Frequent occurrence of extended-spectrum beta-lactamase- and transferable ampc beta-lactamase-producing Escherichia coli on domestic chicken meat in Sweden

Abstract

Forty-four percent of Swedish chicken meat fillets were contaminated with extended-spectrum or transferable AmpC beta-lactamase-producing Escherichia coli strains. Isolates from Swedish chicken meat and broilers were closely related to isolates from chicken meat imported into Sweden; these results indicate a common source of the contamination.

Fig 1

Dendrogram showing the genotypic relatedness of Escherichia coli carrying bla_CMY-2 on an incK plasmid isolated from Swedish broilers, Swedish meat, and meat imported from Denmark and Finland based on pulsed-field gel electrophoresis with XbaI. One isolate from Swedish meat proved to be untypeable with PFGE. For comparison, cluster analyses using the Dice coefficient and unweighted-pair group method using average linkages (UPGMA) were performed, with position tolerance and optimization both set at 1%. The scale bar represents the percentage of similarity, the vertical dotted line indicates ≥90% similarity, and the vertical intact line indicates ≥80% similarity. Resistance to antimicrobials was defined according to EUCAST epidemiological cutoffs. Km, kanamycin; Sm, streptomycin; Su, sulfamethoxazole; Tc, tetracycline.