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BioMed Research International
Volume 2015, Article ID 265042, 8 pages
http://dx.doi.org/10.1155/2015/265042
Research Article

Diffusion and Persistence of Multidrug Resistant Salmonella Typhimurium Strains Phage Type DT120 in Southern Italy

1Department of Basic Medical Sciences Neurosciences and Sense Organs Medical Faculty, University of Bari Piazza G. Cesare Policlinico, 70124 Bari, Italy
2Department of Biology, University of Bari “Aldo Moro”, Via E. Orabona 4, 70125 Bari, Italy
3Department of Infectious, Parasitic and Immune-Mediated Diseases, National Health Institute, 00161 Rome, Italy

Received 13 June 2014; Revised 29 August 2014; Accepted 11 September 2014

Academic Editor: Gundlapally S. Reddy

Copyright © 2015 Danila De Vito et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Sixty-two multidrug resistant Salmonella enterica serovar Typhimurium strains isolated from 255 clinical strains collected in Southern Italy in 2006–2008 were characterised for antimicrobial resistance genes, pulsotype, and phage type. Most strains (83.9%) were resistant to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, and tetracycline (ACSSuT) encoded in 88.5% by the Salmonella genomic island (SGI1) and in 11.5% by the InH-like integron (aadA1) and catA1, sul1, and tet(B) genes. STYMXB.0061 (75%) and DT120 (84.6%) were the prevalent pulsotype and phage type identified in these strains, respectively. Five other resistance patterns were found either in single or in a low number of isolates. The pandemic clone DT104 (ACSSuT encoded by SGI1) has been identified in Italy since 1992, while strains DT120 (ACSSuT encoded by SGI1) have never been previously reported in Italy. In Europe, clinical strains DT120 have been reported from sporadic outbreaks linked to the consumption of pork products. However, none of these strains were STYMXB.0061 and SGI1 positive. The prevalent identification and persistence of DT120 isolates would suggest, in Southern Italy, a phage type shifting of the pandemic DT104 clone pulsotype STYMXB.0061. Additionally, these findings raise epidemiological concern about the potential diffusion of these emerging multidrug resistant (SGI linked) DT120 strains.