A comprehensive review of non-enterica subspecies of Salmonella enterica

Salmonella is a major foodborne pathogen with a complex nomenclature. This genus is composed of two species, S. enterica and S. bongori. S. enterica is divided into six subspecies. S. enterica subspecies enterica is composed of more than 1500 serotypes with some of great importance, such as S. Typhimurium and S. Enteritidis. S. enterica subsp. enterica is responsible of more than 99% of human salmonellosis and therefore it is widely studied. However, the non-enterica subspecies of S. enterica have been little studied. These subspecies are considered to be related to cold-blooded animals and their pathogenicity is very limited. Phenotype and genotype information generated from different studies of non-enterica subspecies reveal poor ability to invade host cells and the absence or modification of important virulence factors. Also, the great majority of human infections due to non-enterica subspecies are related to a previous depressed immune system. Therefore, we propose to treat these subspecies only as opportunistic pathogens. For establish this premise, the present review evaluated, among other things, the genomic characteristics, prevalence, antimicrobial resistance and reported human cases of the non-enterica subspecies.