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"Microorganisms of Concern" Microorganisms of Concern in Production Agriculture

What you will learn Some practical food microbiology Kinds of microorganisms Relative size of microorganisms Molds Bacteria Viruses Parasites

Practical  Food Microbiology Microorganisms are small, living unicellular or multicellular. They include bacteria, viruses, yeasts, molds, and parasites.

They can be…. The good The bad, and The ugly!

Kinds of Microorganisms The Good (or helpful): Add them to foods or they                   are there naturally. They ferment foods to    preserve them and/or                       create unique flavors                and textures. Examples:  cheese, yogurt,                 sour cream, bread, sauerkraut             and pickles.

Kinds of Microorganisms The Bad (or spoilage) Change foods and cause them to “go bad” or spoil. Examples:  Discolored, mushy, or fuzzy vegetables; sour milk; and slimy, putrid meat.

Kinds of Microorganisms The Ugly (disease-causing, pathogenic): Illness can range from mild to life-threatening. Examples include foods      contaminated with Salmonella      or E. coli O157:H7.  Common signs and symptoms  include nausea, vomiting, and diarrhea.

Microorganisms that cause...

Relative size of microorganisms Apple    0.10 m 1 X Mold spore    0.00001 m 1/10,000 Bacterial cell    0.000001 m 1/100,000 Virus    0.000000001 m 1/1,000,000

Relative size of microorganisms

Relative size of microorganisms

Comparison of size of bacterial cell and apple

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Current Problems With Harmful Microorganisms Some people are more vulnerable to foodborne illness: Young children, elderly people, pregnant women. Immuno-compromised individuals. New ways of transmitting organisms: Widespread food distribution system. New food formulations and handling practices. Changes in food choices. New or evolving pathogens: Example -  E. coli 0157:H7

Microorganism That Cause Foodborne Illness Molds – Multi-cellular organisms often producing mycotoxins Bacteria – Single-celled organisms that live independently. Parasites – Intestinal worms or microscopic protozoa that live in a host animal or human. Viruses – Small particles that live and can only replicate in a host.

Examples of Harmful Microorganisms of Concern in Fresh Produce Salmonella species E. coli O157:H7 Shigella species Bacillus cereus Listeria monocytogenes Hepatitis A virus Norwalk-like virus

Harmful Microorganisms & Outbreaks Associated with Produce

Where Microbial Pathogens Live Common in soils… Listeria monocytogenes Bacillus cereus Clostridium botulinum Clostridium perfringens Residents of human and animal intestinal tracts… Salmonella species E. coli O157:H7 Shigella species Campylobacter jejuni Viruses and parasites

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Molds

Molds… Multicellular, visible mycelium and pigmented fruiting structures Growth not as dependent on    temperature as bacteria Exist in dormant state as spores which are resistant to low moisture, high heat, high acidity, or freezing Both spoilage and food safety concern Many molds produce mycotoxins Long-term toxicity Some are carcinogenic

Patulin

Patulin FDA - Patulin is a “significant chemical hazard” Must be addressed and control measures established in juice HACCP plans Post-harvest storage and handling culling scrubbing 25 ppb limit on patulin in juice products

Bacteria

Bacteria... Cause the greatest number of foodborne illnesses. Single-celled organisms that live independently. Invisible to the naked eye: Must be magnified 1,000 times to be seen. 400 million bacteria are equal to a grain of sugar in size.

Bacteria Are Found Everywhere In air, soil, and water In intestines of animals & humans On skins of fruits & vegetables On raw meat, poultry, & seafood On insects & rodents On hand, skin, hair, & clothing of people

The Bacterial Growth Cycle has Four Phases I) lag, II) log, III) stationary, IV) death

Bacteria Increase in Number      by Doubling With ideal conditions, they double every half hour. 1 becomes 2, 2 become 4, 4 become 8, and so on... In 12 hours, 1 cell could multiply into 33 million cells! Usually you start with many bacterial cells, not just one.

Factors Influencing Growth of Bacteria - FATTOM Food Acidity Time Temperature Oxygen Moisture

Factors - FATTOM Food Nutrients, provided by most foods. Acidity Most bacteria grow best at near neutral conditions (pH 6.5 – 7.5) Temperature Temperature danger zone is 40 – 140oF)  Growth increases with temperature Time Growth to dangerous levels can occur after 2 hours Oxygen Some require oxygen to grow, some require little or no oxygen.  Most grow with or without oxygen. Moisture Water requirements vary.  Bacteria need the most.  Yeasts and molds require less

Bacteria tend to form biofilms Adsorption (sec) Attachment (sec–min) Growth and division (hr-day) Slime formation (exopolymers) (hr-day) Attachment of other microorganisms (day-mo)

Biofilms Of concern to the food industry because they prevent sanitizers from reaching surface bacteria

Examples of Biofilms Teeth (dental plaque) Surfaces that are    continuously wet    (drains, floors, food     processing equipment)

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Close-up of a biofilm with formation of polysaccharide matrix

Bacterial death is described by “log reductions”

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The good news about fruit Contamination is the exception rather than the rule Growth on washed whole fruit that is kept refrigerated is likely to be slow Consumers usually discard spoiled fruit pH of most fruits is low

3 Harmful Foodborne Bacteria

E. coli / E. coli O157:H7 E. coli : common microbe in animal and human intestinal tracts. Most strains of E.coli are not harmful. But harmful strains, such as E. coli 0157:H7, cause severe illness.

E. coli O157:H7 First recognized as human pathogen in 1982. Outbreaks often associated with undercooked ground beef. Produce associated outbreaks have involved lettuce, unpasteurized apple cider & juice, radish sprouts, and alfalfa sprouts.

E. coli O157:H7 Naturally exists in animals without symptoms cattle, sheep, deer, dogs, cats, other animals Can contaminate/grow on fresh produce: minimally processed cantaloupe watermelon cubes shredded lettuce sliced cucumbers mesclun lettuce

Foodborne Illness Caused by E. coli O157:H7 < 10 cells may cause illness Causes severe cramps, bloody diarrhea, vomiting, dehydration. Severe complications can include kidney failure, strokes, seizures, and sometimes painful death. Onset 3 - 9 days; lasts 2 - 9 days, unless there are complications.

Salmonella species More than 2300 types. About 200 types cause human illness. Comes from intestinal tracts of poultry, pigs, birds, and insects. Also can be carried by humans. Infective dose – a few cells to millions.

Salmonella species Isolated from many types of raw fruits and vegetables – not a frequent event. Outbreaks linked to: tomatoes bean sprouts melons unpasteurized orange juice and apple juice

Foodborne Illnesses Caused by Salmonella Illness causes nausea, vomiting, abdominal cramps, diarrhea, fever, and headache. Symptoms occur in 12 - 48 hours and last      2 - 6 days in otherwise healthy people. May last weeks in immuno-compromised people. Secondary problems such as reactive arthritis or pericarditis may result in some patients.

Contamination of Fruits and Vegetables by E. coli O157:H7 and Salmonella Wild or domestic animals. Improperly composted animal manure. Fruits and vegetables dropped on the ground have a higher chance of being contaminated by manure. Water may carry and spread organisms. Farm and packing house workers

Listeria monocytogenes Widely distributed in nature. In soil, sewage, fresh water sediments. In silage, decaying plant matter. In animal intestinal tracts. Animal carriers may not be sick. Found in raw foods. Meats, unpasteurized milk. Vegetables, cut fruits.

Why is Listeria of Particular Concern in Packinghouses? Grows in cool moist environments Probably can be found in most packinghouses Found in soil, decaying plant residue, equipment, bins, drains, coolers, animals, humans High Lethality US regulatory “Zero Tolerance” in Ready-To-Eat Foods Reference: “Guidelines for Controlling Listeria monocytogenes in Small- to Medium-Scale Packing and Fresh-Cut Operations”. Suslow and Harris.

Foodborne Illness Caused  by Listeria monocytogenes Causes flu-like symptoms in healthy people. May progress to meningitis, blood poisoning, abortion in pregnant women, or death. Symptoms appear within 1 day to 3 weeks. Duration depends on treatment. High fatality rate in immune-compromised individuals (20-30%).

Viruses

Viruses… Excreted in feces by infected individuals. Can be carried by raw produce, uncooked food. Persists for weeks or months       on crops or in soils. Examples Hepatitis A on lettuce,          raspberries, and strawberries.

Virus Transmission Viruses can be transmitted to plants and fresh fruits and vegetables by: People. Tractors, equipment, clippers. Insects. Viruses can also cause plant and animal diseases. By preventing virus transmission, plant diseases can be decreased and produce safety can be increased.

How Viruses Reproduce All viruses require a host cell to     multiply. The virus invades a cell, uses the    cell’s equipment to replicate its own    nucleic acid and protein coat, and    then releases the new viruses from the cell. In bacteria, this process can be achieved in 30-60 minutes and in animals, it usually requires 12-24 hours.

One Virus of Concern:  Hepatitis A An infected person can spread the disease to others well before symptoms are present.

Parasites

Parasites Single-celled microorganisms. Exist as cysts outside animals; require animal or human intestinal tract to multiply and spread. Spread by fecal contamination of water or fresh produce. Examples of outbreaks: Giardia: raw vegetables, fruits. Cryptosporidium: unpasteurized apple juice. Cyclospora: imported raspberries, basil, mesclun lettuce.

Parasites: Cryptosporidium Cysts in water or food infect intestinal cells. Infection causes illness and allows the parasite to reproduce. Causes watery diarrhea, stomach cramps, nausea, and fever. Symptoms 2 -10 days after          ingestion; can last 4 days to      4 weeks.

Parasites: Cyclospora Cyclospora parasites infect the small intestine. Causes watery diarrhea (sometimes explosive), loss of appetite, bloating, stomach  cramps, nausea,vomiting, muscle aches, low-grade fever, weight loss, and fatigue. Some cases are without symptoms. Symptoms 1 week after consuming contaminated food or water, can last more than a month and can return    later.

Parasites: Giardia Common parasite that infects animal and human intestines. Causes diarrhea, abdominal cramps, nausea, and vomiting. Symptoms 1-2 weeks after ingestion of cysts in contaminated food or water. Lasts 4-6 weeks in healthy people, but can last years in some cases.

Controlling the Spread of Hepatitis A and other Viruses on the Farm Proper sanitation on the farm including care of equipment and in-field sanitation.

Controlling the Spread of Viruses and Parasites Training farm and packinghouse workers and encouraging them to practice proper hygiene can greatly reduce the risk of contaminating fresh fruits and vegetables with Hepatitis A.

Handwashing Information Study of handwashing <2 times/day in restaurants, foodservice, healthcare settings 94 % say they wash their hands 68% of those observed actually washed their hands FDA estimates poor handwashing contributes to 80 million cases of illnesses in U.S

Proper handwashing and appropriate field sanitation facilities reduce risk.

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