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What is the leading cause of venereal warts?
Which physical findings are commonly associated with pelvic inflammatory disease (PID)?
When should a urine culture be ordered?
What do 105 CFU/mL represent in a urine culture?
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How do the VDRL and RPR tests differ from the FTA-ABS test?
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Which symptoms differentiate upper tract infections like pyelonephritis from lower tract infections like cystitis?
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Which organism is most likely to cause acute prostatitis?
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What can be a consequence of delayed treatment for urethritis in women?
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What is an important factor that can help prevent urinary tract infections?
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What is a mechanical issue that can increase the risk of upper tract disease?
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What is a common risk factor for urinary tract infections (UTIs) in women?
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How often do women experience a urinary tract infection (UTI) by the age of 32?
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What is the primary mechanism through which bacteria typically enter the urinary tract?
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Which of the following immunoglobulins has been described in relation to UTI prevention?
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Which strain of Escherichia coli is most commonly associated with urinary tract infections?
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What contributes to the increased incidence of UTI in women compared to men?
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What activity is considered a risk factor for trauma to the urethra in women?
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What virulence characteristic enhances the ability of certain E. coli strains to adhere to uroepithelial cells?
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Which agent is used to prevent urinary tract infections by reducing fimbria adhesion molecule expression?
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Which of these organisms is associated with causing stone formation?
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What factor contributes to the survival and growth of urinary pathogens in the urine?
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What is the estimated incidence of UTI in women annually?
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Which of the following factors is least likely to affect the development of a symptomatic urinary tract infection?
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What role do immunoglobulins play in urinary tract health?
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What mechanism plays a significant role in UTI development in women?
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What is the role of fimbria in E. coli pathogenesis in urinary tract infections?
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Which of the following is a unique feature of pyelonephritis strains of E. coli compared to cystitis strains?
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What is a major consequence of the balance between bacterial virulence factors and host capabilities?
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What characteristic is associated with the adherence capabilities of E. coli during urinary infections?
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Which factor increases the likelihood of renal stones in the presence of Proteus mirabilis?
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What role does IgA protease play in the infection process of Proteus mirabilis?
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How does urine composition generally impact bacterial growth in healthy individuals?
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Which mechanical factor significantly increases the risk of urinary tract infection (UTI)?
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What physiological condition associated with pregnancy contributes to an increased incidence of UTIs?
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Which of the following statements about flagella expression in bacteria is TRUE?
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What is the primary role of endotoxins in the development of pyelonephritis?
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Which host factor is NOT associated with an increased incidence of UTIs?
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What effect does the presence of renal calculi have on the urinary tract?
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Which of the following describes the role of motile bacteria with flagella in the urinary tract?
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Study Notes
Pathogenesis of UTIs
- The balance between bacterial virulence factors and host factors determines the development of UTIs.
- Bacteria typically ascend the urethra into the bladder and can reach the renal parenchyma through the ureters.
- The most common UTI culprit is Escherichia coli, which possesses virulence factors like:
- Increased adhesion to urethral epithelial cells
- Resistance to serum cidal activity
- Hemolysin production
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E. coli adheres through fimbriae or pili on the bacterial surface.
- Pyelonephritis strains have high adherence due to their expression of P fimbriae, which target glycophospholipids in uroepithelial cell membranes.
- Cystitis strains have intermediate adherence.
- Trimethoprim-sulfamethoxazole (TMP-SMX) can reduce the synthesis and expression of fimbria adhesion molecules.
- Other virulence factors include:
- Production of essential nutritional factors for bacterial growth in urine (guanine, arginine, glutamine).
- Proteus mirabilis produces urease, which increases urine pH, enhancing bacterial growth and potentially leading to renal stones.
- Proteus also produces IgA protease and hemolysin.
- Motile bacteria with flagella can ascend the ureter against urine flow.
- Endotoxins from gram-negative bacteria can contribute to pyelonephritis by decreasing ureteral peristalsis, leading to urinary stasis and facilitating bacterial ascent to the kidneys.
Host Factors
- Urine's high urea concentration and low pH generally inhibit bacterial growth.
- Pregnant women have urine more conducive to bacterial growth, increasing their UTI risk.
- Diabetic patients often have glucose in their urine, creating a favorable medium for bacterial growth.
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Mechanical factors are crucial:
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Obstruction:
- Urinary flow obstruction is a major predisposing factor for UTIs.
- Benign prostatic hypertrophy, urethral strictures, and defective bladder contraction (e.g., in spinal cord injury) can lead to bladder outlet obstruction, increasing post-void residual urine and UTI risk.
- Intrarenal obstruction due to renal calculi, polycystic kidney disease, and sickle cell disease also elevate the risk of renal infection.
- Proteus and urea-splitting organisms can cause stone formation and become entrapped within the stones.
- Vesicoureteral reflux (defective bladder-ureteral valves) increases the risk of upper tract infection.
- Urethra Length: Women have a shorter urethra, increasing their susceptibility to bacterial entry into the bladder.
- Trauma & Colonization: Trauma to the urethra (e.g., sexual intercourse, spermicide use) and history of UTI are risk factors. Colonization of the vaginal area near the urethra is another important risk factor for UTIs in women.
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Obstruction:
- Immunological Factors: IgA and IgG antibodies against bacterial cell wall antigens have been described, but their role in protecting against colonization and invasion of the urinary tract is still being explored.
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Description
Explore the intricate details of UTI pathogenesis, focusing on the role of bacterial virulence factors and host defenses. This quiz delves into how Escherichia coli adheres to the urinary tract and the factors influencing UTI development. Understand the significance of treatment options like TMP-SMX in managing these infections.
