1. Diagnosis of
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Typhoid Fever
A Clinical Problem Based Learning
Deepa Babin
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2. Case study
• A 20 years old male medical student presented with fever
since one week. The temperature chart shows step ladder
pattern of fever. On clinical examination patient is having
mild hepatomegaly.
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• 1. What can be your provisional diagnosis?
• 2. What are the microbiological investigations for diagnosing
this condition?
• 3. What is the importance of Antibiotic sensitivity in this
condition?
• 4. How you will prevent this infection?
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3. Observe the Step Ladder Pattern
of Temperature
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4. Answer
• It can be case of Enteric fever
Microbiological diagnosis
• Specimens: Blood , Bone marrow ,Blood clot, Stool and
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Urine can be cultured
• The best isolation rates from blood have
been seen in the first week of illness, with
faeces in the second week and with urine
the third week of illness. 4

5. Blood Cultures in Typhoid Fevers
• Bacteremia occurs
early in the disease
• Blood Cultures are
positive in
1st week in 90%
2nd week in 75%
3rd week in 60%
4th week and later in
25%

6. Isolation of the organism
Blood culture- Castaneda Biphasic medium
• Add a minimum of 10 ml of venous blood
from an adult patient to each of 50 ml of
Bile broth and Biphasic medium with
nutrient agar as slant and Brain heart
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infusion broth as liquid medium
• From children at least 5 ml blood should
be inoculated in each of the bottles.
• Incubate the inoculated media at 37oC
overnight and subculture into
• MacConkey agar
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• Blood agar

7. Further Incubation up to 7 days
• Incubate up to 7 days if subcultures fail to
yield any bacterial growth.
• Subculture again on day 7 and if no
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growth is obtained blood culture may be
declared as negative for enteric fever
bacilli.
• Periodic subcultures are made after day 2,
5 and 7 on MacConkey agar.
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8. Clot culture
• The clot culture has following advantages over
blood culture namely
• Serum is available for antibody titration.
• The clot can be put in blood culture bottles and
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can be broken either mechanically or by adding
streptokinase, if available.
Urine culture
• Urine culture is positive in a quarter to one third
of cases, but there seems to be no regular
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excretion pattern in the urine

9. Clot culture
• Clot cultures are more
productive in yielding
better results in
isolation.
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• A blood after clotting,
the clot is lysed with
Streptokinase ,but
expensive to perform in
developing countries.
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10. Culture Medias
Mac Conkeys agar
Deoxycholate citrate agar (DCA)
Selenite F broth as enrichment
medium.
Cultural characters
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DCA - pale yellow colonies, 2-3 mm
in diameter, moist, circular and
smooth convex surface.
MacConkeyagar-non lactose
fermenting colonies
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11. Salmonella on Mac Conkey's agar
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12. Salmonella on XLD agar
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13. Biochemical reactions I M Vi C TSI U
_ + _ _ K/A H2s _
• Catalase positive and Oxidase
negative.
• I M Vi C _ + _ _
• TSI - K/A with H2S
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• Urease Negative
• Gram smear-Gram negative
bacilli
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14. Slide agglutination
• On the basis of biochemical reactions, the
organism has been identified as Salmonella; its
identity can be confirmed with slide agglutination
test, using polyvalent 'O' and polyvalent 'H'
antisera against salmonellae.
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• For identification monovalent 'O' specific
antiserum for S.typhi is factor 9.
• To perform this test 1 drop each of normal saline
is placed at two different sites on a clean glass
slide.
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15. Slide agglutination tests
• In slide agglutination
tests a known serum
and unknown culture
isolate is mixed,
clumping occurs within
few minutes
• Commercial sera are
available for detection
of A, B,C1,C2,D, and E.

16. Slide agglutination
• A loopful of biochemically suspect colony of
Salmonella is emulsified in both. One of these is
kept as central and another is tested first with
polyvalent 'O' antiserum against Salmonella.
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• If this gives visible agglutination within 2
minutes, the process is repeated with
polyvalent 'H' antiserum and then with factor 9
antiserum
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17. Other methods of Diagnosis of Typhoid
fever
• WIDAL TEST
• Serum agglutinins raise abruptly during the 2nd or 3rd
week.The widal test detects antibodies against O,
H,AH,BH antigens
• Two serum specimens obtained at intervals of 7 – 10
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days to read the raise of antibodies.
• Serial dilutions on unknown sera are tested against the
antigens for respective Salmonella
• False positives and False negative limits the utility of the test
O > 1 in 160
H > 1 in 320
Typhidot
Detects specific IgM and IgG antibodies to S. typhi 17

18. . Antimicrobial susceptibility testing
• The emergence and spread of S.typhi
resistant to multiple antibiotics shows
the need for susceptibility testing.
• Multi-drug resistant typhoid fever has
become endemic in many developing
countries.
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• Resistant to Chloramphenicol,
Ampicillin and Trimethoprim
sulfamethoxazole.
• Choice of drug
• Fluoroquinolones
(ciprofloxacin,Ofloxacin)
Third gen
Cephalosporins(Cefotaxime,Ceftri 18
azone,Ceftazidime)

19. BACTEK and Radiometric based
methods are in recent use
• BACTEK methods in
isolation of Salmonella
is a rapid and sensitive
method in early
diagnosis of Enteric
fever.
• Many Microbiology
Diagnostic Laboratories
are upgrading to
Bactek methods

20. Prevention
• Good Sanitary measures
• Typhoid vaccine(TAB Vaccine)
Heat inactivated phenol
preserved vaccine.
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• Divalent vaccine in India
• Dosage- Two doses four weeks
apart with single booster dose
every three years
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21. • Programme created for Medical and
Paramedical students for orientation on
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Clinical Based Learning
• Email
• deepababin@gmail.com
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