title: Antimicrobial susceptibility of Salmonella isolates from healthy pigs and chickens (2008-2011).
abstract: Using the agar dilution method, antimicrobial susceptibility to human-use antibiotics was determined among Belgian faecal Salmonella isolates from healthy pigs and broiler chickens. Both epidemiological cut-off values and clinical breakpoints were applied for interpretation of the results. Cephalosporin-resistant isolates were examined for the presence of genes encoding CTX-M, SHV, TEM and CMY β-lactamases. All isolates with decreased quinolone susceptibility were screened for plasmid-borne genes qnr, qepA and aac(6')-Ib-cr. In all, 368 Salmonella isolates were recovered from pigs and 452 from chickens. Clinical resistance to ciprofloxacin was absent in isolates of both host species, and was 1.9 and 13.1% to cefotaxime in pig and poultry isolates, respectively. Decreased susceptibility to cefotaxime amounted to 2.2 and 0.7%, whereas for ciprofloxacin this was 3.0 and 23.0% in pig and poultry isolates, respectively. Ciprofloxacin decreased susceptibility was limited to few serovars, mainly Paratyphi B. Multidrug resistance was markedly higher for pig isolates (39.7%) than for chicken isolates (17.3%). Sixty-six cefotaxime-resistant isolates, 59 from chickens and 7 from pigs, were phenotypically determined as ESBL/AmpC producers; predominantly Paratyphi B and Typhimurium serovars. BlaCTX-M (mostly blaCTXM-1, but also blaCTXM-2 and blaCTXM-9) and blaTEM-52 were the predominant ESBL genes. Only few isolates expressed SHV-12 or an AmpC enzyme (CMY-2). Isolates of four serovars carried qnr genes: Brandenburg and Llandof from pigs, both qnrS; Indiana and Paratyphi B from chickens with qnrB and qnrA. The latter isolate carried blaCTX-M-9 and was the only strain with a plasmid-borne quinolone resistance gene among the ESBL/AmpC producers. This Salmonella survey confirms that the ESBL/AmpC producers are particularly prevalent in chickens (12.8%), and much less in pigs (1.9%). A link between plasmid-borne quinolone resistance genes and ESBLs/AmpC was uncommon.
authors.affiliation: Bayer Animal Health GmbH, Leverkusen, Germany. Electronic address: anno.jong@bayer.com.
authors.forename: Anno
authors.initials: A
authors.lastname: de Jong
authors.affiliation: Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium.
authors.forename: Annemieke
authors.initials: A
authors.lastname: Smet
authors.affiliation: Bayer Animal Health GmbH, Leverkusen, Germany.
authors.forename: Carolin
authors.initials: C
authors.lastname: Ludwig
authors.affiliation: Bayer Animal Health GmbH, Leverkusen, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Stephan
authors.affiliation: Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium.
authors.forename: Evelyne
authors.initials: E
authors.lastname: De Graef
authors.affiliation: Animal Health Care Flanders, Torhout, Belgium.
authors.forename: Mia
authors.initials: M
authors.lastname: Vanrobaeys
authors.affiliation: Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium.
authors.forename: Freddy
authors.initials: F
authors.lastname: Haesebrouck
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D001530:Belgium; D002511:Cephalosporins / Q000494:pharmacology*; D002645:Chickens / Q000235:genetics / Q000382:microbiology*; D002939:Ciprofloxacin / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D005243:Feces / Q000382:microbiology; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000706:statistics & numerical data / Q000662:veterinary; D012475:Salmonella / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D013045:Species Specificity; D034421:Sus scrofa / Q000235:genetics / Q000382:microbiology*; D013552:Swine; D001618:beta-Lactamases / Q000235:genetics
chemical_list: D000890:Anti-Infective Agents; D001426:Bacterial Proteins; D002511:Cephalosporins; D002939:Ciprofloxacin; D001618:beta-Lactamases
keywords: Antimicrobial resistance; Chickens; Mechanisms of resistance; Pigs; Surveillance