Food Microbiology - Exam 1

Contamination of foods is from what organisms?

• Microorganisms that spoil foods

• Pathogenic microorganisms - cause food poisoning

Sanitation, control, and inspection: What are they and how do they work together?

• Interventions that manipulate intrinsic and extrinsic factors.

• Unity and collaboration between academia/research, industry, regulatory agenices.

What are “Good” microorganisms

• Non-pathogens

• Probiotics

• Microorganisms that preserve foods

USDA: What part of the government?

• Housed at the cabinet level

USDA: Missions

• Food safety

• Nutrition

USDA: Agencies

• FSIS: Food Safety Inspection Service

• ARS: Agricultural Research Service

USDA: What do they oversee

• Meat

• Poultry

• Processed egg products

USDA: Recall power

• USDA CANNOT issue recalls, but FSIS can detain or seize products during inspection.

FDA: What part of the government?

• Within the department of health and human services

FDA: Mission

• Ensuring that foods are safe for human consumption

FDA: What do they oversee?

• Efficacy and safety of drugs, cosmetics, medical devices, and some electronics.

• Foods other that meat, poultry, and processed egg.

FDA: Recall power

• Food Safety Modernization Act → Gives FDA power to issue mandatory recalls.

CDC: What is it?

• Center for Disease Control and Prevention

• Not actually a regulatory agency

• Research and illness tracking

Early history of fermentation

• 7000 BC

• References to food spoilage and preservation

• Food processing by Egyptians and Romans

Robert Hooke

• First illustrated book on microscopy

Antoine Van Leeuwenhoek

• Early microscope to view protozoa in river water (also bacteria in tooth scrapings)

Scientists and debunking spontaneous generation

• Francisco Redi

• John Tuberville Needham - Boiled and covered meat, still allowed for microbial growth

• Lazzaro Spallanzani - Boiled meat while letting air escape, sealed carefully and immediately, prevented microbial growth

Role of oxygen in food preservation

• Discoveries from 1770-1810 led to understanding about how heating and boiling drives off oxygen

• Gay-Lussac - Preservation of meats and veg by boiling in sealed containers.

  • Nicolas Appert - Canning process for Napoleons army

• Schroeder and van Dusch - Meat broth remained without microbial growth when in contact with filtered air.

Louis Pasteur

• Father of microbiology

• Definitively disproved spontaneous generation with a swan-necked flask experiment

• Pasteurization

• Fermentation as a result of living microorganisms.

Scientists and Sanitation

• Joseph Lister - Antiseptic

• John Snow - Epidemiology

Angelina Fanny Hesse

• Unpaid scientific illustrator and assistant to her husband in Robert Kochs lab

• Suggested agar rather than gelatine for bactial isolation (resistant to heat and bacterial degradation)

• No credit until 1983

Otto Frank

• Jewish, refugee, businessman selling pectin for food preservation.

Mary Hunt

• “Moldy Mary”

• Actively searched for a Penicillium strain in 1940s that could mass-produce the antibiotic

Balbina Johnson

• Discovered Bacitracin

• Isolated from Bacillus strain found in wound of Margaret Tracy

• Showed to inhibit pathogenic bacteria (Staphylococci)

Dr. Ruth Ella Moore

• Trailblazer for women and African American’s in STEM; first to join many societies

• Expanded research on Mycobacterium tuberculosis - contributed to learning control of the disease (as well as zoonotic TB), Lactobacillus acidophilus and its role in dental cavities.

James M Jay

• Published “Modern Food Microbiology” in multiple languages and “Negroes in Science: Natural Science Doctorates, 1876-1969”

Norwalk/Norovirus

• Virus

Cryptosporidium

• Parasite

Cyclospora

• Parasite

Giardia

• Parasite

Toxoplasma

• Parasite

Saccharomyces

• Fungi → Yeast

Aspergillus

• Fungi → Mold

Clostridium

• Bacteria → Gram-Positive → Spore former → Anaerobe

Bacillus

• Bacteria → Gram Positive → Spore former → Aerobe

Lactobacillus

• Bacteria → Gram positive → Non-spore former → Rods

Listeria

• Bacteria → Gram positive → Non-spore former → Rods

Lactococcus

• Bacteria → Gram positive → Non-spore former → Cocci

Leuconostoc

• Bacteria → Gram positive → Non-spore former → Cocci

Staphylococcus

• Bacteria → Gram positive → Non-spore former → Cocci

Campylobacter

• Bacteria → Gram negative → Facultative rods

Escherichia

• Bacteria → Gram negative → Facultative rods

Salmonella

• Bacteria → Gram negative → Facultative rods

Shigella

• Bacteria → Gram negative → Facultative rods

Vibrio

• Bacteria → Gram negative → Facultative rods

Yersinia

• Bacteria → Gram negative → Facultative rods

Phylum Actinobacteria

• Micrococcus

• Propionibacterium

• Corynebacterium

• Bifidobacterium

Phylum Firmicutes

• Clostridium

• Bacillus

• Staphylococcus

• Lactic acid bacteria (LAB)

• Listeria

Phylum Proteobacteria

• Escherichia

• Salmonella

• Shigella

• Yersinia

• Campylobacter

• Vibrio

• Brucella

Classification and Taxonomic Hierarchy

• Order → Family → Genus → Species → Subspecies → Serovar

• “Our family get’s seriously spicy sauce”

Criteria for cell division

• Morphology and staining

• Physiological/biochemical reactions

• Newer methods that evaluate genetic relatedness and genome similarities.

Gram-positive bacteria

• Thick, peptidoglycan cell wall is the outermost later

• Teichoic acid

Gram-negative bacteria

• Cella walls are thinner and more complex (overall)

  • Between the plasma membrane and outer membrane

  • Outer membrane has LPS

Yeast

• 3-4 micrometers, up to 20.

• Budding, some spore-formers.

• Responsible for food fermentation and spoilage

  • Saccharomyces cerevisiae (bread)

Mold

• Hyphae (10-100 micrometers)

• Spore formers

• Possible toxin production

• Tolerant of low pH

• Can be psychrophilic

• Responsible for food flavors and spoilage

  • Penicillium → Blue cheese

Viruses

• Attaches to a host cell to inject nucleic acid

  • Reassembles within cell and releases

• Hep A - Fecal-oral

• Human norovirus - Viral gastroenteritis

Parasites

• Obtain food and energy from other living entities

• Protozoa (unicellular eukaryotes): Cryptosporidium, Giardia, Cyclospora.

• Associated with raw, contaminated, or undercooked foods.

Prions

• Proteinaceous infectious particles

• Self-replicating

• Long incubation time with neural symptoms

• Bovine Spongiform Encephalopathy (BSE)

• Creutzfeldt-Jakob Disease

• Poorly understood

Colonization of cells causes symptoms, can be invasive or non-invasive

Infection

Combines infection and intoxication diseases

Toxicoinfection

True food poisoning, toxin responsible for disease/illness symptoms.

Intoxication

Examples of infections

• Pathogenic E Coli

• Salmonella

• Listeria

Virulence factors to help attach, disrupt cell lining, movement between cells.

Invasive

Virulence factors limited to attachment (adhesions and other effector proteins)

Noninvasive

Invasive/Non-invasive application

• It might not matter how much contamination is present at the food upon consumption, since the pathogen can grow in the gut and cause illness.

Intoxication examples

• Staph aureus

• Bacillus cereus

• Clostridium perfringens

• Clostridium botulinum

• Mycotoxin diseases

Intoxication application

We must concern ourselves with how much the microorganism grows in the food, since the dose (toxin) is the poison.

Toxicoinfection examples

• Infant botulism

• Colonizes the gut and produces a toxin that leads to symptoms (floppy baby syndrome)

  • Types of E Coli

  • Vibrio cholerae

  • Perfringens

Toxicoinfection application

• Some microorganisms will have the ability to cause a multitude of symptoms through both infection and intoxication, which is sometimes determined by immune status.

The largest global number of deaths are due to what microorganisms

• Salmonella Typhi, Taenia solium, Hep A, aflatoxin

The largest global number of illnesses are due to what microorganisms

• Campylobacter jejuni, non-typhoidal Salmonella, Norovirus

Global foodborne illness death/contraction data

• 600 million individuals contract foodborne illness

  • Children make up 40%

• 420,000 individuals die of foodborne illness

  • 125,000 child deaths

• Loss of 33 million healthy life years

Global monetary statistics of foodborne illness

• Global loss of $110 billion USD

  • Productivity and medical expenses

• 15 billion USD to treat foodborne illnesses

How many foodborne pathogens cause the most death, illness, and money loss.

• 31 foodborne pathogens

United States foodborne illness statistics

• 48 million people sick each year

  • 128,000 hospitalizations

  • 3,000 deaths

• Est $50-80 billion USD lost per year

Cost of foodborne illnesses is calculated by what?

• Monetized costs - medical, productivity, travel, childcare, rehab, recalls, public education, etc.

• Non-monetized costs - pain and suffering, risk aversion, lost leisure, etc.

Complication of foodborne illness estimates

• Some diseases caused by multiple agents

• Transmission through non-food fomites

• Food transmission and infectious doses differ between pathogens and host factors

• Laboratory testing and confirmation is extremely difficult, many go unconfirmed or unreported to public health authorities

• For every 1 reported cause, 20-38 go unreported

Consequences of foodborne illnesses - Reactive regulations

• Zero tolerance - Listeria monocytogenes in RTE

• Big 7 STEC adulteration in non-intact beed

• Labeling regulation

  • Allergens, other ingredients

• Trade regulations

Why do we need to know contamination sources?

• Outbreaks and traceback

  • Recalls

• Prevention

  • Corrective actions - within the process, recalls

  • New regulations - canning and pasteurization laws

  • GAPs and GMPs - guidelines and best practices

• Prosecution

  • Bluebell ice cream, Peanut Corp of America

Sources of contamination

Humans, waste, and environment.

Soil contamination

• Dirt is made up of dust, decomposing material, feces, etc.

• 1g = 108 microorganisms

• Frequent contaminant of produce

  • Bacillus, Pseudomonas, Clostridium spp.

  • Raw can be risky

Sewage and manure contamination

• Compost - should be treated before use (120 days)

• From gastrointestinal tract of human and animals

• Listeria, Enterobacteriaceae (Salmonells, E. Coli)

Air/wind contamination

• Carries dirt, dust, debris, moisture droplets

• Spreads bacterial and fungi spores

  • Ex: Clostridium

• Complication due to natural weather patterns, weather events, GAPs

Water contamination

• Source of many widespread outbreaks

• Runoff from fields can carry pathogens

• Routine checks for coliforms and E Coli

• Variety of standards depending on use

• Irrigation, washing, food processing

Food handling contamination

• Cross-contamination

• Emetic spread

• Fecal-oral route

• Toxin producers on skin

  • Staph aureus

• Gloves or no gloves?

Food processing environment contamination

• Biofilms

• Workers

• Animals (hair, hide, head)

• Meats

  • Muscle tissue is sterile before fabrication

  • Processing, fabrication, and evisceration of meat can transfer pathogens

    • Red meat - Staphy, Micrococcus, Pseudomonas, Salmonella, E Coli

    • Poultry - Campylobacter, Salmonella, E Coli, Clostridium

  • Whole cuts or subprimals vs communuted/ground

  • Packaging as a control (aerobic, anaerobic, modified atmosphere)

Natural vs Adulteration

• Raw produce

• Raw meats

  • Shiga-toxin producing E Coli (STEC)

• Milk - raw vs pasteurized

  • Prepared or ready to eat foods