133220649 Salmonella Infections an Update

7/28/2019 133220649 Salmonella Infections an Update

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SalmonellaInfections

an updateDr.T.V.Rao MD

Dr.T.V.Rao MD 1



Salmonella• Causes Infections in Humans and

vertebrates,• Enteric Fever ( Typhoid fever )• Gastroenteritis•

Septicemias,• Carrier state a concern

Dr.T.V.Rao MD 2



Salmonella• A Very complex group• Contains more > 2,000 spp•

Typed on the basis of Serotyping, and speciestyping• Divided into two groups

1 Enteric fever group2 Food poisoning group – Septicemias.

Dr.T.V.Rao MD 3



Key points

• There are more than 2000 different antigenictypes of Salmonella; those pathogenic to man

are serotypes of S. enterica.• Most serotypes of S. enterica cause food-borne gastroenteritis and have animalreservoirs.

•

S. enterica serotypes Typhi and Paratyphicause typhoid fever.

Dr.T.V.Rao MD 4



Enteric FeverTyphoid Fever

• Caused by Salmonella typhi, and otherGroups 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 5



Typhoid fevers are prevalent in manyregions in the World



Typhoid Mary Most DangerousWoman in America

Dr.T.V.Rao MD 7



Typhoid Mary

• A famous example is“Typhoid” Mary Mallon,who was a food handler

responsible for infectingat least 78 people,killing 5. These highlyinfectious carriers pose

a great risk to publichealth.



Typhoid Mary• "Typhoid Mary," real name Mary Mallon,

worked as a cook in New York City in the early1900s. Public health pioneer Sara Josephine

Baker, MD, PhD tracked her down afterdiscovering that she was the common linkamong many people who had become ill fromtyphoid fever She was traced to typhoidoutbreaks a second time so she was put inprison again where she lived until she died.



Morphology of Salmonella

• Gram negativebacilli

• 1-3 / 0.5microns,

•

Motile byperitrichousflagella

Dr.T.V.Rao MD 10



S.typhi with Flagella

Dr.T.V.Rao MD 11



Bacteriology – Typhoid fever

• The GenusSalmonella belong toEnterobacteriaceae

• Facultative anaerobe• Gram negative bacilli• Distinguished from

other bacteria byBiochemical andantigen structure

Dr.T.V.Rao MD 12



Different types of Salmonella

I - enterica II - salamae

IIIa -arizonae IIIb -diarizonae IV -houtenae V - bongori VI - indica



Cultural Characters• Aerobic / Facultatively anaerobic• Grows on simple media – Nutrient agar,• Temp 15 – 41ºc / 37º c•

Colonies appear as large 2 -3 mm, circular, lowconvex,• On MacConkey medium appear

Colorless ( NLF )

Selective Medium - Wilson Blair Bismuth sulphidemedium. Produce Jet black coloniesH2 S produced by Salmonella typhi

Dr.T.V.Rao MD 14



Enrichment MediumLiquid Medium

• Selenite F medium• Tetrathionate broth• Above medium are used for

isolation of Salmonella fromcontaminated specimens

• Particularly stool specimens..Dr.T.V.Rao MD 15



Identifying Enteric Organisms

• Isolates which are Non lactose fermenting• Motile, Indole positive• 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 testsDr.T.V.Rao MD 16



Biochemical Charac ters• 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 H 2S

Dr.T.V.Rao MD 17



Resistance of Salmonella

• 55º c – 1 hour•

60º c – 15 MT• Boiling ,Chlorination,

Pasteurization Destroy theBacilli.

Dr.T.V.Rao MD 18



Antigenic structure of Salmonella• Two sets of antigens• Detection by serotyping• 1 Somatic or 0 Antigens contain long chain

polysaccharides ( LPS ) comprises of heatstable polysaccharide commonly.

• 2 Flagellar or H Antigens are stronglyimmunogenic and induces antibody formationrapidly and in high titers following infection orimmunization. The flagellar antigen is of a dualnature, occurring in one of the two phases.

Dr.T.V.Rao MD 19



SalmonellaAntigenic Structure

• H – Flagellar antigens• O – Somatic antigen,• Vi – Surface antigen in some species only• H antigens also called flagellar antigens, heat

labile protein,• Boiling destroys antigenicity• When mixed with Antiserum produces agglutination

and fluffy clumps are produced• H antigens are strongly immunogenic Induces

antibodies rapidly,

Dr.T.V.Rao MD 20



Antigens – Salmonella ( cont )

Dr.T.V.Rao MD 21

• 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 temp50º – 55º c

• O antigens are less immunogenic. than H antigens



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

Dr.T.V.Rao MD 22



Classification of Salmonella

• Classified on the basis of Kauffmann-White Scheme

• Structure of 0 and H antigens aretaken into consideration,

• More than 2000 speciescharacterized.

Dr.T.V.Rao MD 23



Kauffmann – White scheme• Serotype 0 antigens H antigens

Phase 1 2

1.Typhi 9, 12 ,(Vi) d 1,22 Paratyphi A 1,2. 12 a -3 Paratyphi B 1,4,5, 12 b 1,2

4 Typhimuruim 1,4,5, 12 I 1,75 Enteritidis 1,9, 12 g m 1,2

Dr.T.V.Rao MD 24



Antigenic Variation inSalmonella

• May be phenotypic / Genotypic• H to O = loss of Flagella

May be phase variation from I toII

V to W variationS to R variation

Dr.T.V.Rao MD 25



Pathogenicity• Salmonella are definite parasites to

humans.•

Eg S.typhi.• S.paratyphi A, B ,C• Other groups Salmonella• The important clinical syndromes1. Enteric fever, Septicemias,

gastroenteritis. Dr.T.V.Rao MD 26



Enteric Fever: S. typhi• Ileocecal penetration• intraluminal multiplication•

mononuclear response (macrophages)• Salmonella remains alive• 2nd week - lymphoid hyperplasia (mesenteric

lymph nodes)• back to bowel



Enteric FeverTyphoid

• Typhoid – caused by S.typhi• Paratyphoid Caused by

Paratyphi A,B,C• Typhoid --- Like Typhus• Infective dose ID 50 / 10 7,

Dr.T.V.Rao MD 28



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 infiltrationwith monocular cells• Leads to Necrosis, Sloughing and formation of

chacterstic typhoid ulcers



Rashes in Typhoid• May present with rash,

rose spots 2 -4 mm indiameter raised discreteirregular blanching pinkmaculae's found infront of chest

• Appear in crops of uptoa dozen at a time

• Fade after 3 – 4 days



Dr.T.V.Rao MD 31



Events in a Typical typhoid Fever

Dr.T.V.Rao MD 32



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

Dr.T.V.Rao MD 33



Infective Dose• For human infections, the number of bacteria

that must be swallowed in order to causeinfection is uncertain and varies with the

serotype. In most of these the medianinfective dose for most serotypes, includingTyphi, has varied from 106 to 109 viableorganisms. However, investigation of outbreaks suggests that in natural infectionthe infective dose might be fewer than 1000viable organisms.

Dr.T.V.Rao MD 34



Pathology and Pathogenesis

• Bacteremia Spread to Liver, Gallbladder, Spleen, Bone marrow,

Lymph nodes, Lungs, Multiply inkidneys

Once again spill into Blood streamCauses clinical illness.

Dr.T.V.Rao MD 35



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 )

Dr.T.V.Rao MD 36



What is Enteric FeverTyphoid Fever

• 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 avariant of S. Java, is more likely to cause non-typhoidal diarrhoea. The clinical features tend tobe more severe with S. Typhi (typhoid fever).After penetration of the ileal mucosa theorganisms pass via the lymphatic's to the

mesenteric lymph nodes, whence after a periodof multiplication they invade the bloodstream viathe thoracic duct.

Dr.T.V.Rao MD 37



Progress in Enteric Fever• The liver, gall bladder, spleen, kidney and bone

marrow become infected during this primarybacteraemic phase in the first 7-10 days of theincubation period. After multiplication inthese organs, bacilli pass into the blood,causing a second and heavier bacteraemia,

the onset of which approximately coincideswith that of fever and other signs of clinicalillness.

Dr.T.V.Rao MD 38



Progress in Enteric Fever

• From the gall bladder, a further invasionof the intestine results. Peyer's patchesand other gut lymphoid tissues becomeinvolved in an inflammatory reaction,and infiltration with mononuclear cells,

followed by necrosis, sloughing and theformation of characteristic typhoid ulcersoccurs.

Dr.T.V.Rao MD 39



Immunity in Typhoid

• Typhoid bacilliare

Intracellularpathogens• Cell mediated

immunity iscrucial

Dr.T.V.Rao MD 40



DiarrheaNauseaVomitingStomach painHeadacheFever

Onset 12-72 hours afterinfection



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 42



Events in a Typical typhoid Fever

Dr.T.V.Rao MD 43



Complications of Enteric fever

• Intestinal perforation,• Hemorrhage,• Circulatory collapse.• Bronchitis Bronchopneumonia,• Meningitis,• Cholecystitis,• Arthritis,Periostitis / Nephritis,• Osteomyletis,

Dr.T.V.Rao MD 44



Relapses in Typhoid Fever

• Apparent recovery can be followed byrelapse in 5-10% of untreated cases.Relapse is usually shorter and of mildercharacter than the initial illness, but canbe severe and may be fatal. Severeintestinal haemorrhage and intestinalperforation are serious complicationsthat can occur at any stage of the illness.

Dr.T.V.Rao MD 45



Other complications• Causes relapses in

particular topatients treatedwithchloramphenicol.

• S.paratyphiproducesepticemias.

Dr.T.V.Rao MD 46



Typhoid carriers• Salmonella enterica causes

approximately 16 million cases of typhoidfever worldwide, killing around 500,000per year. One in thirty of the survivors,however, become carriers. In carriers thebacteria remain hidden inside cells andthe gall bladder, causing new infectionsas they are shed from an apparently

healthy host.



Carrier Stage in Typhoid Fever• Most people infected with salmonella

continue to excrete the organism in theirstools for days or weeks after complete clinical

recovery, but eventual clearance of thebacteria from the body is usual. A few patientscontinue to excrete the salmonellae for

prolonged periods. The term chronic carrier isreserved for those who excrete salmonellaefor a year or more.

Dr.T.V.Rao MD 48



Carrier Stage in Typhoid Fever• 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 entericfever: up to 5% of convalescents from typhoidand a smaller number of those who have

recovered from paratyphoid fever becomechronic carriers, many for a lifetime.

Dr.T.V.Rao MD 49



Carrier Stage in Typhoid Fever• The bacilli are most commonly present in the

gall bladder, less often in the urinary tract,and are shed in faeces and sometimes inurine. The long duration of the carrier stateenables the enteric fever bacilli to survive inthe community in non-epidemic times and to

persist in small and relatively isolatedcommunities.

Dr.T.V.Rao MD 50



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

Dr.T.V.Rao MD 51



Epidemiology• Sanitation has great role• Source an active patient or a Carrier shed the

Bacilli.• Who are carriers.

Convalescent carrier 3 weeks to 3 monthsTemporary carrier 3 months to 1 year

Chronic carrier > 1 year,Women attain more carrier stage

Dr.T.V.Rao MD 52



Epidemiology (Contd)• 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, FoodHIV patients potentially susceptible for Typhoid

disease.

Dr.T.V.Rao MD 53



Bacteriological Diagnosis of Typhoid Fever

• Selective media, such as Deoxycholate-citrate agar or xylose-lysine Deoxycholateagar, are used for the isolation of salmonella bacteria from faeces. Fluidenrichment media, such as Tetrathionateor selenite broth, are also useful todetect small numbers of salmonellae infaeces, foods or environmental samples.

Dr.T.V.Rao MD 54

B t i l i l Di i f




• Suspicious colonies from the cultureplates are tested directly for thepresence of Salmonella somatic (O)antigens by slide agglutination andsubcultured to peptone water for thedetermination of flagellar (H) antigenstructure and further biochemicalanalysis.

Dr.T.V.Rao MD 55

B t i l i l Di i f




• A presumptive diagnosis of salmonellosiscan often be made within 24 h of thereceipt of a specimen, althoughconfirmation may take another day, andformal identification of the serotypetakes several more days. A negativereport must await the result of enrichment cultures - at least 48 h.

Dr.T.V.Rao MD 56



How we Diagnose Typhoid Fever• Diagnosis is made by any blood, bone marrow

or stool cultures and with the Widal test(demonstration of salmonella antibodiesagainst antigens O-somatic and H-flagellar ). Inepidemics and less wealthy countries, afterexcluding malaria, dysentery or pneumonia, atherapeutic trial time with chloramphenicol is

generally undertaken while awaiting theresults of Widal test and cultures of the bloodand stool.

Dr.T.V.Rao MD 57

L b Di i f



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 58



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 MacConkeyAt regular intervals

Dr.T.V.Rao MD 59



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%4 th week and later in 25%

Dr.T.V.Rao MD 60

C t d ’ th d f



Castaneda’s method of Blood Culture

• Double medium used Solid/Liquid medium inthe 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 61



Salmonella on Mac Conkey's agar

Dr.T.V.Rao MD 62



Salmonella on XLD agar

Dr.T.V.Rao MD 63



Clot culture• Clot cultures are more

productive in yieldingbetter results inisolation.

• A blood after clotting,the clot is lysed withStreptokinase ,but

expensive to performin developingcountries.

Dr.T.V.Rao MD 64

B t d R di t i b d th d



Bactec and Radiometric based methodsare in recent use

• Bactek methods inisolation of Salmonellais a rapid and sensitivemethod in earlydiagnosis of Entericfever.

• Many MicrobiologyDiagnostic Laboratoriesare upgrading to Bactekmethods

Dr.T.V.Rao MD 65



Biochemical Characters

• Non Lactose fermenter,• Motile• Indole – MR + VP - Citrate +• Ferment Glu/Mal/Man•

Do not ferment Lactose/Sucrose

Dr.T.V.Rao MD 66



Slide agglutination tests• In slide agglutination

tests a known serumand unknown cultureisolate is mixed,clumping occurs withinfew minutes

• Commercial sera are

available for detectionof A, B,C1,C2,D, and E.

Dr.T.V.Rao MD 67



Culturing other Specimens

• Feces Enrichment in Tetrathionate brothand Selenite broth

•

Culturing in MacConkey/DCA/WilsonBlair medium – Large black colonies.• Urine Culture – positive in 25 %• Other samples

Bone Marrow,Bile,CSF/Sputum

Dr.T.V.Rao MD 68



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 69



Widal Test• In 1896 Widal A professor of

pathology and internalmedicine at the University of Paris (1911 –29), he developed a

procedure for diagnosingtyphoid fever based on the factthat antibodies in the bloodof an infected individual cause

the bacteria to bind togetherinto clumps (the Widalreaction).

Dr.T.V.Rao MD 70



Widal test• S.typhi O and H tubes• Paratyphi A/B H agglutinins only•

Common antigens O in all Factor sharing12• Significance• I st week negative.• Titers raise in 2nd week Raise of titers

diagnosticDr.T.V.Rao MD 71

Diagnosis of Enteric Fever



Diagnosis of Enteric FeverWidal test

• Serum agglutinins raise abruptly during the 2 nd or 3 rd week

• The Widal test detects antibodies against O and Hantigens

• Two serum specimens obtained at intervals of 7 – 10days 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



Widal Test• Single test not diagnostic.• Paired samples tests• Diagnostic.

O > 1 in 80H > 1in 160

H agglutinins appear firstFalse positives in Unapparent infection,

ImmunizationPreviously infected

Dr.T.V.Rao MD 73



Widal test• Anamnestic response previous

infection and responding tounrelated infection

• Other Diagnostic testsCIE and ELISA

Detection of Circulating antigensCo agglutination test.

Dr.T.V.Rao MD 74



Limitation of Widal Test• The Widal test is

time consumingand often timeswhen diagnosis isreached it is toolate to start anantibiotic regimen.

• In spite of severallimitation manyPhysicians dependon Widal Test

Dr.T.V.Rao MD 75

False Positive and Negative Reactions



False Positive and Negative Reactionswith WIDAL Test

• The Widal test should be interpreted inthe light of baseline titers in a healthylocal population. This is especially

important when there is a high localprevalence of non-typhoid salmonellosis.The Widal test may be falsely positive inpatients who have had previousvaccination or infection with S typhi.

Dr.T.V.Rao MD 76

False Positive and Negative Reactions



False Positive and Negative Reactionswith WIDAL Test

• Widal titers have also been reported inassociation with the dysgammaglobulinaemiaof chronic active hepatitis and other

autoimmune diseases.64 '8 '9 False negativeresults may be associated with earlytreatment, with "hidden organisms" in bone

and joints, and with relapses of typhoid fever.Occasionally the infecting strains are poorlyimmunogenic.

Dr.T.V.Rao MD 77

Diagnosis of Carriers and



Diagnosis of Carriers andEnvironments

• Fecal carriers byisolation fromspecimens. or Bileaspirated.

• Sewer swabs•

Bacteriophagetyping

Dr.T.V.Rao MD 78



Prophylaxis• TAB vaccine

S.typhi 1,000 millionsS Paratyphi A,B 750 millions.

Injected subcutaneously 0.5 mlat 4 – 6 weeks.

Live Oral Vaccine TyphoralMutant S.typhi strain Ty 2 1a Lacking enzyme UDP

galctose 4 epimerase 10 to9Viable bacilliGiven orally 1 – 3 – 5 days

Dr.T.V.Rao MD 79



Key points• Antibiotics have no place in the

management of salmonella

gastroenteritis unless invasivecomplications are suspected.• Clean water, sanitation and hygienic

handling of foodstuffs are the keys toprevention.

Dr.T.V.Rao MD 80



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



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

Dr.T.V.Rao MD 82

Treatment



Treatment

• Chloramphenicol 1948 /1970 resistance.• Other Important drugs

AmpicillinAmoxicillin,Furazolidine

CotromoxazoleChloramphenical resistance /Mexico

KeralaDr.T.V.Rao MD 83



Antimicrobial Therapy in Typhoid•

With prompt antibiotic therapy, more than99% of the people with typhoid fever arecured, although convalescence may lastseveral months. The antibioticchloramphenicol Some Trade NamesCHLOROMYCETINis used worldwide, but increasing resistance toit has prompted the use of other antibioticsBACTRIMSEPTRANor ciprofloxaci n

O h D



Other Drugs• Fluroquinolones

Ciprofloxacillin,

PefloxacillinOfloxacillinCeftazidimeCeftriaxone /Cefotoxaime

Dr.T.V.Rao MD 85

C li i i h id



Coalition against Typhoid• Since May 2011, the

Coalition against Typhoid(CaT) has featured monthlyarticles in the WHO’s Global

Immunization Newsletters(GIN). The articles, writtenby CaT members fromaround the world, highlightimportant work being doneto accelerate adoption of typhoid vaccines.

Dr.T.V.Rao MD 86

F d P i i



Food Poisoning• The laboratory diagnosis of bacterial food

poisoning depends on isolation of the causalorganism from samples of faeces or suspectedfoodstuffs. The more common food-poisoning

serotypes, such as Enteritidis or Typhimuruim,may be characterized more fully by phage typingand antibiotic resistance typing (see above).Strains can be differentiated further by plasmidand pulsed-field gel electrophoresis typing sothat the isolates from patients may be matchedwith those from the infected food and from asuspected animal source.

Dr.T.V.Rao MD 87

S l ll G i i



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.

Dr.T.V.Rao MD 88

Nontyphoidal Salmonella



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

Dr.T.V.Rao MD 89

Mechanism of Pathogenicity



g yGastroenteritis

• 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

Nontyphoidal Salmonella:



o typ o da Sa o e a: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 byloose, bloody stool; Pseudo appendicitis (rare)

• Stool culture will remain positive for 4-5 weeks• < 1% will become carriers

Dr.T.V.Rao MD 91

Nontyphoidal Salmonella:



ypBacteremia and Endovascular Infections

• 5% develop septicemia; 5-10% of septicemia patientsdevelop 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 proceedinggastroenteritis are particularly at risk.- Both are rare, but can cause complications that may leadto death

Dr.T.V.Rao MD 92

S l ll G t t iti



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

Dr.T.V.Rao MD 93

Di g i d T t t



Diagnosis and Treatment

• Isolation byculturing

• Rarely needantibiotics.

• More frequent in

Developednations.

Dr.T.V.Rao MD 94

S l ll ti i



Salmonella septicemias• S.cholera suis• Deep abscess,

Endocarditis• Isolation from

Blood and Pus.• Chloramphenicol

highly effective

Dr.T.V.Rao MD 95



Don’t eat raw or undercookedfood

Cross-contamination of foodsshould be avoidedDo not prepare food or pourwater if you are infected withthe bacteria



Wash hands, kitchen surfaces, and utensilswith soap and water after they have comein contact with raw meat or poultry

Wash hands after contact with animalfeces

Avoid direct/indirect contact betweenreptiles and infants

Si l h d h i d hi



Simple hand hygiene and washingcan reduce several cases of Typhoid



• The Programme Created by Dr.T.V.Rao MD for

Medical and Paramedical Students in the

Developing World• Email

• [email protected]

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133220649 Salmonella Infections an Update