Salmonella Flashcards
➢General features of Salmonella:
● Oxidase (-ve)
● Catalase (+ve)
● Glucose fermenter
● Facultative Anaerobe
● Changes Nitrate to Nitrite
● Motile (differentiate it from Shigella)
● Produces H2S except S.Paratyphi A (differentiate it from Shigella)
● facultative intracellular bacteria
➢Virulence Factors
. Structural Factors:
● O-Antigen : Cell Wall
● H-Antigen : Flagella
● K-Antigen : Capsule(Vi antigen ) why🤗
- Toxin (Endotoxin)
Clinical outcomes of the infection of salmonella
- Acute gastritis (gastroenteritis)
- Bacteremia
- Typhoid fever (enteric fever)
- Carrier (Asymptomatic)
Acute gastritis in salmonella cause by ? Type of food ?incubation period? Presentation ?
● Salmonella Enteritidis
● Salmonella Typhimurium
Poultry and eggs
8 - 48 hrs
watery inflammatory diarrhea
Bacteremia in salmonella
● By Salmonella Choleraesuis
● In immunocompromised patients
● Causes metastatic abscesses in previously damaged areas (e.g.infarctions, aneurysms)
● Causes vascular graft infection.
Cause of Enteric fever in salmonella
● Typhoid fever: Salmonella typhi (CASE)
● Paratyphoid fever (weaker than typhoid fever): Salmonella Paratyphi (A,B or C)
Case presentation of Typhoid feve
First week :
● Faggit sign (Step ladder fever+ Relative Bradycardia)
● Constipation
Second week:
● Rose spots
● Diarrhea
● Abdominal distention
● Hepatosplenomegaly
If not treated Typhoid fever case
neuropsychiatric symptoms :
coma, depression, confusion (seeing goats at night)
➢Complications of typhoid fever
● Nephro-typhoid
● Peritonitis
● Abscesses (liver or spleen abscesses)
● Osteomyelitis in sicklers (because they suffer from auto splenectomy)
● Multisystemic diseases (pneumonia, meningitis, arthritis, etc..)
Presentation of nephro typhoid
- Symptoms of typhoid fever
- Edema
- Severe albuminuria
- Severe hematuria
Nephro-typhoid usually occurs in patients who live in areas endemic with???
Urinary schistosomiasis.
عشان كدا لازم نعالجها اول
➢ Transmission of typhoid fever
● Enteric fever group : Salmonella Typhi Transmission : from humans by (=orofecal transmission)
● Non-enteric fever group : Salmonella Enteritidis and Typhi Murium Transmission: animal sourcesهي دي بتجيب الحنة دي نان
➢Pathogenesis of Typhoid Fever
قصة 😉
Lymph. blood. lymph. blood
● After swallowing the bacteria it goes to Peyer’s patches in the ilium and multiplies there.
● Then it enter bloodstream causing primary bacteremia (asymptomatic)
● Goes to the thoracic duct and multiplicate there
● Returns to the bloodstream causing secondary bacteremia (fever appears)
● Then it enters the reticuloendothelial system (liver, bone marrow, spleen, etc..) and multiplicates there.
● Since it’s a facultative intracellular bacteria, it can live inside macrophages because of its Vi antigen (no bacteremia = no fever), and leave the macrophages (causing bacteremia = fever), enter, leave, enter, leave, …=Recurrent waves of bacterimea
PATHOGENESIS OF FAGGIT’S SIGN
● toxic myocarditis:Damages the heart - > Bradycardia
● Since it’s a facultative intracellular bacteria, it can live inside macrophages because of its Vi antigen (no bacteremia = no fever), and leave the macrophages (causing bacteremia = fever), enter, leave, enter, leave, …=Recurrent waves of bacterimea This explains the stepladder fever caused by the bacteria.
Where the carrier has salmonella
● In patients with cholecystitis / cholelithiasis gallbladder
➢Diagnosis of salmonella
- Specimen collection:
● First week : Blood or Bone Marrow biopsy
● Second week: Stool (there is diarrhoea) or Blood
● Third week: Stool or urine
- Microscopy: Gram (-ve) bacilli with flagella
- Culture:
● MacConkey agar
● XLD : pink colonies with black centers due to H2S. (differentiate it from Shigella)
● Salmonella Shigella agar: Salmonella colonies are colorless with black center, while shigella are colorless,
● TSI agar *There are than 17 cultures, - Biochemical tests:
● Oxidase (-ve)
● Motility (+ve) (to differentiate it from Shigella)
● Urease (-ve) (to differentiate it from Proteus)
● Sugar fermentation test -> detection of production of H2S (+ve) -> All Salmonella subtypes produce H2S except S. Paratyphi A. We differentiate it from Shigella by the Motility test
- Serology:
a. Widal test ( =Tube dilution method)
b. ELISA
c. Typhi dot
d. Tube-X
➢Treatment of salmonella
- Gastroenteritis: Rehydration
- Typhoid fever: CC:
● Ciprofloxacin (contraindicated in pregnancy and children less than 8 years old)
● Cotrimoxazole
- Gallbladder carrier:
● Ciprofloxacin
● Ampicillin
● If not eradicated => Cholecystectomy
- Bacteremia: Ciprofloxacin
➢ Prevention of salmonella
🤌🤌🤌 اصبري وستنالي
TAB vaccine (Typhi, Paratyphi A & Paratyphi B). They are 3:
- Capsular polysaccharide vaccine: can either be:
- Conjugated -to proteins- to increase its immunogenicity (given to children)
- Unconjugated (given to adults)
- Killed vaccine
- Life attenuated vaccine (protection rate 90%) : contraindicated in children, pregnant ladies and immunocompromised people)
