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Chapter 79. Urinary Tract Infections and Prostatitis

Student Questions

Which of the following is the most common bacterial cause of acute cystitis in a healthy, 22-year-old woman?

A. Klebsiella pneumoniae

B. Escherichia coli

C. Staphylococcus saprophyticus

D. Proteus mirabilis

Answer: B

Option A: Incorrect. Klebsiella, Proteus, and Staphylococcus saprophyticus are all known to cause UTIs, but their combined incidence is 10% to 20%, making them much less common causes than E. coli.

Option B: Correct. Although all of the listed answers are known to cause UTIs, E. coli is by far the most common, causing more than 80% of cases of acute cystitis.

Option C: Incorrect. Klebsiella, Proteus, and Staphylococcus saprophyticus are all known to cause UTIs, but their combined incidence is 10% to 20%, making them much less common causes than E. coli.

Option D: Incorrect. Klebsiella, Proteus, and Staphylococcus saprophyticus are all known to cause UTIs, but their combined incidence is 10% to 20%, making them much less common causes than E. coli.

Which of the following best represents a first-line empiric treatment for acute cystitis in an otherwise healthy, nonpregnant female?

A. Trimethoprim/sulfamethoxazole 1 DS tablet by mouth every 12 hours for 5 days

B. Fosfomycin 3 grams orally as a one-time dose

C. Nitrofurantoin 100 mg by mouth every 12 hours for 7 days

D. Amoxicillin 500 mg by mouth every 8 hours for 7 days

Answer: B

Option A: Incorrect. Trimethoprim/sulfamethoxazole is an appropriate option, but a 3-day treatment is recommended.

Option B: Correct. Fosfomycin is considered a first-line treatment option as a one-time dose, so this is the best answer.

Option C: Incorrect. Nitrofurantoin is also an appropriate empiric treatment, but 5 days is recommended.

Option D: Incorrect. Amoxicillin is no longer recommended for empiric therapy due to high resistance and low efficacy.

In order for trimethoprim/sulfamethoxazole to be a viable first-line option for the empiric treatment of acute cystitis, resistance of E. coli should be less than which of the following percentages?

A. 5%

B. 10%

C. 20%

D. 25%

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