Phenotypic and molecular characterisation of multiresistant monophasic Salmonella Typhimurium (1,4,[5],12:i:-) in Greece, 2006 to 2011

Recently, multiresistant Salmonella enterica serovar 1,4,[5],12:i:-, a monophasic variant of S. Typhimurium (1,4,[5],12:i:1,2) emerged, and is now among the most common serovars isolated from humans in many countries. In Greece, monophasic Typhimurium which was recorded for the first time in human isolates in 2007 (0.3% of total isolates), increased sharply thereafter, and since 2009 is the third most frequent serovar. In the present study, 119 S. enterica 1,4,[5],12:i:- strains of human, animal and food origin, isolated during the period between 2006 and 2011, were examined. Strains verified as monophasic Typhimurium variants by polymerase chain reaction (PCR) (97 strains), were further characterised by phenotypic (antibiotic resistance and phage typing) and molecular (pulsed-field gel electrophoresis - PFGE) methods. The results indicate that multiple clones of multiresistant monophasic Typhimurium are circulating in Greece. The most frequently encountered clone in humans and pigs was that of phage type DT120, R-type ASSuTSpTm and PFGE profile STYMXB.0010, while in poultry other clones were detected. The data indicate that pigs may be a reservoir of this clone in Greece. .