Urinary Tract Infections — MCQs
A boy is suffering from acute pyelonephritis. The most specific investigation to confirm the diagnosis is:
Which one of the following gram-positive organisms is the most common cause of UTI among sexually active women?
A 25 year old female, presents to the clinic with dysuria, urinary frequency and urgency. After a laboratory workup a diagnosis of cystitis is made. Which is the first line drug for the treatment for this patient?
A man presents with a history of dysuria and urethral discharge after having unprotected sexual intercourse. What is the treatment of choice for this infection?
An 8-year-old boy during a routine checkup is found to have E. coli 100,000 CFU/mL on a urine culture, obtained by mid-stream clean-catch void. The child is asymptomatic. Which is the most appropriate next step in the management?
A 58-year-old man with a history of smoking presents with hematuria. What is the most likely diagnosis?
Following urinary tract infection associated with extraction of a bladder stone, a 64-year-old woman developed gram-negative septicemia. Which statement is true for gram-negative bacterial septicemia?
Which of the following types of kidney stones are commonly associated with urinary tract infections?
What is the most common presentation for IgA nephropathy?
Struvite stones are primarily composed of which metal?
Urinary Tract Infections Indian Medical PG Practice Questions and MCQs
Question 1: A boy is suffering from acute pyelonephritis. The most specific investigation to confirm the diagnosis is:
- A. Urine culture (Correct Answer)
- B. Leucocyte esterase test
- C. Nitrite test
- D. Bacteria in gram stain
Explanation: Urine culture - A **urine culture** is considered the gold standard for diagnosing urinary tract infections, including pyelonephritis, as it identifies the specific **pathogen** and its **antibiotic susceptibility** [1]. - It quantifies the number of bacteria present (colony-forming units/mL), confirming significant bacteriuria indicative of infection [2]. *Leucocyte esterase test* - The **leucocyte esterase test** detects enzymes produced by neutrophils, indicating the presence of **white blood cells (pyuria)** in the urine. - While suggestive of inflammation and infection, it is not specific to pyelonephritis and can be positive in other conditions like cystitis or contamination. *Nitrite test* - The **nitrite test** detects nitrites produced by some gram-negative bacteria (e.g., *E. coli*) that convert urinary nitrates to nitrites. - A positive result suggests bacteriuria but is not specific, as some pathogens do not produce nitrite, and it doesn't quantify bacterial load or identify the organism. *Bacteria in gram stain* - Direct visualization of **bacteria in a Gram stain** of uncentrifuged urine can indicate bacteriuria, especially if numerous organisms are seen [1]. - However, it provides preliminary information and cannot definitively identify the species, quantify bacterial load, or determine antibiotic sensitivity, which are crucial for confirming pyelonephilitis and guiding treatment [1].
Question 2: Which one of the following gram-positive organisms is the most common cause of UTI among sexually active women?
- A. Staphylococcus aureus
- B. Staphylococcus saprophyticus (Correct Answer)
- C. Enterococcus
- D. Staphylococcus epidermidis
Explanation: ***Staphylococcus saprophyticus*** - This organism is a common cause of **urinary tract infections (UTIs)**, particularly in sexually active young women. - It is known for its ability to adhere to uroepithelial cells and is **novobiocin-resistant**, distinguishing it from other coagulase-negative staphylococci. *Staphylococcus aureus* - While *Staphylococcus aureus* can cause UTIs, it's typically associated with **catheter-associated infections** or hematogenous spread, not primarily UTIs in sexually active women. - It is a **coagulase-positive** staphylococcus and often linked to more severe infections. *Enterococcus* - **Enterococci**, such as *Enterococcus faecalis*, are a common cause of UTIs, especially in hospitalized patients or those with urinary tract abnormalities. - However, they are less frequently the primary cause in otherwise healthy, sexually active women compared to *S. saprophyticus*. *Staphylococcus epidermidis* - *Staphylococcus epidermidis* is part of the normal skin flora and is a common **contaminant** in urine cultures. - It infrequently causes true UTIs and is generally only pathogenic in immunocompromised individuals or those with **indwelling medical devices**.
Question 3: A 25 year old female, presents to the clinic with dysuria, urinary frequency and urgency. After a laboratory workup a diagnosis of cystitis is made. Which is the first line drug for the treatment for this patient?
- A. Cephalexin
- B. Norfloxacin
- C. Amoxicillin
- D. Nitrofurantoin (Correct Answer)
Explanation: ***Nitrofurantoin*** - **Nitrofurantoin** is the most widely recommended first-line antibiotic for uncomplicated **cystitis** due to its excellent efficacy against common urinary pathogens, especially **E. coli**. - It achieves high concentrations in the urine and has a low rate of resistance, making it an excellent choice for this condition. - It is preferred over other antibiotics due to antimicrobial stewardship principles and minimal impact on gut flora. *Cephalexin* - While generally effective against some urinary pathogens, **cephalexin** is typically reserved as a second-line agent for uncomplicated cystitis, particularly if there are contraindications to or resistance to first-line agents. - Its broad-spectrum activity may contribute to increased resistance development if used routinely as first-line. *Norfloxacin* - **Norfloxacin** is a **fluoroquinolone** that, while effective for UTIs and sometimes used in regional practice, is generally not recommended as the preferred first-line for uncomplicated cystitis due to concerns about increasing antibiotic resistance and potential for serious side effects (e.g., tendinitis, QT prolongation, CNS effects). - Current antimicrobial stewardship guidelines recommend reserving fluoroquinolones for more complicated urinary tract infections or when other first-line options are not suitable. *Amoxicillin* - **Amoxicillin** is generally not recommended as a first-line agent for cystitis due to high rates of **bacterial resistance**, particularly among **E. coli** strains, which are the most common cause of UTIs. - Its efficacy against common urinary pathogens is often lower compared to other first-line options.
Question 4: A man presents with a history of dysuria and urethral discharge after having unprotected sexual intercourse. What is the treatment of choice for this infection?
- A. Erythromycin
- B. Azithromycin
- C. Ceftriaxone (Correct Answer)
- D. Penicillin G
Explanation: ***Ceftriaxone*** - The combination of **dysuria** and **urethral discharge** following unprotected sexual intercourse is highly suggestive of **gonorrhea**. - **Ceftriaxone** is the recommended first-line treatment for uncomplicated gonococcal infections due to increasing antibiotic resistance. *Erythromycin* - Erythromycin is primarily used for atypical bacterial infections, such as those caused by *Mycoplasma pneumoniae* or *Chlamydia trachomatis*. - While it can be used for chlamydia, it is not the preferred treatment for suspected gonorrhea. *Azithromycin* - Azithromycin is often used in combination with ceftriaxone for gonorrhea to cover potential co-infection with **Chlamydia trachomatis**. - However, **monotherapy with azithromycin is not recommended for gonorrhea** due to concerns about emerging resistance and suboptimal efficacy. *Penicillin G* - Penicillin G was historically used to treat gonorrhea, but this is no longer the case due to widespread **resistance** of *Neisseria gonorrhoeae* strains. - Its primary use now is for susceptible bacterial infections, such as syphilis and certain streptococcal infections.
Question 5: An 8-year-old boy during a routine checkup is found to have E. coli 100,000 CFU/mL on a urine culture, obtained by mid-stream clean-catch void. The child is asymptomatic. Which is the most appropriate next step in the management?
- A. Prophylactic antibiotics for 6 months
- B. Administer long term urine alkalinizer
- C. Treat as an acute episode of urinary tract infection
- D. No therapy (Correct Answer)
Explanation: ***No therapy*** - The presence of **bacteria** in the urine (**bacteriuria**) without any accompanying symptoms like fever, dysuria, or flank pain is defined as **asymptomatic bacteriuria (ASB)**. - In healthy, asymptomatic children, ASB generally requires **no antibiotic treatment**, as it rarely progresses to symptomatic infection or causes renal damage and may even protect against symptomatic UTIs by competitive inhibition. *Treat as an acute episode of urinary tract infection* - This child is **asymptomatic,** therefore, he does not have an acute urinary tract infection (UTI). - Treating asymptomatic bacteriuria can lead to **antibiotic resistance** and unnecessary side effects without clinical benefit. *Prophylactic antibiotics for 6 months* - **Prophylactic antibiotics** are reserved for children with recurrent symptomatic UTIs or significant anatomical abnormalities like **vesicoureteral reflux (VUR)**, which are not indicated here. - Using long-term antibiotics in an asymptomatic child can contribute to the development of **antibiotic-resistant organisms**. *Administer long term urine alkalinizer* - **Urine alkalinizers** are used in specific conditions like certain types of **kidney stones (e.g., uric acid stones)** or to enhance the excretion of certain drugs, not for asymptomatic bacteriuria. - There is **no evidence** to support the use of urine alkalinizers in managing asymptomatic bacteriuria or preventing UTIs.
Question 6: A 58-year-old man with a history of smoking presents with hematuria. What is the most likely diagnosis?
- A. Bladder cancer (Correct Answer)
- B. Renal cyst
- C. Pyelonephritis
- D. Prostate cancer
Explanation: ***Bladder cancer*** - **Smoking** is the strongest risk factor for bladder cancer, and **painless hematuria** is its most common presenting symptom [1]. - The combination of a long-term smoker and gross hematuria makes this the most concerning diagnosis [1]. *Renal cyst* - **Renal cysts** are typically asymptomatic and rarely cause gross hematuria unless they are large, complicated, or rupture. - While common, they are less likely to be the cause of hematuria in a smoker without other symptoms. *Pyelonephritis* - **Pyelonephritis** is an upper urinary tract infection characterized by fever, flank pain, dysuria, and often microscopic hematuria, but gross hematuria is less common. - This patient presents with hematuria without signs of infection. *Prostate cancer* - **Prostate cancer** usually presents with urinary obstructive symptoms (e.g., hesitancy, weak stream, nocturia) or is found incidentally on screening. - While microscopic hematuria can occur, gross hematuria as the sole presenting symptom is rare.
Question 7: Following urinary tract infection associated with extraction of a bladder stone, a 64-year-old woman developed gram-negative septicemia. Which statement is true for gram-negative bacterial septicemia?
- A. Many of the adverse changes can be accounted for endotoxin release. (Correct Answer)
- B. Pseudomonas is the most common organism isolated.
- C. Central venous pressure (CVP) is high.
- D. The cardiac index is low.
Explanation: ***Many of the adverse changes can be accounted for endotoxin release.*** - Gram-negative bacteria contain **lipopolysaccharide (LPS)** in their outer membrane, which acts as an **endotoxin**. - During infection and bacterial lysis, **LPS** is released, triggering a severe inflammatory response leading to **septic shock**, **coagulopathy**, and **organ dysfunction**. *Pseudomonas is the most common organism isolated.* - While *Pseudomonas aeruginosa* can cause severe infections, **Escherichia coli** is the most common gram-negative bacterium isolated in cases of **septicemia** originating from the urinary tract [1]. - Other common culprits include **Klebsiella pneumoniae** and **Proteus mirabilis**. *Central venous pressure (CVP) is high.* - In **septic shock**, patients typically exhibit **vasodilation** and **capillary leak**, leading to **hypovolemia** and a **low CVP**, indicating reduced preload. - A high CVP would suggest fluid overload or right heart failure, which is not typical in the initial stages of gram-negative septicemia. *The cardiac index is low.* - **Septic shock** is characterized by an initial phase of **hyperdynamic circulation**, where the **cardiac index** is often **high** due to decreased systemic vascular resistance and increased cardiac output striving to maintain perfusion. - While prolonged or severe shock can eventually lead to myocardial depression and a reduced cardiac index, the initial response is typically hyperdynamic.
Question 8: Which of the following types of kidney stones are commonly associated with urinary tract infections?
- A. Struvite stones (Correct Answer)
- B. Cystine stones
- C. Xanthine stones
- D. Calcium oxalate stones
Explanation: ***Struvite stones*** - **Struvite stones** (magnesium ammonium phosphate) are strongly associated with **urinary tract infections (UTIs)** caused by urease-producing bacteria like *Proteus* and *Klebsiella*. - These bacteria hydrolyze urea into ammonia and carbon dioxide, increasing urine pH and promoting the precipitation of struvite, often forming **staghorn calculi** [1]. *Cystine stones* - **Cystine stones** are caused by a **genetic defect** in amino acid transport, leading to increased excretion of cystine, ornithine, lysine, and arginine (COLA) in the urine. - They are not directly associated with UTIs but rather with a rare inherited metabolic disorder called **cystinuria**. *Xanthine stones* - **Xanthine stones** are very rare and typically occur in individuals with **xanthinuria**, a genetic disorder characterized by a deficiency in xanthine oxidase. - They are also not linked to UTIs but are a consequence of abnormal purine metabolism. *Calcium oxalate stones* - **Calcium oxalate stones** are the most common type of kidney stone, resulting from high levels of calcium and oxalate in the urine, often due to dietary factors, malabsorption, or idiopathic hypercalciuria. - While UTIs can complicate any kidney stone, **calcium oxalate stones** are not primarily *caused* by UTIs. [1]
Question 9: What is the most common presentation for IgA nephropathy?
- A. Nephritic syndrome
- B. Nephrotic syndrome
- C. Microscopic hematuria
- D. Repeated gross hematuria (Correct Answer)
Explanation: ***Repeated gross hematuria*** - The hallmark of **IgA nephropathy** is recurrent episodes of **gross hematuria**, particularly following **respiratory infections** [1]. - It is often associated with **renal impairment** but can present initially with **visible blood** in the urine [1]. *Nephritic syndrome* - While IgA nephropathy can lead to nephritic features, it does not commonly present primarily as **nephritic syndrome**, which includes hypertension and edema. - Nephritic syndrome is characterized by significant **proteinuria** and acute renal failure, rather than the classic presentation of hematuria [2]. *Microscopic hematuria* - Although **microscopic hematuria** can occur in IgA nephropathy, it is not the most common and noticeable presentation; **gross hematuria** is more characteristic [1]. - Microscopic hematuria lacks the acute visual symptoms seen in cases proving the diagnosis. *Nephritic syndrome* - This option is a repetition of and does not provide any additional unique characteristics specific to **IgA nephropathy**. - It shares the same clinical features discussed previously and is thus not representative of the most common presentation.
Question 10: Struvite stones are primarily composed of which metal?
- A. Magnesium (Correct Answer)
- B. Calcium
- C. Sodium
- D. Potassium
Explanation: ***Magnesium*** - **Struvite stones** are primarily composed of **magnesium ammonium phosphate**, formed in the presence of urease-producing bacteria. - The presence of magnesium is a defining component of these **infection-related stones**. *Calcium* - **Calcium** is the primary component of the most common type of kidney stones, **calcium oxalate** and **calcium phosphate stones**. - These are typically unrelated to bacterial infections, unlike struvite stones. *Sodium* - **Sodium** is not a primary component of any common type of kidney stone. - While high sodium intake can increase the risk of stone formation, it does not directly form the stone matrix. *Potassium* - **Potassium** is not a characteristic component of kidney stones. - It plays a role in urinary pH regulation but is not directly incorporated into stone formation.
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