Infections of Gram Negative Bacteria

1. ABOUT INFECTION
2. OVERVIEW ABOUT IMMUNITY
3. INFECTION OF GRAM NEGATIVE BACTERIA
4. INFECTION BY SALMONELLA
Cause of infection
Causative agent
Virulence factors
Pathogenesis
Laboratory Diagnosis
Prophylaxis
Treatment
Preventive measures.

1. INFECTION AND IMMUNITY
INFECTIONS OF GRAM NEGATIVE BACTERIA
SALMONELLA
Dr. Smita Milind Dharmadhikari
Associate Professor
Department of Microbiology
Government College of Arts and Science,
Aurangabad

2. POINTS TO BE DISCUSS
•1. ABOUT INFECTION
•2. OVERVIEW ABOUT IMMUNITY
•3. INFECTION OF GRAM NEGATIVE BACTERIA
•4. INFECTION BY SALMONELLA
•Cause of infection
•Causative agent
•Virulence factors
•Pathogenesis
•Laboratory Diagnosis
•Prophylaxis
•Treatment
•Preventive measures.

3. INFECTION
Invasion and growth of
germs in the body
germs may be bacteria,
viruses, yeast, fungi, or
other microorganisms
Some cancer treatments
can weaken the immune
system, which may lead to
infection.
When the body’s immune
system is strong, it can
often fight the germs and
cure an infection
An infection can cause
fever and other health
problems, depending
on where it occurs in
the body

4. Sources
of
Infection

5. Causative Agent
Viruses and related
agents such
asviroids(HIV, R
hinovirus,Lyssaviru
sessuch asRabies
virus,Ebolavirusan
dSevere acute
respiratory
syndrome
coronavirus 2)
Bacteria
Mycobacterium
tuberculosis,
Staphylococcus
aureus,
Escherichia coli,
Clostridium
botulinum, and
Salmonellaspp.)
Fungi
yeasts -Candida,
Fungi -
Aspergillus,
Pneumocystis
spp,
anddermatophy
teshuman-
pathogenic
genus
Cryptococcus

6. Causative Agent
Parasites, which are
usually divided into:
[5]
•Unicellular organisms
(e.g.malaria,Toxoplasm
a,
•Babesia)
•Macroparasites(worms
or helminths)
includingnematodes,
such asparasitic
roundworms
andpinworms,tapewor
ms(cestodes), and
flukes (trematodes, such
asschistosomiasis)
Arthropodssuch
asticks,mites,fleas,
andlice, can also
cause human disease,
which conceptually
are similar to
infections, but
invasion of a human
or animal body by
these macroparasites
is usually
termedinfestation.
Prions and
other non
microbial
agents-
mutagen,carci
nogen,polluta
nts

7. General Signs and Symptoms of Infection
•Fever(this is sometimes the only sign of an
infection).
•Chills and sweats.
•Change in cough or a new cough.
•Sore throat or new mouth sore.
•Shortness of breath.
•Nasal congestion.
•Stiff neck.
•Burning orpainwith urination.

8. What is Immunity
•state of protection from infectious diseases
•Immune System have following functions:
•Defense against invading pathogens (viruses &
bacteria)
•Removal of 'worn-out' cells (e.g., old RBCs) & tissue
debris (e.g., from injury or disease)
•Identification & destruction of abnormal or mutant
cells (primary defense against cancer)
•Rejection of 'foreign' cells (e.g., organ transplant)
•Inappropriate responses:
•Allergies -response to normally harmless substances
•Autoimmune diseases

9. Overview of the Immune System
Immune System
Innate
(Nonspecific)
1
o
line of defense
Adaptive
(Specific)
2
o
line of defense

10. A typical immune response
INNATE IMMUNITY
Rapid responses to a
broad range of microbes
ACQUIRED
IMMUNITY
Slower responses to
specific microbes
External defensesInternal defenses
Skin
Mucous membranes
Secretions
Phagocytic cells
Antimicrobial proteins
Inflammatory
response
Natural killer cells
Humoralresponse
(antibodies)
Cell-mediated
response
(cytotoxic
lymphocytes)
Invading
microbes
(pathogens)
Complement

11. •Hematopoiesis
•Early in hematopoiesis, stem cell
(HSC)differentiates to either
•Lymphoid progenitor cell
•Myeloid progenitor cell
•Hematopoietic Homeostasis
•Life Span of RBCs---120 days
•Life Span of WBCs -1 day to 20-30
years

12. Innate immune system: components of Blood
Complement proteins
Coagulation proteins
Cytokines
WBCs

14. Monocytes circulate in blood and
then migrate into tissue and
differentiate into specific
macrophages
Intestinal macrophages in gut
Alveolar macrophages in lung
Histiocytesin connective tissue
Kupffercells in the liver
Mesangialcells in the kidney
Microglial cells in the brain
Osteoclasts in bone
Activated macrophages are
more effective than resting ones
○Complex antigens are phagocytized, the resulting phagosomefuses with a lysosome
○The digested antigen is then eliminated through exocytosis
○Some of it is presented on membrane on MHC
○Phagocytosis is enhanced when antibody is attached to the antigen
○Antibody acts as opsonin: molecule that binds to both antigen and phagocyte

15. Granulocytes –Neutrophils
Multi-lobed nucleus, light granules
1
st
to arrive at site of inflammation
High #’s is 1
st
indication of infection
Phagocytize
Generate antimicrobial agents
Neutrophils are very short lived when compared to
macrophages
Granulocytes –Eosinophils
Phagocytize
Play a role in parasitic organisms
Granulocytes –Basophils
Nonphagocytic
Play a role in allergic reactions
Mast cells
Play important role in development of allergies

16. CYTOKINES
Small proteins –secreted by cells of the immune system, -
Affect the behaviour of other cells
signalling molecules-Key players in innate and acquired immunity
Cells producing cytokines
Neutrophils –when they encounter a pathogen
Macrophages –when they encounter a pathogen
NK cells –on encountering a microbe infected cell /tumour cell
Lymphocytes –when they are activated
Examples of cytokines-Interferons, Interleukins, Tumour necrosis factor (TNF)

17. Lymphocytes-
B cells and T cells
Adaptive immunity
Small lymphocytes
Those that have not
interacted with antigen
are called naïve
Interaction with antigen
–proliferation into
effector cells (i.e. plasma
cells) and memory cells

18. DIFFERENCES BETWEEN T AND B LYMPHOCYTES
S.N.CharacteristicsBlymphocytes (B cells) T lymphocytes (T cells)
1.
Site of
Maturation
B lymphocytes both originate
and mature in the bone
marrow.
T lymphocytes mature in the thymus
after its origination in the bone
marrow.
2.Position
Mature B cells occur mostly
outside the lymph node.
Mature T cells occur mostly inside the
lymph node.
3.Distribution
Germinal centersof lymph
nodes, spleen, gut, respiratory
tract; also subcapsularand
medullary cords of lymph
nodes.
Parafollicularareas of cortex in lymph
nodes, periarteriolarin the spleen.
.4.Receptors
TheB-cellreceptors (BCRs)
constitute of membrane
antibodies known as
immunoglobulin surface
receptors.
Surface receptors are called T-cell
receptors (TCRs) and differ from
membrane antibodies.
5.Binds with
Extracellular antigens such as
bacteria, free viruses and
other circulating free foreign
material.
The foreign antigen in association
with self-antigen only such as a virus-
infected cell

19. DIFFERENCES BETWEEN T AND B LYMPHOCYTES
S.N.Characteristics Blymphocytes (B cells) T lymphocytes (T cells)
6.
The need of
Antigen
Processing
Antigen processing is not
necessary.
Antigen processing is necessary.
7.Connection
They bind directly with the antigens
on the surface of the invading virus
or bacteria.
They can only bind to antigens on the
outside of infected cells and not directly.
8.
C3complement
receptor
Receptors for C3complement
present.
Receptors for the C3 complement are
absent.
9.
Cell Surface
Marker
CD19 is the cell surface markers of
B cells.
CD3 is the cell surface markers of T cells.
10.
Microvillion the
cell surface
Present Absent
11.
Types of Active
Cells
They differentiate into plasma cells
and memory cells.
They differentiate into many subsets of T
cells such as Cytotoxic T cells (CD8+ T cells),
Helper T cells (CD4+ T cells) and suppressors
cells along with memory cells.

20. DIFFERENCES BETWEEN T AND B LYMPHOCYTES
S.N.Characteristics Blymphocytes (B cells) T lymphocytes (T cells)
12.Abundance
It constitutes about 20% of
lymphocytes in the blood.
It constitutes about 80% of lymphocytes in
the blood.
13.Secretory Product
Antibodies are the chief secretory
product of B cells.
Cytokines (lymphokines) are the chief
secretory product of T cells.
14.Type of Immunity
Involved in humoral (antibody-
mediated) immunity.
Involved in cell-mediated immunity.
15.Life Span
They have comparatively a shorter
life span.
They have a comparatively longer life span.
16.Relationship
Since B cells are also Antigen
Presenting cells, they present
antigens to T-cells.
They help to activate B cells and aid in
antibody production against antigens which
are T-dependent.
17.Functions
Help eliminate free foreign invaders
by enhancing immune responses
against them; provide immunity
against most foreign antigens and
bacteria.
Help lyse virus-infected cells and tumor
cells; provide immunity against most viruses
and intracellular bacterial pathogens; help B
cells in antibody production.

21. Primary
Thymus and bone marrow
Place of maturation of lymphocytes
Secondary
Lymph nodes, spleen, mucosa-associated lymphoid
tissues such as gut-associated lymphoid tissues
Mature lymphocytes interact with antigen
Bone marrow
Lymphocytes arise there, T cells go to thymus to
mature,Bcells mature here
90% of plasma IgGand IgA comes from B cells in the
bone marrow
Thymus
T cell development and maturation
Bilobedorgan above heart, surrounded by
capsule and divided into lobules
Outer part of lobule is cortex, inner is medulla
Network of epithelial cells, dendritic cells, and
macrophages
Thymus will induce death of those T cells that
can’t: Recognize self-MHC molecules
Those that interact with MHC molecules too
strongly (could produce autoimmune disorder)
Function decreases with age

22. DIFFERENCES BETWEEN Gram Positive and Gram Negative Bacteria
S.N. Characteristics Gram Positive Gram Negative
1. Gram Reaction
Retain crystal violet dye and stain
blue or purple on Gram’s staining.
Accept safraninafter decolorization
and stain pink or red on Gram’s
staining.
2. Cell wall thickness
Thick (20-80 nm),multi-layered
Peptidoglycan, rigid and less
elastic. Outer membrane present
Thin (8-10 nm),single layered
Peptidoglycan, less rigid and more
elastic. No outer membrane
3.
Aromatic and Sulfur-
containing amino acid in cell
wall,
periplasmicspace
Absent
No
Present
Present
4.
Chemical composition of
cell wall
High Techoicacid low Lipid and
Lipoprotein Content,
No lipopolysaccharide
Verylow Techoicacid ,High Lipid and
Lipoprotein Content,
Lipopolysaccharidepresent
5. Morphology
Usually coccior spore forming
rods (exception : Lactobacillus
and Corynebacterium). Few are
pathogenic.
Usually non-spore forming rods
(Exception : Neisseria). Most are
pathogenic

23. Infections of Gram Negative Bacteria
Sr.No.Name of Pathogen Morphology Name of Disease
1 Neisseria meningitidis
Neisseriagonorrhoea
G –veoval or spherical
cocci
Meningococcal meningitis
Gonorrhea
2 Escherichia coli G –vecoccobacillary
rods
UTI,Diarrhea,
3 Klebsiellapneumoniae G –vecapsulatedrodsPneumonia,
UTI,Septicemia
4 Shigelladysenteriae G –veshort rods Bacillary dysentery
5 Salmonella typhi G –veshort rods Enteric fever
Gastroenteritis
Septicemia
6 Vibrio cholerae G –veshort curved
rods,commashape
Cholera
7 Pseudomonas aeruginosa G –veshort rods Hospital cross infections

24. Infections of Gram Negative Bacteria
Sr.No.Name of Pathogen Morphology Name of Disease
8 Yersinia pestis G-verodswith rounded ends
and convex sides
Plague
9 Haemophillus
influenzae
G –veshoet
rods,pleomorphic
Meningitis,
Pneumonia,Bronchitis
10 BordetellapertussisG –veovoid coccobacillary
rods
Whooping Cough
11 Brucellaabortus G –veshort rods arranged in
chain
Brucellosis
12 Mycobacterium
tuberculosis
G –vestrightor curved rodsTuberculosis

25. •History
•In 1885, pioneering American veterinary scientist, Daniel E.
Salmon, discovered the first strain of salmonella from the
intestine of a pig. This strain was called Salmonella
choleraesuis.
•In 1880s, the typhoid bacillus was first discovered by Eberthin
spleen sections and mesenteric lymph nodes from a patient
who died from typhoid.
•Robert Koch confirmed a related finding and succeeded in
cultivating the bacterium in 1881.
•Serodiagnosisof typhoid was thus made possible by 1896.
•Wright and his team prepared heat killed vaccine from S.typhi
in 1896

26. 1.The best known carrier was "Typhoid Mary“; Mary Mallon was a
cook in Oyster Bay, New York in 1906 who is known to have
infected 53 people, 5 of whom died.
2.Later returned with false name but detained and quarantined after
another typhoid outbreak.
3.She died of pneumonia after 26 years in quarantine.

27. Infection by Gram Negative Bacterium -Salmonella
•Salmonellais rod-shaped(bacillus)Gram-negative bacteriaof the
familyEnterobacteriaceae.
•The two species ofSalmonellaareSalmonella enterica
•andSalmonella bongori.
•S. entericais the type species and is further divided into sixsubspecies
that include over 2,600serotypes.
•Salmonellawas named afterDaniel Elmer Salmon(1850–1914), an
Americanveterinary surgeon.
•Salmonellaspecies are non-spore-forming, predominantlymotile
enterobacteriawith cell diameters between about 0.7 and 1.5μm,
lengths from 2 to 5μm, and peritrichousflagella(all around the cell
body).
•They arechemotrophsobtaining their energy fromoxidation and
reduction reactionsusing organic sources.
•They are alsofacultative anaerobes, capable of generatingATPwith
oxygen ("aerobically") when it is available, or whenoxygenis not
available, using other electron acceptors or fermentation
("anaerobically").
•

28. Infection By Salmonella spp
•An infectious feverish disease caused by the bacterium
Salmonella typhi(Salmonella entericaSerovarTyphi) and
less commonly by Salmonella paratyphi.
•The term enteric fever or typhoid fever is a communicable
disease, found only in man and includes both typhoid fever
caused by S.typhiand paratyphoid fever caused by S.
paratyphiA, B and C .
•It is an acute generalized infection of the reticulo
endothelial system, intestinal lymphoid tissue, and the gall
bladder
•Theinfectionalwayscomesfromanotherhuman,eitheran
illpersonorahealthycarrierofthebacterium.The
bacteriumispassedonwithwaterandfoodsandcan
withstandbothdryingandrefrigeration.

29. •Epidemology
•According to the World Health Organization, globallysome 16
million cases occur annually resulting in more than 600,000
deaths.
•More than 62% of the global cases occur in Asia, of which, 7
million occur annually in South East Asia.
•Other countries with a high incidence include Central and
South America, Africa and Papua New Guinea.
•World largest outbreak of typhoid in SANGLIon December
1975 to February 1976 . This disease is endemic in India
•1992: 3,52,980 cases with 735 deaths
•1993: 3,57,452 cases and 888 deaths
•1994: 2,78,451 cases and 304 deaths
•Case fatality rate due to typhoid has beenvarying between
1.1% to 2.5 %in last few years.

30. Antigens of Salmonella
Sr.
No.
CharacteristicsO Antigen H Antigen
1.Types Somatic Antigen Flagellar antigen
2.Composition Polysaccharide Proteinacious
3.Antibody formationRapid and Early Rapid and Sustained
4.Level Falls off quickly Persists for longer periods
5.Production Produces granular clumps.
Produces cottony, fluffy
precipitates.
6.Observation
Round bottom Felix tube are
used to see agglutination.
Conical bottom Dreyer’s tube
are used to see agglutination.
7.
Heat and alcohol
sensitivity
heat stableand resistant to
alcohol
heat-labileand sensitive to
alcohol
8.Extraction
Trichloro-acetic acid is used
for extraction
Formaldehyde is used for
extraction
9.Immunogenicity
Less immunogenic-Abs
produce with low titre.
Highly immunogenic-Abs
produced with high titre.

31. Antigens of Salmonella
•Vi antigen
•It is surface polysaccharide producing antigen enveloping the
O antigen.
•Invented by Felix and describe as antigen related to virulence
of Salmonella.
•It is heat labile,destroyedby acid and alkali but resistant to
alcohol and formaldehyde.
•Strains of S.typhishowing Vi Ag are more virulent but fail to
agglutinate with O antiserum in widaltest.
•It can be identified by phage typing.
•Polysaccharide act as Virulent factor inhibiting phagocytosis,
resisting complement activation and bacterial lysis.

32. Virulence factors of Salmonella-Molecular design
SalmonellaentericaserovarTyphi(S.Typhi), the etiologic agent of
typhoid fever, is a human restricted pathogen.
The molecular mechanism ofSalmonellapathogenicityis complex.
PathogenicSalmonellaspp. shows presence of specific pathogenicity
genes, often organized in so-calledpathogenicity islands(PIs).
Thetype III secretion system(T3SS) proteins encoded by
twoSalmonellaPIs (SPIs) are associated with the pathogenicity at
molecular level.
The T3SS encoded by SPI-1 contains invasion genes
SPI-2 is responsible for intracellular pathogenesis
(systemic infection)
The understanding of the mechanisms by whichSalmonellaevade the
host defensesystem and establish pathogenesis will be important for
proper disease management.

33. Routes of transmission
Thediseaseistransmittedbyfaeco-oralrouteorurine–oralroutes–
eitherdirectlythroughhandssoiledwithfaecesorurineofcasesor
carriersorindirectlybyingestionofcontaminatedwater,milk,food,or
throughflies.Contaminatedice,ice-creams,andmilkproductsarea
richsourceofinfection.

34. Pathogenecity

35. Ingestion of contaminated food or water.
Salmonella invade small intestine and enter the bloodstream
Invade small intestine and enter the bloodstream
Carried by white blood cells in the liver, spleen, and bone marrow
Multiply and reenter the bloodstream.
Bacterium invadethe gallbladder, biliary system, and the lymphatic
tissue of the bowel and multiply in high numbers.
Then pass into the intestinal tract and can be identified for
diagnosis in cultures from the stool tested in the laboratory.
Salmonella typhiinfecting the body via the Peyer'spatches of the
small intestine.
The bacteria migrates to mesenteric lymph nodes and arrive via
the blood in the liver and spleen during the first exposure.
After multiple replication in the above locations, the bacteria
migrates back into the Peyer'spatches of the small intestine for the
secondary exposure and consequently the clinical symptoms are
seen.
Inflammation in the small intestine leads toulcers and necrosis.

36. 36Clinical Syndromes of Salmonella
Salmonellosis= Generic term for disease
Enteritis(acute gastroenteritis)
Enteric fever(prototype is typhoid feverand
less severe paratyphoid fever)
Septicemia(particularly S. choleraesuis, S. typhi,
and S. paratyphi)
Asymptomatic carriage(gall bladder is the
reservoir for Salmonella typhi)

37. 1
st
week
The body temperature rises slowly, and fever fluctuations are seen
with relativebradycardia(Fagetsign),malaise, headache, and cough.
A bloody nose (epistaxis) is seen in a quarter of cases, and abdominal
pain is also possible.
A decrease in the number of circulating white blood cells (leukopenia)
occurs witheosinopeniaand relativelymphocytosis.
Blood cultures are positiveforSalmonella entericasubsp. enterica
serovarTyphi.
TheWidaltestis usually negative in the first week.
SYMPTOMS

38. SYMPTOMS
2nd week
In the second week, the person is often too tired to get up, with high fever
in plateau around 40°C (104°F) and bradycardia(sphygmothermic
dissociation or Fagetsign), classically with adicroticpulsewave.
Deliriumcan occur, where the patient is often calm, but sometimes
becomes agitated. This delirium has led to typhoid receiving the nickname
"nervous fever".
Rose spotsappear on the lower chest and abdomen in around a third of
patients.Rhonchi(rattling breathing sounds) are heard in the base of the
lungs.
The abdomen is distended and painful in the right lower quadrant, where
a rumbling sound can be heard.
Diarrheacan occur in this stage, but constipation is also common.
The spleen and liver are enlarged (hepatosplenomegaly)and tender, and
livertransaminasesare elevated.
The Widaltest is strongly positive, with antiOand antiHantibodies.(1:640)
Blood cultures are sometimes still positive at this stage.

39. SYMPTOMS
3
rd
week
In the third week of typhoid fever, a number of complications can
occur:Intestinalhaemorrhage due to bleeding in congestedPeyer's
patchesoccurs; this can be very serious, but is usually not fatal.
Intestinal perforation in the distalileumis a very serious complication and
is frequently fatal. It may occur without alarming symptoms
untilsepticaemiaor diffuseperitonitissets in.
Encephalitis
Respiratory diseases such aspneumoniaandacute bronchitis
Neuropsychiatric symptoms (described as "muttering delirium" or "coma
vigil"), with picking at bedclothes or imaginary objects
Metastatic abscesses,cholecystitis,endocarditis, andosteitis
The fever is still very high and oscillates very little over 24 hours.
Dehydrationensues, and the patient is delirious (typhoid state). One-third
of affected individuals develop a macular rash on the trunk.
Low platelet count (thrombocytopenia) can sometimes be seen.
[

40. Rose spots High fever
Diarrhea
Typhoid Meningitis
Aches and pains
Chest congestion

41. Laboratory Diagnosis
•Samples/Specimens-
•Blood,Stool,Urine
•CulturalCharacterizationusingselectiveanddifferential
media.
•MolecularlevelidentificationbyPCR
•SerologicaldiagnosisbyWidaltest(SlideandTubetest)
•Antimicrobialsusceptibilitytesting.
•Blood cultures are positive in 70-80% of cases during the
1st week.
•Stool and urine cultures are usually positive (45-75%)
during the 2nd-3rd week.
•Bone marrow aspirate cultures give the best confirmation
(85-95%)
•The tracing of carriers in cities by sewer –swab technique

42. •Blood Culture
•A positive blood culture is diagnostic.
•Bacteremia occurs early in the disease and blood cultures are
positive appro. In 90% cases in first week of fever,75% in 2
nd
week and 60% in 3
rd
week.
•Blood (5-10 ml) is collected in specific blood culture media
containing sodium polyethanolsulphonate(inhibit bactericidal
action of blood) and 0.5% bile.
•Development of pale pink colourcolonies after overnight
incubation at 370C are further identified and confirmed
biochemically.
•Culture declearednegative only after incubation for 10 days.

43. Stool/Urine Culture
Wilson and Blair bismuth sulphitemedium jet black colony
with a metallic sheen

44. Serological diagnosis Widaltest
A test involving agglutination of typhoid bacilli when they
are mixed with serum containing typhoid antibodies from
an individual having typhoid fever; used to detect the
presence of Salmonella typhiand S. paratyphi.“
Two types of tubes are used-Dreyer’s tube (conical
tapering bottom for H agglutination and Felix
tubes(round bottom) for O agglutination).
Reaction temp.50-55 0C for two hrsand then overnight
at RT or overall at 37 0C overnight
H agglutination shows loose,cotton-woolyclumps.
O agglutination shows disc like pattern at bottonof tube.

45. Standard test tube method
Takefoursetsof8testtubesandlabelthem1to8forO,H,AHandBHantibody
detection.
PipetteintothetubeNo.1ofallsets1.9mlofisotonicsaline.
Toeachoftheremainingtubes(2to8)add1.0mlofisotonicsaline.
TothetubeNo.1tubeineachrowadd0.1mloftheserumsampletobetestedand
mixwell.
Transfer1mlofthedilutedserumfromtubeno.1totubeno.2andmixwell.
Discardthe1mlofthedilutedserumfromtubeno.7ofeachset.

46. Tubeno.8inallsets,servesasasalinecontrol.Nowthedilutionoftheserum
sampleachievedineachsetisasfollows:
Tubeno.12345678(control)
Dilutions1:201:401:801:1601:3201:6401:1280–
Toalltubes(1to8)ofeachsetaddonedropoftherespectiveWIDALTEST
antigensuspension(O,H,AH,BH)fromreagentvialsandmixwell.
Coverthetubesandincubateat37Covernight(approx.18hrs).
Dislodgethesedimentedbuttongentlyandobserve.

47. Interpretation
•Thehighestdilutionofthepatientsseruminwhich
agglutinationsoccursisnoted,ex.ifthedilutionis1in160
thenthetiteris160.
•Agglutinationindilutionupto<1:60isseeninnormal
individuals.
•Agglutinationindilution1:160issuggestiveofSalmonella
infection.
•Agglutinationindilutionofandmorethan1:320is
confirmatoryofEntericfever.

48. •Laboratory Diagnosis
•Polymerase chain reaction (PCR) can be
performed on peripheral mononuclear cells.
The test is more sensitive than blood culture
alone (92% compared with 50-70%)but
requires significant technical expertise.
•Blood clot culture test.
•Bacteriophage typing(Salmonella typhiA and
E phages specific to Vi antigen of S.typhi)

49. RAPID TESTS FOR DIAGNOSING TYPHOID
•Typhidot–this test that detects presence of IgMand
IgGin one hour (sensitivity>95%, Specificity 75%)
•Typhidot-M, that detects IgMonly (sensitivity 90%
and specificity 93%) . Produced against
lipopolysaccharide antigens.
•Typhidotrapid (sensitivity 85% and Specificity 99%)
is a rapid 15 minute immunochromatographictest to
detect IgM.
•IgMdipstick test

50. Prophylaxis
THREE TYPES OF VACCINES
1.TAB Vaccine-
•Heat killed typhoid bacillus vaccine
•First develop by AlmrothWright during Boer war in South Africa.
•Vaccine is given in 2 doses of 0.5 ml subcutaneously at an interval of
4-6 weeks.
•Killed vaccines do not provide cell mediated immunity.
2.Live Oral Vaccine
3.Typhoralis live vaccine of stable mutant of S.typhistrain Ty2 1a
lacking the enzyme UDP-galactose-4 epimerase.
4.Vaccine is enteric coated capsule containing 10
9
viable lyophilised
mutant bacilli,doseis one capsule per day taken 1 hrbefore food
on day 1,3 and 5.

51. Injectable Typhim–Vi
1.It contain purified Vi polysaccharideantigen(25ugm per
dose) from S. typhiTy2 1a mutant.
2.This single-dose injectable typhoid vaccine, from the
bacterial capsule of S. typhistrain of Ty21a.
3.This vaccine is recommended for use in children over 2
years of age.
4.Sub-cutaneous or intramuscular injection
5.Efficacy : 64% -72%

52. SIDE EFFECTS.
Injectable Typhim-Vi
The most common adverse reactions are injection
site pain, erythema, and induration, which almost
always resolve within 48 hours of vaccination.
Occasional fever, flu-like episodes, headache,
tremor, abdominal pains, vomiting, diarrhea, and
cervical pains have been reported.
Typhoral
Nausea, abdominal pain and cramps, vomiting,
fever, headache, and rash or urticariamay occur in
some instances but are rare.

53. Indications for Vaccination
1.Travelers going to endemic areas who will be
staying for a prolonged period of time,
2.Persons with intimate exposure to a documented
S. typhicarrier
3. Microbiology laboratory technologists who work
frequently with S. typhi
4.Immigrants
5. Military personnel

54. Treatment
Consultations
•An infectious disease specialist or surgeon should be consulted.
Surgical Care
•Usually indicated in cases of intestinal perforation.
•Most surgeons prefer simple closure of the perforation with drainage
of the peritoneum.
•Small-bowel resection is indicated for patients with multiple
perforations.
•If antibiotic treatment fails to eradicate the hepatobiliarycarriage, the
gallbladder should be resected.
•Cholecystectomy is not always successful in eradicating the carrier
state because of persisting hepatic infection.

55. Management and Treatment of typhoid fever:
Sr.NoName Dose
1 ChloramphenicolThe recommended dosage is 50 -75 mg per kg
per day for 14 days divided into four doses per
day, or for at least five to seven days after
defervescence.
2 CephalosporinCeftriaxone: 50-75 mg per kg per day one or two
doses.
Cefotaxime: 40-80 mg per kg per day in two or
three doses.
Cefoperazone: 50-100 mg per kg per day
3 Amoxicillin (Trimox, Amoxil, Biomox)daily dose of 75-100
mg/kg tid(three times a day) for 14 d.
4 Dexamethasone
(Decadron)
Initial dose of 3 mg/kg by slow i.v.infusion over
30 minutes.
1 mg/kg 6 hourly for 2 days.

56. Diet
•Fluids and electrolytes should be monitored and replaced
diligently.
•Oral nutrition with a soft digestible diet is preferable in the
absence of abdominal distension or ileus.
Activity
•No specific limitations on activity are indicated.
•Rest is helpful, but mobility should be maintained if
tolerable.
•The patient should be encouraged to stay home from work
until recovery.

57. Control of Typhoid fever
MEASURES DIRECTED TO RESERVOIR
a) Case detection and treatment
b) Isolation
c)Disinfection of stools and urine
d)Detection & treatment of carriers
MEASURES AT ROUTES OF TRANSMISSION
a)Water sanitation
b) Food sanitation
c) Excreta disposal
d) Fly control
MEASURES FOR SUSCEPTIBLES
a)Immunoprophylaxis
b)Health education

58. •MDR is mediated by plasmidThe genes for antibiotic resistance in S
typhiand S paratyphiare acquired into a region called an integronfrom
Escherichia coliand other gram-negative bacteria via plasmids.
•Quinolone resistance is frequently mediated by single point mutations in
the quinolone-resistance–determining region of the gyrAgene.
•Nalidixicacid resistant: MIC of fluoroquinolonesfor these strains was 10
times that for fully susceptible strains.
Antibiotic resistance

59. •Keep the premises and kitchen utensils
clean. Dispose rubbish properly.
•Keep hands clean and fingernails
trimmed.
•Wash hands properly with soap and
water before eating or handling food,
and after toilet or changing diapers.
•Drinking water should be from the
mains and preferably boiled.
•Purchase fresh food from reliable
sources. Do not patronize illegal
hawkers.
•Avoid high-risk food like shellfish, raw
food or semi-cooked food.
•Wear clean washable aprons and caps
during food preparation.
•Clean and wash food thoroughly.
•Scrub and rinse shellfish in clean
water. Immerse them in clean water
for sometime to allow self-purification.
•Store perishable food in refrigerator,
well covered
•
HEALTH PROMOTION