Download Salmonella

Salmonella
Dr. Ban sahib abed al-nabi
zoonotic disease unit
post graduate lecture
Genus : Salmonella
Species In human
Diseases
1. S. typhi
Causes typhoid fever
2. S. para typhi
causes para typhoid fever
3. S. enteritidis
causes food poisoning
4. S. typhimurium
causes food poisoning
In cattle & sheep
Diseases
1. S. dublin
Enteritis & septicaemia
2. S. typhimurium
Enteritis & septicaemia
Species in goat
Disease
1. S. typhimurium
2. S. enteritidis
3. S. hadar
causes enteritis
=
=
Species in poultry & bird
Disease
1. S. pullorum
2. S. gallinarum
3. S. arizonae
4. S. enteritidis
5. S. typhimurium
causes white diarrhoea
causes fowl typhoid
causes
enteritis,septicaemia
=
=
Salmonella as pathogens
Salmonella species are facultative
intracellular pathogens . Many
infections are due to ingestion of
contaminated
food. Salmonella serovars can be
divided into two main groups—
typhoidal and
nontyphoidal Salmonella.
Nontyphoidal serovars are more
common, and usually cause selflimiting gastrointestinal disease. They
can infect a range of animals, and
are zoonotic, meaning they can be
transferred between humans and
other animals.
Morphology & S taining :
It is a Gram negative bacteria , cocco bacilli or straight
rod with rounded ends .
some times they develop into pleomorphic forms or
very short coccobacilli after prolonged culture on
media .
Micro scopic appearance & Incubation period :
G ram stain
Negative
Morphology
cocco bacilli or straight rod with
rounded end
Motility
Capsule
by peritrichous flagella (actively motile)
except S. pullorum & S. gallinarum
observed with mucoid strains
Spore
Non
Temperature
37 c on media without any addition
Time
16- 24 hours
Atmosphere
Aerobic & facultative an aerobic
Natural Habitat
• Salmonellae live in the intestinal tracts of warm and cold
blooded animals. Some species are ubiquitous. Other
species are specifically adapted to a particular host.
• In humans, Salmonella are the cause of two diseases called
salmonellosis:
– enteric fever (typhoid), resulting from bacterial invasion of the
bloodstream
– acute gastroenteritis, resulting from a foodborne infection .
– The majority of infected animals become subclinical excretors .
– Salmonella can survive for 9 months or more in the
environment such as moist soil , water , faecal & animal feeds .
Isolation & Identification of salmonella :
1.Enrichment broth
Mannitol Selenite broth & Tetera thionate
broth & Soy peptone broth for salmonella
isolation from stool specimen .
These fluid a useful medium which allows the
growth of salmonella but inhibits other enteric
organisms .
1. MacConkey agar & desoxy cholate citrate agar :
(DCA)
The medium & colonies are pale yellow- straw smooth &
non lactose Ferment .
lactose fermenting
Non lactose Fermenting
• Escherichia coli
• Klebsiella pneumoniae
Salmonella spp
Shigella
proteus
2. Salmonella- Shigella agar (ss agar) :
Its selective for salmonella .
Colonies are colorless with black center .
Non lactose ferment .
3. Xylose lysine desoxy cholate (XLD) :
Red colonies with black centers of H2S
producing . Non lactose ferment .
4. Brilliant green agar :
Red colonies & medium . Non lactose ferment .
Smooth circular entire edges .
5. Bismuth sulfite agar :
Is highly selective for salmonella & one of the
most sensitive media to detect H2S production.
Colonies are black surrounding by metallic sheen
on the surface.
6. Hektoen enteric agar (HE) :
Colonies are blue-Green with black due to H2S
production. Non lactose ferment .
Biochemicals test :
• salmonella don’t ferment lactose, sucrose but
ferment glucose, maltose , mannitol .
•
•
•
positive
Negative
TSI/ p/y +H2S
simmon citrate +
Motility test/ motil +H2S
VP/
Negative
Negative
MR/ positive
urease test -