Antibiotic resistance of Salmonella enterica isolates from Greece mediated by tetA, qnrA and qnrB resistant genes

Abstract number: P760

Objectives: The antibiotic resistance of fifty Salmonella enterica strains, isolated from animal and food sources in Greece and its association with resistance genes and plasmids were investigated.

Methods: Antibiotic susceptibility of the Salmonella enterica isolates was determined by dilution antimicrobial susceptibility tests in accordance to the M100-S16 method and the interpretive criteria of the Clinical and Laboratory Standards Insitute (CLSI, 2006). The MICs were determined as the lowest concentrations of antimicrobial agents that inhibited visible growth. PCR assays were performed to identify the presence of genes conferring resistances. Nucleotide sequences of PCR products were aligned and compared to GenBank homologue sequences ( The plasmid content of the resistant isolates was investigated by pulsed field gel electrophoresis (PFGE) after cleavage with Sau3AI restriction enzyme.

Results: Twelve isolates were resistant to tetracycline (MIC >128mg/ml), five to ampicillin (MIC >128mg/ml) and three to nalidixic acid (MIC >128mg/ml) and ciprofloxacin (MIC >128 mg/ml). The tetA gene was highly prevalent in Salmonella strains of our study, being detected in nine tetracycline-resistant isolates. Meanwhile qnrA and qnrB genes were detected in the three quinolone resistant strains. The extended sequence analysis of the products beard high identities when compared to GenBank sequences. Finally no specific bands in pulsed-field gel electrophoresis (PFGE) patterns could be attributed to plasmid DNA.

Conclusions: This is to the best of our knowledge the first report of tetA, qnrA and qnrB resistant genes in Salmonella enterica isolates in Greece. Plasmids and transposons carrying resistant genes have been isolated from salmonellas in many countries. As they seem to be more broadly distributed among enterobacteria than first assumed, our further work would be focused on the distribution of these DNA elements among resistant Salmonella enterica serovars.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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