Salmonella enterica serovar Typhimurium isolates from animal origin encoding blaCTX-M1 and harbouring a non-common integron profile related to a Salmonella Genomic Island 1 variant
Abstract number: P2014
Rodríguez I., Beutlich J., Schroeter A., Helmuth R., Barownick W., Guerra B.
Objectives: Molecular characterisation of antimicrobial resistance (R) in seven Salmonella (S.) Typhimurium isolates showing an ESBLs phenotype and collected from different animals (4 from horse, 2 from cat and 1 from bird) in the same German region during 20032006.
Methods: Among the S. enterica isolates from animal and food origin (20032007) collected in the National Reference Laboratory for Salmonella (NRL-Salm) collection (Berlin) showing full or intermediate resistance to ceftiofur (MIC 4 mg/L), 7 S. Typhimurium isolates were selected for this work. All of them came from the same German region, but were isolated from different years/animals. Their susceptibility to 17 antimicrobial agents (including the b-lactams ampicillin and ceftiofur, and amoxycillin/clavulanic acid) by broth microdilution, and also for a broader panel of 11 b-lactams by the disc-diffusion method was tested. Molecular methods as PCR amplifications/sequencing, isoelectric focusing, PFGE with XbaI, plasmid profile analysis and Southern-hybridisation were used to characterize the resistance determinants and resistant isolates.
Results: All seven S. Typhimurium isolates were DT104L and shared a common R-pattern: [AMP-AMCI-CEF-CXM-TIC-PRL-EFT-CRO-CTX-CPD]-[CHL-FLO]-GEN-KAN-TET-SUL, with only minor variations in some antimicrobials: [CAZ-ATM]-STR-SPE-TMP-SXT. The R-genotype contained in all cases [blaCTX-M1-blaPSE-1]-floR-tet(G)-sul1-aadB. Other genes as blaTEM-1, strA-strB, aadA1 or sul2 were also present in some isolates. The strains harboured two class 1 integrons with variable regions of 700 bp and aadB genes, and 1200 bp with blaPSE-1. The detection of this characteristic integron profile together with the presence of the genes floR and tetG suggests the presence of a SGI1-variant. The seven S. Typhimurium isolates present the same characteristic XbaI-profile (frequent in DT104 strains), with variations related to the presence of plasmids. Three different plasmid patterns were found, all of them containing the S. Typhimurium virulence plasmid (90 kb) detected by spvC PCR. The blaCTX-M1 genes were located on three different plasmids with sizes between 90110 kb.
Conclusions: The presence of blaCTX-M1 and the integron profile 700 bp/ aadB, 1200 bp/ blaPSE-1 in combination with a similar XbaI-type in seven Typhimurium isolates from the same region, are indicative for the presence of a clone in the area which could have changed through time and different animal hosts.
|Session name:||18th European Congress of Clinical Microbiology and Infectious Diseases|
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