Introduction to Food Microbiology and Surveillance for Foodborne Illness

1. Introduction to Food Microbiology and Surveillance for Foodborne Illness Kali Kniel, Ph.D. Associate Professor, Microbial Food Safety Department of Animal and Food Sciences

2. Foodborne illness (FBI) • Infection or intoxication caused by transfer of microbial or chemical contaminants from food or drinking water to a human • Over 250 different foodborne diseases and are constantly changing due to emerging microorganisms

3. Food Related Illness and Death in the US • Centers for Disease Control and Prevention (CDC), Dr. Elaine Scallan and others, 2011 • 47.8 million cases, of which, an estimated • 9.4 million illnesses caused by 31 known pathogens • 38.4 million illnesses caused by unspecified agents • 128,000 hospitalizations • 3000 deaths • Are numbers meaningful? • Baseline data • Underreporting/mild disease

4. Salmonella - National incidence of the top three serotypes 1970-2001 Typhimurium Enteritidis Heidelberg

5. Outbreaks vs Cases • Case: an instance of a particular disease • Outbreak: an incident in which 2 or more cases of a similar illness result from eating the same food (2 or more unrelated cases) • Exception: 1 case of a chemical-related fbi or Clostridium botulinum poisoning constitutes an outbreak

6. Surveillance drives the cycle of public health prevention Surveillance Epidemiologic investigation Prevention Measures Applied Targeted Research

7. Changes in outbreak scenarios • Classic “church supper” or Sunday picnic are now multi-state outbreaks • Need information to design useful fbi control programs

8. Microbiology Basics • What’s the difference between a bacteria, a virus, a protozoa, a helminthe, a chemical? • Which ones may grow in your food? Does that matter? • What’s an infection and what is an intoxication?

9. Bacteriology Basics • Characterization by spore formation • Characterization by shape • Characterization by Gram stain (1884) • Gram positive (purple) • Gram negative (pink) Outer membrane Peptidoglycan Peptidoglycan Plasma membrane Plasma membrane Periplasmic space

11. Bacterial Growth

12. Viral Growth

13. Parasite Growth

14. Microbiology Basics • Factors affecting growth and/or illness • Nutrients • pH • Water availability (Aw) • Temperature • Atmosphere • Manipulate these in terms of Food Preservation & Food Safety • How?

15. Process Foods to Enhance Quality & Safety • What factors can enhance a shelf life and the safety of the product? • Pasteurized milk • Bagged salads • Packaged deli meats • Ready to eat sliced apples • Technologies • Heat (pasteurization) • Enhanced packaging films, active packaging • High pressure processing

16. Foods Most Often Involved • Beef-ground beef • Produce • Seafood-fish, shellfish • Other meats • Dairy products • Ready-to-eat (RTE)/Ready-to-heat (RTH)/Ready-to-cook (RTC) • Why?

17. Most Common Agents • Campylobacter • Salmonella • Staphylococus aureus • Escherichia coli O157:H7 • Clostridium perfringens • Listeria monocytogenes • Viruses (Norovirus, Hepatitis A) • Protozoa (Cryptosporidium, Cyclospora, Toxoplasma)

18. Clinical Features • Transmission • Pathogenesis • Host factors • Organism factors • Carriers • Recognizing FBI • Control and prevention

19. Symptoms • Acute symptoms most common • Often self-limiting • Chronic sequelae more common • Diarrhea (5 types), cramps, nausea, fever, vomiting, body aches • >3 or 4 loose stools within a 24 hour period • Warning sign is bloody diarrhea

20. Factors contributing to outbreaks • Improper holding temperature • Danger zone 40-140°F • Inadequate cooking • Improper cooling • Improper reheating • Poor personal hygiene • Cross-contamination • Poor storage practices

21. Biofilm development biology.binghamton.edu/davies/research.htm

22. Factors Affecting Disease • Microorganism factors • Gene expression • Potential for damage or stress to microorganism • Interaction of microorganism with food • pH susceptibility • Interaction with other microorganism

23. Factors Affecting Disease • Host factors • Immunocompromised • Age • Pregnancy • Medications, chemotherapy, diabetes • Gastric acid

25. Changing Epidemiology-Agent • Newly recognized pathogens • non-O157 shiga-toxin producing E. coli • Cyclospora cayetanensis • New variant CJD • New resistance • Salmonella Typhimurium DT 104 • Salmonella Newport • Ciprofloxacin resistant Campylobacter

26. Foodborne Outbreak Scenarios • Traditional scenario • usually event associated, or affects a discrete population • acute and localized • high inoculum, high attack rate • Newer scenario • diffuse and widespread • low-level contamination of widely distributed food product

27. A large outbreak in one place may be obvious

28. An outbreak with cases dispersed in many places may be difficult to detect, unless • We test the pathogens from all the cases, and • We find they are infected with precisely the same bacterial strain

29. FB Disease Surveillance • Disease Prevention and Control • Knowledge of Disease Causation • Administrative Guidance

30. Burden of Illness http://www.cdc.gov/foodnet/surveillance_pages/burden_pyramid.htm

31. Foodborne Outbreak Surveillance • Local Health Departments • Patient complaints • Laboratory, HCW CMR reports • State Health Departments • Foodborne outbreak reports • Salmonella serotyping • PFGE • Federal Health Agencies (CDC and regulatory) • PulseNet and FoodNet

32. Surveillance • Passivesurveillance occurs when health agencies are contacted by cases, physicians or laboratories, which report illnesses or laboratory results to them. • In activesurveillance, the health agencies regularly contact physicians and laboratories to make sure that reportable diseases have been reported and required clinical specimens or isolates have been forwarded to state laboratories for further analysis.

33. Disease Reporting • Passive surveillance system • Mandatory disease reporting to LHD • LHD case follow-up and further investigation if needed • LHD transmit data to DHS to CDC • For select agents, must report immediately

34. Notifiable foodborne diseases • Food Net - Foodborne Diseases Active Surveillance Network (CDC, USDA, FDA) • Salmonella,Shigella, Campylobacter, Escherichia coli O157, Listeria monocytogenes, Yersinia enterocolitica, Vibrio and Cryptosporidium and Cyclospora

35. Objectives of FoodNet • Determine the burden of foodborne illness in the United States • Monitor trends in the burden of specific foodborne illness over time • Attribute the burden of foodborne illness to specific foods and settings • Develop and assess interventions to reduce the burden of foodborne illness

36. PulseNet • A national network of public health and food regulatory agency laboratories coordinated CDC. • The network consists of: state health departments, local health departments, and federal agencies (USDA/FSIS, FDA). • PulseNet participants perform standardized molecular subtyping (or “fingerprinting”) of foodborne disease-causing bacteria by pulsed-field gel electrophoresis (PFGE). • PFGE can be used to distinguish strains of organisms at the DNA level. DNA “fingerprints,” or patterns, are submitted electronically to a dynamic database at the CDC. These databases are available on-demand to participants—this allows for rapid comparison of the patterns

37. Objectives of PulseNet • Detect foodborne disease case clusters by PFGE • Allow for real-time communication among state, local health departments, and international partners • Facilitate early identification of common source outbreaks • Help food regulatory agencies identify areas where implementation of new measures are likely to increase the safety of our food supply

38. DNA Fingerprinting by PFGE ? • Isolates are obtained from patients, food, etc • DNA is isolated • DNA is cut into fragments with an enzyme • DNA fragments loaded into a gel matrix and are separated using an electric field

39. What is PFGE? Large Fragments Small Fragments

40. 3 1 4 2

43. Surveillance Data Limitations • Many but not all foodborne pathogens are reportable diseases to the local health dept from physicians & laboratories • Underreporting issues • Estimated that for every 1 case of Salmonella that is diagnosed, 38 cases are undiagnosed • Not all reported cases are foodborne • Person to person, animal contact, water

44. The outbreak… • So what happens when surveillance indicates that an fbi outbreak is occurring?

45. Initial Call • Calls from physicians reporting patients with symptoms of fbi • Call from Community Health Department • Increase in laboratory reports

46. Steps in Outbreak Investigation 1. Verify the Diagnosis

47. Steps in Outbreak Investigation • Verify the diagnosis • Confirm the outbreak Steps 1 and 2 are interchangeable

48. What could account for the increase in cases?

49. What could account for the increase in cases? Real increase • Increase in population size • Changes in population characteristics • Random variation • Outbreak Artificial increase • Increased examination of stools • New testing protocol • Changes in reporting procedures

50. Initial Investigation • Any other way to see if there is a relationship between these isolates?