Major Foodborne Pathogens & Their Characteristics
Food microbiology at an advanced level requires detailed knowledge of specific pathogens, their ecological niches, and the diseases they cause. Salmonella spp.: gram-negative, facultative anaerobe; found in poultry, eggs, and raw meat; causes salmonellosis (gastroenteritis) with 12–72 hour incubation; destroyed by cooking to 75°C internal temperature. Listeria monocytogenes: gram-positive, facultative anaerobe; uniquely psychrotrophic (grows at refrigeration temperatures, 0–4°C); found in ready-to-eat meats, soft cheeses, and smoked fish; causes listeriosis—dangerous for pregnant women, elderly, and immunocompromised individuals; high fatality rate (~20%). Campylobacter jejuni: leading cause of bacterial gastroenteritis in developed nations; associated with raw/undercooked poultry; very low infectious dose (~500 cells); does not grow below 30°C. Staphylococcus aureus: produces heat-stable enterotoxins in food before consumption; the toxin causes illness even if the bacteria are killed by cooking (because toxins withstand boiling). Associated with food handled by infected food handlers (nose, skin). Clostridium botulinum: produces the most potent biological toxin known; grows in anaerobic conditions (canned food, vacuum-packed products); produces heat-resistant endospores; toxin is inactivated by boiling for 10 minutes but spores require autoclaving at 121°C for 3 minutes.