Microbiology Chapter 32: waterborne and foodborne bacterial and viral diseases

Salmonellosis

MOST COMMON bacterial food infection in the US and second only to norovirus in total number of cases

Norovirus is

MOST common viral cause of food-borne illness in the United States

E-coli frequently contaminates

Meat -b/c it is found in animal's digestive tract

Food poisoning (food intoxication)

-A disease caused by the ingestion of food that contains preformed microbial toxins; ingestion and activity of the toxin is what causes the illness -The microorganism that produced the toxin does not have to grow in the host and may not even be alive at the time the contaminated food is consumed Example: exotoxin of Clostridium botulinum and superantigen toxins of Staphylococcus and Streptococcus -MORE ACUTE THAN FOOD INFECTION

Botulism

-A severe and often fatal food poisoning -Caused by an exotoxin produced by Clostridium botulinum (hypotonia, decreased muscle tone, Flaccid paralysis, botox-prevent you from being able to contract muscles) -Botulinum is a neurotoxin but is destroyed by heat -Average of 110 cases annually 45% infants cases 30% wound cases 25% foodborne cases -Home-prepared foods are a common source of illness *HONEY = can cause botulism

Yersinia enterocoliticia

-An enteric bacterium commonly found in the intestine of domestic animals and causes foodborne infections from contamination of meats and dairy products -Most serious consequences enteric fever, a severe, life-treatening infection

Staphylococcal Enterotoxins

-Are heat stable and are stable to stomach acid -Most strains of S. aureus produce only one or two of these toxins, and some strains are nonproducers -Any of the staph enterotoxins can cause food poisoning -Staph enterotoxins are also superantigens and can lead to potent lethal toxic shock (produce large T cell response and inflammatory response)

Antimicrobial chemicals added to foods to help preserve them

Nitrites, sulfites, propionate, and benzoate along with others, find worldwide application in the food industry for enhancing or preserving food texture, color, freshness, or flavor

Prions

-Are proteins that adopt novel conformations, inhibiting normal protein function and causing degeneration of host neural tissues -Human prion diseases are characterized by neurological symptoms including depression, loss of motor coordination, and eventual dementia. -A foodborne human disease called varient Creutzfeldt-Jakob disease (vCJD) has been linked to consumption of meat products from cattle suffering from bovine spongiform encephalopathy (BSE), a disease caused by a prion.

Cholera is

The most widespread and potentially dangerous waterborne disease

indicator organisms

-presence of indicator organism signals potential for waterborne disease; potable and recreational waters are routinely tested for theses Example: Coliform bacteria, E-coli

Coliform

-widely used indicator for microbial water contamination -gram-negative, nonsporulating, facultatively aerobic rods that ferment lactose with gas formation within 48 hours at 35C -Useful because many of them inhabit the intestinal tract of humans and animals -presence of Coliform in water indicates likely fecal contamination

Two types of foodborne diseases

1) Food Infection 2) Food Poisoning -Some fall into both categories

Foodborne disease epidemiology

1) One standard method is isolation of pathogen 2) Isolation from food -requires treatment of food to suspend microorganism in a homogenous solution (stomacher) 3) Isolation from diseased patient

With respect to spoilage, a food or food product fall into one of three categories

1) Perishable Foods -Must be stored under conditions that inhibit microbe growth 2) Semiperishable Foods -Must be stored under conditions that inhibit microbe growth 3) Nonperishable Foods -Categories differ primarily in regard to their moisture content, as measured by the water activity

Eight microorganisms that account for the great majority of foodborne illness, hospitalizations, and deaths in the United States

1) Salmonella species 2) Clostridium perfringens 3) Campylobacter jejuni 4) Staphylococcus aureus 5) Listeria monocytogenes 6) Escherichia coli 7) Toxoplasma (a protist( 8) Norovirus

Common sources of waterborne disease transmission

1) potable water used for drinking and cooking -untreated or improperly treated water used for drinking or food preparation 2) recreational water from public ponds, lakes, swimming pools, etc

Food Spoilage

A change in the appearance, smell, or taste of a food that makes it unacceptable to the consumer, whether or not the change is due to microbial growth -Foods are rich in organic matter, and the physical and chemical characteristics of a food determine its susceptibility to microbial activity -Many foods provide an excellent medium for the growth of bacteria and fungi. Properly stored food can still undergo food spoilage but is usually not a vehicle for disease assuming that it was free of pathogens to begin with. -Fresh foods are typically spoiled by a wide variety of bacteria and fungi

Listeriosis

A gastrointestinal food infection caused by Listeria monocytogenes that may lead to bacteremia and meningitis -Listeria monocytogenes is a gram-positive, nonsporulating coccobacillus that is acid, salt, and cold tolerant (psychrotolerant) and facultatively aerobic -Minor foodborne pathogen in terms of number of cases observed per year, infections can be very severe and cause 20% of all deaths from foodborne illnesses in the US -Primarily seen in the elderly, pregnant women, newborns, and adults with weakened immune systems, transplant patients (immunocompromised) -Mortality rate of listeriosis is 16%, particularly in pregnant women and fetuses -Intracellular pathogens (taken up in phagosomes of phagocytic cells -No food product is safe from contamination -Uptake of the pathogen by phagocytes results in the proliferation of the bacterium

Food Infection

A microbial infection resulting from the ingestion of pathogen-contaminated food followed by growth of the pathogen in the host -Occurs from the ingestion of food containing sufficient numbers of viable pathogens to cause colonization and growth of the pathogen in the host, resulting in disease.

Viruses

About 70% of annual foodborne infections in the US are caused by norovirus

Most common cause of bacterial food poisoning

Staphylococcus aureus Clostridium botulinum Clostridium perfringens

water quality

The single MOST important factor for ensuring public health -water intended for human use becomes a vehicle for disease

Goal of food storage and preservation methods

To slow or stop the growth of microorganisms that spoil food or that can cause foodborne disease. -Goal of food preservation is to slow the growth of spoilage microbes

Major waterborne pathogens (Bacteria)

Vibrio cholerae (Cholera) Legionella pneumophila (Legionellosis) Salmonella enterica (typhi) (typhoid fever) Escherichia coli (GI illness) Pseudomonas aeruginosa (Nosocomial pneumonia, septicemia, and skin infections) Campylobacter jejuni (GI illness)

Most important pathogenic bacteria transmitted by water

Vibrio cholerae and Salmonella enterica (typhi)

Enteroinvasive E. coli (EIEC)

bacillary dysentery, blood and mucus in the stool, more common in developing countries -Invasion of intestine, causes bleeding

Enteroaggregative E. coli (EAEC)

causes diarrhea in young patients and AIDS patients

Desiccation

dehydration; the process of being rendered free from moisture -Removes moisture needed by microbes for growth -Solar drying and commercial drying -NOT RELIABLE, many microbes withstand desiccation -Bacteriophage: kill specific bacteria such as Listeria and Salmonella. -Does NOT make food completely sterile, but does remove the majority of pathogens that can grow. Example: MREs (military, camping)

Most strains of Escherichia coli can be presumptively identified based on which characteristic?

indole positive

Dysentery

infection of the intestines resulting in severe diarrhea with the presence of blood and mucus in the feces.

Fermentation

is the anaerobic (anaerobic respiration) of organic compounds (generally carbohydrates) Glucose --> ethanol + CO2

Pasteurization (high-sensitive liquids)

limited heat treatment, the use of controlled heat to reduce the microbial load, including both pathogens and spoilage organisms, in heat-sensitive liquids. -Does NOT sterilize liquids but reduces microbial numbers and eliminates pathogens -used to reduce the bacterial load -Extremely high temperature for extremely short period of time because we are not trying to kill all the bacteria

Norovirus

most common viral cause of foodborne disease in US -Single-stranded plus-sense RNA virus related to poliovirus -Characterized by diarrhea, often accompanied by nausea and vomiting -Recovery is typically spontaneous and rapid, usually within 24-48 hours (24-hour bug)

Enteropathogenic E. coli

profuse, water diarrhea, with fever vomiting, produce effacement (thinning) of gut surfaces

Food spoilage microbes are often:

psychotolerant, meaning that although they grow best at temperatures above 20C, they can also grow at refrigeration temperature (3-5C)

Freezers

reduces growth considerably, but slow growth still occurs in pockets of liquid trapped within frozen food; in general, a lower storage temperature results in less microbial growth and slower spoilage, but storage temperatures below -20C is too expensive for routine use and also can negatively affect food appearance, consistency, and taste -Allows for longer storage but is NOT suitable for all foods

Heating:

reduces the bacterial load and can even sterilize a food product and is especially useful for the preservation of liquids or high-moisture foods. -Used to reduce the bacterial load (pasteurization) of a product or to sterilize it (canning)

potable water

safe for human consumption -Nearly 80% of drinking water disease outbreaks are due to bacterial pathogens- Legionella (causes legionellosis)

Refrigeration:

slows microbial growth, but a remarkable number of microorganisms, particularly bacteria, can grow at refrigerator temperatures -slows microbial growth rate and delays spoilage

Food infections are

the MOST COMMON foodborne illness in the US and account for the top five leading foodborne illnesses.

Enterotoxigenic E. coli (ETEC)

traveler's diarrhea, watery diarrhea, low-grade fever, nausea and vomiting -Toxin

Diffusely adherent E. coli (DAEC)

typically associated with the development of urinary tract infections; may play a role in inflammatory bowel disease

Public health and water quality

*water that looks transparent may still be contaminated with high numbers of microorganisms and thus pose a risk of disease. -It is impractical to screen water for every pathogenic organism present and so potable and recreational waters are routinely tested for specific indicator organisms, the presence of which signals the potential for waterborne disease

Signs and Symptoms of Salmonellosis

-Begin after pathogen (salmonella), a gram-negative facultatively aerobic rod related to E-coli colonizes the intestinal epithelium -Salmonella species normally inhabit the intestine of warm-blooded and many cold-blooded animals and are common in sewage -Accepted species for pathogenic Salmonella is enteria -MOST common form of salmonellosis is enterocolitis -Ingestion of food containing viable cells of salmonella results in colonization of both the small and large intestines. -Cells of Salmonella invade phagocytic cells and grow intracellularly, spreading to adjacent cells as host cells die. -After invasion, Salmonella deploy several virulence factors including endotoxins, enterotoxins, and cytotoxins that damage and kill host cells -Symptoms of entercolitis typically appear 8-48 hours after ingestion and include headache, chills, vomiting, and diarrhea followed by a fever that can last for several day. -Disease normally resolves without intervention in 2-5 days -Patients may she Salmonella in their feces for several weeks and some becomes healthy carriers -May reach food through fecal contamination from food handlers, food production animals such as chicken, pig, and cattle harbor Salmonella that are pathogenic, and these may be carried through to fresh foods such as eggs, meat, and dairy products. -Can be traced to products such as custards, cream cakes, meringues, pies, eggnogs made with uncooked eggs -Ability to cause disease is dependent on its ability to adhere to gut mucosa; has a high ID50 (infectious dose needed to kill 50% of test group)

Examples of fermented foods

-Bread -sausage -meats -cheese, buttermilk, yogurt -fermented and pickled vegetables -Soy sauce *Are food products that are produced or enhanced by fermentation reactions catalyzed by microorganisms

Clostridium perfringens and Clostridium botulinum

-Cause serious food poisoning -Perfringens = gas grene -Produce endospores that may not be killed during cooking/canning process

Typhoid fever

-Caused by Salmonella enterica (typhi), which is a gram-negative, peritrichously flagellated bacterium related to E-coli and other enteric bacteria -Transmitted in feces-contaminated water and is primarily restricted to areas where sewage treatment and general sanitation are absent or poorly maintained -Well-entrenched endemic disease in Africa, India, and Indonesia -HAS BEEN VIRTUALLY ELIMINATED IN DEVELOPED COUNTRIES AS A RESULT OF WATER TREATMENT -Symptoms progress in stages: 1) ingested contaminated water reaches the intestine where they grow and enter the lymphatic system and the bloodstream; the first symptoms appear and include a mild fever, headache, and general malaise. 2) Liver and spleen become heavily infected and fever becomes more intense, pt becomes delirious, serious diarrhea and severe abdominal pain followed by intestinal bleeding and small intestine perforation leading to sepsis (systemic infection and inflammation) Treatment: Antibiotic therapy and fluid replacement for dehydration -Gallstones can become infected and serve as a long-term reservoir for the pathogen (Example: Typhoid Mary)

Cholera

-Caused by Vibrio Cholera -virulence did to enterotoxin -contaminated water /improperly cooked food (shellfish) -Rice water stool -55-70% mortality -oral rehydration therapy -can be controlled by application of water treatment -Largely restricted for developing countries (Africa, Southeast Asia, Indian continent, Central South America) -

Salmonellosis

-Food infection enterocolitis or other gastrointestinal disease caused by any of several subspecies of the bacterium Salmonella -A gastrointestinal disease typically caused by ingesting food contaminated with Salmonella or by handling Salmonella-contaminated animals or animal products

Most common form of food poisoning

Clostridium perfringens -Responsible for 248,000 annual cases -large number of cells (>10 ^8) must be ingested (HIGH INFECTIOUS DOSE; OPPOSITE OF NOROVIRUS) -Enterotoxin is produced in the intestinal tract six to 15 hours after consumption

Pathogenesis, Diagnosis, and Treatment of Legionella pneumophila (Legionellosis)

-L. pneumophila invade the lungs and grow within macrophages and monocytes -Infections are often asymptomatic or produce only a mild cough, sore throat, mild headache, and fever; self-limiting cases that resolve in 2-5 days -Detection is usually done by culture of the organism from bronchial washings, pleural fluid, or other bodily fluids or tissues; serological tests can detect anti-Legionella antibodies -Treatment: antibiotics rifampin and erythromycin

Pathogenic Escherichia coli

-Most strains of Escherichia coli (gram-negative, rod shaped) are common microbiota in the human colon and are not pathogenic -However, a few strains are potential foodborne (an occassionally waterborne pathogens) and produce potent enterotoxins -All are intestinal parasites -These pathogenic strains are grouped based on the type of toxin they produce and their specific disease syndromes -Example: Shiga toxin-producing E. coli

Sources of Salmonella

-Poultry intestines and droppings, transferred to humans from reptiles and amphibians, fresh chicken breasts and eggs

Food Infection

-Results from ingestion of food containing sufficient numbers of viable pathogens to allow growth of the pathogen and disease in the host.

Viruses

-The largest number of annual foodborne infections are thought to be caused by viruses -Example: enteroviruses such as poliovirus, norovirus, and hepatitis A are shed into water or food from feces -Norovirus" responsible for most infections -Rotavirus, hepatitis A, and astrovirus are responsible for the rest

drinking water

-Undergoes extensive treatment that includes both filtration and chlorination -Filtration: removes turbidity and many microorganisms -Chlorination: makes drinking water safe; chlorine gas is a strong oxidant and oxidizes both organic matter dissolved in water and microbial cells themselves -Drinking water chlorination facilities add sufficient chlorine to allow a residual level to remain in the water all the way to the consumer

Norovirus

-Virus transmitted in water and causes human disease -Common cause of gastrointestinal illness d/t contaminated water/food -Easily transmitted person to person or to food by the fecal-oral route (cruise ships, long-term care facilties) -MOST COMMON sources of waterborne norovirus are well water or recreational waters that have been contaminated with sewage. -A single-stranded plus-sense RNA virus and is the LEADING CAUSE OF GASTROINTESTINAL ILLNESSES Symptoms: vomiting, diarrhea, and malaise of relatively short duration Diagnosis: combination of observing symptoms and direct detection of either viral RNA by RT-PCR or viral antigens by enzyme immunoassay in samples of feces or vomit

Cholera

-a severe gastrointestinal diarrheal disease that is now largely restricted to countries in the developing world Cause: ingestion of contaminated water containing cells of VIBRIO CHOLERAE; a gram-negative and motile curved species of Proteobacteria. -contracted from contaminated food, especially improperly cooked shellfish -Attach to epithelial cells in the small intestine where they grow and release CHOLERA TOXIN, a potent ENTEROTOXIN -toxin causes severe diarrhea and can result in dehydration and death Treatment: oral liquid and electrolyte replacement therapy is most effective Morality: 55-77% Diagnosis: feces, more liquid than solid; easily cultured on selective agar medium Prevention: adequate sewage treatment and a reliable source of drinking water -eliminated from water waste during proper sewage treatment and drinking water purification procedures -controlled by application of water treatment

fecal coliform bacteria

-important for water safety assessment -Ecoli = key Coliform ; presence of E. coli in a water sample is taken as evidence of fecal contamination and means that the water is unsafe for human consumption

recreational water

-include freshwater aquatic systems such as ponds, streams, and lakes, as well as public swimming pools and wading pools. -Can be sources of waterborne disease and cause more disease outbreaks than due to drinking water -frequently linked to parasitic pathogens

Fresh foods are spoil by both

Bacteria and fungi -Spoilage organisms are those that can gain access to the food and use the available nutrients Example: E-coli frequently contaminates meat products because it is found in animal's digestive tracts

Clostridal Food Poisoning

Clostridium perfringens and Clostridium botulinum -endospore-forming anaerobic bacteria that cause serious food poisoning -Canning and cooking procedures kill vegetative cells of these species but many may not kill endospores

Legionellosis

Causative agent: Legionella pneumophila bacteria -Waterborne pathogen whose transmission was originally linked to evaporating cooling devices -Major pathogen in residential water systems where it persists in biofilms that form on interior surfaces of water pipes and also within the cells of certain microbial parasites -Biofilms protect it from chlorine present in potable water

Legionellosis

Causes by legionella pneumophila, gram-negative bacteria -common in cooling towers and evaporative condensers of large air conditioning systems -Pathogen grows in the water and is disseminated (spread) in humidified aerosols -Normally transmitted in aerosols -identification by fluorescence microscopy -Relatively resistant to heating and chlorination -Infection is NOT spread from person to person -Treatment: antibiotics is effective -Prevention: improving maintenance and design of water-dependent cooling and heating systems and water delivery systems

Foodborne Diseases outbreak

Cluster of cases caused by microorganisms in a single source of food -Widespread, multiple disease outbreaks caused by processing plant or food distribution center -Spinach and Escherichia coli (O157:H7) -E. Coli (O157:H7) well studied and quickly traced

indicator organisms

Coliform bacteria, E-coli (key); indicates fecal contamination

Major Waterborne Pathogens (Parasites)

Cryptosporidium parvum (Cryptosporidiosis) Giardia intestinalis (Giardiasis) Schistosoma (Schistosomiasis)

waterborne diseases

Diseases caused by microorganisms that are transmitted in contaminated water. Infection commonly results during bathing, washing, drinking, in the preparation of food, or the consumption of infected food. eg cholera, typhoid, botulism. -begin as infectious (or occasionally as toxemias) and contaminated water may cause an infection even if only small numbers of pathogens are present -Whether or not exposure causes disease is a function of the virulence of the pathogen and the ability of the host to resist infection

Indicator organisms are A. Coliforms B. Enterococci C. Suggestive of fecal contamination D. Used in water quality tests E. All of the choices are correct

E)

Shigella

Enteric bacterium causes the food infection shigellosis -Shigella infections are the result of fecal to oral contamination, but food and water are occasional vehicles -cause nearly 100,000 causes of severe foodborne invasive gastroenteritis each year

Norovirus

Fecal-oral transmission or via contamination of food and water -Profuse, watery diarrhea for 3-5 days, vomiting in early stages -LOW INFECTIOUS DOSE; 1-20 viruses

Fermented foods

Food and beverages that have been preserved through the metabolic activities of microorganisms -The fermentation process yields large amounts of preservative chemicals -The major bacteria important in the fermented foods industry are organic acid-producing bacteria such as lactic acid bacteria (fermented milks), the acetic acid bacteria (pickling), and the propionic acid bacteria (certain cheeses) -Saccharomyces cerevisiae (yeast) produces alcohol as the preservative in the production of alcoholic beverages. -High levels of organic acids or alcohol generated from these fermentation prevents the growth of both spoilage organisms and pathogens in the fermented product.

Staphylococcal Food Poisoning

Food poisoning is often caused by toxins produced by Staphylococcus aureus -A powerful form of food poisoning caused by enterotoxins produced by gram-positive bacteria -Commonly associated with the skin and upper respiratory tract and is a frequent cause of pus-forming wounds. -S. aureus can grow aerobically or anaerobically in many common foods and produce a suite of enterotoxins -When consumed, the toxins cause gastrointestinal symptoms characterized by one or more of nausea, vomiting, diarrhea, and dehydration. -Rapid onset of symptoms (gastritis) within 6 hours of ingestion, depending on the amount of enterotoxin produced.

Foodborne Disease

Foodborne illnesses resemble waterborne illnesses in being common-source diseases. -Most foodborne disease outbreaks are due to improper food handling and preparation by domestic consumers; these typically affect only a few people and are rarely reported. -However, occasional disease outbreaks due to breakdowns in safe food handling and preparation at restaurants or food-processing and distribution plants can affect large numbers of people in geographically widespread regions.

Semiperishable Foods

Foods of intermediate water activity that have a limited shelf life because of their potential for spoilage by growth of microorganisms -Includes: potatoes, apples, nuts -Must be stored with care to limit microbial growth

Nonperishable foods

Foods of low water activity that have an extended shelf life and are resistant to spoilage by microorganims -Include sugar and flour -Have low moisture content and have much longer shelf life than either perishable or semi-perishable foods

Perishable foods

Fresh foods generally of high water activity that have a very short shelf life because of spoilage by microbial growth -includes meats, fruits, vegetables -typically have higher moisture content and must be stored in conditions to limit microbial growth

Major protist pathogens

Giardia intestinalis, Cryptospordium parvum, Cyclospora cayetanessis, and Toxoplasma gondii. - G. intestinalis and C. parvum are spread in foods when contaminated water is used to wash, irrigate, or spray crops -Fresh fruits are often implicated as vehicles for protists -Toxoplasma gondii is a protist spread primarily through cat feces, but it can also be found in raw or undercooked meat, especially pork.

Bacillus cereus

Grows in food that is cooked and left to cool slowly; grows in foods such as rice, pasta, meats, or sauces that are cooked and left at room temperature to cool slowly. -When endospores germinate, toxin is produced; reheating may kill B. cereus cells, but the toxin is heat-stable and may remain active -Endospore producing bacterium and produces two enterotoxins that cause different symptoms -Emetic form: symptoms primarily nausea and vomiting -Diarrheal form: diarrhea and gastrointestinal pain -causes diarrhea and vomiting

Prions

Normal protein in the brain (PRP C) is transformed into a prion protein (PRPsc) -Altered protein spontaneously convert PRP C into PRPsc proteins -Accumulation of PRPsc causes plaques and spongiform damage in the brain -Can cause disease when transferred to a new host (contaminated instruments, infected meat) -Proteinaceous infectious particles; contain NO genetic material -Cause transmissible spongiform encephalopathies 1) Creutzfeldt-Jacob Disease (CJD) 2) Gerztmann-Strussler-Scheinker Disease 3) Kuru 4) Fatal familial insomnia 5) Scrapies in sheep and goats 6) Bovine spongiform encephalopathy (BSE)

Major Waterborne Pathogens (Viruses)

Norovirus (GI illness) Hepatitis A (Viral Hepatitis)

Four microbes that account for nearly 90% of all foodborne illnesses

Norovirus, Salmonella, Clostridium perfringes, and Campylobacter -Norovirus is the most common culprit (60%)

Shiga Toxin-Producing Escherichia coli (STEC) / Enterohemorrhagic Eschericia coli (EHEC)

STEC) strains produce verotoxin, an enterotoxin similar to the Shiga toxin produced by Shigella dysenteriae -This toxin inhibits protein synthesis and induces bloody diarrhea and kidney failure -STEC strains are also called enterohemorrhagic (EHEC). -THe most widely distributed STEC is E. coli O157:H7 -Following ingestion of food or water containing STEC, the bacteria infect the small intestine where they grow and produce verotoxin, which causes a blood diarrhea and initiates signs of kidney failure -50% of STEC infections are caused by the consumption of contaminated uncooked or undercooked meat, particularly ground beed

Cholera signs and symptoms

Severe watery feces or "rice water stool" vomiting muscle cramps Fluid losses (1 liter per hour) Loss of volume, acidosis, potassium depletion, Severe thirst, flaccid skin, sunken eyes, leading to convulsions and coma -Hypotension, tachycardia, cyanosis, shock

Canning

Sterilizes the food but requires careful processing in a container at the correct temperature for the correct length of time. -If viable microorganisms remain in a can or glass jar, their growth can produce gas, resulting in bulges or even explosions. -The environment inside a can or sealed jar is anoxic, and an important genus of anaerobic bacteria that can grow in canned foods is the endospore-forming Clostridium, one species of which causes Botulism. -Not always 100% effective; failure results in swollen cans (DO NOT EAT)

Legionella pneumophila

a gram-negative, obligately aerobic rod-shape species of Gammaproteobacteria and show complex nutritional requirements including an unusually high requirement for iron. -Isolated from terrestrial and aquatic habitats -Relatively resistant to heating and chlorination, so it can spread through drinking water distribution systems -Found in large numbers in improperly sanitized cooling towers and evaporative condensers of large air conditioning systems; showerheads. -Pathogen grows in water and is disseminated in humidified aerosols. -Elimination: hyperchlorination or by heating water to greater than 63C

Campylobacter

along with salmonellosis and perfringens food poisoning, Campylobacter infections are in the top three most common bacterial foodborne diseases in the United States -Gram-negative and motile spiral-shaped Epsilonproteobacteria that grow best at reduced oxygen tension (microaerophillic) -C. jejuni and C. fetus are MOST commonly linked to human foodborne illness. -Most common cause of bacterial diarrhea in the United States (more than 2 million cases of bacterial diarrhea per year) -Transmitted to humans via contaminated food, most commonly undercooked pork, poultry, raw shellfish -Organism multiplies in the small intestine, invades the epithelium, and causes inflammation. -C. jejuni is sensitive to gastric acid, cell numbers as high as 10 ^4 may be required for infection; may be lowered if person is taking a medication that suppresses gastric acid or if pathogen is ingested in food -Infection causes a high fever, headache, malaise, nausea, abdominal cramps, and diarrhea with water, frequently blood emission -Symptoms subside within a week.

Major methods of food preparation:

altering the temperature, acidity, moisture level of the food, or treating it with radiation or chemicals that prevent microbial growth