Bacterial Food And Water Pathogens Flashcards
(14 cards)
Describe Aremanos hydrophila
Characteristics:
• Gram-negative, rod-shaped, motile (polar and lateral flagella).
• Aerobic or facultatively anaerobic.
Sources: Contaminated water, fish, shellfish, and undercooked meat.
Symptoms: Watery or loose stools, abdominal cramps, fever; rare bloody diarrhea.
Immune Evasion: Biofilm formation and adhesion via flagellar glycosylation.
Prevention: Avoid untreated water, ensure proper cooking of seafood/meat.
Describe Brucella
Characteristics:
• Gram-negative, coccobacillus, non-motile, non-spore-forming.
• Intracellular pathogen.
Sources: Unpasteurized milk/cheese, undercooked meat, contact with infected animals.
Symptoms: Fever, joint/muscle pain, fatigue; chronic cases may involve organ damage.
Immune Evasion: Survives intracellularly in macrophages, avoiding immune detection.
Prevention: Pasteurization of dairy, protective gear for high-risk occupations.
Describe campylobacter
Characteristics:
• Gram-negative, spiral-shaped, motile (polar flagella).
• Microaerophilic.
Sources: Undercooked poultry, contaminated water, unpasteurized milk.
Symptoms: Diarrhea (often bloody), abdominal pain, fever.
Prevention: Proper food handling, avoiding cross-contamination.
Describe clostridium botulinum
Characteristics:
• Gram-positive, anaerobic, spore-forming rod.
• Produces neurotoxins.
Sources: Improperly canned foods, honey (infant botulism).
Symptoms: Muscle weakness, paralysis, respiratory failure.
Prevention: Proper food preservation, avoiding honey for infants.
Describe clostridium perfringens
Characteristics:
• Gram-positive, anaerobic, spore-forming rod.
Sources: Reheated meat dishes, gravies.
Symptoms: Watery diarrhea, abdominal cramps.
Describe salmonella
Sources: Raw eggs, poultry, reptiles.
Symptoms: Diarrhea, fever, vomiting.
Describe STEC
Characteristics:
• Gram-negative, rod-shaped, motile (peritrichous flagella) .
• Produces Shiga toxin (Stx), which inhibits protein synthesis in host cells .
Sources:
• Contaminated lettuce, undercooked beef, and unpasteurized dairy .
• Ruminants (e.g., cattle) are primary reservoirs; transmission linked to heavy rainfall .
Symptoms:
• Bloody diarrhea (50% of cases), abdominal cramps, fever .
• Complications: Hemolytic uremic syndrome (HUS) in children or thrombotic thrombocytopenic purpura (TTP) in adults .
Immune Evasion:
• Suppresses cellular immune responses in cattle, reducing lymphocyte proliferation .
Describe listeria monocytogenes
Listeria monocytogenes
Characteristics:
• Gram-positive, facultative anaerobic rod, motile at low temperatures (≤30°C) .
• Beta-hemolytic and catalase-positive .
Sources:
• Processed meats, unpasteurized dairy, smoked fish, and raw vegetables .
• Persists in food processing environments .
Symptoms:
• Fever, muscle aches, gastrointestinal distress; severe cases lead to meningitis, septicemia, or pregnancy complications .
Immune Evasion:
• Modifies peptidoglycan to resist lysozyme degradation, evading innate immune detection .
• Uses actin polymerization (“actin rockets”) for cell-to-cell spread without extracellular exposure .
Describe v.cholerae
Characteristics:
• Gram-negative, curved rod, highly motile (single polar flagellum) .
• Facultative anaerobe; serogroups O1 and O139 cause cholera .
Sources:
• Contaminated water or undercooked seafood .
Symptoms:
• Profuse watery diarrhea (“rice-water stools”), vomiting, dehydration (not explicitly detailed in sources but consistent with cholera).
Describe staphylococcus aureus
Staphylococcus aureus is a Gram-positive, non-spore-forming, nonmotile, cocci-shaped bacterium
It is a facultative anaerobe
It can contaminate foods through handling, especially ready-to-eat foods like sandwiches, cooked meats, unpasteurized milk and dairy products, salads, and bakery items. It thrives in foods that are handled frequently and stored at improper temperatures.
Symptoms:
Infections can range from minor skin issues (boils, impetigo, abscesses) to serious conditions (pneumonia, endocarditis, sepsis). Food poisoning from S. aureus causes rapid-onset symptoms—nausea, vomiting, abdominal cramps, and diarrhea—typically within 30 minutes to 8 hours after eating contaminated food
Evades immune system by
Coagulase, toxins, antibody-binding proteins, DNase
Describe plesiomonas shigelloides
Characteristics:
• Gram-negative, motile, facultatively anaerobic rod, oxidase positive.
• Member of the Vibrionaceae family.
Sources:
• Found in unsanitary or contaminated freshwater (rivers, streams, ponds), aquariums, and fish tanks.
• Associated with raw or undercooked freshwater fish, shellfish (shrimp, oysters), and various animals (cattle, goats, swine, cats, dogs, snakes, toads).
Symptoms:
• Watery (sometimes bloody) diarrhea, abdominal pain, nausea, vomiting, fever, chills.
• Symptoms usually appear 20–24 hours after exposure and last 1–7 days.
Immune Evasion:
• Pathogenesis not fully understood; can cause both secretory and invasive diarrhea, sometimes leading to colitis.
Describe Yesinia enterocolitica
Characteristics:
• Gram-negative, rod-shaped, motile at 22–29°C, nonmotile at body temperature.
• Belongs to the Yersiniaceae family.
Sources:
• Reservoirs include pigs (main source for human infection), other animals, untreated water, and contaminated ready-to-eat vegetables.
• Transmission via undercooked pork, contaminated water, meat, or milk.
Symptoms:
• Watery or bloody diarrhea, fever, abdominal pain, sometimes mimicking appendicitis (pseudoappendicitis).
• Can cause terminal ileitis, mesenteric lymphadenitis, and, rarely, systemic infection in immunocompromised individuals.
Immune Evasion:
• Uses Yop effector proteins (type III secretion system) to inhibit phagocytosis and modulate cytokine release, dampening both innate and adaptive immune responses.
• Can induce apoptosis in immune cells and manipulate inflammatory signaling.
Describe vibrio parahaemolyticus
Vibrio parahaemolyticus
Characteristics:
• Gram-negative, curved rod, motile (single polar flagellum).
• Halophilic (salt-loving), grows in marine environments.
Sources:
• Raw or undercooked shellfish (especially oysters, mussels, clams), and contaminated seawater.
Symptoms:
• Watery diarrhea (occasionally bloody), abdominal cramps, nausea, vomiting, fever, headache.
• Symptoms develop within 24 hours (range: 4–96 hours) and usually last about 3 days.
• Can cause wound infections if seawater contacts open wounds, leading to redness, pain, swelling, and pus.
Describe cronobacter
Who is Susceptible
• Infants, particularly neonates (especially premature or immunocompromised), are most at risk.
• Adults are rarely affected; however, the elderly and immunocompromised individuals may also be susceptible.
Characteristics of the Organism
• Gram-negative, rod-shaped bacterium, size approximately 1–3 μm.
• Motile via peritrichous flagella.
• Non-spore-forming.
• Facultatively anaerobic (can grow with or without oxygen).
• Forms biofilms, aiding environmental persistence.
Sources of Infection
• Main source: Powdered infant formula (PIF), which is not sterile and can be contaminated during manufacturing or preparation.
• Other sources: Milk/dairy products, drinking water, vegetables, meat, cereals, herbs, spices, and low-moisture foods (e.g., dried milk powder, herbal teas, starches).
• Can also be found in domestic environments and on food preparation equipment.
Signs and Symptoms of Infection
• In infants: Sepsis, meningitis, necrotizing enterocolitis, and can result in severe neurological disability or death.
• Reported mortality rates: 42–80% for neonatal meningitis, 15–25% for septicemia.
• In adults: Rare, but may cause urinary tract or wound infections.
mmune Evasion and Adaptation
• Cronobacter forms biofilms and adheres to both living and non-living surfaces, aiding persistence and resistance to cleaning.
• Its desiccation tolerance allows survival in dry environments like powdered formula.
• Adhesion to gut epithelial cells (including in the gut-associated lymphoid tissue, GALT) is mainly non-fimbrial, allowing colonization and evasion of some immune responses.
Prevention and Risk Reduction
• Prepare powdered infant formula with water at 70°C or above to achieve a 4–6 log reduction in Cronobacter contamination.
• Avoid ambient storage of reconstituted formula; refrigerate if not used immediately.
• Maintain strict hygiene in food preparation and feeding equipment.
• Implement risk-based environmental monitoring and sanitation in food production facilities, especially those handling low-moisture foods.
