Medical microbiology

1. Enteric fever
Salmonellainfections
Dr.T.V.RaoMD
Dr.T.V.Rao MD 1

2. TyphoidFeveraImportantCommunicable
diseaseaffectsmanyin theworld
Dr.T.V.Rao MD 2

3. Salmonella
Dr.T.V.Rao MD 3
• Causes Infections in Humans and
vertebrates,
• Enteric Fever ( Typhoid fever )
• Gastroenteritis
• Septicemias,
• Carrier state a concern

4. Dr.T.V.Rao MD 4
Salmonella
• A Very complex group
• Contains more > 2,500 spp
• Typed on the basis of Serotyping, and species
typing
• Divided into two groups
1 Enteric fever group
2 Food poisoning group –
3 Septicemias

5. Dr.T.V.Rao MD 5
Key points
• There are more than 2500 different antigenic
types of Salmonella; those pathogenic to man
are serotypes of S. enterica.
• Most serotypes of S. enterica cause food-
borne gastroenteritis and have animal
reservoirs.
• S. enterica serotypes Typhi and Paratyphi
cause typhoid fever.

6. Enteric Fever
Typhoid Fever
• Caused by Salmonella typhi, and other
Groups called as Paratyphoid A, B, C
• Salmonella typhi - Causes Typhoid
• Salmonella Paratyphi A,B,C Causes
Paratyphoid fevers.
• Food Poison group
• Spread from Animals – Humans
• Causes Gastroenteritis – Septicemias,
Localized Infection
Dr.T.V.Rao MD 6

7. Dr.T.V.Rao MD 7
Salmonella typhi
• The bacterium Salmonella typhi is present only in
human beings and is transmitted through
contaminated food or water. People with this
infection carry the bacterium in their intestines
and bloodstream, and those who have recovered
from the disease could still have the bacterium in
their system; they are known as ‘carriers’ of the
disease. Both ill people and carriers
shed Salmonella typhi in their stool

8. Dr.T.V.Rao MD 8
Food handlers spread the infection
• Both ill people and carriers
shed Salmonella typhi in their stool
• Infection is usually spread when
food or water is handled by a
person who is shedding the
bacterium or if sewage water
leaks into drinking water or food that is then
consumed..

9. Typhoid fevers are prevalent in many
regions in the World

10. Typhoid Mary Most Dangerous
Woman in America
Dr.T.V.Rao MD 10

11. Typhoid Mary
• A famous example is
“Typhoid” Mary
Mallon, who was a
food handler
responsible for
infecting at least 78
people, killing 5.
These highly
infectious carriers
pose a great risk to

12. Typhoid Mary
• "Typhoid Mary," real name Mary Mallon,
worked as a cook in New York City in the early
1900s. Public health pioneer Sara Josephine
Baker, MD, PhD tracked her down after
discovering that she was the common link
among many people who had become ill from
typhoid fever She was traced to typhoid
outbreaks a second time so she was put in
prison again where she lived until she died.

13. French physician Pierre Charles
Alexandre Louis first proposed
the name “typhoid fever”
William Wood Gerhard who was the first
to differentiate clearly between typhus
fever and typhoid in 1837.

14. Carl Joseph Eberth who discovered the
typhoid bacillus in 1880.
Georges Widal who described the
‘Widal agglutination reaction’ of the blood in 1896.

15. Morphology of Salmonella
• Gram negative
bacilli
• 1-3 / 0.5
microns,
• Motile by
peritrichous
flagella
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16. S.typhi with Flagella
Dr.T.V.Rao MD 16

17. Bacteriology –Typhoid fever
• The Genus
Salmonella belong to
Enterobacteriaceae
• Facultative anaerobe
• Gram negative bacilli
• Distinguished from
other bacteria by
Biochemical and
antigen structure
Dr.T.V.Rao MD 17

18. Different types of Salmonella
I.- enterica
II.- salamae
IIIa -arizonae
IIIb -diarizonae
IV.- houtenae
V.- bongori
VI.- indica

19. Dr.T.V.Rao MD 19
Cultural Characters
• Aerobic / Facultatively anaerobic
• Grows on simple media – Nutrient agar,
• Temp 15 – 41ºc / 37º c
• Colonies appear as large 2 -3 mm, circular, low
convex,
• On MacConkey medium appear
Colorless ( NLF )
Selective Medium - Wilson Blair Bismuth sulphide
medium. Produce Jet black colonies
H2 S produced by Salmonella typhi

20. Dr.T.V.Rao MD 20
Enrichment Medium
Liquid Medium
• Selenite F medium
• Tetrathionate broth
• Above medium are used for
isolation of Salmonella from
contaminated specimens
• Particularly stool specimens..

21. Dr.T.V.Rao MD 21
Identifying Enteric Organisms
• Isolates which are Non lactose fermenting
• Motile, Indole negative
• Urease negative
• Ferment Glucose,Mannitol,Maltose
• Do not ferment Lactose, Sucrose
• Typhoid bacilli are anaerogenic
• Some of the Paratyphoid form acid and gas
• Further identification done by slide
agglutination tests

22. Dr.T.V.Rao MD 22
Biochemical Characters
• Glucose ,Mannitol ,Maltose produce A/G
• Salmonella typhi do not produce gas
• Lactose/Salicin/sucrose not fermented.
• Indole –
• Methyl Red +
• V P -
• Citrate +
• Urea –
• H2S – produced by Salmonella typhi
• Paratyphi A do not produce H2S

23. Dr.T.V.Rao MD 23
Resistance of Salmonella
•55º c – 1 hour
•60º c – 15 MT
•Boiling ,Chlorination,
Pasteurization Destroy the
Bacilli.

24. Salmonella
Antigenic Structure
Dr.T.V.Rao MD 24
heat
• H – Flagellar antigens
• O – Somatic antigen,
• Vi – Surface antigen in some species only
• H antigens also called flagellar antigens,
labile protein,
• Boiling destroys antigenicity
• When mixed with Antiserum produces agglutination
and fluffy clumps are produced
• H antigens are strongly immunogenic Induces
antibodies rapidly,

25. Dr.T.V.Rao MD 25
Antigenic structure of Salmonella
• Two sets of antigens
• Detection by serotyping
• 1 Somatic or 0 Antigens contain long
chain polysaccharides ( LPS )
comprises of heat stable
polysaccharide commonly.
•

26. Flagellar Antigens
Dr.T.V.Rao MD 26
• Flagellar or H Antigens are strongly
immunogenic and induces antibody
formation rapidly and in high titers
following infection or immunization.
The flagellar antigen is of a dual
nature, occurring in one of the two
phases.
•

27. Dr.T.V.Rao MD 27
Antigens – Salmonella ( cont )
• O Antigens
• Forms integral part of Cell wall,
• Like Endotoxin
• 0 Antigens unaffected by boiling.
• When mixed with antiserum produce chalky
clumps are formed, take more time reaction,
at high temp 50º – 55º c
• O antigens are less immunogenic. than H
antigens

28. Dr.T.V.Rao MD 28
Antigen (Vi) – Salmonella ( contd )
• Vi antigens
• Many strains in S.typhi covers the O antigens-
prevents agglutination.
• Resembles like K antigens
• Destroyed after boiling at 60º c / 1 hour.
• Vi a polysaccharide
• Acts as virulence factor, protects the bacilli against
Phagocytosis and activity of Complement
• Poorly immunogenic
• Low titer of antibodies are produced, Not diagnostic

29. Dr.T.V.Rao MD 29
Classification of Salmonella
• Classified on the basis of
Kauffmann-White Scheme
• Structure of 0 and H antigens are
taken into consideration,
• More than 2000 species
characterized.

30. Dr.T.V.Rao MD 30
Kauffmann – White scheme
• Serotype 0 antigens H antigens
Phase 1 2
1.Typhi 9,12,(Vi) d 1,2
2 Paratyphi A 1,2.12 a -
3 Paratyphi B 1,4,5,12 b 1,2
4 Typhimuruim 1,4,5,12 I 1,7
5 Enteritidis 1,9,12 g m 1,2

31. Antigenic Variation in
Salmonella
• May be phenotypic / Genotypic
• H to O = loss of Flagella
May be phase variation from I to
II
V to W variation
S to R variation
Dr.T.V.Rao MD 31

32. Dr.T.V.Rao MD 32
Pathogenicity
• Salmonella are definite parasites to
humans.
• Eg S.typhi.
• S.paratyphi A, B ,C
• Other groups Salmonella
• The important clinical syndromes
1. Enteric fever, Septicemias,
gastroenteritis.

33. Enteric Fever: S. typhi
• Ileocecal penetration
• intraluminal multiplication
• mononuclear response (macrophages)
• Salmonella remains alive
• 2nd week - lymphoid hyperplasia (mesenteric
lymph nodes)
• back to bowel

34. Enteric Fever
Typhoid
• Typhoid – caused by S.typhi
• Paratyphoid Caused by
Paratyphi A,B,C
• Typhoid --- Like Typhus
• Infective dose ID50 / 107,
Dr.T.V.Rao MD 34

35. Fever
• All the events coincides with Fever and other
signs of clinical illness
• From Gall bladder further invasion occurs in
intestines
• Involvement of peyr’s patches, gut lymphoid
tissue
• Lead to inflammatory reaction, and infiltration
with monocular cells
• Leads to Necrosis, Sloughing and formation of
chacterstic typhoid ulcers

36. Typhoid fever

37. Rashes in Typhoid
• May present with rash,
rose spots 2 -4 mm in
diameter raised discrete
irregular blanching pink
maculae's found in
front of chest
• Appear in crops of upto
a dozen at a time
• Fade after 3 – 4 days

38. Dr.T.V.Rao MD 38

39. Events in a Typical typhoid Fever
Dr.T.V.Rao MD 39

40. Dr.T.V.Rao MD 40
Pathology and Pathogenesis
• Bacilli enter through ingestion,
• Bacilli attach to Microvilli,ileal mucosa,
penetrate to Lamina propria and sub mucosa
• Phagocytosis by Polymorphs and
Macrophages
• Enters the mesenteric lymph nodes
• Enter the thoracic duct – Blood stream

41. Dr.T.V.Rao MD 41
Infective Dose
• For human infections, the number of
bacteria that must be swallowed in order
to cause infection is uncertain and varies
with the serotype. In most of these the
median infective dose for most
serotypes, including Typhi, has varied
from 106 to 109 viable organisms.

42. Dr.T.V.Rao MD 42
Pathology and Pathogenesis
• Bacteremia Spread to Liver, Gall
bladder, Spleen, Bone marrow,
Lymph nodes, Lungs, Multiply in
kidneys
Once again spill into Blood stream
Causes clinical illness.

43. Ingestion of contaminated food or water
Salmonella bacteria
Invade small intestine and enter the bloodstream
Carried by white blood cells in the liver, spleen, and
bone marrow
Multiply and reenter the bloodstream

44. Dr.T.V.Rao MD 44
Pathology and Pathogenesis
• Multiply abundantly in Gall bladder,
• Bile rich source of Bacteria
• Spill into Intestine, infects payers patches,
Lymph follicles
• Inflammation – Undergo necrosis, Slough off
• Typhoid ulcers
• Typhoid ulcers can cause perforation and
hemorrhage
• Duration of Illness 3 – 4 weeks
• Incubation 7 -14, ( 3-56 days )

45. What is Enteric Fever
Typhoid Fever
Dr.T.V.Rao MD 45
• Enteric fever is caused by strains of S.
Typhi or S. Paratyphi A, B or C;
although S. Paratyphi B, which gene
sequence analysis suggests is a
variant of S. Java, is more likely to
cause non-typhoidal diarrhoea.

46. Dr.T.V.Rao MD 46
S.typhi more serious
• The clinical features tend to be more
severe with S. Typhi (typhoid fever). After
penetration of the ileal mucosa the
organisms pass via the lymphatic's to the
mesenteric lymph nodes, whence after a
period of multiplication they invade the
bloodstream via the thoracic duct.

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

48. Symptoms
• No symptoms - if only a mild exposure; some people become "carriers" of
typhoid.
• Poor appetite,
• Headaches,
• Generalized aches and pains,
• Fever, Lethargy, Lethargy,
• Lethargy,
• Diarrhea,
• Have a sustained fever as high as 103 to 104 degrees Fahrenheit (39 to 40
degrees Celsius),
• Chest congestion develops in many patients, and abdominal pain and
discomfort are common,
• Constipation, mild vomiting, slow heartbeat.

49. Progress in Enteric Fever
Dr.T.V.Rao MD 49
• The liver, gall bladder, spleen, kidney and bone
marrow become infected during this primary
bacteraemic phase in the first 7-10 days of the
incubation period. After multiplication in
these organs, bacilli pass into the blood,
causing a second and heavier bacteraemia,
the onset of which approximately coincides
with that of fever and other signs of clinical
illness.

50. Progress in Enteric Fever
Dr.T.V.Rao MD 50
• From the gall bladder, a further invasion
of the intestine results. Peyer's patches
and other gut lymphoid tissues become
involved in an inflammatory reaction,
and infiltration with mononuclear cells,
followed by necrosis, sloughing and the
formation of characteristic typhoid ulcers
occurs.

51. Immunity in Typhoid
• Typhoid bacilli
are
Intracellular
pathogens
• Cell mediated
immunity is
crucial
Dr.T.V.Rao MD 51

52. Dr.T.V.Rao MD 52
Early symptoms of Typhoid
Fever
• The incubation period is usually 1-2 weeks, and
the duration of the illness is about 3-4 weeks.
Symptoms include:
• Poor appetite
• Headaches
• Generalized aches and pains
• Fever as high as 104 degrees Farenheit
• Lethargy
• Diarrhea

53. 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 53

54. Events in a Typical typhoid Fever
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55. Dr.T.V.Rao MD 55
Complications of Enteric fever
• Intestinal perforation,
• Hemorrhage,
• Circulatory collapse.
• Bronchitis Bronchopneumonia,
• Meningitis,
• Cholecystitis,
• Arthritis,Periostitis / Nephritis,
• Osteomyletis,

56. Dr.T.V.Rao MD 56
Relapses in Typhoid Fever
• Apparent recovery can be followed by
relapse in 5-10% of untreated cases.
Relapse is usually shorter and of milder
character than the initial illness, but can
be severe and may be fatal. Severe
intestinal haemorrhage and intestinal
perforation are serious complications
that can occur at any stage of the illness.

57. Other complications
• Causes relapses in
particular to
patients treated
with
chloramphenicol.
• S.paratyphi
produce
septicemias.
Dr.T.V.Rao MD 57

58. Typhoid carriers
• Salmonella enterica causes
approximately 16 million cases of typhoid
fever worldwide, killing around 500,000
per year. One in thirty of the survivors,
however, become carriers. In carriers the
bacteria remain hidden inside cells and
the gall bladder, causing new infections
as they are shed from an apparently
healthy host.

59. Carriers may be
Carriers may be temporary or chronic.
Temporary (convalescent or incubatory)
carriers usually excrete bacilli up to 6-8
weeks. By the end of one year, 3-4 per cent
of cases continue to excrete typhoid bacilli.
Persons who excrete the bacilli for more than a
year after a clinical attack are called chronic
carriers.

60. Carrier Stage in Typhoid Fever
Dr.T.V.Rao MD 60
• Most people infected with salmonella
continue to excrete the organism in their
stools for days or weeks after complete clinical
recovery, but eventual clearance of the
bacteria from the body is usual. A few patients
continue to excrete the salmonellae for
prolonged periods. The term chronic carrier is
reserved for those who excrete salmonellae
for a year or more.

61. Carrier Stage in Typhoid Fever
Dr.T.V.Rao MD 61
• Chronic carriage can follow symptomatic
illness or may be the only manifestation of
infection. It can occur with any serotype, but
is a particularly important feature of enteric
fever: up to 5% of convalescents from typhoid
and a smaller number of those who have
recovered from paratyphoid fever become
chronic carriers, many for a lifetime.

62. Carrier Stage in Typhoid Fever
Dr.T.V.Rao MD 62
• The bacilli are most commonly present in the
gall bladder, less often in the urinary tract,
and are shed in faeces and sometimes in
urine. The long duration of the carrier state
enables the enteric fever bacilli to survive in
the community in non-epidemic times and to
persist in small and relatively isolated
communities.

63. Dr.T.V.Rao MD 63
Epidemiology
• Developed countries - Controlled.
• Water supply/ Sanitation /Economically
poor.
• S.typhi and S.paratyphi are prevalent in
India
• Previously Typhi are more common
Paratyphoid A on raise.
• Age 5 – 20 years, Sanitation

64. Dr.T.V.Rao MD 64
Epidemiology
• Sanitation has great role
• Source an active patient or a Carrier shed the
Bacilli.
• Who are carriers.
Convalescent carrier 3 weeks to 3 months
Temporary carrier
Chronic carrier
3 months to 1 year
> 1 year,
Women attain more carrier stage

65. Epidemiology (Contd)
Dr.T.V.Rao MD 65
• Bacilli persist in the Gall bladder and kidney
• Food handlers spread the infection
• Cooks great role
• S.typhi and S.paratyphi in humans
• S.para B in Animals,
• Typhoid spread through
Water, Milk, Food
HIV patients potentially susceptible for Typhoid
disease.

66. 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 66

67. Dr.T.V.Rao MD 67
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.

68. Bacteriological Diagnosis of
Typhoid Fever
Dr.T.V.Rao MD 68
• 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.

69. Dr.T.V.Rao MD 69
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.

70. Dr.T.V.Rao MD 70
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

71. Dr.T.V.Rao MD 71
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

72. 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 72

73. Dr.T.V.Rao MD 73
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.

74. Salmonella on Mac Conkey's agar
Dr.T.V.Rao MD 74

75. Salmonella on XLD agar
Dr.T.V.Rao MD 75

76. 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 76

77. 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 77

78. Dr.T.V.Rao MD 78
Biochemical Characters
• Non Lactose fermenter,
• Motile
• Indole – MR + VP - Citrate +
• Ferment Glu/Mal/Man
• Do not ferment Lactose/Sucrose

79. 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 79

80. Dr.T.V.Rao MD 80
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

81. Dr.T.V.Rao MD 81
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

82. 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 82

83. Dr.T.V.Rao MD 83
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

84. 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

85. Dr.T.V.Rao MD 85
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

86. Dr.T.V.Rao MD 86
Widal test
• Anamnestic response previous
infection and responding to
unrelated infection
• Other Diagnostic tests
CIE and ELISA
Detection of Circulating antigens
Co agglutination test.

87. 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 87

88. Dr.T.V.Rao MD 88
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.

89. Dr.T.V.Rao MD 89
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.

90. Dr.T.V.Rao MD 90
OtherSerological tests
• Indirect hemagglutination, indirect fluorescent
Vi antibody, and indirect enzyme-linked
immunosorbent assay (ELISA) for
immunoglobulin M (IgM) and IgG antibodies
to S typhi polysaccharide, as well as
monoclonal antibodies against S typhi
flagellin, are promising, but the success rates
of these assays vary greatly in the literature
• Source of Information [Typhoid Fever Workup Author: John L Brusch, MD, FACP;
Chief Editor: Michael Stuart Bronze, MD Drugs & Diseases > Infectious Diseases
Medscape)

91. Dr.T.V.Rao MD 91
Polymerasechainreaction
• Polymerase chain reaction (PCR) has been used for the
diagnosis of typhoid fever with varying success. Nested
PCR, which involves two rounds of PCR using two
primers with different sequences within the H1-d
flagellin gene of S typhi, offers the best sensitivity and
specificity. Combining assays of blood and urine, this
technique has achieved a sensitivity of 82.7% and
reported specificity of 100%. However, no type of PCR
is widely available for the clinical diagnosis of typhoid
fever.
Source of Information [Typhoid Fever Workup Author: John L Brusch, MD, FACP;
Chief Editor: Michael Stuart Bronze, MD Drugs & Diseases > Infectious Diseases
Medscape)

92. Diagnosis of Carriers and
Environments
• Fecal carriers by
isolation from
specimens. or Bile
aspirated.
• Sewer swabs
• Bacteriophage
typing
Dr.T.V.Rao MD 92

93. Prophylaxis
• TAB vaccine
S.typhi 1,000 millions
S Paratyphi A,B 750 millions.
Injected subcutaneously 0.5 ml
at 4 – 6 weeks.
Live Oral Vaccine Typhoral
Mutant S.typhi strain Ty 2 1a Lacking enzyme UDP
galctose 4 epimerase 10 to9
Viable bacilli
Given orally 1 – 3 – 5 days
Dr.T.V.Rao MD 93

94. Dr.T.V.Rao MD 94
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.

95. Prevention
• Vi Polysaccharide vaccine
– Administered subcutaneously or intramuscular
– Confers protection seven days after injection
– Approximately 50% efficacy after three years
• Ty 21 vaccine
– Live attenuated strain of S. typhi
– Administered orally in capsule form
– Also available in liquid form which can be taken by
children as young as two years of age

96. Dr.T.V.Rao MD 96
Vaccines
• An Inject able vaccine Typhium Vi
• Contains purified Vi polysaccharide
antigen from S.typhi strain Ty2
• A single dose, subcutaneous route
• Given to children > 5 years
• Immunity lasts for 2- 3 years.
• Follow a booster

97. Dr.T.V.Rao MD 97
Treatment
• Chloramphenicol 1948 /1970 resistance.
• Other Important drugs
Ampicillin
Amoxicillin,
Furazolidine
Cotromoxazole
Chloramphenical resistance /Mexico
Kerala

98. Antimicrobial Therapy in Typhoid
• With prompt antibiotic therapy, more than
99% of the people with typhoid fever are
cured, although convalescence may last
several months. The antibiotic
chloramphenicol Some Trade Names
CHLOROMYCETIN
is used worldwide, but increasing resistance to
it has prompted the use of other antibiotics
BACTRIM
SEPTRAN
or ciprofloxacin

99. Other Drugs
• Fluroquinolones
Ciprofloxacillin,
Pefloxacillin
Ofloxacillin
Ceftazidime
Ceftriaxone /
Cefotoxaime
Dr.T.V.Rao MD 99

100. 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 100

101. Salmonella
• WHO: 1,400,000 instances of salmonellosis
in USA
• Salmonella costs per year
US $3,000,000,000
• 2,300 serotypes (S. enterica Typhimurium,
etc)
– wide host range (humans, cattle, horses,
rodents, cats, dogs, birds, reptiles)
• Multi-drug resistant S.e.Typhimurium DT104

102. Diarrhea
 Nausea
 Vomiting
 Stomach pain
 Headache
 Fever
 Onset 12-72 hours after
infection

103. Commonclinical manifestations of
Salmonella
• Most common diseases caused by Salmonella:
• gastroenteritis (self-limiting, 2-5 days)
• enteric/typhoid fever (incubation 1-10/7-14
days, lasts 2-3 wks)
• septicaemia (incubation12-36 hrs, may lead to
chronic infection)
• symptoms and disease manifestation differ in
hosts
103

104. Food Poisoning
• The laboratory diagnosis of bacterial food
poisoning depends on isolation of the
causal organism from samples of faeces
or suspected foodstuffs. The more
common food-poisoning serotypes, such
as Enteritidis or Typhimuruim, may be
characterized more fully by phage typing
and antibiotic resistance typing (see
above). Dr.T.V.Rao MD 104

105. Salmonellosis
• > 2000 known
serotypes
•  200 serotypes are
detected each year in
the United States
• Two most common (in
most countries)
– Salmonella
Typhimurium
– Salmonella Enteritidis

106. Identification of pathogens
Dr.T.V.Rao MD 106
• Strains can be differentiated
further by plasmid and pulsed-
field gel electrophoresis typing so
that the isolates from patients
may be matched with those from
the infected food and from a
suspected animal source.

107. Dr.T.V.Rao MD 107
Salmonella Gastroenteritis
• Zoonotic disease
• S.enteritidis
• S.typhimurium
• S.halder
• S. agana
• S.indiana
• Contaminated poultry, Meat Milk, Milk products.
• Enters the shells of the Intact eggs – Chicken feed,
and Fecal droppings.

108. Dr.T.V.Rao MD 108
Nontyphoidal Salmonella
• General Incubation: 6 hrs-10 days; Duration: 2-7 days
• Infective Dose = usually millions to billions of cells
• Transmission occurs via contaminated food and water
• Reservoir:
a) multiple animal reservoirs
b) mainly from poultry and eggs (80% cases from eggs)
c) fresh produce and exotic pets are also a source of contamination (>
90% of reptile stool contain salmonella bacterium); small turtles ban.
• General Symptoms: diarrhea with fever, abdominal cramps, nausea and
sometimes vomiting

109. Mechanism of Pathogenicity
Gastroenteritis
• ingestion
• absorbed to brush border of epithelial cells of
small intestine and colon
• migrate to lamina propria, Ileocecal
• multiply in lymphoid follicles
• Reticuloendothelial hyperplasia and
hypertrophy

110. Dr.T.V.Rao MD 110
Nontyphoidal Salmonella:
Gastroenteritis
• Incubation: 8-48 hrs ; Duration: 3-7 days for diarrhea &
72 hrs. for fever
• Inoculum: large
• Limited to GI tract
• Symptoms include: diarrhea, nausea, abdominal cramps
and fevers of 100.5-102.2ºF. Also accompanied by
loose, bloody stool; Pseudo appendicitis (rare)
• Stool culture will remain positive for 4-5 weeks
• < 1% will become carriers

111. Dr.T.V.Rao MD 111
Nontyphoidal Salmonella:
Bacteremia and Endovascular Infections
• 5% develop septicemia; 5-10% of septicemia patients
develop localized infections
• Endocarditis: Salmonella often infect vascular sites;
preexisting heart valve disease risk factor
• Arteritis: Elderly patients with a history of back/chest +
prolonged fever or abdominal pain proceeding
gastroenteritis are particularly at risk.
- Both are rare, but can cause complications that may lead
to death

112. Dr.T.V.Rao MD 112
Salmonella Gastroenteritis
• Can occur as cross infection
• 24 hours
• Manifest with Diarrhea, omitting
• Abdominal pain mucous and blood in
stools
• Last for 2 – 4 days
• Some times may lead to septicemias

113. Diagnosis and Treatment
• Isolation by
culturing
• Rarely need
antibiotics.
• More frequent in
Developed
nations.
Dr.T.V.Rao MD 113

114. Dr.T.V.Rao MD 114

115. Salmonella septicemias
• S.cholera suis
• Deep abscess,
Endocarditis
• Isolation from
Blood and Pus.
• Chloramphenicol
highly effective
Dr.T.V.Rao MD 115

116.  Don’t eat raw or undercooked
food
 Cross-contamination of foods
should be avoided
 Do not prepare food or pour
water if you are infected with
the bacteria

117.  Wash hands, kitchen surfaces, and utensils
with soap and water after they have come
in contact with raw meat or poultry
 Wash hands after contact with animal
feces
 Avoid direct/indirect contact between
reptiles and infants

118. Simple hand hygiene and washing
can reduce several cases of Typhoid

119. Dr.T.V.Rao MD 119
Visitfor mostupdatedInformation
• For the most up-to-date information, visit the
Centers for Disease Control and Prevention
Travelers' Health Typhoid resource
(www.cdc.gov/travel)

120. Dr.T.V.Rao MD 120
• ProgramCreatedbyDr.T
.V.Rao
MDforbenefit ofMedicaland
ParamedicalProfessionals in the
developing world
• Email
• doctortvrao@gmail.com