Extended-spectrum β-lactamases and AmpC β-lactamases in ceftiofur-resistant Salmonella enterica isolates from food and livestock obtained in Germany during 2003–07

• Published in: Journal of antimicrobial chemotherapy Vol. 64; no. 2; pp. 301 - 309
• Main Authors: Rodríguez, Irene, Barownick, Wolfgang, Helmuth, Reiner, Mendoza, M. Carmen, Rodicio, M. Rosario, Schroeter, Andreas, Guerra, Beatriz
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.08.2009
• Subjects: Antibiotics. Antiinfectious agents. Antiparasitic agents; antimicrobial resistance; Bacterial diseases; Bacterial diseases of the digestive system and abdomen; Biological and medical sciences; conjugative plasmid; Human bacterial diseases; Infectious diseases; integron; ISEcp1; Medical sciences; PFGE; Pharmacology. Drug treatments; Europe; Germany; PFGE; integron; conjugative plasmid; IS; antimicrobial resistance; Salmonella; Drug susceptibility test; Extended-spectrum β-lactamase; Antimicrobial agent; Integron; Bacteria; Salmonellosis; Enterobacteriaceae; Food; Ceftiofur; β-Lactams; ISEcp1; Infection; Plasmid; Resistance; Cephalosporin derivatives; Antibiotic; Bacteriosis; Isolate; Livestock; Conjugation; Antibacterial agent
• ISSN: 0305-7453; 1460-2091
• DOI: 10.1093/jac/dkp195

Objectives Detection and characterization of extended-spectrum β-lactamases (ESBLs) and AmpC-encoding genes was conducted in German Salmonella isolated from different sources from 2003 to 2007. Methods Non-duplicate German isolates from the National Salmonella Reference Laboratory Collection (2003–07) with ceftiofur MICs of ≥4 mg/L were tested for β-lactam/β-lactamase inhibitor susceptibility, presence of ESBLs or AmpC-encoding genes, class 1 and 2 integrons, other resistance genes, and IS26 and ISEcp1 sequences by PCR/sequencing. The isoelectric point of the β-lactamase was determined. Strains were analysed by PFGE and plasmid profiling. The bla genes were mapped by Southern-blot hybridization. Plasmids were characterized by rep-PCR typing. Results Sixteen isolates (10 Salmonella Typhimurium, 2 Salmonella Anatum, 2 Salmonella Paratyphi B dT + , 1 Salmonella Infantis and 1 Salmonella London) carried blaCTX-M (15 blaCTX-M-1 and one blaCTX-M-15) genes located on self-transferable IncB/O, IncI1 and/or IncN plasmids. Seven of the Salmonella Typhimurium isolates carried the SGI1-M variant. Six isolates (five Salmonella Agona and one Salmonella Kentucky) carried the blaCMY-2 gene on IncI1 conjugative plasmids. blaTEM-20 genes were detected in two Salmonella Paratyphi B dT+ isolates, and blaTEM-52 in one Salmonella Paratyphi B dT+ and one Salmonella Virchow, located on IncI1 plasmids. All Salmonella Paratyphi isolates harboured a 2300 bp/dfrA1-sat2-aadA1 class 2 integron. Conclusions Among the 22 679 German Salmonella isolates investigated, the ESBL and AmpC β-lactamase prevalence was still low; however, it is slowly increasing. Various β-lactamase genes are linked to a variety of genetic elements capable of horizontal DNA transfer. Consequently, their dissemination is likely and demands adequate risk management strategies.