. Regulamento técnico sobre padrões microbiológicos para alimentos. Available at <>. [Accessed November 2015].

Ajiboye R.M., Solberg O.D., Lee B.M., Raphael E., Debroy C. & Riley L.W. 2009. Global spread of mobile antimicrobial drug resistance determinants in human and animal Escherichia coli and Salmonella strains causing communityacquired infections. Clinical Infectious Diseases. 49(3): 365-371.

Alali W.Q., Scott H.M. & Norby B. 2010. Assessing the similarity of antimicrobial resistance phenotypes among fecal Escherichia coli isolates from two aggregated occupational cohorts of humans versus swine using cluster analysis and multivariate statistics. Preventive Veterinary Medicine. 94(1-2): 77-83.

Andraud M., Rose N., Laurentie M., Sanders P., Le Roux A., Cariolet R., Chauvin C. & Jouy E. 2011. Estimation of transmission parameters of a fluoroquinolone-resistant Escherichia coli strain between pigs in experimental conditions. Veterinary Research. 42(1): 44.

Aslam M., Diarra M.S., Service C. & Rempel H. 2009. Antimicrobial resistance genes in Escherichia coli isolates recovered from a commercial beef processing plantt. Journal of Food Protection. 72(5): 1089-1093.

Barcellos D.E.S.N., Sobestiansky J., Linhares D. & Sobestiansky T. 2012. Uso de antimicrobianos. In: Sobestiansky J. & Barcellos D.E.S.N. (Eds). Doenças dos Suínos. 2.ed. Goiânia: Cânone Editorial, pp.836-883.

Barton M.D. 2014. Impact of antibiotic use in the swine industry. Current Opinion in Microbiology. 19(1): 9-15.

Blaha T. 2012. The use of antimicrobial substances in food animals: The big picture. In: 9th International Conference on the Epidemiology and Control of Biological, Chemical and Physical hazards in pigs and pork (Maastricht, Netherlands). pp.131-133.

Burow E., Simoneit C., Tenhagen B-A. & Käsbohrer A. 2014. Oral antimicrobials increase antimicrobial resistance in porcine Escherichia coli - a systematic review. Preventive Veterinary Medicine. 113(4): 364-375.

Center of Disease Control (CDC). 2013. PulseNet Protocols PNL05. Standard Operating Procedure for PulseNet PFGE of Escherichia coli O157:H7, Escherichia coli non-O157 (STEC), Salmonella serotypes, Shigella sonnei and Shigella flexneri, 13p. Available at <>. [Accessed October 2015].

Chantziaras I., Boyen F., Callens B. & Dewulf J. 2014. Correlation between veterinary antimicrobial use and antimicrobial resistance in food-producing animals: a report on seven countries. Journal of Antimicrobial Chemotherapy. 69(3): 827-834.

Clinical and Laboratory Standards Institute (CLSI). 2008. Performance standards for antimicrobial disk and dilution susceptibility test for bacteria isolated from animals; Approved standard. CLSI document M31-A3. 3rd edn. Wayne: Clinical and Laboratory Standards Institute, 99p.

Clinical and Laboratory Standards Institute (CLSI). 2012. Performance standards for antimicrobial susceptibility testing. CLSI document M100-S22. 22nd edn. Wayne: Clinical and Laboratory Standards Institute, 188p.

Codex Alimentarius. 2011. CAC/GL 77-2011. Guidelines for risk analysis of foodborne antimicrobial resistance. Available at <>. [Accessed November 2015].

Dahlberg C. & Chao L. 2003. Amelioration of the cost of conjugative plasmid carriage in Eschericha coli K12. Genetics. 165(4): 1641-1649.

Delsol A.A., Halfhide D.E., Bagnall M.C., Randall L.P., Enne V.I., Woodward M.J. & Roe J.M. 2010. Persistence of a wild type Escherichia coli and its multiple antibiotic-resistant (MAR) derivatives in the abattoir and on chilled pig carcasses. International Journal Food Microbiology. 140(2-3): 249-253.

Doublet B., Schwarz S., Kehrenberg C. & Cloeckaert A. 2005. Florfenicol resistance gene floR is part of a novel transposon. Antimicrobial Agents and Chemotherapy. 49(5): 2106-2108.

Enne V.I., Delsol A.A., Davis G.R., Hayward S.L., Roe J.M. & Bennett P.M. 2005. Assessment of the fitness impacts on Escherichia coli of acquisition of antibiotic resistance genes encoded by different types of genetic element. Journal of Antimicrobial Chemotherapy. 56(3): 544-551.

European Food Safety Authority (EFSA). 2015. ECDC/EFSA/EMA first joint report in the integrated analysis of the consumption of antimicrobial agents and occurrence of antimicrobial resistance in bacteria from humans and foodproducing animals. EFSA Journal. 13(1): 1-114.

European Food Safety Authority (EFSA). 2015. EU Summary Report on antimicrobial resistance in zoonotic and indicator bacteria from humans, animals and food in 2013. EFSA Journal. 13(2): 1-178.

Humphrey B., Thomson N.R., Thomas C.M., Brooks K., Sanders M., Delsol A.A., Roe J.M., Bennett P.M. & Enne V.I. 2012. Fitness of Escherichia coli strains carrying expressed and partially silent IncN and IncP1 plasmids. BMC Microbiology. 12: 53.

Kong H., Hong X. & Li X. 2015. Current perspectives in pathogenesis and antimicrobial resistance of enteroaggregative Escherichia coli. Microbial Pathogenesis. 85: 44-49.

Lee M., Shin E. & Lee Y. 2014. Antimicrobial resistance and integron profiles in multidrug-resistant Escherichia coli isolates from pigs. Foodborne Pathogens and Disease. 11(12): 988-997.

Looft T. & Allen H.K. 2012. Collateral effects of antibiotics on mammalian gut microbiomes. Gut Microbes. 3(5): 463-467.

Melo D.B., Menezes A.P.O., Reis J.N. & Guimarães A.G. 2015. Antimicrobial resistance and genetic diversity of Escherichia coli isolated from humans and foods. Brazilian Journal of Microbiology. 46(4): 1165-1170.

Miller G.Y. & Dickson J.S. 2009. Food safety issues and the microbiology of pork. In: Garcia J.C., Heredia N.L. & Wesley I.V. (Eds). Microbiologically Safe Foods. New Jersey: John Wiley & Sons, pp.209-226.

Millet S. & Maertens L. 2011. The European ban on antibiotic growth promoters in animal feed: From challenges to opportunities. Veterinary Journal. 187(2): 143-144.

Ministério da Agricultura Pecuária e Abastecimento. 2007. Circular Nº 130/2007/CGPE/DIPOA. Exportações de carne suína para os estados-membros da União Europeia. Available at <>. [Accessed November 2015].

Ministério da Agricultura Pecuária e Abastecimento. 2009. Instrução Normativa 26/2009. Regulamento técnico para a fabricação, o controle de qualidade, a comercialização e o emprego de produtos antimicrobianos de uso veterinário. Available at <>. [Accessed November 2015].

Nagaev I., Björkman J., Andersson D.I. & Hughes D. 2001. Biological cost and compensatory evolution in fusidic acid-resistant Staphylococcus aureus. Molecular Microbiology. 40(2): 433-439.

Price L.B., Graham J.P., Lackey L.G., Roess A., Vailes R. & Silbergeld E. 2007. Elevated risk of carrying gentamicinresistant Escherichia coli among U.S. poultry workers. Environmental Health Perspectives. 115(12): 1738-1742.

Quinn P.J., Markey B.K., Leonard F.C., Fitzpatrick E.S., Fanning S. & Hartigan P.J. 2011. Veterinary Microbiology and Microbial Disease. 2nd edn. Iowa: Wiley-Blackwell, 1231p.

Sáenz Y., Zarazaga M., Briñas L., Ruiz-Larrea F. & Torres C. 2003. Mutations in gyrA and parC genes in nalidixic acid-resistant Escherichia coli strains from food products, humans and animals. Journal of Antimicrobial Chemotherapy. 51(4): 1001-1005.

Schwarz S., Silley P., Simjee S., Woodford N., van Duijkeren E., Johnson A.P. & Gaastra W. 2010. Editorial: assessing the antimicrobial susceptibility of bacteria obtained from animals. Journal of Antimicrobrial Chemotherapy. 65(4): 601-604.

Thorsteinsdottir T.R., Haraldsson G., Fridriksdottir V., Kristinsson K.G. & Gunnarsson E. 2010. Prevalence and genetic relatedness of antimicrobial-resistant Escherichia coli isolated from animals, foods and humans in Iceland. Zoonoses Public Health. 57(3): 189-196.

Wang X-M., Jiang H-X., Liao X-P., Liu J-H., Zhang W-J., Zhang H., Jiang Z-G., Lü D-H., Xiang R. & Liu Y-H. 2010. Antimicrobial resistance, virulence genes, and phylogenetic background in Escherichia coli isolates from diseased pigs. FEMS Microbiology Letters. 306(1): 15-21.

Wedel S.D., Bender J.B., Leano F.T., Boxrud D.J., Hedberg C. & Smith K.E. 2005. Antimicrobial-drug susceptibility of human and animal Salmonella Typhimurium, Minnesota, 1997-2003. Emerging Infectious Diseases. 11(12): 1899-1906.

Wu S., Dalsgaard A., Vieira A.R., Emborg H-D. & Jensen L.B. 2009. Prevalence of tetracycline resistance and genotypic analysis of populations of Escherichia coli from animals, carcasses and cuts processed at a pig slaughterhouse. International Journal of Food Microbiology. 135(3): 254-259.



How to Cite

Pissetti, C., Werlang, G. O., Kich, J. D., & Cardoso, M. (2016). Detection of Genotipically Related Multi-resistant Escherichia coli Isolates in Pig Feces and Carcasses. Acta Scientiae Veterinariae, 44(1), 8.




Most read articles by the same author(s)