Bacterial Foodborne Diseases and Pathogens Guide

Statistical Significance and Annual Estimates of Foodborne Illness

CDC General Yearly Estimates (US): - Total foodborne illnesses: Approximately $48$ million cases. - Total hospitalizations: $128,000$ . - Total deaths: $3,000$ .
Etiological Agent Breakdown (Scallan et al., 2011): - Viruses: $5.51$ million illnesses; $157$ deaths. - Bacteria: $3.65$ million illnesses; $861$ deaths. - Parasitic: $0.23$ million illnesses; $333$ deaths. - Total (Etiology known): $9.38$ million illnesses; $1,351$ deaths.
Bacterial Causes of Foodborne Disease (Yearly Comparisons 1999 vs. 2011): - Salmonella (non-typhoidal): Decreased from $1,340,000$ to $1,028,000$ . - Clostridium perfringens: Increased from $248,000$ to $966,000$ . - Campylobacter (jejuni, coli): Decreased from $1,960,000$ to $845,000$ . - Staphylococcus aureus: Increased from $185,000$ to $241,000$ . - Shigella: Increased from $89,600$ to $131,000$ . - STEC non-O157: Increased from $36,000$ to $113,000$ . - Yersinia enterocolitica: Increased from $86,700$ to $98,000$ . - Bacillus cereus: Increased from $27,400$ to $63,400$ . - E. coli O157:H7 (STEC O157): Stable at ~ $63,000$ . - Vibrio parahemolyticus: Increased from $5,200$ to $34,700$ . - Streptococcus: Decreased from $51,000$ to $11,200$ . - Listeria monocytogenes: Decreased from $2,500$ to $1,590$ . - Total Bacterial Cases: Decreased from $4.2$ million to $3.6$ million.

General Mechanisms of Foodborne Disease

Symptom-Based Classification: - Gastrointestinal: Symptoms include diarrhea, vomiting, cramping, and nausea. - Systemic: Affects other organ systems including the Central Nervous System (CNS), kidneys, and vascular system.
Mechanisms of Disease Development: - Infection: Consumption of the live pathogen, which then grows within the host (e.g., bacteria or molds). - Intoxication: Consumption of a pre-formed toxin produced by the pathogen in the food (e.g., bacterial toxins or viruses—though viruses do not grow in food). - Toxico-infection: Consumption of the live pathogen followed by the subsequent production of toxins inside the host.
The "Danger Zone" for Temperature Safety: - Microorganisms grow rapidly between $40^{\circ}\text{F}$ ( $4^{\circ}\text{C}$ ) and $140^{\circ}\text{F}$ ( $60^{\circ}\text{C}$ ). - Freezer temperature: $0^{\circ}\text{F}$ ( $-18^{\circ}\text{C}$ ). - Refrigerator temperature: $40^{\circ}\text{F}$ ( $4^{\circ}\text{C}$ ). - Safe Internal Cooking Temperatures: - Beef, pork, lamb, veal (roasts, steaks, chops): $145^{\circ}\text{F}$ ( $63^{\circ}\text{C}$ ). - Egg dishes, ground meat: $160^{\circ}\text{F}$ ( $71^{\circ}\text{C}$ ). - Poultry, stuffing, casseroles, reheating leftovers: $165^{\circ}\text{F}$ ( $74^{\circ}\text{C}$ ).

The 10 Riskiest Foods (FDA/CSPI Data)

These 10 foods account for $40\%$ of all foodborne outbreaks regulated by the FDA since 1990: 1. Leafy Greens: $363$ outbreaks; $13,568$ cases. Contamination occurs anywhere from source to consumption. 2. Eggs: $352$ outbreaks; $11,163$ cases. High association with Salmonella, primarily in restaurants. 3. Tuna: $268$ outbreaks; $2,341$ cases. Scombroid poisoning caused by inadequate refrigeration. 4. Oysters: $132$ outbreaks; $3,409$ cases. Often gathered from waters contaminated with Norovirus. 5. Potatoes: $108$ outbreaks; $3,659$ cases. Often salmonella/pathogen contamination in salads. 6. Cheese: $83$ outbreaks; $2,761$ cases. Salmonella is the most common contaminant during early production. 7. Ice Cream: $74$ outbreaks; $2,594$ cases. Mostly home-based outbreaks using undercooked eggs. 8. Tomatoes: $31$ outbreaks; $3,292$ cases. Salmonella enters plants via multiple avenues; difficult to remove without cooking. 9. Sprouts: $31$ outbreaks; $2,022$ cases. Seeds are the primary cause of contamination. 10. Berries: $25$ outbreaks; $3,397$ cases. Often contaminated at the country of origin (e.g., 1997 Hepatitis A strawberry outbreak with $2.6$ million pounds).

Bacterial Diseases of the Mouth

Normal Microbiota: - Saliva: Millions of bacteria per ml. - Large intestine: Extremely high numbers. - Feces: $100$ billion bacteria per gram.
Defenses: - Stomach acidity. - Small intestine: Paneth cells. - Protecting functions: Immune system stimulation, antimicrobial effects, physical barrier against pathogens. - Metabolic functions: Vitamin synthesis, digestion of harmful compounds, fermentation of non-digestible substances.
Dental Caries (Tooth Decay): - Pathogen: Streptococcus mutans. - Mechanism: S. mutans uses sucrose to produce dextran (an accumulation sticky biofilm) and plaque. Plaque bacteria produce acid that dissolves tooth enamel, then dentin, potentially reaching the pulp and causing an abscess. - Note: Sugarless candies containing sugar alcohols are not cariogenic because they are not fermented to acid by oral bacteria.
Periodontal Diseases: - Gingivitis: Inflammation of the gums (redness and irritation). - Periodontitis: Progression of gingivitis involving Porphyromonas spp. Symptoms include wobbly teeth, tooth loss, erosion of jaw bone, bleeding, and halitosis. Treated with antibiotics. - Acute Necrotizing Ulcerative Gingivitis (ANUG): Also called "trench mouth" or Vincent’s disease. Caused by Prevotella intermedia. Results in inflamed, eroded gums.

Lower Digestive System Diseases: General Concepts

Infection: Growth of a pathogen. Incubation varies from $12$ hours to $2$ weeks; usually accompanied by fever.
Intoxication: Ingestion of a toxin. Symptoms appear very quickly ( $1$ to $48$ hours after ingestion).
Gastroenteritis: General term for diarrhea and dysentery.
Treatment: Primary treatment for most is oral rehydration therapy.

The Genus Salmonella

General Salmonellosis: - Pathogen: Salmonella enterica (non-typhoid spp.). - Estimates: $1.4$ million infections; $553$ deaths; cost of ~ $2.5$ billion. - Symptoms: Enterocolitis, abdominal cramps, diarrhea, nausea, vomiting, chills, fever. Self-limiting ( $2-3$ days) but can become chronic. - Incubation: $8$ to $72$ hours (usually $18-24$ hours). - Infectious Dose: Variable ( $10$ to $10^{6} CFU/g). - Pathogenesis: Gram-negative rod; invasive. Penetrates epithelial mucosal cells and persists in macrophages. Less than 5\% spread to blood/lymph. - Reservoirs: GI tracts of animals, especially chickens, amphibians, and reptiles.
Typhoid Fever: - Pathogen: Salmonella typhi. - Scope: Prevalent in developing countries (12.5 million cases worldwide). - Pathogenesis: Highly invasive using a capsule and siderophores. Produces endotoxin and Typhoid exotoxin. Bacteria spread via phagocytes. Humans are the ONLY reservoirs. - Symptoms: High fever, significant mortality, rose spots, lethargy, delirium, abdominal pain, and initially bloody diarrhea. - Incubation: 7 $to$ 28 days. - Chronic Carriers: 1-3\% of patients (e.g., "Typhoid Mary" Mallon). - Control: Subunit vaccine for prevention; treated with quinolones and cephalosporins.

Clostridium Species: Perfringens and Botulinum

Clostridium perfringens (Clostridial Food Poisoning): - Characteristics: Gram-positive rods, endospore former. Ubiquitous in soil, dust, and GI tracts. - Symptoms: Profuse watery diarrhea, severe abdominal pain; subsides within 24 hours. Vomiting/nausea are rare. - Infectious Dose: Requires at least $10^{6}$ cells/g of food. - Incubation: 8-24 hours. - Associated Foods: Meat and poultry dishes prepared in advance and cooled slowly.
Clostridium botulinum (Botulism): - Characteristics: Gram-positive, anaerobic, endospore-forming rod. Classified as an intoxication. - Estimates: ~110 $illnesses/year in the US ($ 25\% $foodborne,$ 72\% $infant,$ 3\% wound). - Toxin: Neurotoxin is the most lethal known. LD50 is 0.1 - 1\text{ ng/kg} body weight. - Mechanism: Botulinum toxin slices SNARE proteins, blocking the release of acetylcholine at the synapse. Muscles fail to receive contraction messages, leading to flaccid paralysis. - Symptoms: Double/blurred vision, drooping eyelids, slurred speech, vertigo, difficulty swallowing/breathing. No fever or loss of consciousness. - Outbreaks: - Beached whale (Alaska, 2002): Toxin type E found in raw muktuk (whale skin/blubber). - Baked Potatoes (Texas, 1994): Stored in foil at room temp for 18 hours after baking. - Vichyssoise soup (1971): Led to recall of 90 products after one death. - Treatment: Antitoxin (Equine source), Human-derived antitoxin for infants, and respirators. - Applications: Pharmaceutical (Botox for cosmetic use or muscle spasms) and potential bioterrorism.

Staphylococcus aureus and Bacillus cereus intoxication

Staphylococcus aureus: - Characteristics: Gram-positive cocci in bunches, salt-tolerant. #1 cause of foodborne intoxication. - Mechanism: Produces an enterotoxin that affects the vagus nerve. Reheating kills bacteria but NOT the stable toxin. - Symptoms: Rapid onset (1-6 hours): uncontrollable vomiting, diarrhea, cramps. NO fever. - Outbreak: Sakai, Japan (2000): 14,000 children sickened by Snow Brand Milk due to poor sanitation and reprocessing unsold milk.
Bacillus cereus: - Characteristics: Gram-positive, spore-forming large rod. Widespread in soil/plants. - Emetic (Vomiting) Type: Caused by emetic toxin produced in food (usually rice/starchy foods). Incubation: 1-6 hours. - Diarrheal Type: Caused by enterotoxin produced in the gut. Incubation: 6-14 hours. - Infectious Dose: High (>$10^{6}$ CFU/g). - Outbreak: Virginia day care (1993): Fried rice served to children/staff (14 sick).

Shigella and Campylobacter

Shigella (Bacillary Dysentery): - Characteristics: Gram-negative rod; infected humans are the only reservoir (no environmental/animal pools). - Mechanism: Invades M cells on the epithelial wall, multiplies inside cells, and invades neighbors to avoid immune defense. Forms mucosal abscesses. - Symptoms: Very watery diarrhea with blood, cramps, fever. Can cause Hemolytic Uremic Syndrome (HUS). - Treatment: Fluoroquinolones.
Campylobacter: - Characteristics: Gram-negative curved rod. - Estimates: 2.4 $million infections;$ 100 deaths. - Symptoms: Fever, cramps, diarrhea (sometimes bloody). - Complication: Guillain-Barré syndrome (GBS). 40\% of GBS patients had a prior Campylobacter infection. - Reservoirs: Livestock, birds, pets, and poultry. Twin Cities study found 88\% $of retail poultry positive.</p></li></ul><h3 id="50500fde-a877-4ae3-b2aa-bcca4c260a4b" data-toc-id="50500fde-a877-4ae3-b2aa-bcca4c260a4b" collapsed="false" seolevelmigrated="true">Escherichia coli Pathotypes</h3><ul><li><p><strong>General E. coli:</strong> Gram-negative rod; indicator of fecal contamination. Usually commensal ($ <1\% of gut flora).
Pathogenic Strains: - O157:H7 (STEC): Acquired Shiga toxins from Shigella via phage. Destroys host protein synthesis. High virulence causes Hemorrhagic colitis (bloody diarrhea) and HUS. - HUS (Hemolytic Uremic Syndrome): Affects 8\% of children; results in acute kidney failure due to toxin effect on vascular cells. - Infectious Dose (O157:H7): Very low (1 $to$ 100 CFU/g). - Jack in the Box Outbreak (1993): Over 600 $sick,$ 4 children dead. Found meat was undercooked because high temps made it "too tough." - Genomics: E. coli O157:H7 has ~5,200 $genes vs. ~$ 4,200 in non-pathogenic K-12. Unique regions are called "islands." - O104:H4 (EAHEC): Enteroaggregative strain producing Shiga toxin 2. Outbreak in Europe (3,167 $cases,$ 908 $HUS cases). High incidence of HUS ($ 25\%).

Vibrio Species and Listeria

Vibrio cholerae: - Disease: Cholera. Violent "rice water" diarrhea with mucus. High mortality (>50\%) if untreated. - Blood Type Resistance: AB (most resistant), A, B, O (least resistant/most susceptible). - V. parahaemolyticus: Halophilic; naturally in marine environments. Most common food poisoning in Hong Kong via undercooked seafood. - V. vulnificus: Ingestion leads to septicemia in immunocompromised/liver disease patients. Symptoms: fever, chills, blood-tinged blisters. 50\% mortality.
Listeria monocytogenes: - Characteristics: Gram-positive rod; Psychrotroph (grows at refrigeration temps). Ubiquitous in nature. - Clinical Significance: - Healthy: Mild/asymptomatic. - Susceptible (Old, young, immunocompromised, pregnant): Invasive meningitis or stillbirths in pregnant women. - Infectious Dose (Systemic): Very low (>$100$ cells). - Outbreaks: - 2011 Cantaloupe: Deadliest since 1985. - 2015 Blue Bell Ice Cream/Sabra Hummus: Multi-year persistence. - 2015 Caramel Apples: Hypothesis that sticks puncturing apple skin released juice, which the caramel coating locked in, creating a micro-environment for Listeria growth. - 2018 South Africa Polony: Deadliest listeriosis outbreak in history (1,000 $sick,$ 180$$ deaths).

Helicobacter pylori

Pathology: Causes peptic ulcers. Gram-negative helical rod.
Discovery: Marshall and Warren (1982); Nobel Prize (2005).
Mechanism: - Lives in the gastric mucus layer. - Produces Urease, which splits urea into ammonia and $CO_{2}$ to neutralize stomach acid. - Secretes toxins that cause inflammation and tissue erosion (ulcers).
Treatment: Abandoned bland diets for antibiotic regimens (tetracycline/amoxicillin) combined with proton pump inhibitors (omeprazole).