micro presentation salmonella and sigella

8/2/2019 Micro Presentation Salmonella and Sigella

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Salmonella& Shigella

Lindsey Crites

Adiam Tesfai

Oluwatoyin Adebisi

Smita Singh


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The discovery of salmonella

Daniel Salmon was given the credit, but his

partner Conor Fitzpatrick was the first todiscover salmonella in 1885 when he found it

in his pigs.


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The cell of salmonella


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Salmonella It is a gram negative,

aerobic rod shaped

zoonotic bacteria

that can affectpeople, birds,

reptiles, and other

animals.


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What animals does salmonella present

a problem too?

USDA estimates that salmonella is present on

40% of chickens at slaughter, 12% of pork, and

5% of the beef supply.


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Where does it live at most of the time

Animals are full of salmonella

This kind of bacteria can live in hot and coldtemperatures, rain and drought conditions.

Animals consume salmonella from the soil or

contaminated feed.

The bacteria is then shed alive in the feces.


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Salmonella

Salmonella emerged as a public health problem inthe US in the 1940s

Cases of salmonellosis have been reported for

decades, but the disease is still considered emergingdue to increased incidence on some continents in thepast 25 years. This increase in salmonellosis islargely related to consumption of poultry & egg

products. www.hhs.gov (US Dept. of Health & Human Services)


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Transmission of salmonella

Transmission of this organism from one hostto another is primarily through the air. Thebacteria is shed from an infected bird in the

nasal, fecal material, and feather dust. Theorganism remains stable outside the hostbody and dries as a dusty substance.


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Why do these well known &

documented diseases emerge? Globalization of the food supply Inadvertent introduction of pathogen into new

geographic areas

Travelers, refugees, and immigrants exposed tounfamiliar foodbornehazards while abroad Changes in microorganisms Changes in thehuman population & lifestyle

www.who.int (World Health Organization)


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Salmonella

Gram negativerods

Non-spore forming

Most importantbacteria to causegastroenteritis

Widely distributed in

nature with animals &humans being primaryreservoirs


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Species & Serovars

There is a confusion over the

naming of Salmonella strains.

The Salmonella family includes

over 2,300 serotypes of bacteria.

The strains which we deal greatly are generallydifferent serovars of Salmonella enterica. The three

main serovars of Salmonella enterica areTyphimurium, Enteritidis, and Typhi.


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Species & Serovars

All salmonellae in two species S. enterica

S. bongori

S. entericasubspecies;

S. entericasubsp. Salamae,S. entericasubsp.

arizonae,S. entericasubsp. diarizonae,S. entericasubsp. houtenae,S. entericasubsp. Indica.


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Serotyping

Species & serovars categorized as A, B, C, etc.according to similarities in content of Oantigens

For further classification, H antigens can beused


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Epidemiological Groups

Infect humans only Includes agents of typhoid and paratyphoid fevers

Host-adapted serovars Includes somehuman pathogens that can be

contracted from foods as well as strains that effectpoultry, cattle, horses, sheep, and pigs

Unadapted serovars Pathogenic forhumans and animals and includes

most foodborne serovars


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Growth

Optimum pH is 6.6-8.2; no growth seen >9.0or


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Growth

Generation time at optimal conditions similarto that for E. coli(~ 20 min)

Use amino acids for nitrogen, but some strainscan use nitrite, nitrate, or NH3

Unable to ferment lactose, sucrose, or salicin;can f erment glucose and othermonosaccharides with gas production


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Destruction

Unable to tolerate salt concentrations >9.0%

Destroyed at milk pasteurization temps

Most heat resistant in stationary phase

Increasing incubation temp increases heatresistance

5-7.5 kGyradiation sufficient for inactivation


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Distribution

Primaryhabitat is intestinal tract

Excretion in feces is route of transmission

Also found in water, especially polluted water

When contaminated water is consumed byhumans or animals, the organisms are again

shed through fecal matter, thus continuing thecycle


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Incidence in Animal Feeds

Industry-wide incidence in 1989 was 49%, mostlikely due to contamination

Feed considered to be ultimate source of

salmonellae in breeder/multiplierhouses


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Incidence in Food Products

Found in commercially prepared & packagedfoods

Cake mixes

Cookie doughs

Dinnerrolls

Cornbread mixes

Not found in foods of plant origin


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Typhoid Mary

MaryMallon (1870-1938)

Symptomless carrier of

typhoid bacilli whoworked as a domesticcook

Infected 47 people withtyphoid fever, 3 ofwhom died


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Salmonellosis

Onset of symptoms at 12-14 hours

Symptoms: nausea, vomiting, abdominal pain,headache, chills, diarrhea, often mistake for the

stomach flu. Symptoms for 2-3 days

Mortality rate: 4.1%

Up to 5% of patients become carriers uponrecovery

107 109 cells needed for salmonellosis


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Salmonellosis

Identification is determined by lab tests oninfected persons stool

Most often no treatment is required

Reiters syndrome

Joint pain

Irritation of eyes

Painful urination


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Mode of Action of Salmonella

Binds to intestinal wallsvia proteins

Gains access to inside

body & is taken toliver/spleen

Grows again and re-released into intestine

Causes illness


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Incidence & Vehicle Foods

2-4 mil. infections/yr. (39% children under 10)

Largest outbreak in 1994 involved 224,000 peopledue to ice cream made with milk from a truck thathad previously transported liquid eggs. Cases seen

in 41 states. 2nd largest outbreak (1985) involved 200,000 people

due to 2% milk

S. Typhimurium most frequently

isolated serotype followed byS. Enteritidis


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Recommendations for CookingEggs

BecauseS. Enteritidis is so

highly associated witheggs,

the CDCP recommends:

Avoid raw or undercooked eggs

When eggs are not properly cooked, use pasteurized eggproducts

Eggs should be cooked at >145F for 15 s

Dishes containingraw eggs should be cooked to 160F

Raw eggs should be stored at < 45F at all times


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Incidence of S. Enteritidis in eggs &poultry

The association of S. Enteritidis witheggs andpoultry products is unclear

Some possibleroutes of

S. Enteritidis to eggs include: Transovarial

Egg washing

Food handlers

Translocation from peritoneum to yolk sac or oviduct

Penetration of shell by organisms as eggs pass throughcloaca


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Prevention & Control

Ultimate control byeliminating the organismsfrom animals and humans Only about 35 of the 2,400

serovars account for 90% ofhuman isolates and approx80% of nonhuman isolates

Improper preparation &

handling of foods is primaryfactor in outbreaks


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CompetitiveExclusion to ReduceSalmonellae in Poultry

Feces from salmonella-free birds given tonewlyhatched chicks

Chicks develop a salmonella-free natural biota

Full protection from salmonella in 6-8 hrs

Older birds can also receive treatment

Basic principle is competition for adherencesites


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Vaccinations forSalmonella

Typhoid vaccine available, but not required, inthe USInactivated (killed), injected

Attenuated (weakened), given orally

People should get it if:Traveling abroad to countries where typhoid is

commonPeople in contact with a typhoid carrier

Lab workers who work with the bacteria


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Shigella

Discovered 100+ years ago byJapanese scientist

Kiyoshi Shiga

Gram -Rod shapedNon-spore forming

No flagella (no motility)Aerobic

Glucose Fermentinghttp://www.about-shigella.com/


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ShigellaCharacteristics

Doesnt grow over 50C or below 10C

pH range: 5 to just over 9, best in 6-8 range

Aw and heat resistance similar to E.coli andS

almonella Principally a disease of humans except other

primates such as monkeys and chimpanzees


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Shigellagrowth underrefrigerationconditions (10C, pH 7, 0.5% NaCl)

0

1

2

3

4

5

6

7

8

9

10

0 200 400 600 800 1000

Hours

log(CFU/ml) LCL UCL

Shigella flexneri in Broth Culture


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Shigellagrowth under optimalconditions (35C, pH 7, 0.5% NaCl)

0

1

2

3

4

5

6

7

8

9

10

0 5 10 15 20 25

Hours

log(CFU/ml) LCL UCL

Shigella flexneri in Broth Culture


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Shigellaspecies

4 species recognized:

Shigellasonnei

Shigellaflexneri

Shigellaboydii

Shigelladysenteriae


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Shigellainfection As few of 10 CFU/g of S. dysenteriae can cause

bacillary dysentery

Fecal-oral route

Infected people with poor hygiene

Food handlers Child care workers

Toddlers

20% of cases from contaminated food or water

Food harvested i n area with sewage

Flies breeding in infected feces and then land on food

Drinking or Swimming in infected water


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Developing world

During the Rwanda genocide of1994, approx. 20,000 refugees died inthe first month from dysenterycaused by a multi-antibiotic resistant

strain of Shigella.

S. flexneri is predominant in thedeveloping world

S. dysenteriae type 1 has causedepidemics in Af rica and CentralAmerica with a 5-15% fatality rate.


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United States

S. sonnei is predominant in the U.S. (85% of

shigellosis infections)

Each year about 18,000 confirmed cases of

shigellosis occur in the U.S. and about 450,000cases are estimated since many are not reported.

Shigellosis is more common in summerthan winter.

In the developing world, shigellosis is far morecommon and is present in most communities most of

the time


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Food vehicles

Salads (potato,tuna, shrimp,macaroni, and

chicken), rawvegetables, milkand dairy products,and poultry.

http://vm.cfsan.fda.gov/~mow/chap19.html


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ShigellaInvadingEpithelial Cells


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Shigellain cells

Shigellaflexneriescaping from aninfected epithelial

cell

www.nature.com Courtesyof P. Sansonetti


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Symptoms

Diarrhea (usually bloody) Fever Abdominal cramps

Incubation period 12 hrs 6 d ays,usually 2-4 days

Shigella may be passed on without knowledge,

because symptoms are not always expressed Children and elderly are most susceptible to severecases requiring hospitalization


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Bodys response

Resolves in 5 to 7 days Hemolytic Uremic Syndrome (HUS) Usually a full recovery, but sometimes several

months to haveregular stools 3% of people infected withS.flexneri, will later

develop Reiters syndrome (genetically predisposed)

www.richmond.edu


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Treatment

Antibiotics 5 day treatment

Ampicillin, trimethoprim/sulfamethoxazole,nalidixic acid, or ciprofloxacin

New antibiotic resistant strains (multidrug)

Antidiarrheal agents, likeImodium, are likelyto make the illness worse.

No vaccines


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Prevention

Even if no symptoms are present, food handlersshould not prepare food if they carry the Shigellabacterium

Proper hygiene

Treat drinking water

Travelers: drink only treated orboiled water, eat onlycooked hot foods orfruit you have peeled.

Wash hands with soap carefully and frequently,especially aftergoing to the bathroom, afterchangingdiapers, and before preparing foods orbeverages


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Shiga Toxin

Also called the

verotoxin, is produced by:

Shigella dysenteriae

Escherichia coliO157:H7

The onset of symptoms is generally within a few

hours. There is no antidote for the toxin.

The toxin acts on the lining of the blood vessels, the

vascular endothelium It acts to inhibit protein synthesis within target cells.


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Recent Outbreaks Outbreaks of Shigella sonnei Infection Associated with

Eating Fresh Parsley -- United States and Canada, July-August 1998

Shigella sonnei Outbreak Associated with Contaminated

Drinking Water Island Park, Idaho, August 1995

Outbreak of Shigella flexneri 2a

Infections on a Cruise Ship Aug. 1994


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How does ourgovernment helpprotect against shigellosis?

EPA Safe drinking waterFDA Food processing, preparation, and

inspectionCDCMonitors frequency of infectionsAssists state and local health departments with

outbreaksDetermine means of transmissionDevise control measures


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The Foodborne and DiarrhealDiseases Branch

Part of the CDC

An innovative public health investigative andconsultative group that identifies causes,sources and solutions for bacterial foodborneand diarrheal inf ections to prevent the

disability and death those diseases cause.


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New Research

Vaccines

Incidence, prevalence, disease burden andserotype distribution of shigellosis

Oral S. flexneriserotype 2a vaccine candidate

Parenteral injection vaccination type, test resulted

in 74% protection against S. sonnei


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Protection with tracking

Public Health Departments should know about Shigellosis cases. Theykeep records of the infecting species, and when cases increase, they knowwhere and how to intervene.

Hello. My name is ___________and Im calling from the _______StateHealth Department. Im calling because there have been several cases

of_______________ in our community and we are working to identify thesource of inf ection, so we can prevent additional illness in the community.We understand that you are one of the people who had this illness. Iwould like to ask you some questions about your illness and foods that youate before becoming ill, that will help us in this work. This will take about____ minutes. Can we go ahead?

Ifno: Is there a convenient time I can call you back? Day___________Time___:___ am pm


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Dont forget to washyourhands

Thank you!

micro presentation salmonella and sigella

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