title: Antimicrobial resistance profiles of Shiga toxin-producing Escherichia coli O157 and Non-O157 recovered from domestic farm animals in rural communities in Northwestern Mexico.
abstract: BACKGROUND
  Antimicrobial resistance in Shiga toxin-producing Escherichia coli (STEC) O157 and non-O157 is a matter of increasing concern. The aim of the present study was to investigate the antimicrobial resistance profiles of STEC O157 and non-O157 recovered from feces of domestic farm animals in the agricultural Culiacan Valley in Northwestern Mexico.
  
  
  RESULTS
  All of the examined STEC strains showed susceptibility to five antimicrobials, ceftazidime, ceftriaxone, ciprofloxacin, nalidixic acid, and trimethoprim-sulfamethoxazole. However, resistance to the four antimicrobials, ampicillin, cephalothin, chloramphenicol, and kanamycin was commonly observed. Interestingly, non-susceptibility to cephalothin was predominant among the examined STEC strains, corresponding to 85 % (22/26) of the O157:H7 from cattle, sheep and chicken and 73 % (24/33) of the non-O157 strains from cattle and sheep. Statistical analyses revealed that resistance to ampicillin was significantly correlated to 38 % (10/26) of STEC O157:H7 strains from multiple animal sources. Another significant correlation was found between serotype, source, and antimicrobial resistance; all of the O20:H4 strains, recovered from sheep, were highly resistant to tetracycline. Multidrug resistance profiles were identified in 42 % (22/53) of the non-susceptible STEC strains with clinically-relevant serotypes O8:H9, O75:H8, O146:H21, and O157:H7.
  
  
  CONCLUSIONS
  STEC O157 and non-O157 strains, recovered from domestic farm animals in the Culiacan Valley, exhibited resistance to classes of antimicrobials commonly used in Mexico, such as aminoglycosides, tetracyclines, cephalosporins and penicillin but were susceptible to fluoroquinolones, quinolones, and sulfonamides. These findings provide fundamental information that would aid in the surveillance of antimicrobial resistance in an important agricultural region in Northwestern Mexico.
authors.affiliation: Faculty of Chemical and Biological Sciences (FCQB), The Autonomous University of Sinaloa (UAS), Josefa Ortiz de Domínguez y Blvd. de las Américas S/N, Ciudad Universitaria, 80013 Culiacan, Sinaloa México.
authors.forename: Bianca A
authors.initials: BA
authors.lastname: Amézquita-López
authors.affiliation: U.S. Department of Agriculture/Agricultural Research Service, Western Regional Research Center, Produce Safety and Microbiology Research Unit, 800 Buchanan Street, Albany, CA 94710 USA.
authors.forename: Beatriz
authors.identifier: 0000-0001-5010-9889
authors.initials: B
authors.lastname: Quiñones
authors.affiliation: Faculty of Chemical and Biological Sciences (FCQB), The Autonomous University of Sinaloa (UAS), Josefa Ortiz de Domínguez y Blvd. de las Américas S/N, Ciudad Universitaria, 80013 Culiacan, Sinaloa México.
authors.forename: Marcela
authors.initials: M
authors.lastname: Soto-Beltrán
authors.affiliation: U.S. Department of Agriculture/Agricultural Research Service, Western Regional Research Center, Produce Safety and Microbiology Research Unit, 800 Buchanan Street, Albany, CA 94710 USA.
authors.forename: Bertram G
authors.initials: BG
authors.lastname: Lee
authors.affiliation: U.S. Department of Agriculture/Agricultural Research Service, Western Regional Research Center, Produce Safety and Microbiology Research Unit, 800 Buchanan Street, Albany, CA 94710 USA.
authors.forename: Jaszemyn C
authors.initials: JC
authors.lastname: Yambao
authors.affiliation: Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco (CIATEJ), Normalistas 800, Colinas de La Normal, 44270 Guadalajara, Jalisco Mexico.
authors.forename: Ofelia Y
authors.initials: OY
authors.lastname: Lugo-Melchor
authors.affiliation: Research Center in Food & Development (CIAD), Food Safety National Research Laboratory (LANIIA), Carretera a El Dorado Km5.5, Col. Campo El Diez, 80110 Culiacan, Sinaloa Mexico.
authors.forename: Cristóbal
authors.initials: C
authors.lastname: Chaidez
keywords: Antibiotics; Antimicrobial resistance; Domestic farm animals; Escherichia coli O157:H7; Escherichia coli non-O157; Mexico; Shiga toxin