3. Salmonellae are gram-negative bacilli belong
to enterobactereace which cause a spectrum
of characteristic clinical syndromes including.
gastroenteritis.
enteric fever.
Bacteremia.
Endovascular infections.
And focal infections such as osteomyelitis or
abscesses.
4. Antigens: located in the cell capsule
H (flagellar antigen).
O (Somatic or cell wall antigen).
Vi (polysaccharide virulence)
“widel test”
5. Antigenic structure of Salmonella
H( flagella ) antigens
O (somatic) antigens
Vi (Virulence) capsular
polysaccharide antigens
6. Epidemiology of typhoid fever
Salmonellae are named for the pathologist Salmon,
who first isolated salmonella choleraesuis from
porcine intestine.
Salmonella are effective commensals and pathogens
that cause a spectrum of diseases in humans and
animals
7. Epidemiology
continues to be a global health problem
areas with a high incidence include Asia,
Africa and Latin America
affects about 6000000 people with more
than 600000 deaths a year. 80% in Asia .
sporadic occur usually, sometimes have
epidemic outbreaks.
8.
9. Risk factors
Defects in cellular-mediated immunity (AIDS, Transplant
patients & malignancy).
Defects in phagocytic function .
Altered stomach PH ( patients on anti-ulcer drug).
Prolonged use of antibiotics (altered gut flora).
Injured gut barrier (bowel disease or surgery).
Splenectomy or functional asplenia (sickle cell dis)
10. Source of infection
Cases and chronic carriers
Cases discharge from incubation, more in
2~4 weeks after onset, a few (about 2~5%)
last longer than 3 months
chronic carrier
12. Susceptibility and immunity
All seasons, usually in summer and
autumn.
Most cases in school-age children and
young adults.
both sexes equally susceptible.
14. ingested orally
Stomach barrier (some Eliminated)
enters the small intestine
Penetrate the mucus layer
enter mononuclear phagocytes of ileal peyer's
patches and mesenteric lymph nodes
proliferate in mononuclear phagocytes
spread to blood. initial bacteremia (Incubation
period).
Pathogenesis
15. Pathogenesis
enter spleen, liver and bone marrow
(reticulo-endothelial system)
further proliferation occurs
A lot of bacteria enter blood again.
(second bacteremia).
Recovery
16. Diagnosis
Diagnosis of typhoid fever is made by
Clinical examination
Blood, bone marrow, or stool cultures for S.
typhi
Serological Tests
17. Clinical manifestations
Incubation period: 3～60 days(7～14).
The initial period (early stage)
First week.
Insidious onset.
Fever up to 39~400C in 5~7 days
Chills, tired、sore throat、
cough ,abdominal discomfort and
constipation .
18. second and third weeks.
Sustained high fever、partly remittent
fever or irregular fever. Last 10～14 days.
Gastro-intestinal symptoms: anorexia、
abdominal distension or pain、diarrhea
or constipation
Neuropsychiatric manifestations:
confusion、blunt respond even delirium
and coma or meningism
19. Circulation system:
relative bradycardia .
splenomegaly、hepatomegaly
toxic hepatitis.
roseola :30%, maculopapular rash
a faint pale color, slightly raised
round or lenticular, fade on pressure
2-4 mm in diameter, less than 10 in number
on the trunk, disappear in 2-3 days.
22. Fulminate infection:
rapid onset, severe toxemia and
septicemia.
High fever,chill,circulation failure,
shock, delirium, coma, myocarditis,
bleeding and other complications,
DIC et all.
25. Bacteriological examinations:
Blood culture:
the most common use
80~90% positive during the first 2 weeks of illness
50% in 3rd week
not easy in 4th week
re-positive when relapse and recrudesce
26. The bone marrow culture
the most sensitive test
specially in patients pretreated with antibiotics.
Urine and stool cultures
increase the diagnostic yield
positive less frequently
stool culture better in 3~4 weeks
27. Tube agglutination test.
five types of antigens:
somatic antigen(O),flagella(H) antigen, and paratyphoid fever
flagella(A,B,C) antigen.
Detects anti O and H antibodies in serum
Diagnosis of Typhoid and Paratyphoid cases
Carriers of typhoid bacilli possess antibody against the
Vi antigen of S. typhi. (Vi tires seem to correlate better
with the carrier state than do O or H titres).
For this reason, the use of Vi agglutination for
detection of carriers was suggested .
WIDAL Test
29. How do you read Widal test results for
typhoid fever?
The highest dilution of the patients serum in
which agglutinations occurs is noted, ex. if the
dilution is 1 in 160 then the titer is 160.
Agglutination in dilution up to <1:60 is seen
in normal individuals . Agglutination in dilution
> 1:160 is suggestive of Salmonella infection
30. Complications
Intestinal hemorrhage
Commonly appear during the second-third week of
illness
serious bleeding in about 2~8%
a sudden drop in temperature、 rise in pulse、and
signs of shock followed by dark or fresh blood in the
stool.
31. Toxic hepatitis:
common,1-3 weeks
hepatomegaly, ALT elevated
get better with improvement of diseases in 2~3
weeks
Toxic myocarditis.
seen in 2-3 weeks, usually severe toxemia.
Bronchitis, bronchopneumonia.
seen in early stage
35. Prognosis:
Case fatality 0.5～1%.
but high in old ages、infant、and serious
complications
Have immunity for ever after diseases
About 3% of patients become fecal
carriers .
36. TREATMENT
General treatment
isolation and rest
good nursing care and supportive
treatment
close observation T,P,R,BP,abdominal
condition and stool .
suitable diet include easy digested food or
half-liquid food.drink more water
intravenous injection to maintain water and
acid-base and electrolyte balance
37. Symptomatic treatment:
for high fever.
For delirium,coma or shock,
2-4mg dexamethasone in addition to
antibiotics reduces mortality.
38. Etiologic and special treatment
Antibiotics
1. Quinolones:
first choice
it’s highly against S.typhi
penetrate well into macrophages,and achieve high
concentrations in the bowel and bile lumens
Norfloxacin (～14 days).
Ofloxacin (10～14days).
ciprofloxacin (14 days)).
39. 2. Cephalosporines:
third generation effective(10~14 days).
3. Macrolides
4.Treatment of complication.
Intestinal bleeding:
bed rest, stop diet, close observation T,P,R,BP.
intravenous saline and blood transfusion and
attention to acid-base balances.
sometimes , operative.
40. Perforation:
early diagnosis.
stop diet.
decrease down the stomach pressure.
intravenous injection to maintain electrolyte
and acid-base balances.
use of antibiotics.
sometimes operative.
41. Toxic myocarditis:
bed rest, cardiac muscle protection drugs,
dexamethasone, digoxin.
5.Chronic carrier:
Ofloxacin or ciprofloxacin 4～6 weeks.
Ampicillin plus probenecid 4～6 weeks.
TMP+SMZ
2 tabs. Bid. 1～3 months.
Cholecystitis may require cholecystectomy.
42. Nursing care
Isolation & barrier nursing is indicated
Trace source of infection.
Notification of the case to the infection control nurse in
the hospital.
43. Prevention
Education on hygiene practices like hand washing after
toilet use & avoidance of eating in non hygienic
restaurants.
Antibiotic prophylaxis is not needed for house-hold
contacts.
Proper handling & refrigeration of food even after
cooking.
Salmonella vaccine is available but affectivity is low
(50% protection).
44. Prognosis
With early diagnosis and prompt treatment most patients
with typhoid fever will recover in due time.
Fever & toxicity subsides within 72 hours of antibiotic
treatment.
Mortality is > 50% in untreated severe typhoid fever
particularly in children & elderly.
Recrudescence is rare but chronic carrier state is
reported in 10% of patients.
