Urinary tract anti-infective agents include antibiotics and urinary antiseptics used to prevent and treat infections of the urinary tract. B.Pharm students should master classification (nitrofurans, sulfonamides, trimethoprim, fluoroquinolones, beta-lactams, aminoglycosides, fosfomycin, methenamine), mechanisms of action, pharmacokinetics, renal dosing, resistance mechanisms and common adverse effects. Understanding spectrum against uropathogens, drug interactions, pregnancy and pediatric considerations, and antimicrobial stewardship is vital for rational therapy. This concise, clinically focused overview emphasizes classification, therapeutic choices and safety to prepare you for exams and practice. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. Which of the following is classified as a urinary antiseptic commonly used for lower urinary tract infections?
- Nitrofurantoin
- Ciprofloxacin
- Fosfomycin
- Gentamicin
Correct Answer: Nitrofurantoin
Q2. What is the principal mechanism of action of nitrofurantoin?
- Inhibition of folate synthesis by acting as a PABA analogue
- Reduced by bacterial flavoproteins to reactive intermediates that damage DNA
- Inhibition of DNA gyrase and topoisomerase IV
- Inhibition of MurA (enolpyruvyl transferase)
Correct Answer: Reduced by bacterial flavoproteins to reactive intermediates that damage DNA
Q3. Which agent is preferred as a safe single-dose option for uncomplicated cystitis in pregnancy?
- Nitrofurantoin
- Fosfomycin
- Trimethoprim
- Ciprofloxacin
Correct Answer: Fosfomycin
Q4. Fosfomycin exerts its antibacterial effect by which mechanism?
- Blockade of protein synthesis at 30S ribosomal subunit
- Inhibition of DNA gyrase
- Inhibition of MurA enzyme involved in peptidoglycan synthesis
- Disruption of bacterial cell membrane
Correct Answer: Inhibition of MurA enzyme involved in peptidoglycan synthesis
Q5. Methenamine is useful in urinary tract infection prophylaxis because it:
- Is a broad-spectrum systemic antibiotic
- Releases formaldehyde in acidic urine, acting as an antiseptic
- Inhibits bacterial DNA replication
- Blocks folate synthesis
Correct Answer: Releases formaldehyde in acidic urine, acting as an antiseptic
Q6. Sulfonamides inhibit bacterial growth by acting as analogues of which compound?
- Folic acid (dihydrofolate)
- Para-aminobenzoic acid (PABA)
- Uridine diphosphate (UDP)
- Peptidoglycan monomers
Correct Answer: Para-aminobenzoic acid (PABA)
Q7. Trimethoprim’s primary target in bacteria is:
- Dihydrofolate reductase
- RNA polymerase
- Topoisomerase IV
- Peptidyl transferase
Correct Answer: Dihydrofolate reductase
Q8. Which combination is classically synergistic for urinary infections by blocking sequential steps in folate synthesis?
- Trimethoprim + Nitrofurantoin
- Sulfonamide + Trimethoprim
- Fosfomycin + Methenamine
- Ciprofloxacin + Gentamicin
Correct Answer: Sulfonamide + Trimethoprim
Q9. Nitrofurantoin demonstrates good activity against which common uropathogen?
- Pseudomonas aeruginosa
- Escherichia coli
- Proteus mirabilis
- Serratia marcescens
Correct Answer: Escherichia coli
Q10. What is the usual oral dosage regimen for fosfomycin trometamol in uncomplicated cystitis?
- Single 3 g oral dose
- 500 mg twice daily for 7 days
- 1 g every 8 hours for 5 days
- 250 mg once daily for 3 days
Correct Answer: Single 3 g oral dose
Q11. Fluoroquinolones act by inhibiting which bacterial enzymes?
- Dihydrofolate reductase and dihydropteroate synthase
- DNA gyrase (topoisomerase II) and topoisomerase IV
- RNA polymerase and peptidyl transferase
- MurA and transpeptidase
Correct Answer: DNA gyrase (topoisomerase II) and topoisomerase IV
Q12. Which urinary anti-infective concentrates well in urine and is generally used only for lower urinary tract infections (not pyelonephritis)?
- Gentamicin
- Nitrofurantoin
- Meropenem
- Vancomycin
Correct Answer: Nitrofurantoin
Q13. Which class of urinary anti-infective is contraindicated in neonates due to risk of kernicterus (bilirubin displacement)?
- Sulfonamides
- Fosfomycin
- Methenamine
- Nitrofurantoin
Correct Answer: Sulfonamides
Q14. A serious adverse effect associated with fluoroquinolones is:
- Bone marrow suppression leading to aplastic anemia
- Tendonitis and tendon rupture
- Nephrotoxicity causing renal tubular acidosis
- Severe hemolysis in G6PD deficiency exclusively
Correct Answer: Tendonitis and tendon rupture
Q15. Methenamine’s antibacterial activity depends on:
- Renal tubular secretion by organic anion transporters
- Conversion to formaldehyde in acidic urine
- Inhibition of bacterial ribosomes
- Enhancement of host immune response
Correct Answer: Conversion to formaldehyde in acidic urine
Q16. Which urinary anti-infective class binds to the 30S ribosomal subunit and is used parenterally for severe UTI/pyelonephritis?
- Aminoglycosides (e.g., gentamicin)
- Beta-lactams (e.g., ampicillin)
- Fosfomycin
- Nitrofurantoin
Correct Answer: Aminoglycosides (e.g., gentamicin)
Q17. The most common molecular mechanism of resistance to trimethoprim is:
- Increased efflux pumps specific for trimethoprim
- Production of an altered dihydrofolate reductase enzyme
- Mutation in DNA gyrase genes
- Overproduction of PABA
Correct Answer: Production of an altered dihydrofolate reductase enzyme
Q18. Which urinary anti-infective is generally preferred when renal function is severely reduced (severe renal impairment)?
- Nitrofurantoin
- Fosfomycin
- Trimethoprim-sulfamethoxazole at standard dose
- Oral aminoglycosides
Correct Answer: Fosfomycin
Q19. Which urinary anti-infective has a known risk of hemolytic anemia in patients with G6PD deficiency?
- Nitrofurantoin
- Fosfomycin
- Methenamine
- Cefalexin
Correct Answer: Nitrofurantoin
Q20. Which of the following urinary agents is NOT effective against Pseudomonas aeruginosa?
- Ciprofloxacin
- Piperacillin-tazobactam
- Meropenem
- Nitrofurantoin
Correct Answer: Nitrofurantoin
Q21. For long-term prophylaxis in recurrent uncomplicated UTIs, which agent is commonly used at low dose?
- Nitrofurantoin low-dose prophylaxis
- Ciprofloxacin daily prophylaxis
- Fosfomycin daily prophylaxis
- Methenamine high-dose continuous therapy
Correct Answer: Nitrofurantoin low-dose prophylaxis
Q22. A common resistance mechanism to fosfomycin involves:
- Plasmid-mediated beta-lactamase production
- Mutation in glycerophosphate transporter (decreased uptake)
- Overexpression of dihydrofolate reductase
- Alteration of 30S ribosomal binding site
Correct Answer: Mutation in glycerophosphate transporter (decreased uptake)
Q23. A known adverse effect of sulfonamides relevant to urinary therapy is:
- Crystalluria and potential urinary tract obstruction
- Permanent auditory nerve damage
- Marked hypertension
- Pseudomembranous colitis exclusively
Correct Answer: Crystalluria and potential urinary tract obstruction
Q24. Trimethoprim can cause which metabolic disturbance in patients, especially when combined with ACE inhibitors or potassium-sparing diuretics?
- Hypokalemia due to renal wasting
- Hyperkalemia due to reduced potassium secretion
- Severe hyponatremia from SIADH
- Metabolic alkalosis from bicarbonate retention
Correct Answer: Hyperkalemia due to reduced potassium secretion
Q25. Long-term use of nitrofurantoin has been associated with which serious pulmonary complication?
- Bronchiectasis
- Pulmonary fibrosis
- Acute asthma induction
- Pulmonary embolism
Correct Answer: Pulmonary fibrosis
Q26. Which class of antibiotics used in urinary infections exhibits time-dependent killing and typically requires maintaining concentrations above MIC for efficacy?
- Fluoroquinolones
- Aminoglycosides
- Beta-lactams
- Nitrofurans
Correct Answer: Beta-lactams
Q27. Which oral cephalosporin is commonly used for uncomplicated urinary tract infections?
- Cefixime
- Aztreonam
- Ciprofloxacin
- Fosfomycin
Correct Answer: Cefixime
Q28. Which urinary anti-infective class is contraindicated in pregnancy because of potential cartilage and joint toxicity in the fetus?
- Beta-lactams
- Fluoroquinolones
- Methenamine
- Sulfonamides
Correct Answer: Fluoroquinolones
Q29. According to many guidelines, the recommended first-line oral therapy for uncomplicated cystitis in women (when local resistance allows) is:
- Nitrofurantoin for 5 days
- Fosfomycin single 3 g dose
- Ciprofloxacin for 3 days
- Trimethoprim-sulfamethoxazole for 10 days only
Correct Answer: Nitrofurantoin for 5 days
Q30. Which antimicrobial stewardship principle is most appropriate when selecting therapy for uncomplicated lower urinary tract infection?
- Use the broadest-spectrum agent to ensure coverage
- Prescribe the longest possible duration to prevent relapse
- Use narrow-spectrum agents for the shortest effective duration
- Always choose parenteral therapy to maximize bioavailability
Correct Answer: Use narrow-spectrum agents for the shortest effective duration
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
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