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What is the primary characteristic of Enterobacterales?
What is the primary characteristic of Enterobacterales?
Which of the following infections is commonly associated with Enterobacterales?
Which of the following infections is commonly associated with Enterobacterales?
Which biomolecule's resistance is noted in Enterobacterales?
Which biomolecule's resistance is noted in Enterobacterales?
What does the term 'enteric' imply about the habitat of Enterobacterales?
What does the term 'enteric' imply about the habitat of Enterobacterales?
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What is a common mechanism of drug resistance found in Enterobacterales?
What is a common mechanism of drug resistance found in Enterobacterales?
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Which of the following is NOT considered a clinically important organism of Enterobacterales?
Which of the following is NOT considered a clinically important organism of Enterobacterales?
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What laboratory feature is commonly used to identify Enterobacterales?
What laboratory feature is commonly used to identify Enterobacterales?
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Which of the following species is an example of Pseudomonas?
Which of the following species is an example of Pseudomonas?
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Which group of pathogens includes species that are not considered normal flora?
Which group of pathogens includes species that are not considered normal flora?
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What characteristic is common among most members of the Enterobacterales family?
What characteristic is common among most members of the Enterobacterales family?
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What is a significant consequence of Lipopolysaccharide (LPS) in the pathogenesis of Gram-negative bacteria?
What is a significant consequence of Lipopolysaccharide (LPS) in the pathogenesis of Gram-negative bacteria?
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Which of the following is a potential effect of endotoxin release due to Lipopolysaccharide in the body?
Which of the following is a potential effect of endotoxin release due to Lipopolysaccharide in the body?
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Which virulence factor aids bacteria in binding to host cells?
Which virulence factor aids bacteria in binding to host cells?
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Which Enterobacterales species is specifically known for producing toxins like haemolysins?
Which Enterobacterales species is specifically known for producing toxins like haemolysins?
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What type of metabolic capacity do most Enterobacterales exhibit in relation to carbohydrates?
What type of metabolic capacity do most Enterobacterales exhibit in relation to carbohydrates?
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What feature of the Gram-negative cell wall contributes to its pathogenicity?
What feature of the Gram-negative cell wall contributes to its pathogenicity?
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What is the most appropriate empiric treatment for a urinary tract infection caused by E.coli that is susceptible to nitrofurantoin?
What is the most appropriate empiric treatment for a urinary tract infection caused by E.coli that is susceptible to nitrofurantoin?
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In the case of a 36-year-old female presenting with vomiting and left flank pain, which condition is most likely related to the symptoms described?
In the case of a 36-year-old female presenting with vomiting and left flank pain, which condition is most likely related to the symptoms described?
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Which microbiology investigation is most important initially for the patient with suspected pyelonephritis?
Which microbiology investigation is most important initially for the patient with suspected pyelonephritis?
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For the infant suspected of meningitis, which of the following pathogens is most likely to be the causative agent?
For the infant suspected of meningitis, which of the following pathogens is most likely to be the causative agent?
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What is the likely causative pathogen for a 2-day-old baby presenting with tachypnoea and irritability?
What is the likely causative pathogen for a 2-day-old baby presenting with tachypnoea and irritability?
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Which treatment regimen is appropriate for an infant with suspected meningitis from the cases described?
Which treatment regimen is appropriate for an infant with suspected meningitis from the cases described?
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What is the significance of E.coli being resistant to trimethoprim in the second case scenario?
What is the significance of E.coli being resistant to trimethoprim in the second case scenario?
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Why is nitrofurantoin not suitable in the second case for the treatment of pyelonephritis?
Why is nitrofurantoin not suitable in the second case for the treatment of pyelonephritis?
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Which virulence factor of Enterobacterales is primarily responsible for helping bacteria avoid phagocytosis?
Which virulence factor of Enterobacterales is primarily responsible for helping bacteria avoid phagocytosis?
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What is the role of Lipopolysaccharide (LPS) in the pathogenicity of Enterobacterales?
What is the role of Lipopolysaccharide (LPS) in the pathogenicity of Enterobacterales?
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In the context of Enterobacterales, what does the term 'facultative anaerobes' indicate?
In the context of Enterobacterales, what does the term 'facultative anaerobes' indicate?
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What is a significant consequence of the endotoxin release from Lipopolysaccharide during an infection?
What is a significant consequence of the endotoxin release from Lipopolysaccharide during an infection?
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Which characteristic of the Enterobacterales' cell wall significantly contributes to its overall structural integrity?
Which characteristic of the Enterobacterales' cell wall significantly contributes to its overall structural integrity?
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Which group of bacteria within Enterobacterales is primarily considered important for enteric infections?
Which group of bacteria within Enterobacterales is primarily considered important for enteric infections?
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What does the term 'motile with flagellae' imply about Enterobacterales?
What does the term 'motile with flagellae' imply about Enterobacterales?
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What type of response does the activation of cytokines due to endotoxin release typically result in?
What type of response does the activation of cytokines due to endotoxin release typically result in?
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Which of the following statements accurately describes the Enterobacterales family?
Which of the following statements accurately describes the Enterobacterales family?
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What plays a significant role in the pathogenesis of infections caused by Pseudomonas species?
What plays a significant role in the pathogenesis of infections caused by Pseudomonas species?
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Which approach is most effective in preventing the spread of infections caused by clinically important Enterobacterales?
Which approach is most effective in preventing the spread of infections caused by clinically important Enterobacterales?
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Which characteristic distinguishes Enterobacterales in a laboratory diagnosis?
Which characteristic distinguishes Enterobacterales in a laboratory diagnosis?
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In terms of clinical significance, which complication is often associated with infections caused by Enterobacterales?
In terms of clinical significance, which complication is often associated with infections caused by Enterobacterales?
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Which of the following best explains the increasing antibiotic resistance observed in Enterobacterales?
Which of the following best explains the increasing antibiotic resistance observed in Enterobacterales?
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Which key factor is crucial for effectively treating infections caused by clinically important Enterobacterales?
Which key factor is crucial for effectively treating infections caused by clinically important Enterobacterales?
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What is the primary function of coliforms among the Enterobacterales?
What is the primary function of coliforms among the Enterobacterales?
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What laboratory result is significant in diagnosing the second case scenario?
What laboratory result is significant in diagnosing the second case scenario?
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Which empiric treatment is recommended for a patient with pyelonephritis and E.coli susceptible to cefuroxime?
Which empiric treatment is recommended for a patient with pyelonephritis and E.coli susceptible to cefuroxime?
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Which symptom would most likely indicate a progression of infection in the first case scenario?
Which symptom would most likely indicate a progression of infection in the first case scenario?
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What is the most critical initial microbiology investigation for a patient with suspected pyelonephritis in the second case scenario?
What is the most critical initial microbiology investigation for a patient with suspected pyelonephritis in the second case scenario?
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In the third case scenario, which pathogens are the most common causative organisms for meningitis in a 2-day-old baby?
In the third case scenario, which pathogens are the most common causative organisms for meningitis in a 2-day-old baby?
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What is a key concern regarding the management of the patient in the second case scenario?
What is a key concern regarding the management of the patient in the second case scenario?
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In the context of antibiotic susceptibility, what would the resistance of E.coli to trimethoprim indicate for treatment choices?
In the context of antibiotic susceptibility, what would the resistance of E.coli to trimethoprim indicate for treatment choices?
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Which aspect of the CSF laboratory report is integral for diagnosing meningitis in the third case scenario?
Which aspect of the CSF laboratory report is integral for diagnosing meningitis in the third case scenario?
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Study Notes
Enterobacteriaceae
- A family of gram-negative rod-shaped bacteria
- Commonly found in the intestines (GIT)
- Often responsible for intra-abdominal, respiratory tract, and bloodstream infections
- A common cause of antibiotic resistance
- Beta-lactamase production
- Includes extended-spectrum beta-lactamases (ESBLs)
- Beta-lactamase production
Enterobacteriaceae: Classification
- Escherichia coli & Klebsiella spp. are important pathogens.
- Proteus spp., Serratia spp., Enterobacter spp., and Citrobacter spp. are less important pathogens.
- Salmonella spp., Shigella spp. and Yersinia spp. are covered in future lectures.
- Toxin-producing E.coli is important and is covered in Enteric infections.
Enterobacteriaceae: Microbiology
- Most are motile with flagellae.
- Facultative anaerobes (can survive with or without oxygen).
- Ferment glucose and other carbohydrates.
- Can be lactose fermenters or non-lactose fermenters.
Enterobacteriaceae: Structure
- The cell wall contains lipopolysaccharide (LPS) O-antigen.
- The capsule contains K-antigen.
- Fimbriae and flagella are present (H-antigen).
- LPS is composed of O-side-chains and lipid A.
Enterobacteriaceae: Pathogenesis
- Enterobacteriaceae can infect via contact, environment, and AMR.
- They use adhesins and pili to attach to cells.
- LPS and toxins damage host cells.
- Capsular structures help evade the immune system.
- Enterobacteriaceae can spread further after gaining access to the host.
Enterobacteriaceae: Virulence Factors
- Adhesins: Aid in binding to host cells, e.g., fimbriae.
- Capsules: Help avoid phagocytosis but are poor immunogens.
- Lipopolysaccharide: A potent inducer of the host immune response via endotoxin release (lipid A).
- Endotoxin activates complement, cytokines, and WBCs.
- Can lead to decreased platelet count, disseminated intravascular coagulation (DIC), fever, hypotension, and death.
- Toxins: e.g., haemolysins of E.coli.
- Antimicrobial resistance: e.g., via plasmid exchange.
Case Scenario 1: Urinary Tract Infection (UTI)
- Presenting symptoms: Urinary frequency, dysuria, otherwise systemically well.
- Diagnosis: Cystitis (most likely).
- Empiric treatment: Nitrofurantoin, Trimethoprim, or Fosfomycin.
- Laboratory findings: Urine white cell count >100/µl.
- Outcome: E.coli isolated from urine, susceptible to Nitrofurantoin and Trimethoprim. Symptoms resolved with a 3-day course of nitrofurantoin.
Case Scenario 2: Pyelonephritis
- Presenting symptoms: Vomiting, left flank pain, temperature of 38.8 °C.
- Diagnosis: Pyelonephritis (most likely).
- Important microbiology investigations: MSU and blood cultures.
- Empiric treatment: IV Cefuroxime +/- Gentamicin.
- Laboratory findings: Urine white cell count >100/µl.
- Outcome: Escherichia coli isolated from urine, resistant to Trimethoprim/Co-amoxiclav but susceptible to Nitrofurantoin, Cefuroxime, and Gentamicin.
Case Scenario 3: Neonatal Meningitis
- Presenting symptoms: Tachypnoea, feeding poorly, irritable when handled.
- Diagnosis: Meningitis suspected.
- Most likely causative pathogen: E.coli.
- Empiric treatment: IV Cefotaxime/Amoxicillin/Gentamicin.
- Laboratory findings: CSF white cell count 600/µl.
Pseudomonas spp. & Related Genera
- Pseudomonas spp. are covered in a separate lecture.
Enterobacterales
- A family of gram-negative bacilli (rod-shaped)
- Found in the intestines
- Common causes of intra-abdominal, respiratory tract & bloodstream infections
- Increasing antibiotic resistance:
- Beta-lactamase production including extended-spectrum beta-lactamases (ESBLs)
Enterobacterales: Classification
- Important organisms: Escherichia coli, Klebsiella spp., Proteus spp.
- Less important pathogens (not normal flora): Serratia spp., Enterobacter spp., Citrobacter spp.
- Important, covered in next lecture: Salmonella spp., Shigella spp., Yersinia spp., Toxin-producing E.coli
Enterobacterales: Microbiology
- Most are motile with flagellae
- Facultative anaerobes
- Ferment glucose and other carbohydrates
- May be lactose fermenters or non-lactose fermenters
Enterobacterales: Structure
- Cell wall: Contains lipopolysaccharide O-antigen
- Capsule: Contains K-antigen
- Fimbriae: Small hair-like structures
- Flagella: Tail-like structures (H-antigen)
Enterobacterales: Pathogenesis
- Gets in: Portal of entry is often contact, environment, or AMR
- Gets out & spreads further: Adhesins, pili, LPS, toxins
- Attaches to cells: Adhesins, pili
- Causes damage to host cells: LPS, toxins
- Defeats/evades the immune system: Capsule
Virulence Factors
- Adhesins: Help bacteria bind to host cells e.g. fimbriae
- Capsules: Help bacteria avoid phagocytosis, but are poor immunogens
-
Lipopolysaccharide (LPS): Potent inducer of the host immune response via endotoxins release (lipid A)
- Endotoxin: Activates complement, cytokines & WBCs, decreases in platelets, results in DIC (Disseminated Intravascular Coagulation), fever, hypotension, and death
- Toxins: e.g. haemolysins of E.coli
- Antimicrobial resistance: Through plasmid exchange
Case Scenario 1
- Presenting symptoms: Urinary frequency & dysuria
- Most likely diagnosis: Cystitis
- Empiric treatment: Nitrofurantoin PO for 3 days, Trimethoprim PO for 3 days, Fosfomycin single dose
- Laboratory Report: Urine white cell count >100/µl, E.coli isolated from urine
Case Scenario 2
- Presenting symptoms: Vomiting, left flank pain, temperature of 38.8oC
- Most likely diagnosis: Pyelonephritis
- Most important microbiology investigations: MSU & Blood cultures
- Empiric treatment: IV Cefuroxime +/- Gentamicin
- Laboratory Report: Urine white cell count >100/µl, Escherichia coli isolated from urine
Case Scenario 3
- Presenting symptoms: Tachypnoea, feeding poorly, irritable when handled
- Most likely cause: E.coli
- Empiric treatment: IV Ceotaxime/Amoxicillin/Gentamicin
- Laboratory Report: CSF white cell count 600/µl (normally 0-5/µl)
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Description
This quiz covers key concepts related to the Enterobacteriaceae family of bacteria, including their classification, microbiological characteristics, and significance in infections. It highlights important pathogens, their antibiotic resistance mechanisms, and unique features such as motility and fermentation abilities.
