DIAGNOSIS OF TYPHOID FEVER updated

1. DIAGNOSIS OF TYPHOID FEVER
updated
Dr.T.V.Rao MD
Dr.T.V.Rao MD 1

2. Typhoid fever
common problem in developing
Countries

3. Manifest with
Rose spots
High fever
Diarrhea
Typhoid Meningitis
Aches and pains
Chest congestion

4. Clinical manifestation
• Head ache, malise,anorexia ,coated tongue
• Abdominal discomfort,
• Constipation / Diarrhea
• Step ladder type fever,
• Relative bradycardia,
• A soft palpable spleen
• Hepatomegaly
• Rose spots appear
Dr.T.V.Rao MD 4

5. Over view of Diagnosis of Typhoid
Fever
• Infection with typhoid or
paratyphoid fever results in
a very low-grade
septicaemia. A single blood
culture is positive in only
half of cases. Stool culture is
not usually positive during
the early phase of the
disease. Bone marrow
culture increases the
diagnostic yield to about
80% of cases.
Dr.T.V.Rao MD 5

6. Bacteriological Diagnosis of Typhoid Fever
• Selective media, such as Deoxycholate-
citrate agar or xylose-lysine Deoxycholate
agar, are used for the isolation of
salmonella bacteria from faeces. Fluid
enrichment media, such as Tetrathionate
or selenite broth, are also useful to
detect small numbers of salmonellae in
faeces, foods or environmental samples.
Dr.T.V.Rao MD 6

7. Bacteriological Diagnosis of
Typhoid Fever
• Suspicious colonies from the culture
plates are tested directly for the
presence of Salmonella somatic (O)
antigens by slide agglutination and
subcultured to peptone water for the
determination of flagellar (H) antigen
structure and further biochemical
analysis.
Dr.T.V.Rao MD 7

8. Bacteriological Diagnosis of
Typhoid Fever
• A presumptive diagnosis of salmonellosis
can often be made within 24 h of the
receipt of a specimen, although
confirmation may take another day, and
formal identification of the serotype
takes several more days. A negative
report must await the result of
enrichment cultures - at least 48 h.
Dr.T.V.Rao MD 8

9. How we Diagnose Typhoid Fever
• Diagnosis is made by any blood, bone marrow
or stool cultures and with the Widal test
(demonstration of salmonella antibodies
against antigens O-somatic and H-flagellar ). In
epidemics and less wealthy countries, after
excluding malaria, dysentery or pneumonia, a
therapeutic trial time with chloramphenicol is
generally undertaken while awaiting the
results of Widal test and cultures of the blood
and stool.
Dr.T.V.Rao MD 9

10. Laboratory Diagnosis of
Typhoid Fever
• 1 Isolation of Bacilli. A Gold standard
• 2 Diagnosis for presence of Antibodies,
• Positive Blood culture – A gold standard
• Isolation from Feces and Urine ?
• Detection of Antibodies Inconclusive.
• Newer methods
Detection of antigen in Blood and Urine
Dr.T.V.Rao MD 10

11. Blood Culture
1 st week Positive in 90 %
2 nd week Positive in 75 %
3 rd week Positive in 60 %
> 3 weeks positive in 25 %
Draw 5 – 10 cc of Blood by venipuncture.
ADD to 50 -100 ml of Bile broth.
Incubate at 37 c /Subculture in MacConkey
At regular intervals
Dr.T.V.Rao MD 11

12. 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%
Dr.T.V.Rao MD 12

13. Castaneda’s method of
Blood Culture
• Double medium used Solid/Liquid medium in
the same Bottle.
• Bottle contains Bile broth/agar slant,
• For subculture the bottle is merely tilted.
• A subculture into MacConkey at regular
intervals,
• Reduces the chances of contamination
• Increases the chances of isolation.
Dr.T.V.Rao MD 13

14. Salmonella on Mac Conkey's agar
Dr.T.V.Rao MD 14

15. Salmonella on XLD agar
Dr.T.V.Rao MD 15

16. Clot culture
• Clot cultures are more
productive in yielding
better results in
isolation.
• A blood after clotting,
the clot is lysed with
Streptokinase ,but
expensive to perform
in developing
countries.
Dr.T.V.Rao MD 16

17. Bactec 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
Dr.T.V.Rao MD 17

18. Biochemical Characters
• Non Lactose fermenter,
• Motile
• Indole – MR + VP - Citrate +
• Ferment Glu/Mal/Man
• Do not ferment Lactose/Sucrose
Dr.T.V.Rao MD 18

19. 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.
Dr.T.V.Rao MD 19

20. Culturing other Specimens
• Feces Enrichment in Tetrathionate broth
and Selenite broth
• Culturing in MacConkey/DCA/Wilson
Blair medium – Large black colonies.
• Urine Culture – positive in 25 %
• Other samples
Bone Marrow,Bile,CSF/Sputum
Dr.T.V.Rao MD 20

21. Why we still use Widal test
• The Widal test is an
old serologic assay
for detecting IgM
and IgG to the O and
H antigens of
salmonella. The test
is unreliable but is
widely used in most
developing countries
because of its low
cost. Dr.T.V.Rao MD 21

22. Serology
• WIDAL Test – Tube agglutination test.
• Detects O and H antibodies
• Diagnosis of Typhoid and Paratyphoid
• Testing for H agglutinins in Dryers tubes, a
narrow tube floccules at the bottom
• Testing for O agglutinins in Felix tubes, Chalky
• Incubated at 37º c overnight
Dr.T.V.Rao MD 22

23. Widal Test
• In 1896 Widal A professor of
pathology and internal
medicine at the University of
Paris (1911–29), he developed a
procedure for diagnosing
typhoid fever based on the fact
that antibodies in the blood
of an infected individual cause
the bacteria to bind together
into clumps (the Widal
reaction).
Dr.T.V.Rao MD 23

24. Widal test
• S.typhi O and H tubes
• Paratyphi A/B H agglutinins only
• Common antigens O in all Factor sharing
12
• Significance
• I st week negative.
• Titers raise in 2nd week Raise of titers
diagnostic Dr.T.V.Rao MD 24

25. Diagnosis of Enteric Fever
Widal test
• Serum agglutinins raise abruptly during the 2nd or 3rd
week
• The Widal test detects antibodies against O and H
antigens
• Two serum specimens obtained at intervals of 7 – 10
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
• The interpretative criteria when single serum
specimens are tested vary
• Cross reactions limits the specificity

26. Widal Test
• Single test not diagnostic.
• Paired samples tests
• Diagnostic.
O > 1 in 80
H > 1in 160
H agglutinins appear first
False positives in Unapparent infection,
Immunization
Previously infected
Dr.T.V.Rao MD 26

27. Widal test
• Anamnestic response previous
infection and responding to
unrelated infection
• Other Diagnostic tests
CIE and ELISA
Detection of Circulating antigens
Co agglutination test.
Dr.T.V.Rao MD 27

28. Limitation of Widal Test
• The Widal test is
time consuming
and often times
when diagnosis is
reached it is too
late to start an
antibiotic regimen.
• In spite of several
limitation many
Physicians depend
on Widal Test
Dr.T.V.Rao MD 28

29. False Positive and Negative Reactions
with WIDAL Test
• The Widal test should be interpreted in
the light of baseline titers in a healthy
local population. This is especially
important when there is a high local
prevalence of non-typhoid salmonellosis.
The Widal test may be falsely positive in
patients who have had previous
vaccination or infection with S typhi.
Dr.T.V.Rao MD 29

30. False Positive and Negative Reactions
with WIDAL Test
• Widal titers have also been reported in
association with the dysgammaglobulinaemia
of chronic active hepatitis and other
autoimmune diseases.64 '8 '9 False negative
results may be associated with early
treatment, with "hidden organisms" in bone
and joints, and with relapses of typhoid fever.
Occasionally the infecting strains are poorly
immunogenic.
Dr.T.V.Rao MD 30

31. Diagnosis of Carriers and
Environments
• Fecal carriers by
isolation from
specimens. or Bile
aspirated.
• Sewer swabs
• Bacteriophage
typing
Dr.T.V.Rao MD 31

32. Culturing and Identifying remain the
Gold standard
• Newer serologic assays
for S. enterica serotype
Typhi infection are
occasionally used in
outbreak situations and
are somewhat more
sensitive and specific than
the Widal test, but are
not an adequate
substitute for blood,
stool, or bone marrow
culture.
Dr.T.V.Rao MD 32

33. Is there a definitive test to diagnose
Typhoid fever
• Because there is no
definitive serologic test
for typhoid or
paratyphoid fever, the
initial diagnosis often has
to be made clinically. The
combination of a history
of risk for infection and a
gradual onset of fever
that increases in severity
over several days should
raise suspicion of typhoid
or paratyphoid fever.
Dr.T.V.Rao MD 33

34. Newer methods in diagnosis of
Typhoid Fever
• The serum samples
can be tested by
using newer
methods
Multi-Test Dip-S-
Ticks, TyphiDot, and
TUBEX to detect
immunoglobulin G
(IgG), IgG and IgM,
and IgM,
respectively.Dr.T.V.Rao MD 34

35. Immunoassays in Typhoid Fever
• The immunoassay is
also used for the
diagnosis. The
immunoassay are based
on the detection of the
O and Vi antigens of S.
typhi in blood or urine
using conglutination,
ELISA, or counter
current
immunoelectrophoresis
. Dr.T.V.Rao MD 35

36. Experimental and Molecular Methods
• Polymerase chain
reaction and DNA
probe method
attempt to employ
S.typhi genes and
hybridize them with
labelled specific
gene probes were
also used.
Dr.T.V.Rao MD 36

37. Key points
• Antibiotics have no place in the
management of salmonella
gastroenteritis unless invasive
complications are suspected.
• Clean water, sanitation and hygienic
handling of foodstuffs are the keys to
prevention.
Dr.T.V.Rao MD 37

38. Coalition against Typhoid
• Since May 2011, the
Coalition against Typhoid
(CaT) has featured monthly
articles in the WHO’s Global
Immunization Newsletters
(GIN). The articles, written
by CaT members from
around the world, highlight
important work being done
to accelerate adoption of
typhoid vaccines.
Dr.T.V.Rao MD 38

39. • Programme Created by Dr.T.V.Rao MD
for Medical and Paramedical students in
the Developing world
• Email
• doctortvrao@gmail.com
Dr.T.V.Rao MD 39