Emergence and Spread of an Atypical Salmonella enterica subsp. enterica Serotype 4,5,12:i:− Strain in Spain

Salmonella sp. serotyping is a very useful epidemiological tool to detect outbreaks in the developed world (5, 10). The Spanish National SalmonellaReference Laboratory routinely serotypes Salmonella sp. strains from most Spanish Autonomous Communities (AACC) for epidemiological surveillance (8, 9). In August of 1997 an atypical Salmonella enterica subsp. entericaserotype 4,5,12:i:− strain was detected. This strain either could be a monophasic strain of serotype Typhimurium (4,5,12:i:1,2) or serotype Lagos (4,5,12:i:1,5) or could represent a new serotype (7). The incidence of this serotype rapidly increased, and this serotype became the fourth most frequently encountered Salmonella sp. serotype in Spain during the second semester of 1997 (2.2% annual incidence). The aim of this study was to establish the incidence and possible origin of this serotype and to provide further characterization.