Lecture 12- Campy and Salmonella

8/13/2019 Lecture 12- Campy and Salmonella

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Leading Causes of Foodborne Infections

Norovirus Campylobacter

Salmonella

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Campylobacter

Genus Campylobacter 16 species and 6 subspecies

C. jejuni and C. coli are most common cause of humandiarrheal disease worldwide

First recognized in 1979

Gram-negative, motile, nonsporulating, spiral rod-shapedbacterium

Microaerophilic

Fragile cells

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Microaerophilic environment of ~ 5% oxygen, 8% CO 2,and 87% N 2 for growth

Mesophilic - growth temp: 32 - 45C, with optimum~42C

Prefer amino acids to carbohydrates for nutrient source

Grow slowly and are poor competitors

Campylobacter growth requirements

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Campylobacter Growth Requirements

Sensitive to: Oxygen NaCl low pH temperature Drying

Survive well during refrigeration and for months in the

frozen state Difficult to culture in the laboratory

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Enteric M/O

Skin/feathers Presence of Campy: 10 5 cfu/carcass rinse Effectiveness of santizer or hot-water dips:

Natural Habitat of Campylobacter

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Presence of Campylobacter in food

Raw meats (beef, lamb, pork, chicken, and turkey),milk, eggs, vegetables, mushrooms, and clams

In heat-processed food, their presence in heat-processed food is due to post-processing

contamination or improper heat treatment

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Campylobacteriosis Onset: 2-5 days after consumption of contaminated food

Duration: 2-3 days

Infective dose: Very low 500 cells Target population: Everyone

Primary symptoms: Abdominal cramps, profuse diarrhea,

nausea, vomiting and fever occasional bloody diarrhea Secondary symptoms: fever, headache, and chills

Rarely fatal

Disease caused by Campylobacter

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Campylobacter Mechanism of Pathogenesis

Flagella

CDTtoxins

Inflammation,Cell damage,

Diarrhea

Campylobacter

Chemotaxisand

motility

Invasion andentrapmentinside the

vacuole

Loss ofabsorptivemicrovilli

Fig 25.5, Ray and Bhunia 10


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Complications Resulting fromCampylobacteriosis

Guillian-Barre Syndrome Antibody production against Campylobacter

antigen Impaired nerve function and ascending paralysis

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Complications Resulting fromCampylobacteriosis

Reiters Syndrome Arthritis

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Diagnosis of Campylobacteriosis

Rarely diagnosed in the past We just recently became aware that this is the leading

cause of bacterial foodborne illness

Difficult to grow in the lab Easier to detect with DNA-based methods

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Treatment for Campylobacteriosis

Usually self-limiting Palliative therapy: hydration, rest

Antibiotics can shorten duration of infection

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Prevention of Campylobacteriosis

On farm: Reducing animal carriage of Campylobacter

Difficult Sanitation Prevention of carcass/egg contamination

At home: Avoid cross contamination Thoroughly cook poultry products AVOID CROSS CONTAMINATION

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Foodborne Infections caused bySalmonella

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Salmonella

Gram-negative

Motile rods

Facultative anaerobes Nonsporulating

Mesophilic Temp range of 546C, with optimum of

35-37C

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Salmonella - Nomenclature Genus - Salmonella Species - enterica and bongori

Subspecies of S. enterica Enterica, Salamae, Arizonae, Diarizonae,Houtenae, Bongori

Serovar (aka serotype) Typhimurium, Enteriditis, etc. Serovar based on antigen types Antigen: molecule that stimulates an immune response in the

host O Antigen somatic antigen H Antigen- flagellar antigen K Antigen capsular antigen

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Salmonella - Nomenclature

Example: Salmonella enterica subsp. entericaTyphimurium

Over 2000 serotypes belong to the subspeciesenterica, and all of them are pathogenic to humans.

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Salmonella species, subspecies, serotypes, and their usual habitats

Salmonella species andsubspecies

No. of serotypeswithin subspecies

Usual habitat

S. enterica subsp. enterica 1,454 Warm-blooded animals

S. enterica subsp. salamae 489 Cold-blooded animals and theenvironment b

S. enterica subsp. arizonae 94 Cold-blooded animals and theenvironment

S. enterica subsp. diarizonae 324 Cold-blooded animals and theenvironment

S. enterica subsp. houtenae 70 Cold-blooded animals and theenvironment

S. enterica subsp. bongori 32 Cold-blooded animals and theenvironment

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aW > 0.94 required for growth

pH > 4.5 required for growth

Sensitive to heat destroyed by cooking,pasteurization and greater thermal treatments

Dont cause spoilage Can grow in foods without changing quality

Salmonella growth requirements andsensitivities

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All Salmonella enterica Intestines of mammals, especially poultry

Food association Poultry, beef, pork, lamb, raw milk and dairy products, eggs, produce

Presence in meat/poultry products and produce fecal contamination Presence in eggs usually a different story

Most common culprits

S. Typhimurium poultry/meat, some produce S. Enteriditis eggs Others S. Tennesee, S. Dublin, etc.. New outbreaks with produce

and some meat/poultry

Natural Habitat and Presence of Salmonella in Food

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Contamination of Eggs with S. Enteritidis

S. Enteriditis translocates from intestine of laying hen to theovary and oviduct

Natural internal contamination of eggs

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Salmonellosis Onset: 8-24h after consumption of contaminated food Duration of illness: 2-3 days

Infective dose > 10 5 cells Target population: Everyone, but higher in YOPIs Primary symptoms: Gastroenteritis

Nausea , Vomiting, abdominal cramping, diarrhea (sometimesbloody), fever

Secondary symptoms: chills, aches Mortality rate:

Disease caused by Salmonella

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Salmonella Mechanism of Pathogenesis inIntestinal Epithelium

Fig 25.1, Ray and Bhunia

Step 1 Salmonella binds to intestinal

epithelial cell, induces membraneruffling, and then invades

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Salmonella Mechanism of Pathogenesis inIntestinal Epithelium

Step 2 Salmonella multiplies inside hostvacuole

Step 3 Salmonella secretes pathogenic

factors into host cytoplasm using a TypeThree Secretion System

Results:

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Salmonella can enter macrophages Via passage from epithelial cells or via entering M-cells

Bacterium survives inside of macrophages and can travelto other areas of the body

Salmonella Evasion of Host Immune System

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Salmonella - Pathogenesis Overview

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Easier to detect than Campylobacter Collection of fecal samples from infected individuals Collection of food samples Detection

culturing in lab DNA-based detection (PCR)

Diagnosis of Salmonella

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Treatment for Salmonellosis

Rehydration, rest

Antibiotics for severe cases

Patients may be hospitalized

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Prevention of Salmonellosis

On farm: Reducing animal carriage of Salmonella Sanitation Subtherapeutic antibiotics,

Probiotics, reduction of stress

At home: Thoroughly cook poultry products Proper cooling AVOID CROSS CONTAMINATION

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Lecture 12- Campy and Salmonella