Salmonella enteritidis Flashcards
GRAM-NEGATIVE RODS RELATED TO THE ENTERIC TRACT
Disease of Salmonella enteritidis
1_Enterocolitis
2_Sepsis with metastatic abscesses occasionally.
Characteristics of Salmonella enteritidis
1_Facultative gram-negative rods. 2_Nonlactose-fermenting.
3_Produces H2S.
4Motile, in contrast to Shigella.
5 More than 1500 serotypes.
Habitat of Salmonella enteritidis
enteric tract of humans and animals (e.g., chickens and domestic livestock).
Transmission of Salmonella enteritidis
fecal–oral route.
Pathogenesis of Salmonella enteritidis
1_Invades the mucosa of the small and large intestines.
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2Can enter blood, causing➡️➡️ sepsis.
3 Infectious dose is at least (((100,000))) organisms, much greater than the infectious dose of Shigella.
4_ Infectious dose is high because organism is inactivated by stomach acid.
5_Endotoxin in cell wall; no exotoxin.
6_Predisposing factors include lowered stomach acidity from either antacids or gastrectomy. Sickle cell anemia predisposes to Salmonella osteomyelitis.
Infectious dose of Salmonella enteritidis is at least _______ organisms
100,000
Why Infectious dose of Salmonella enteritidis is high ??
because organism is inactivated by stomach acid
Type of toxin in Salmonella enteritidis
Endotoxin in cell wall ; no exotoxin
Predisposing factors to Salmonella enteritidis
include lowered stomach acidity from either antacids or gastrectomy. Sickle cell anemia predisposes to Salmonella osteomyelitis.
Laboratory Diagnosis of Salmonella enteritidis
1(((Gram-stained smear and culture.))) 2Non–lactose-fermenting colonies on EMB or MacConkey’s agar.
3 TSI agar shows alkaline slant and acid butt, with gas and H2S.
4 Biochemical and serologic reactions used to identify species.
5_ Can identify the organism by using known antisera in agglutination assay.
Widal test detects antibodies in patient’s serum to the O and H antigens of the organism but is not widely used.
Salmonella enteritidis on EMB or MacConkey’s agar.
Non–lactose-fermenting colonies
Salmonella enteritidis on TSI
TSI agar shows alkaline slant and acid butt, with gas and H2S.
identify the organism
Biochemical and serologic reactions used to identify species.
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Can identify the organism by using known antisera in agglutination assay. Widal test detects antibodies in patient’s serum to the O and H antigens of the organism but is not widely used.
Treatment of Salmonella enteritidis
1_Antibiotics usually not recommended for uncomplicated ((enterocolitis)).
2_Ceftriaxone or other drugs are used for sepsis, depending on sensitivity tests
Prevention of Salmonella enteritidis
1_ Public health measures (e.g., sewage disposal, chlorination of the water supply, stool cultures for food handlers, and handwashing prior to food handling).
2_Do not eat raw eggs or meat. No vaccine is available.