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Phenotypic and genotypic characterisation of antimicrobial resistance in Turkish Salmonella infantis isolates from chicken and minced meat

Abstract number: 1733_10

Avsaroglu D., Junker E., Helmuth R., Schroeter A., Akcelik M., Bozoglu F., Noeckler K., Guerra B.

Objectives: Characterisation of the resistance (R) phenotypes and underlying molecular mechanisms in Salmonella (S.) Infantis strains isolated from Turkish foods.

Methods: 100 Salmonella isolates were isolated from foods bought in free markets in Ankara (2005–2006). One of the most prevalent serotypes was Infantis (13 isolates). Nine of these S. Infantis isolates were considered as epidemiological unrelated strains (different isolation date or place). The nine strains (7 from chickens and 2 from minced meat) were tested for susceptibility to 17 antimicrobial agents by broth microdilution. Resistant strains were screened for 16 R-genes, class 1 and 2 integrons and mutations in the quinolone-R determining regions. Strains were typed by XbaI-PFGE and plasmid profile.

Results: The strains showed two similar XbaI-PFGE-patterns (differences affecting two bands). Six strains showed PFP1 and 3 PFP2. One big plasmid (>200 kb) was present in all of them. All strains were multiresistant, with resistances to 7–9 antimicrobials (6–7 R-determinants). Two phenotypic R-patterns were found: [kanamycin–neomycin–nalidixic acid–streptomycin–spectimomycin–sulfamethoxazole–tetracycline–trimethoprim–sulfamethoxazole/trimethoprim] in eight strains, and the same R-pattern without [kanamycin–neomycin] in one. One R-determinant was responsible for each resistance: aphA1 for kanamycin, aadA1-like for streptomycin-spectinomycin (no strA or strB were found); sul1 for sulfamethoxazole (no sul2 or sul3 were present); tet(A) for tetracycline (no tet(G) or tet(B)); and dfrA14 for trimethoprim (no dfrA1, A12, A7 or A17 were present). All strains harboured a class 1 integron carrying an aadA1 gene. No class 2 integrons were detected. All strains were resistant to nalidixic acid and showed reduced susceptibility to ciprofloxacin (0.25–0.5 microg/mL) conferred by mutations in the gyrA (Ser83 to Tyr83) and parC (Thr57 to Ser57) genes. No quinolone-R genes qnrA, qnrB or qnrS were found.

Conclusions:S. Infantis isolated from foods in Turkey exhibit a wide repertoire of genetic elements to survive under antimicrobial pressure. One specific PFGE-type carrying a big plasmid (>200 kb), and with the antimicrobial multi-R pheno/genotype [KAN-NEO]-[STR-SPE]-SUL-TET-[TMP-SXT]-NAL/aphA1-aadA1-sul1-tet(A)-dfrA14-[gyrA^Tyr83-parC^Ser57) is widespread. Since S. Infantis frequently causes human infections, the wide spread of such a multiresistant clone within foods should be considered as a public concern.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Subject:
Location: ICC, Munich, Germany
Presentation type:
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