Enterobacteriaceae: Genus - Salmonella
27 October 2020 22:13
The Enterobacteriaceae: Genus Salmonella
Genus Salmonella Classification:
Salmonella classification in the 21st century is complex. There are only two species within the genus
salmonella which are: Salmonella bongori and salmonella enterica. It is within the enterica where
most of the human pathogens reside. Salmonella enterica is divided into 7 sub-species and from
there the species are divided up until 2,600 serovars (species with different antigenic properties).
99% of human and animal infections (typhoidal salmonella in human, and non-typhoidal salmonella
in human and animals )come from subspecies 1 of the salmonella enterica.
Typhoid salmonella infections:
- Typhoid fever - S.typhi
- Paratyphoid fever - S.paratyphi, S.paratyphi deltaTer, S. paratyphi C
Non-typhoid salmonella infections:
- Gastroenteritis
Self-limiting (non-invasive):
○ S.Typhimurium
○ S.Enteritidis + 1500 others
Bacteraemia (invasive):
○ S.Typhimurium
○ S.Enteritidis
○ S.Dublin
○ S.Virchow
○ S.Heidelberg
- Extra-intestinal
Focal Infection:
○ S.Choleraesuis
○ S.Typhisuis
○ S.Typhimurium
○ S.Enteritidis
○ S.Dublin
Bacteraemia:
○ S.Choleraesuis
○ S.Typhisuis
○ S.Typhimurium
○ S.Enteritidis
○ S.Dublin
○ S.Virchow
○ S.Heidelberg
○ S.Bovismorbificans
The split in typhoidal and non-typhoidal is based on the disease syndrome. Typhoid and paratyphoid
fever is prolonged whilst extra-intestinal infections is usually acute and metastatic (spreadable)
gastroenteritis is characterised by diarrhoea.
Salmonella enterica subspecies are enterica serovar Typhimurium ------> Salmonella
Typhimurium --------> S. Typhimurium
Genera Salmonella: General characteristics:
• Non-lactose fermenter (E. coli ferments lactose but Shigella does not)
• Indole test negative (E. coli positive; Shigella variable)
Various selective medias can distinguish Salmonella from E.coli/ Shigella by:
H₂S (hydrogen sulphide) production
Acid production during carbohydrate fermentation e.g. XLD media, SS media
XLD media:
• E.coli - Yellow colonies
E-Salmonella Page 1
27 October 2020 22:13
The Enterobacteriaceae: Genus Salmonella
Genus Salmonella Classification:
Salmonella classification in the 21st century is complex. There are only two species within the genus
salmonella which are: Salmonella bongori and salmonella enterica. It is within the enterica where
most of the human pathogens reside. Salmonella enterica is divided into 7 sub-species and from
there the species are divided up until 2,600 serovars (species with different antigenic properties).
99% of human and animal infections (typhoidal salmonella in human, and non-typhoidal salmonella
in human and animals )come from subspecies 1 of the salmonella enterica.
Typhoid salmonella infections:
- Typhoid fever - S.typhi
- Paratyphoid fever - S.paratyphi, S.paratyphi deltaTer, S. paratyphi C
Non-typhoid salmonella infections:
- Gastroenteritis
Self-limiting (non-invasive):
○ S.Typhimurium
○ S.Enteritidis + 1500 others
Bacteraemia (invasive):
○ S.Typhimurium
○ S.Enteritidis
○ S.Dublin
○ S.Virchow
○ S.Heidelberg
- Extra-intestinal
Focal Infection:
○ S.Choleraesuis
○ S.Typhisuis
○ S.Typhimurium
○ S.Enteritidis
○ S.Dublin
Bacteraemia:
○ S.Choleraesuis
○ S.Typhisuis
○ S.Typhimurium
○ S.Enteritidis
○ S.Dublin
○ S.Virchow
○ S.Heidelberg
○ S.Bovismorbificans
The split in typhoidal and non-typhoidal is based on the disease syndrome. Typhoid and paratyphoid
fever is prolonged whilst extra-intestinal infections is usually acute and metastatic (spreadable)
gastroenteritis is characterised by diarrhoea.
Salmonella enterica subspecies are enterica serovar Typhimurium ------> Salmonella
Typhimurium --------> S. Typhimurium
Genera Salmonella: General characteristics:
• Non-lactose fermenter (E. coli ferments lactose but Shigella does not)
• Indole test negative (E. coli positive; Shigella variable)
Various selective medias can distinguish Salmonella from E.coli/ Shigella by:
H₂S (hydrogen sulphide) production
Acid production during carbohydrate fermentation e.g. XLD media, SS media
XLD media:
• E.coli - Yellow colonies
E-Salmonella Page 1
