10 Questions
What is the optimal temperature for STEC growth?
37 °C
Which E. coli is responsible for most foodborne infections resulting in death?
EHEC
What is the minimum pH level at which some STEC can grow?
4.4
What is the minimum water activity (aw) at which some STEC can grow?
0.95
What is the recommended internal temperature for cooking meats to prevent STEC infection?
70 °C
What is the characteristic of Salmonella that makes it a primary cause of food infections?
Its high resistance to environmental conditions
What is the typical duration of untreated Salmonella infection?
4-7 days
What is the primary cause of diarrhea in newborns and children under 2 years of age?
EPEC
What is the characteristic of Escherichia coli that causes dysentery-like bloody diarrhea?
EIEC
What is the minimum infectious dose of Salmonella reported in the literature?
10^8-10^9 cfu/g
Study Notes
E. coli
- Infection is more common in hot summer months
- EIEC produces heat-sensitive (LT) or heat-stable (ST) toxins
- ETEC is associated with children's diarrhea and tourist diarrhea
- EHEC is responsible for most foodborne infections resulting in death
- STEC can cause severe foodborne disease and produces Shiga-toxins
- STEC can grow in temperatures ranging from 7 °C to 50 °C, with an optimum temperature of 37 °C
- Some STEC can grow in acidic foods, down to a pH of 4.4, and in foods with a minimum water activity (aw) of 0.95
- High virulence and low Minimum Infective Dose (MID) of 10-100
Prevention
- Cook meats thoroughly to at least 70 °C
- Regular hand washing, particularly before food preparation or consumption, and after toilet contact
- Wash fruits and vegetables carefully, especially if they are eaten raw
Enterobacteriaceae
- Gram negative
- Motile
- Facultative anaerobes
- Surface antigens: O, H, and Vi
- More than 2500 strains
Salmonella
- Widely distributed in the intestinal tract of domestic and wild animals
- Can pass through the entire food chain from animal feed and primary production
- High resistance to environmental conditions and long-term viability in food
- One of the most important reasons for food infections
Salmonella Infections
- Caused by fecal contamination by ill or asymptomatic chronic carriers
- Fever is documented at presentation in more than 75% of cases
- Gastroenteritis is the most common clinical presentation of non-typhoidal Salmonella infection
- Illness usually lasts 4-7 days, and most people recover without treatment
- Minimal infection dose is reported to be 10^8-10^9 cfu/g
E. coli Outbreak
- 855 cases of HUS and 2,987 cases of acute gastroenteritis attributed to the outbreak
- Death was reported for 35 (4.1%) of the patients identified with HUS and 18 (0.6%) of the patients with EHEC gastroenteritis
- Total 53 deaths
Learn about the characteristics of Enterobacteriaceae, a family of Gram-negative bacteria, and Salmonella, a type of bacteria found in the intestinal tract of animals.
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