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Questions and Answers
What type of agar produces rose-pink colonies due to lactose fermentation?
What type of agar produces rose-pink colonies due to lactose fermentation?
Which of the following diseases is NOT caused by E. coli?
Which of the following diseases is NOT caused by E. coli?
What is one of the virulence factors of E. coli that helps in adherence to mucosal cells?
What is one of the virulence factors of E. coli that helps in adherence to mucosal cells?
Which antigen associated with E. coli interferes with phagocytosis?
Which antigen associated with E. coli interferes with phagocytosis?
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What are the two types of enterotoxins produced by enterotoxigenic strains of E. coli?
What are the two types of enterotoxins produced by enterotoxigenic strains of E. coli?
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Which biochemical characteristic is IMVC ++ -- related to?
Which biochemical characteristic is IMVC ++ -- related to?
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What type of bacteria is E. coli classified as in terms of morphology?
What type of bacteria is E. coli classified as in terms of morphology?
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Which strain of E. coli is known to cause haemorrhagic colitis?
Which strain of E. coli is known to cause haemorrhagic colitis?
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Which characteristic is NOT common to the Enterobacteriaceae family?
Which characteristic is NOT common to the Enterobacteriaceae family?
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Which of the following genera is NOT classified as a lactose fermenter within Enterobacteriaceae?
Which of the following genera is NOT classified as a lactose fermenter within Enterobacteriaceae?
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Which statement correctly describes the Enterobacteriaceae family's metabolic properties?
Which statement correctly describes the Enterobacteriaceae family's metabolic properties?
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Which of the following genera is known to cause opportunistic infections?
Which of the following genera is known to cause opportunistic infections?
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Which of the following is a primary habitat for the Enterobacteriaceae family?
Which of the following is a primary habitat for the Enterobacteriaceae family?
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From which source can commercially prepared biochemical test kits (API 20E) be used for the differentiation of Enterobacteriaceae?
From which source can commercially prepared biochemical test kits (API 20E) be used for the differentiation of Enterobacteriaceae?
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Escherichia, Klebsiella, and Enterobacter share which common feature?
Escherichia, Klebsiella, and Enterobacter share which common feature?
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Which pathogenic genus within the Enterobacteriaceae is primarily associated with opportunistic infections rather than primary pathogenic diseases?
Which pathogenic genus within the Enterobacteriaceae is primarily associated with opportunistic infections rather than primary pathogenic diseases?
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What is the main characteristic of Enteroinvasive E. coli (EIEC)?
What is the main characteristic of Enteroinvasive E. coli (EIEC)?
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What type of toxin is produced by Enterohaemorrhagic E. coli (EHEC)?
What type of toxin is produced by Enterohaemorrhagic E. coli (EHEC)?
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What is a serious complication associated with EHEC infections?
What is a serious complication associated with EHEC infections?
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Which group of patients are particularly affected by Enteroaggregative E. coli (EAEC)?
Which group of patients are particularly affected by Enteroaggregative E. coli (EAEC)?
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Which method is NOT used for the identification of Enteroaggregative E. coli (EAEC)?
Which method is NOT used for the identification of Enteroaggregative E. coli (EAEC)?
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What is a recommended treatment for E. coli infections causing diarrhoea?
What is a recommended treatment for E. coli infections causing diarrhoea?
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What is a primary method used to detect verotoxin in suspected EHEC infections?
What is a primary method used to detect verotoxin in suspected EHEC infections?
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EIEC are characterized as which type of fermenters?
EIEC are characterized as which type of fermenters?
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What organism is a key indicator of faecal pollution in water samples?
What organism is a key indicator of faecal pollution in water samples?
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Which of the following statements about Klebsiella pneumoniae is true?
Which of the following statements about Klebsiella pneumoniae is true?
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Which characteristic is associated with Klebsiella pneumoniae?
Which characteristic is associated with Klebsiella pneumoniae?
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What type of infections are commonly associated with Klebsiella rhinoscleromatis?
What type of infections are commonly associated with Klebsiella rhinoscleromatis?
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What role do enzymes elastase and protease play in the pathogenicity of Pseudomonas aeruginosa?
What role do enzymes elastase and protease play in the pathogenicity of Pseudomonas aeruginosa?
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What biochemical activity is Klebsiella pneumoniae characterized by?
What biochemical activity is Klebsiella pneumoniae characterized by?
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Why is Pseudomonas aeruginosa particularly problematic in hospital environments?
Why is Pseudomonas aeruginosa particularly problematic in hospital environments?
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What is a characteristic biochemical activity of Pseudomonas aeruginosa?
What is a characteristic biochemical activity of Pseudomonas aeruginosa?
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Which species of Proteus is commonly associated with urinary tract infections?
Which species of Proteus is commonly associated with urinary tract infections?
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What is the primary reason why strains of Pseudomonas aeruginosa isolated from cystic fibrosis patients have increased adherence to mucous membranes?
What is the primary reason why strains of Pseudomonas aeruginosa isolated from cystic fibrosis patients have increased adherence to mucous membranes?
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Which of the following diseases is NOT caused by Klebsiella pneumoniae?
Which of the following diseases is NOT caused by Klebsiella pneumoniae?
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Which antibiotic combination is commonly used to treat infections caused by Pseudomonas aeruginosa?
Which antibiotic combination is commonly used to treat infections caused by Pseudomonas aeruginosa?
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What type of infections are commonly associated with Proteus species?
What type of infections are commonly associated with Proteus species?
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Which of the following is a characteristic of Proteus infections?
Which of the following is a characteristic of Proteus infections?
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What is a distinguishing biochemical activity of Proteus species?
What is a distinguishing biochemical activity of Proteus species?
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Which characteristic is true for Pseudomonas species?
Which characteristic is true for Pseudomonas species?
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What property does Pseudomonas have that contributes to its pathogenicity?
What property does Pseudomonas have that contributes to its pathogenicity?
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How do Proteus species typically behave on nutrient agar?
How do Proteus species typically behave on nutrient agar?
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Which of the following is NOT a common infection caused by Pseudomonas?
Which of the following is NOT a common infection caused by Pseudomonas?
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Which antibiotics are Proteus species MOST often sensitive to?
Which antibiotics are Proteus species MOST often sensitive to?
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Study Notes
Enterobacteriaceae (Lactose Fermenters & Proteus)
- The Enterobacteriaceae family consists of gram-negative bacilli.
- They are commonly found in the colon of humans and animals, often as part of the normal flora.
- They cause various diseases with different pathogenic mechanisms.
- A widely used biochemical test kit for differentiating Enterobacteriaceae species is API 20E.
Pseudomonas
- Pseudomonas are gram-negative, motile bacilli.
- They are common causes of hospital-acquired infections.
- Common infections include urinary tract infections, wound infections, otitis externa, corneal ulcers (in contact lens users), pneumonia, sepsis with ecthyma gangrenosum, osteomyelitis, and endocarditis (in intravenous drug users).
- These infections are often severe and commonly occur in hospitalized or immunocompromised patients.
Klebsiella
- Klebsiella pneumoniae are gram-negative, non-motile, and capsulated bacilli.
- They are normal inhabitants of the intestinal and respiratory tracts.
- Often cause hospital-acquired infections due to multi-drug resistance.
- Common infections include pneumonia and urinary tract infections.
- Klebsiella rhinoscleromatis can cause a granuloma in the nose and throat (rhinoscleroma).
- Klebsiella ozaenae is associated with atrophic rhinitis
Morganella morganii and Providencia rettgeri
- These genera are similar to Proteus in certain characteristics but are distinct.
- They are gram-negative, non-lactose fermenters, and generally resistant to many antibiotics.
- They are often found in soil, water and the intestines of humans.
- They are a common cause of urinary tract infections (UTIs).
General Characteristics of the Family Enterobacteriaceae
- Gram-negative bacilli
- Non-spore forming
- Aerobic or facultative anaerobic
- Ferment glucose
- Oxidase negative
- Catalase positive
- Reduce nitrate to nitrite
E. coli
- E. coli are normal inhabitants of the human intestine.
- Some strains cause various diseases, including urinary tract infections (the most common type), hospital-acquired infections, neonatal meningitis, pneumonia, sepsis, and intestinal diseases (e.g., traveler's diarrhea, hemorrhagic colitis).
- Uropathogenic E. coli specifically colonize the urinary tract and cause cystitis and pyelonephritis.
Virulence factors in E.coli
- Pili (colonization factors) aid in adhering to intestinal cells.
- K antigens (capsular polysaccharides) interfere with phagocytosis.
- Endotoxin (LPS) triggers endotoxic shock.
- Heat-labile and heat-stable toxins (LT, ST) cause water secretion from intestinal cells, leading to diarrhea, particularly from Enterotoxigenic E. coli (ETEC).
- Verotoxin and Shiga toxin cause hemorrhagic colitis, a severe form of bloody diarrhea from Enterohemorrhagic E. coli (EHEC).
- Enteropathogenic E. coli (EPEC) adhere tightly to intestinal cells, disrupting microvilli and leading to diarrhea.
- Enteroinvasive E. coli (EIEC) invade intestinal cells and cause dysentery-like illness.
- Enteroaggregative E. coli (EAEC) adhere to intestinal cells in aggregates and cause acute, persistent diarrhea, often in immunocompromised patients.
Diagnosis of Enterobacteriaceae infections
- Samples (urine, pus, stool, CSF) are cultured on various media.
- Pink lactose-fermenting colonies on MacConkey's agar are further identified by morphology and biochemical tests.
- For diarrhea cases, isolated E. coli are tested to confirm the pathotype (serotyping, ELISA for verotoxin detection).
Treatment
- Treatment for E. coli infections depends on the site and sensitivity pattern of the isolated organism.
- Diarrheal diseases typically do not require antibiotic treatment but rehydration is crucial. However antibiotics may shorten the duration of diarrhea.
- Antibiotic sensitivity tests are crucial to choosing the correct antibiotic for infections, especially for resistant strains.
Additional Notes
- Some species within the Enterobacteriaceae family, Proteus, are highly resistant to antibiotics, requiring sensitivity tests before treatment.
- The slides mention objectives for various species (e.g., Escherichia coli, Klebsiella, Proteus). These are not separate topics but aspects of study within the larger Enterobacteriaceae discussion.
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Description
Test your knowledge on E. coli and related bacteria in this microbiology quiz. Covering topics such as lactose fermentation, virulence factors, and metabolic characteristics, this quiz will challenge your understanding of the Enterobacteriaceae family. Perfect for students studying microbiology or preparing for exams.
