2. Typhoid or enteric fever is a clinical
syndrome characterized by constitutional
and gastro intestinal symptoms ,head
ache. Typhoid fever is a bacterial
infection of the intestinal tract and
occasionally the bloodstream.
Typhoid is caused by Salmonella enterica
serovar typhi (Salmonella typhi)
These waterborne gram negative aerobes
are transmitted by consumption of
contaminated food or drink.
3. Salmonella enterica (formerly Salmonella choleraesuis) is a rod-
shaped flagellated facultative anaerobic ,gram negative bacterium.
Kingdom : eubacteria
Family : Enterobacteriaciea
Genus : Salmonella
Species : S. Enterica
Salmonella enterica has 6 subspecies
and each subspecies that differ by
antigenic specificity.
Secreted proteins are of major
importance for the pathogenesis
of infectious diseases caused by Salmonella enterica.
4. Antigens: located in the cell capsule
• H (flagellar antigen).
• O (Somatic or cell wall antigen).
• Vi (polysaccharide virulence )
Endotoxin
Resistance:
• Lives for 2-3 weeks in water.
• 1-2 months in stool.
• Dies out quickly in summer
Resistance to drying and cooling
S.enterica serotype typhi
Member of family Enterobacteriaciea
5. Ingestion of the bacteria via
contaminated food or water.
About 3%-5% of patients become
carriers of the bacteria after the
acute illness.
These chronic carriers may have
no symptoms.
Flies
6. Salmonella Typhi
P
survives the acidity of the stomach A
invades the Peyer’s Patches of the intestinal wall T
macrophages (Peyer’s Patches) H
the bacteria is within the macrophages and survives
O
G
bacteria spreads via the lymphatics while inside the macrophages
E
access to Reticuloendothelial system, liver, spleen, gallbladder and N
bone marrow
E
First week: elevation of the body temperature
Second week: abdominal pain, spleen enlargement and rosespots S
Third week: necrosis of the Peyer’s Patches I
leads to perforation, bleeding and, if left untreated, death…… S
7. Poor appetite
Malaise
Cough
Sore throat
Headaches
Generalized aches and pains
Fever ascends in step wise fashion after 7 to 10 days reaches plateau.
Sustained fever as high as 103 F-104 F (39 C-40 C)
Lethargy
Diarrhea.
Chest congestion develops in many patients, abdominal pain, distention
and discomfort are common.
About 10% of patients have recurrent symptoms (relapse) after feeling
better for one to two weeks.
Spleenomegaly
Relative bradycardia
Rash(rose spots) appear during 2nd weak of disease. The individual spot,
found on the trunk, is a pink papule 2-3mm in diameter that fades on
pressure. It disappears in 2-3 days
8. Stage One: Stage Two:
A slowly rising Continuing high fever
temperature Extremely distended
Relative bradycardia abdomen
malaise (discomfort or
uneasiness), headache Considerable weight loss
and cough. Bradycardia continues
In ¼ of cases, epistaxis Delirium is frequent,
(acute hemorrhage from frequently calm and
the nostril) can occur. sometimes agitated.
Stage Three: Stage Four:
A number of complications can occur: Defervescence (very
Intestinal hemorrhage due to bleeding high fever)
Intestinal perforation commences that
Encephalitis (inflammation of the brain) continues into the
Fever is still very high
fourth week.
Dehydration occurs and increases delirium
Lies motionless with eyes half-opened
9.
10. WBC count is decreased
Leukocytopenia(specially eosinophilic
leukocytopenia).
Blood culture: Identification of
Bacteremia occurs early Salmonella
in the disease •Sub cultures are done
Blood Cultures are after overnight incubation
positive in at 37 centigrade ,and
•1st week in 90% subcultures are done on
•2nd week in 75% MacConkey's agar
•3rd week in 60% Subcultures are repeated
•4th week and later in 25% upto 10 days after further
incubation.
11. The bone marrow culture •Urine and stool cultures
• You may have this test if you have • A stool sample is collected in a
an unexplained fever clean container and placed under
conditions that allow bacteria or
• Bone marrow culture is an other organisms to grow.
• The type of infection is identified
examination of the soft, fatty tissue by noting the appearance of the
growth, by performing chemical tests
found inside certain bones. This
on the stool sample, and by looking at
tissue, called bone marrow, the sample under a microscope.
produces blood cells.
• Doctor removes a small sample of
fluid bone marrow through a needle.
12. The duodenal string test
Involves swallowing a string to obtain a sample from the upper part of
the small intestine
You swallow a string with a weighted gelatin capsule on the end.
Four hours later it is pulled back out.
Any bile, blood, or mucus attached to the string is examined under the
microscope for cells and parasites .
Culture bile is useful for the diagnosis of carriers.
Rose spots:
Not used routinely
13. WIDAL TEST
INTRODUCTION:
Enteric fever specific agglutinins (antibodies) are detected in patients after 15 days of
fever. BCG vaccinated patient’s serum may show elevated titre of all three ‘H’
agglutinins. Stained salmonella antigens are used to detect and identify specific
antibodies in serum samples from patients suffering from enteric fever.
PRINCIPLE:
Bacterial suspension which carry antigen will agglutinate on exposure to antibodies to
salmonella organisms.
SAMPLE :
Fresh seurm is preferred. In case of any delay performing the test, serum should be
stored at 20 - 80 C.
REAGENTS:
1. Antigen suspension, S. typhi O.
2. Antigen suspension, S. typhi H.
3. Antigen suspension, S. paratyphi ‘AH’.
4. Antigen suspension, S. paratyphi ‘BH’.
5. Polyspecific positive cotrol
6. Glass Slides with 6 reaction circles and
Mixing sticks.
15. SEMI QUANTITATIVE METHOD :
•Pipette one drop of isotonic saline into the first reaction circle and then
place 5, 10, 20, 40, 80 ul of the test sample on the remaining circles.
• Add to each reaction circle, a drop of the antigen which showed
agglutination with the test sample in the screening method.
16. STANDARD TUBE TEST METHOD
1. Take 3sets of 5 test tubes and label them 1 to 5 for O, H, AH and BH
antibody detection.
2. Pipette into the tube No.1 of all sets 1.9 ml of isotonic saline.
3. To each of the remaining tubes (2 to 5) add 1.0 ml of isotonic saline.
4. To the tube No.1 tube in each row add 0.1 ml of the serum sample to be
tested and mix well.
17. •Transfer 1.0 ml of the diluted serum from tube
no.1 to tube no.2 and mix well.
•Transfer 1.0 ml of the diluted sample from tube
no.2 to tube no.3 and mix well. Continue this
serial dilution till tube no.4 in each set.
•Discard 1.0 ml of the diluted serum from tube
No.4 of each set.
•Tube No.5 in all the sets, serves as a saline
control. Now the dilution of the serum sample
achieved in each set is as follows:
Tube No. : 1 2 3 4 5 (control)
Dilutions 1:20 1:40 1:80 1:160 1:320
•To all the tubes (1 to 5) of each set add one drop
of the respective WIDALTEST antigen
suspension (O, H, AH and BH) from the reagent
vials and mix well
•Incubate at 370 C overnight(18 hours)
18. INTERPRETATION OF RESULTS:
SLIDE TEST METHOD
•Agglutination is a positive test result and if the positive reaction
is observed with 20 ul of test sample, it indicates presence of
clinically significant levels of the corresponding antibody in the
patient serum.
•No agglutination is a negative test result and indicates absence
of clinically significant levels of the corresponding antibody in
the patient serum.
QUANTITATIVE METHOD
•The titre of the patient serum using Widal test antigen
suspensions is the highest dilution of the serum sample that
gives a visible agglutination.
•The sample which shows the titre of 1:80 or more should be
considered as clinically significant.
19. Etiologic and special treatment
1.Quinolones:
it’s highly against S.typhi penetrate well into macrophages,and achieve
high concentrations in the bowel and bile lumens
•Norfloxacin (0.1～0.2mg tid～qid/10～14 days).
•Ofloxacin (0.2 mg tid 10～14days).
•ciprofloxacin (0.25 mg tid) caution: not in children and pregnant
2.Chloramphenicol:
For cases without multiresistant S.typhi.
Children in dose of 50～60mg/kg/per day.
adult 1.5～2g/day. tid.
Unable to take oral medication, the same dosage given intravenously
20. 3.Cephalosporines:
Cefoperazone and Ceftazidime.
2～4g/day .10~14 days.
Chronic carrier:
•Ofloxacin 0.2 bid or ciprofloxacin 0.5 bid, 4～6 weeks.
•Ampicillin 3～6g/day tid plus probenecid 1～1.5g/day. 4～6 weeks.
•Cholecystitis may require cholecystectomy.
Adequate waste disposal and protection of food and water supplies
from contamination are important public health measures to
prevent typhoid fever.
Carriers can’t work as food handlers.
21. Immunization is not always effective but should be considered for
household contacts of a typhoid carrier, for travellers to endemic areas
and during epidemic outbreaks.
A multiple dose oral live-attenuated Ty21a vaccine is supplied as enteric
coated capsules.
The capsules must be refrigerated and taken with cool liquids atleast 1
hour before meals. Boosters for every 5 years.
This vaccine is not recommended for infants,children less than 6 years
and immunosuppressed patients.
A single dose Vi capsular polysaccharide(Vi CPS) vaccine is available
for parenteral use. Boosters for every 2 years.
This vaccine is not recommended for infants younger than 2 years.
Both the vaccines are of equal efficacy but oral vaccine causes fewer side
effects.
22. •MICROBIOLOGY by MICHAEL J.PELCZAR,JR. ,E.C.S.CHAN, NOEL R.KRIEG
5th ed
•APPLIED MICROBIOLOGY by VINITHA KALE , KISHORE BHUSARI 2nd ed
•MICROBIOLOGY by PRESCOTT, HARLEY 7th ed
• Cruickshank, R(1962) Medical Microbiology, 12th Ed, P:4003.
•www.medscape.com
•www.giantmicrobes.com
•www.kindnessofstrangerstravel.com
•www.sabin.org
•www.immunize.org
