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Questions and Answers
What differentiates pathogenic strains of E.coli from commensal strains?
Which of the following is a leading cause of community-acquired urinary tract infections (CA-UTIs)?
Which symptom is NOT typically associated with cystitis?
What is the primary role of type 1 fimbriae in uropathogenic E.coli (UPEC)?
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In diagnosing urinary tract infections, which urine dipstick result is indicative of UTI presence?
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What is a common complication of untreated pyelonephritis?
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Which type of diarrhea is primarily caused by E.coli in travelers?
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What is the significance of identifying a pathogen with over 100,000 cfu/ml in a midstream urine sample?
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What distinguishes primary pathogens in the Enterobacteriaceae family from opportunistic pathogens?
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Which type of gastroenteritis is most commonly caused by Enterobacteriaceae?
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Which of the following measures can help prevent infections caused by Enterobacteriaceae?
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Which diagnostic method is most effective for identifying Escherichia coli in clinical specimens?
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What is a common complication associated with urinary tract infections caused by Enterobacteriaceae?
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Which of the following species is classified as a primary pathogen within the Enterobacteriaceae family?
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What physiological characteristic is common among Enterobacteriaceae?
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Which feature of the Enterobacteriaceae outer membrane aids in nutrient transport?
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What distinguishes invasive gastroenteritis from non-invasive gastroenteritis based on stool examination?
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Which Klebsiella species is primarily responsible for antibiotic-related colitis?
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What is a distinctive feature of pneumonia caused by Klebsiella pneumoniae?
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Which diagnostic method can identify the presence of various pathogens in fecal samples?
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What is a key virulence factor of Klebsiella pneumoniae that complicates its treatment?
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Given the patient's condition, which of the following biological samples would be the most appropriate for microbiological studies in suspected urinary tract infection?
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In the case of a patient developing malodorous diarrhea after being placed on Ceftriaxone, which type of infection should be considered?
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What underlying condition in the hypothetical patient increases the risk for urinary tract infections?
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Study Notes
Enterobacteriaceae
- Large family of gram-negative bacilli, over 50 genera and hundreds of species.
- Ubiquitous in nature, found in water, soil, vegetation, and the gastrointestinal tract of animals and humans.
- Major cause of bacteremia, urinary tract infections, intra-abdominal infections, pneumonia, gastroenteritis, and other infections.
Escherichia coli
- Most common gram-negative bacillus isolated from patients with sepsis.
- Leading cause of community-acquired (CA) and hospital-acquired (HA) urinary tract infections (UTIs).
- One of the most frequent causes of gastroenteritis.
- A major cause of traveler's diarrhea.
- Second cause of neonatal meningitis (after Streptococcus agalactiae).
Uropathogenic E. coli (UPEC)
- Frequently produce P-fimbriae or type 1 fimbriae.
- Colonize the urethra and ascend to the bladder leading to cystitis (1 in 2 women will experience at least one episode).
- Can ascend to the kidneys causing pyelonephritis.
Infections
- Cystitis: Dysuria, urinary urgency, smelly urine, possibly bloody. Does not usually cause high fever.
- Pyelonephritis: High fever, chills, vomiting, pain in the costovertebral angle (Giordano's sign).
- Pyelonephritis: A serious infection, may lead to bacteremia and sepsis.
UPEC Adherence and Biofilm Formation
- Type 1 fimbriae bind to the bladder epithelium.
- UPEC bind to epithelial cells and form a biofilm.
- Deletion of type 1 fimbriae prevents adherence and biofilm formation.
- Urine flow does not effectively clear bacterial colonies.
- UPEC can invade the bladder epithelium, leading to inflammation and urinary tract infection.
Diagnosing UTIs
- Costovertebral tenderness: May indicate pyelonephritis.
- Giordano sign: Pain in the costovertebral angle, suggests pyelonephritis.
- Urine dipstick: Positive for white blood cells (WBCs), possibly red blood cells (RBCs), nitrates, and leukocyte esterase.
- Urinalysis: WBCs, possibly RBCs, and microorganisms.
- Urine culture: Midstream urine sample identifies pathogens. Greater than 100,000 colony-forming units (cfu) per milliliter is significant.
Klebsiella
- Four species cause human disease: Klebsiella pneumoniae, K. oxytoca, K. granulomatis, and K. rhinoscleromatis.
- Klebsiella pneumoniae: Causes lobar necrotic pneumonia, UTIs, liver abscesses, septicemia in hospitalized patients, wound infections, intra-abdominal infections, and others.
- Klebsiella oxytoca: Causes antibiotic-related colitis.
- K. pneumoniae pneumonia: Distinctive features include severity, susceptibility in alcoholics, frequent upper lobe involvement, abscess formation, and production of "currant jelly" sputum (hemoptysis).
- Klebsiella pneumoniae: One of the most resistant nosocomial bacteria, frequently a Carbapenem-resistant Enterobacteriaceae (CRE).
Critical Thinking
- 80-year-old bedridden patient with a urinary catheter, high fever, disorientation, confusion, and low blood pressure.
- Admission: Required due to high fever, disorientation, confusion, and low blood pressure.
- Infection: Likely due to urinary catheterization and symptoms.
- Biological samples: Blood, urine, and any potential sources of infection (urinary catheter, wound drainage, etc.).
- Ceftriaxone: A broad-spectrum antibiotic.
- Day 3 - fever and diarrhea: May indicate a new infection; potential sources include Clostridium difficile, Klebsiella, or other bacteria.
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Description
Explore the diverse family of Enterobacteriaceae and the prominent role of Escherichia coli in human health. This quiz covers the pathogenicity of Uropathogenic E. coli and its implications in various infections like UTIs and gastroenteritis. Test your knowledge on these critical topics in microbiology.
