Browse all questions

The Big 6 are highly infectious pathogens easily transmitted by food workers: Norovirus, Hepatitis A, Shigella, Shiga toxin-producing E. coli (such as O157:H7), Salmonella Typhi, and nontyphoidal Salmonella. A worker diagnosed with any of these must be excluded or restricted and reported to the health department. The other choices list toxins, parasites, and toxin-forming bacteria that are not the reportable Big 6.

TCS/PHF foods support rapid bacterial growth because they are moist, protein-rich, and low in acid; cooked rice is a classic example that can grow Bacillus cereus if left in the danger zone. Whole lemons, dry pasta, and sugar are not TCS because they lack available moisture or are too acidic. Supervisors must give TCS foods strict time and temperature control.

FAT-TOM stands for Food, Acidity, Time, Temperature, Oxygen, and Moisture — the six factors that let bacteria multiply. Controlling any one of them, usually time and temperature, slows or stops growth. The other options misname one or more factors.

Most disease-causing bacteria grow best in foods with a pH between 4.6 and 7.5. Lowering the pH below 4.6 with acid, like the vinegar or citrus in salsa, inhibits their growth, which is why acidified foods are safer. Very alkaline conditions are also unfavorable, but kitchens control risk mainly by acidifying and refrigerating.

While the danger zone spans 41°F to 140°F in NYC, bacteria reproduce most rapidly between about 70°F and 125°F, where a single cell can double roughly every 20 minutes. Below 41°F growth slows sharply, and at 140°F or above most bacteria stop growing or die. Keeping TCS food out of the 70°F to 125°F band during cooling and holding is critical.

Nontyphoidal Salmonella is commonly linked to poultry, eggs, and cross-contamination, with diarrhea, fever, and cramps appearing about 6 to 72 hours after eating. Cooking eggs and poultry to required temperatures and preventing cross-contact controls it. Hepatitis A causes jaundice, botulism causes paralysis, and Listeria most affects pregnant and immunocompromised people.

Shiga toxin-producing E. coli (STEC), such as O157:H7, is associated with undercooked ground beef and can cause bloody diarrhea and hemolytic uremic syndrome, especially in children. NYC requires ground meat be cooked to 158°F to destroy it. Norovirus and Staph cause vomiting-type illness, and Vibrio is tied to raw shellfish.

Hepatitis A is a virus shed in feces and transmitted by infected workers who do not wash their hands properly; cooking is not a reliable control because the virus is fairly heat-tolerant and contamination often occurs after cooking. Rigorous handwashing, excluding diagnosed workers, and avoiding bare-hand contact with ready-to-eat food are the key defenses. A vaccine also exists for prevention.

Norovirus is the leading cause of foodborne illness outbreaks and spreads easily from an infected worker to ready-to-eat foods; it causes sudden vomiting and diarrhea 12 to 48 hours after exposure and is highly contagious. Workers with vomiting or diarrhea must be excluded. Perfringens is tied to time-abused stews, Trichinella to undercooked pork or game, and ciguatoxin to certain reef fish.

Shigella spreads by the fecal-oral route: infected workers who fail to wash their hands, and flies that move between feces and food. Good hand hygiene, worker exclusion, and pest control are the main defenses. It is not airborne, and properly canned or pasteurized foods are not typical sources.

Listeria monocytogenes is unusual because it grows even at refrigeration temperatures below 41°F and is especially dangerous to pregnant women, newborns, and the elderly, causing miscarriage and severe illness. Control includes discarding deli products by their use-by dates, keeping cold holding as cold as possible, and cleaning walk-ins. Most other pathogens stop growing near 41°F.

Anisakis is a roundworm found in marine fish that can cause abdominal illness when fish is eaten raw or undercooked. The control is freezing the fish to required parameters, for example -4°F for the specified time, before serving it raw, which kills the parasite. Neither acidifying sushi rice nor handwashing destroys parasites already in the fish flesh.

Scombroid (histamine) poisoning occurs when fish such as tuna, mahi-mahi, and mackerel are time-temperature abused, letting bacteria convert the fish's natural histidine into histamine, a toxin that cooking cannot destroy. Symptoms appear within minutes: flushing, rash, headache, and a peppery taste. Prevention is strict cold-chain control from receiving onward, because once the toxin forms it cannot be removed.

Ciguatoxin accumulates in large reef predators through the food chain and is heat-stable, odorless, and tasteless, so cooking and normal inspection cannot make the fish safe. The main defense is purchasing fish from approved, reputable suppliers who avoid implicated species and harvest areas. It is unrelated to storage temperature or farming.

Shellfish toxins originate from toxic algae that molluscan shellfish filter and concentrate; these biotoxins are not destroyed by cooking or freezing. The control is purchasing shellfish only from approved, certified sources and keeping the shellstock identification tags for 90 days for traceback. Handwashing and cooking temperature do not address a toxin already present in the shellfish.

Highly susceptible populations — the very young, the elderly, pregnant women, and immunocompromised individuals — are more likely to become seriously ill or die from foodborne pathogens. Establishments serving these groups, such as hospitals and nursing homes, must take extra precautions, like not serving raw or undercooked animal foods. Healthy young adults generally have stronger defenses.

Staphylococcus aureus is often carried in the nose and on skin or infected wounds; when transferred to food that is then time-abused, it produces a heat-stable toxin causing rapid vomiting within 1 to 6 hours. Because reheating will not destroy the toxin, prevention relies on hand hygiene, covering wounds, no bare-hand contact with ready-to-eat food, and temperature control. Salmonella and Hepatitis A have much longer onset times.

Clostridium botulinum thrives in anaerobic, low-acid, moist conditions such as improperly home-canned goods, untreated garlic-in-oil mixtures, and temperature-abused reduced-oxygen-packaged foods. Its toxin attacks the nervous system and can be fatal. Oxygen exposure, high acidity below pH 4.6, and dryness inhibit it, which is why proper canning and acidification matter.

Bacillus cereus forms spores that survive cooking and can produce toxins when cooked rice or starchy foods are held in the danger zone. Rapid cooling and proper hot holding prevent the spores from germinating and producing toxin. Vibrio is linked to shellfish, Campylobacter to poultry, and Listeria to deli and refrigerated foods.

A worker who is jaundiced must be excluded from the food establishment and reported to the regulatory authority, because jaundice can signal Hepatitis A infection. Restriction or gloves are not sufficient for a jaundiced or Big 6-diagnosed worker. Reporting protects the public and lets the health department investigate.

Workers experiencing vomiting or diarrhea must be excluded from food handling because these symptoms often indicate a contagious gastrointestinal pathogen like Norovirus. They may return only after being symptom-free for the required time, commonly 24 to 48 hours, or when cleared per policy. Allergies and minor aches unrelated to foodborne illness are not exclusion criteria.

Very rapid onset, often under 6 hours, points to a preformed toxin, as with Staphylococcus aureus or Bacillus cereus emetic toxin, because the toxin is already present and does not need to multiply in the body. Infections like Salmonella take longer, and Hepatitis A and Listeria have onset measured in weeks. Knowing onset helps trace the offending food.

This is cross-contamination: pathogens such as Salmonella and Campylobacter from raw chicken transfer via the board and knife to tomatoes that will be eaten without cooking. Preventing it requires separate or cleaned-and-sanitized equipment, color-coded boards, and proper sequencing. Because the salad is not cooked, there is no later kill step to destroy the pathogens.

Proper, frequent handwashing, especially after using the restroom, handling raw food, or touching the face, is the most effective way a worker prevents transmitting pathogens like Norovirus, Hepatitis A, and Shigella. Handwashing should use warm water, soap, 20 seconds of scrubbing, and a single-use towel. A hat and a quiet kitchen do not stop fecal-oral pathogen spread.

Salmonella Typhi (typhoid) is one of the Big 6 reportable pathogens; a diagnosed worker must be excluded and may return only with clearance from the regulatory authority or a medical release. A single day off or gloves is not adequate. Supervisors must report the diagnosis and follow the health department's return-to-work requirements.

Cut melons, cut leafy greens, and cut tomatoes are specifically designated TCS foods once cut, because cutting exposes moist, nutrient-rich interior tissue that supports pathogen growth. They must be held at 41°F or below. A whole intact melon, dry flour, and acidic vinegar are not TCS.

Vomit and diarrhea can spread Norovirus widely, so establishments must follow a written cleanup procedure: isolate the area, use proper protective equipment, clean and disinfect with an effective agent, and discard any exposed food. A dry rag or air freshener does not disinfect and can aerosolize the virus. Having and following this procedure is a supervisor responsibility.

Trichinella spiralis is a parasitic roundworm historically linked to undercooked pork and wild game such as bear. Cooking pork to the required minimum internal temperature destroys it. Norovirus is a virus, and Salmonella and Bacillus cereus are bacteria, not parasites.

Viruses such as Norovirus and Hepatitis A cannot reproduce in food; they need a living host, so they spread mainly through infected food workers, contaminated water, and the fecal-oral route. Bacteria, by contrast, can multiply rapidly in TCS food within the danger zone. This is why worker hygiene and exclusion are the key controls for viral contamination.

Vibrio vulnificus is found in raw or undercooked shellfish, particularly oysters, and can cause life-threatening bloodstream infection in people with liver disease or weakened immunity. Control includes buying from approved sources, keeping shellstock cold, and advising high-risk guests via the consumer advisory. Perfringens and Bacillus cereus are tied to temperature-abused cooked foods, not raw oysters.

Clostridium perfringens, nicknamed the cafeteria or buffet germ, grows in large batches of meats, gravies, and stews that are cooled too slowly or held in the danger zone. It causes diarrhea and cramps 8 to 16 hours later, usually without much vomiting. Rapid cooling and proper hot holding at 140°F or above prevent it.

Campylobacter jejuni is a leading cause of bacterial diarrheal illness, linked to raw or undercooked poultry, unpasteurized milk, and untreated water. Cooking poultry to 165°F and avoiding cross-contamination controls it. Botulism causes paralysis, Listeria targets high-risk groups, and Bacillus cereus is tied to starchy foods.

Certain molds produce mycotoxins that can be harmful, and because mold threads and toxins penetrate soft and moist foods, such items should be discarded rather than merely trimmed. Simply cutting visible mold off soft foods does not remove the hazard. Molds are not limited to freezers, and not all are harmless.

Cooking kills living bacteria and parasites, but it does not reliably destroy preformed toxins such as Staph toxin, histamine (scombroid), and ciguatoxin, which are heat-stable. That is why preventing toxin formation through temperature control and approved suppliers is essential. Live pathogens like Salmonella, Campylobacter, and Trichinella are, in contrast, destroyed by proper cooking.

A worker with a sore throat accompanied by fever should be restricted from working with exposed food, and excluded when serving highly susceptible populations, because such symptoms can indicate a transmissible infection like strep. Gloves do not substitute for restriction. The supervisor must know these symptom-based rules to protect customers.

Beyond undercooked ground beef, STEC has been linked to contaminated raw leafy greens like romaine and to unpasteurized juice or apple cider, because the organism can contaminate produce in the field or during processing. Washing produce, buying pasteurized juice, and sourcing from approved suppliers reduce risk. Shelf-stable canned and dry items are not typical sources.

When time alone, not temperature, is used as a public health control, TCS food may be out of temperature control for a maximum of 4 hours before it must be discarded; a 6-hour limit applies only under specific rules where the food starts at 41°F and never exceeds 70°F. This limits how long bacteria can multiply. Leaving food out indefinitely allows pathogens to reach dangerous levels.

Bacteria vary in oxygen needs: aerobic bacteria require oxygen, while anaerobes such as Clostridium botulinum grow in oxygen-free environments like canned or reduced-oxygen-packaged foods. This is why reduced-oxygen packaging and canning create special botulism risks if not controlled. Oxygen clearly does affect which organisms grow.

Water activity measures the moisture available for bacteria; foods with low water activity — dry crackers, hard candy, dry beans — do not readily support growth and are not TCS. Moist foods like cooked rice, cut melon, leafy greens, and deli meats have high water activity and must be temperature controlled. Reducing available moisture by drying is a preservation method.

Active managerial control means the person in charge proactively designs and enforces systems — staff training, hygiene rules, temperature monitoring, and supplier controls — to prevent the known risk factors rather than reacting after the fact. Waiting for inspectors or complaints is reactive and unsafe. Certification helps, but ongoing supervision and monitoring are essential.