7.2 Common Foodborne Pathogens

The FDA Food Code "Big 6"

The FDA Food Code identifies six pathogens as highly infectious and singles them out under §2-201.11 for mandatory action: a food employee who is diagnosed with any of them must be reported to the person-in-charge and is generally excluded or restricted from work. These are the "Big 6":

The two viruses, Norovirus and Hepatitis A, spread by the fecal-oral route: tiny amounts of feces transfer from an infected worker's hands to ready-to-eat food. Because viruses do not multiply in food and a tiny dose causes illness, the only real defenses are thorough handwashing, no bare-hand contact with RTE food, and keeping sick workers out of the kitchen.

The Big 6 Bacteria in Detail

Nontyphoidal Salmonella is the workhorse of foodborne illness, carried in the intestines of poultry and reptiles and contaminating chicken, turkey, and eggs; onset is typically 6–72 hours with diarrhea, fever, and cramps. The control is cooking poultry to an internal 165°F and avoiding cross-contamination. Salmonella Typhi causes typhoid fever, a more serious illness spread through water and food handled by carriers.

Shigella is spread by food workers with poor hand hygiene and by flies that travel from feces to food; it takes very few cells to cause illness, so handwashing and pest control are essential.

Shiga toxin-producing E. coli (STEC), including O157:H7, lives in cattle intestines and contaminates ground beef and raw produce (lettuce, sprouts, unpasteurized juice). Because grinding spreads surface contamination throughout the meat, the Food Code requires cooking ground beef to 155°F for 17 seconds. STEC can cause hemolytic uremic syndrome (HUS), a life-threatening kidney complication, especially in children.

Big 6 takeaway: report and exclude any handler diagnosed with these six. They are the pathogens most likely to spread from one infected worker to many guests.

Other Major Pathogens and Toxins

Many important pathogens are not on the Big 6 list but are still heavily tested:

• Listeria monocytogenes: unique because it grows at refrigeration temperatures. Found in deli meats and soft cheeses (feta, Brie, queso fresco); it is especially dangerous to pregnant women, causing miscarriage. Reheat deli meats to 165°F and use pasteurized dairy.
• Clostridium perfringens: the "buffet/cafeteria germ" that multiplies in foods held too long at improper temperatures (gravies, stews, large batches of meat). Control by rapid cooling and proper hot-holding at 135°F or above.
• Bacillus cereus: the "fried-rice" organism. Spores survive cooking; if cooked rice or pasta sits at room temperature, it produces a heat-stable toxin. Cool and reheat properly.
• Staphylococcus aureus: carried in the nose, skin, and infected cuts of food handlers, who deposit it on RTE food where it produces a heat-stable toxin that cooking will not destroy. Control through hygiene and temperature.
• Clostridium botulinum: grows without oxygen in improperly canned, vacuum-packed, or anaerobic foods, producing a deadly neurotoxin.
• Campylobacter jejuni: linked to raw poultry and unpasteurized milk.

Seafood Toxins and Parasites

Some seafood hazards are toxins the food handler cannot cook out: Scombroid (histamine) poisoning from improperly chilled tuna/mahi-mahi, and Ciguatera from large reef fish — both prevented at receiving and storage, not by cooking. Vibrio comes from raw oysters. Anisakis is a parasite (roundworm) in fish controlled by cooking to 145°F or by freezing fish that will be served raw (e.g., sushi).

Reporting, Exclusion, and Restriction

The Food Code turns pathogen knowledge into specific personnel rules. A food employee must report to the person-in-charge if they are diagnosed with any Big 6 pathogen, or if they have certain symptoms. The manager then applies one of two actions:

• Exclusion — the worker may not enter the establishment to work. Required for vomiting or diarrhea, for a diagnosed Big 6 illness, and for jaundice within the last 7 days.
• Restriction — the worker may stay but cannot handle food or clean equipment, used for milder situations such as a sore throat with fever in a facility serving a high-risk population.

Returning to work usually requires being symptom-free for at least 24 hours or written medical/health-department clearance. For the two vaccine-relevant viruses, only Hepatitis A has a widely used vaccine; there is no vaccine for Norovirus, so hygiene is the sole control.

Quick Pathogen-to-Food Cheat Sheet

Memorizing these characteristic pairings is the fastest way to answer scenario questions: the exam describes a food and an error, and the right answer names the pathogen and its matching control.