Emerging foodborne pathogens

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Emerging food-borne pathogens

• Pieter Gouws
• Food Microbiology Research Group
• University of the Western Cape

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Little bugs
BIG Trouble !!
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• Throughout the world, food production has become
  more complex. Raw materials are often sourced
  globally, and the food is processed through an
  increasing variety of complex techniques.
• Food safety issues, such as E.coli 0157, Listeria
  are never far from the newspaper headlines,
  becoming grounds for increasing public concern

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NEWS 24 hours ?

• E. coli bug kills 2 year old
• Water source of deadly bug
• Kroger recalls 90 tons of meat
• Outbreak affects 500 people
• CNN
• BBC
• www.foodsafetynet.com

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Food Poisoning

• They are diseases contracted by ingestion of
  contaminated food (intoxication / infection)
• Two-thirds of all food poisoning outbreaks
  involve bacteria
• The rest are caused by viruses, parasites, fungi
  and chemicals

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The scale of the problem

• Major disease in developing countries
• 1000 million cases of acute diarrhea occur in
  children under 5 years in Africa and Asia
• 5 million cases are fatal
• Contaminated food and water

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Food related illness and death (USA) - 1998

• 76 million cases
• 325 000 hospitalizations
• 5 000 deaths
• Salmonella, Listeria, Campylobacter and E.coli
  O157H7 are responsible for 75 of all deaths

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Food-borne disease

• Many food-borne pathogens initially cause acute
  gastrointestinal effects and then, through a
  variety of mechanisms, go on to cause further
  damage in the human body
• Symptoms usually vomiting, nausea, abdominal
  pain, diarrhea, aches and pains, and fever

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Foodborne diseases
Foodborne illness is a major and complex problem
that is likely to become a greater problem as we
become a more global society

• Factors that influence the incidence of foodborne
  disease
• Emerging pathogens
• Outbreak investigation
• Risk assessment
• Role of Government and Industry
• Consumer education

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Why do foodborne diseases emerge ?

• Globalization of food supply
• Travelers, refugees, immigrants
• Introduction of pathogens into new geographic
  areas
• Minimal food processing
• Change in microorganisms
• Change in Human population
• Ageing, malnutrition, Aids
• Change in lifestyle
• Fast foods etc.
• Antibiotic use

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Food Safety

• is evaluated in terms of acceptable levels of
  risks
• is enhanced by systematically concentrating upon
  minimizing opportunities for contamination at
  every point from farm to the table

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High risk groups

• Pregnant women, unborn
• Listeria
• Infant
• Campylobacter, E. coli, Listeria
• Elderly
• Salmonella, Campylobacter, Listeria
• HIV /AIDS, TB
• All pathogens

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Least Wanted Microorganisms

• Campylobacter jejuni
• Salmonella
• Listeria monocytogenes
• E.coli O157H7
• Clostridium botulinum
• Staphylococcus aureus
• Shigella
• Toxoplasma gondii
• Vibrio
• Yersinia enterocolitica
• Norwalk virus

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Campylobacter
Listeria
E coli O157
?
Salmonella
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Campylobacter

• Campylobacter jejuni
• Campylobacter coli
• 14 species
• Europe adults 18 23years of age
• SA children 2 6 years of age
• Foods - Milk and raw meat products
• High frequency among animals
• From penguins to professors

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Campylobacter disease

• Infective dose very low (500 cells)
• Symptoms within 2 to 5 days
• Last for 2 3 days, but in some cases 3 weeks
• Abdominal cramps, profuse diarrhea (bloody),
  nausea, vomiting, fever headache
• The organism may be shed for more than 2 months
  after symptoms subside
• Arthritis, meningitis, Guillain-Barrre Syndrome
• Mortality rate 0.001

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Salmonella

• 2200 serovars
• Non lactose fermenter
• Gastrointestinal tract of animals, birds, pets,
  frogs, turtles etc
• Foods
• Beef, poultry eggs, milk
• Chocolate
• Salads
• Lunch?

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Salmonella disease

• Infective dose 105 106 cells
• Symptoms within a day
• Individual remains a carrier for several months
• Abdominal cramps, diarrhea, vomiting, chills,
  fever
• Can be fatal for infants and elderly
• Mortality rate 1 (15 elderly and in HIV
  patients)

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EHEC

• E. coli O157H7
• Cells survive well at 20C
• Ready-to-eat foods
• Hamburgers
• Frankfurters
• Apple cider
• Salads
• Strawberries
• Mortality rate 2

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Listeria Disease and Symptoms

• Sporadic outbreaks
• Symptoms 1 7 days
• Flu-like symptoms
• Fever, abdominal cramps, diarrhea
• Sensitive groups
• Pregnant women, unborn fetus, new born, infants,
  HIV/Aids
• Septicemia, meningitis, endocarditis
• Mortality rate very high
• Infective dose low
• 1000 cells

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Foodborne Listeriosis

• Listeria monocytogenes
• Opportunistic disease
• Highly fatal (30 40 )
• Grow at refrigerated temperature
• Gram (), psychrotrophic, facultative anaerobic,
  nonsporulating, motile rod.
• Cells resistant to freezing, drying, high salt.
• HOCl no / little effect on Listeria biofilms
• Pasteurization ?
• Ability to form biofilms

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Listeria

• Nutritional requirements, typical as for other
  Gram ()
• BHI broth / agar Enrichment Fraser broth
• Listeria selective agar
• Palcam / Oxford / Rapid L mono agar
• pH 6-8 ave, 4.1 min, 9.6 max
• Temp 0.5 C - 44C, optimum 35 C
• aw 0.90 Glycerol, 0.93 sucrose, 0.92 NaCl

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Listeria (recent outbreaks SA)

• Ice cream
• Chocolate ice cream
• Spices
• Pepper corns
• Cheese
• Feta with pepper
• Soft cheeses, blue cheese
• Patè
• Minced meat / hamburgers
• Smoked Salmon / Trout
• Avocados
• Export to USA!

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Cost of an outbreak ?

• Sara Lee (1998)
• 50 million
• Thorn Apple Valley (1999)
• 45 million, bankrupts the company
• Bar-S Foods (2001)
• 20 million

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Listeria - habitat

• Environment
• Soil, sewage, water
• Plants and dead vegetation
• Animal feces
• Foods and Humans
• Food handlers
• Animal and plant origin
• Raw milk
• Soft cheeses
• Fresh and frozen meats
• Poultry
• Seafoods
• Fruits and vegetables

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Listeria survey in the Western Cape
308 samples tested, 113 L. monocytogenes, 37
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Survey Oct 2001 Jan 2002
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Detection

• Classical and standard methods of analysis dont
  allow for rapid and direct identification
• Products with short shelf life?
• 24 Hour method ?
• To develop PCR based technology
• SANBI UWC
• Bioinformatics

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Food stuffs 25 g
225ml Fraser ½ broth
Streak on Rapid L.mono
30C-24h
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24-48h at 37C
Streak on Oxford / Palcam
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1
Fraser broth 0.1 in 10 ml
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Direct identification On Rapid L.mono
24-48h at 37C
24-48h at 37C
2-3
Selection of colonies
2-3
Streak on Oxford / Palcam
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Identification
24-48h at 37C
4-5
PCR ?
Selection of colonies
4-5
Streak on Rapid L.mono
Identification
2-3
6-7
Direct identification On Rapid L.mono
4-5
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Development of PCR for Listeria monocytogenes

• Specific DNA sequence
• Listeriolysin (hlyA) gene
• Highly specific for L. monocytogenes
• Do not amplify DNA present in any other Listeria
  or non-Listeria organisms
• Identify presumptive positives within 3-4 hours
• Can be used with enrichment broth cultures

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PCR detection

• L. monocytogenes A
• L. monocytogenes
• L. ivanovii
• L. innocua
• Control

730bp
1 2 3 4 5
Identification of Listeria monocytogenes from
foods by PCR
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South African Products

• Cheese
• Soft cheeses - water
• Blue cheese - Mystery
• Patè Raw product
• Minced meat Cross contamination
• Smoked Salmon Imported with raw product, and
  cross contamination
• Smoked Trout - Water from airconditioner units
• Avocados Chlorine bath
• Sushi cleaning tools

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Controlling Listeria in processing plants

• Introduced into plants
• People or equipment entering the plant
• The organism that take up residence in plant
  (biofilms)
• From raw materials (contamination of product)
• Separating raw products from semi-finished and
  finished product is a KEY factor
• Linear flow of product through the operation
• Control traffic flow patterns between raw
  ingredients and the processed products

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Other pathogens

• Vancomycin resistant Staph
• Multiple antibiotic resistant E coli, Salmonella
• Norwalk virusses
• Giardia and Cryptosporidium
• BSE mad cows disease
• Arcobacter

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Approach to control

• HACCP
• Sampling programs
• End product testing
• Environmental monitoring plan
• Sanitation
• Irradiation

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Problems in SA industry

• Incomplete separation of raw products and post
  process environments
• Inadequate control of personnel and production
  activities in critical post process zones
• Use of cleaners/sanitizers that are not removing
  biofilms, penetrating organic build-up, etc
• Incomplete coverage of equipment/surfaces with
  cleaners/sanitizers during cleaning activities
• Using processing equipment that is not easily
  cleanable
• Inadequate control of chilling and cold storage,
  allowing outgrowth of Listeria monocytogenes
  during extended product shelf life

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Food Processing environment

• Floors and floor drains
• Standing water
• Residues and food contact surfaces
• Ability to attached to stainless steel
• Cleaning tools
• Refrigeration condensation units
• Measures to control of Listeria will have to be
  applied more rigorously and with more attention
  to detail than measures for the control of
  traditional pathogens

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Factors that influence the incidence of foodborne
disease

• Primary foodborne pathogens
• Food Supply system
• Pre-slaughter practices
• Poor farm management
• Contaminated water supplies
• Growth promoters (antibiotics)
• Wild and domestic animals
• Slaughter process
• Food Processing
• Temp, processing treatments, disinfectants
• Preparation and consumption of food in the home

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Food Safety Management Systems

• Codex general Principles of Food Hygiene (GMP)
• Legislative Requirements
• Hazard Analysis and Critical control points
  (HACCP)
• Integration and linking
• Total Food Safety System

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GMP guidelines

• Operational Methods and Personnel Practices
• Storage methods, handling of material
• Personal hygiene
• Cleaning Practices
• Cleaning schedule, procedure and equipment
• Pest Control
• Crawling / flying (Whats happening after hours?)
• Maintenance for Food Safety
• Building, equipment and services
• Adequacy of Food Safety Program
• Procedures, records, recall
• Supplier quality assurance

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Sanitation

• Safety and Quality
• Consumer driven
• Long shelf life
• Defect free
• The enemy - Listeria
• 4 x 4
• Pre-rinse
• Wash to remove soil
• Rinse
• Sanitize to kill/reduce Listeria
• Control and Validation
• Training

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Risk assessment

• Risk evaluation
• Identify problem, establish risk profile, etc
• Risk management
• Option assessment, option implementation,
  monitoring and review
• Risk communication
• All interested parties, opportunity for input
• The outcome of the risk management process, is
  the development of standards, guidelines and
  other recommendations for food safety

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Risk Evaluation Scientific Hazard
identification Risk profile
Risk Management Select and implement Control
options
Risk Communication Interactive exchange of
information
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YourBiggestFood SafetyRisk
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Sick Food Workers

• Easiest way to spread foodborne disease
• Cross contamination
• Via the Hands
• Toilet
• Blows his nose
• Sneezes
• Infected wounds, cuts, pimples
• Illness policy?

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Role of Government and Industry

• Food Industry
• Responsible for ensuring the safety of foods
• Implement Food Safety management
• Research related to food safety
• SHARE THE INFORMATION!!
• Educate their workers
• Government
• Regulatory systems
• Policies should be based on scientific principles
• Design activities to maintain and improve food
  safety
• Stimulate private, public, universities and
  consumer group activities

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Biotechnology at UWC

• To develop molecular based methods for detection
  and typing (PCR)
• To improve methods for preservation and control
  of foodborne pathogens
• Molecular epidemiology
• To develop methods for HACCP

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Public at large safer food supply
Food safety issues continue to dominate the news
headlines. BSE, E.coli, Salmonella, growth
promoters, pesticides, etc. The onus is on
everyone involved in food production and
processing to address these consumer concerns.

• It is our aim to develop novel methods and
  processes for the food and water industry, and to
  train students in these fields to effectively
  serve the industries in South Africa.

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Thank you

• NRF
• WRC
• Poultry Abattoirs
• Ostrich Abattoirs
• Red Cross Childrens Hospital
• SANBI Win Hide
• University of Lund - Peter Radstrom
• University of Nottingham Christine Dodd
• University of Pretoria - Volker Brozel
• University of Cape Town - Al Lastovica
• UWC - Postgraduate students

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Prof Pieter Gouws Food Microbiology Research
Group University of the Western Cape Tel 021 959
2557 Fax [phone] Cel 082 202
3367 Pgouws_at_uwc.ac.za