Foodborne Bacterial Infections ◾ 339
Current Nomenclature System
The serovars of Salmonella were found to have a high degree of relatedness in the DNA. It was proposed
on this basis that the genus Salmonella should have only one species, Salmonella enterica, and six subspecies, two of which are from the Arizona group (Table 26.1). The specific epithets that are used before
(e.g., typhimurium for Salmonella typhimurium) should be considered as a serotypic name, and the
strains of a serotype can be distinguished by numerals, letters, and a combination as of now. It is recommended that in formal publications, the complete name of the species and subspecies should be given
(e.g., Salmonella enterica subsp. enterica). Then serotype names could be used (e.g., ser. Typhimurium;
not italicized). The currently acceptable format is Salmonella enterica ser. Typhimurium. 2
In this text, the previous method has been replaced for most serovars (e.g., Sal. typhimurium).
The two serotypes that have been associated with frequent incidence of foodborne illness of
Salmonella, Sal. enterica ser. Typhimurium and Sal. enterica ser. Enteritidis, are in subspecies 1.
Salmonella is again grouped based on its sensitivity to specific phage types (PT) and designated
PT4, PT8, PT13, PT13a, PT23, DT104 (definitive type), and so forth.
Predominant Serotypes in Salmonellosis
Among the six subspecies, Salmonella enterica subsp. enterica includes most serotypes that are frequently associated with foodborne salmonellosis. However, two of the more than 2000 serotypes,
serotype Typhimurium and serotype Enteritidis, are involved in higher frequencies worldwide.
While many animals, including food animals and pets, harbor serotype Typhimurium in a carrier
state, serotype Enteritidis can infect the ovaries of poultry, especially chicken, and can be transmitted through eggs. 3 Increasing numbers of serotype Enteritidis have also been isolated from
chicken carcass rinse in samples collected between 2000 and 2005, and the predominant phage
types are PT 13 and PT 8. The CDC in the United States has identified the top 20 serovars of
Salmonella enterica serotypes that were involved in recent outbreaks (Table 26.2).
Because of the increase in antibiotic use in the feed of food animals and birds, there is an
increase in multidrug resistant (MDR) strains among Sal. enterica serotypes. One that has created
table 26.1 Six Subspecies of Genus Salmonella
1. Salmonella enterica subsp. a enterica
2. Salmonella enterica subsp. salamae
3a. Salmonella enterica subsp. arizonae
3b. Salmonella enterica subsp. diarizonae
4. Salmonella enterica subsp. houtenae
5. Salmonella enterica subsp. bongori
a The relationship between this subspecies scheme
and Kauffman’s subgenus scheme are as follows:
subspecies 1 corresponds to subgenus I, subspecies 2 corresponds to subgenus II, subspecies 3a
and 3b correspond to subgenus III, and Arizona
hinshawii, subspecies 4 corresponds to subgenus
IV, and subspecies 5 constitutes six atypical serotypes from subgenus II and IV.
Current Nomenclature System
The serovars of Salmonella were found to have a high degree of relatedness in the DNA. It was proposed
on this basis that the genus Salmonella should have only one species, Salmonella enterica, and six subspecies, two of which are from the Arizona group (Table 26.1). The specific epithets that are used before
(e.g., typhimurium for Salmonella typhimurium) should be considered as a serotypic name, and the
strains of a serotype can be distinguished by numerals, letters, and a combination as of now. It is recommended that in formal publications, the complete name of the species and subspecies should be given
(e.g., Salmonella enterica subsp. enterica). Then serotype names could be used (e.g., ser. Typhimurium;
not italicized). The currently acceptable format is Salmonella enterica ser. Typhimurium. 2
In this text, the previous method has been replaced for most serovars (e.g., Sal. typhimurium).
The two serotypes that have been associated with frequent incidence of foodborne illness of
Salmonella, Sal. enterica ser. Typhimurium and Sal. enterica ser. Enteritidis, are in subspecies 1.
Salmonella is again grouped based on its sensitivity to specific phage types (PT) and designated
PT4, PT8, PT13, PT13a, PT23, DT104 (definitive type), and so forth.
Predominant Serotypes in Salmonellosis
Among the six subspecies, Salmonella enterica subsp. enterica includes most serotypes that are frequently associated with foodborne salmonellosis. However, two of the more than 2000 serotypes,
serotype Typhimurium and serotype Enteritidis, are involved in higher frequencies worldwide.
While many animals, including food animals and pets, harbor serotype Typhimurium in a carrier
state, serotype Enteritidis can infect the ovaries of poultry, especially chicken, and can be transmitted through eggs. 3 Increasing numbers of serotype Enteritidis have also been isolated from
chicken carcass rinse in samples collected between 2000 and 2005, and the predominant phage
types are PT 13 and PT 8. The CDC in the United States has identified the top 20 serovars of
Salmonella enterica serotypes that were involved in recent outbreaks (Table 26.2).
Because of the increase in antibiotic use in the feed of food animals and birds, there is an
increase in multidrug resistant (MDR) strains among Sal. enterica serotypes. One that has created
table 26.1 Six Subspecies of Genus Salmonella
1. Salmonella enterica subsp. a enterica
2. Salmonella enterica subsp. salamae
3a. Salmonella enterica subsp. arizonae
3b. Salmonella enterica subsp. diarizonae
4. Salmonella enterica subsp. houtenae
5. Salmonella enterica subsp. bongori
a The relationship between this subspecies scheme
and Kauffman’s subgenus scheme are as follows:
subspecies 1 corresponds to subgenus I, subspecies 2 corresponds to subgenus II, subspecies 3a
and 3b correspond to subgenus III, and Arizona
hinshawii, subspecies 4 corresponds to subgenus
IV, and subspecies 5 constitutes six atypical serotypes from subgenus II and IV.