Pre-test

Infectious Diseases Pre-Test Questions

General Principles

1. Killing patterns: What is the difference between time-dependent and concentration-dependent killing, and which PK/PD parameter best predicts efficacy for each (T>MIC, Cmax/MIC, AUC/MIC)?

2. Classifying by killing pattern: Classify the following as time-dependent or concentration-dependent: beta-lactams, aminoglycosides, fluoroquinolones, vancomycin, daptomycin, linezolid, and azithromycin. How does this explain extended-infusion beta-lactams and once-daily aminoglycosides?

3. Bactericidal vs bacteriostatic: What is the difference between bactericidal and bacteriostatic antibiotics? Classify these common agents: beta-lactams, vancomycin, daptomycin, aminoglycosides, fluoroquinolones, metronidazole, linezolid, tetracyclines, macrolides, and clindamycin.

4. When cidal activity matters: In which infections does bactericidal activity matter most clinically, and why?

Beta-lactams

5. Penicillin G: What are two classic infections still treated with penicillin G, and what is the role of benzathine penicillin?

 

6. Ampicillin spectrum: What are the main organisms covered by ampicillin?

 

7. Ampicillin-Sulbactam (Unasyn): When sulbactam is added to ampicillin, which important organisms are now covered that ampicillin alone does not cover?

 

8. Piperacillin-Tazobactam (Zosyn), spectrum gain: Compared to Unasyn, what expanded coverage do we gain with piperacillin-tazobactam?

 

9. Zosyn gaps: Name three common organisms not covered by Zosyn.

 

10. Cefazolin: What is the spectrum of cefazolin, and why is it the standard agent for surgical prophylaxis?

 

11. Ceftriaxone spectrum: What are the main organisms covered by ceftriaxone, and what are its important gaps (name at least three organisms it does not cover)?

 

12. Ceftriaxone → Cefepime: When switching from ceftriaxone to cefepime, what spectrum is gained, and what is lost (if anything)?

 

13. Ceftazidime spectrum: What is the spectrum of ceftazidime? How does it compare with cefepime, particularly in Gram-positive coverage?

 

14. Cefepime vs Zosyn: What is the main difference in spectrum between cefepime and piperacillin-tazobactam?

 

15. Carbapenems vs Zosyn: What do carbapenems cover that Zosyn does not?

 

16. Ertapenem vs Meropenem: What are the key spectrum differences between ertapenem and meropenem? Which important bacteria are not covered by ertapenem?

 

17. Cefoxitin: What is the spectrum of cefoxitin, and why is it now considered inadequate for anaerobic coverage?

 

18. Severe MSSA infections: What is the classic drug of choice for severe MSSA infections?

 

19. Cefepime side effect: What unusual side effect is important to remember for cefepime?

 

20. No renal adjustment: Which beta-lactams do not require dose adjustment in renal failure?

 

21. Cephalosporins and Enterococcus: True or false: Enterococci are resistant to all cephalosporins. What is the one unusual role for ceftriaxone in Enterococcus faecalis endocarditis, and how is it combined with ampicillin?

 

22. Anti-pseudomonal beta-lactams: List all beta-lactams with Pseudomonas coverage.

 

23. MRSA and beta-lactams: Which beta-lactam antibiotic covers MRSA, and in what situations is it used?

 

24. Ceftaroline: What is the spectrum of ceftaroline? Which important organisms does it NOT cover (name at least three), and what are its main clinical uses?

25. Aztreonam spectrum: What is the antimicrobial spectrum of aztreonam, and in what clinical situation is it most commonly used?

 

26. Beta-lactam allergy: A patient reports a penicillin allergy. What is the true cross-reactivity risk with cephalosporins, and which feature of the drug determines it?

 

Aminoglycosides

27. Gentamicin: What is the spectrum of gentamicin, what are its two major toxicities, and why is it never used alone for Gram-positive infections?

 

Macrolides

28. Azithromycin spectrum: What are the main organisms covered by azithromycin?

 

29. Azithromycin special uses: Name two infections where azithromycin is preferred because of its activity against atypical bacteria.

 

Fluoroquinolones

30. Quinolone spectrum differences: How does the spectrum of ciprofloxacin differ from levofloxacin and moxifloxacin?

 

31. Quinolone toxicities: List three serious adverse effects common to all quinolones.

 

32. Quinolone elimination: Which fluoroquinolone does not require renal dose adjustment, and why?

 

Trimethoprim-Sulfamethoxazole (Bactrim)

33. Bactrim spectrum: Name three major organisms covered by Bactrim.

 

34. Bactrim contraindications: What are two major contraindications for Bactrim use?

 

Linezolid

35. Linezolid spectrum: What resistant Gram-positive organisms does linezolid cover?

 

36. Linezolid toxicities: Name two important side effects of linezolid that can occur with prolonged use.

 

37. Linezolid interactions: What common drug interaction makes linezolid risky in patients on certain antidepressants?

 

Daptomycin

38. Daptomycin spectrum: What is the main role of daptomycin in severe Gram-positive infections?

 

39. Daptomycin contraindication: Why can't daptomycin be used for pneumonia?

 

40. Daptomycin toxicity: What muscle-related toxicity is associated with daptomycin, and what lab test should be monitored?

 

Nitrofurantoin (Macrobid)

41. Macrobid use: What is the main clinical use for nitrofurantoin (Macrobid)?

 

42. Macrobid contraindications: Why should nitrofurantoin be avoided in patients with poor renal function?

 

43. Macrobid toxicity: What rare but serious pulmonary side effect can occur with long-term nitrofurantoin use?

 

Tetracyclines

44. Doxycycline spectrum: List three unusual or "special" organisms covered by doxycycline.

 

45. Doxycycline contraindications: Why is doxycycline generally avoided in children under 8 years old?

 

46. Doxycycline side effects: Name two side effects of doxycycline, one related to sun exposure and one to the GI tract.

 

47. Doxycycline vs minocycline: How do doxycycline and minocycline differ in spectrum (e.g., Acinetobacter, Stenotrophomonas, MRSA), tissue/CNS penetration, and side effects (vestibular toxicity, skin and tooth discoloration)?

48. Omadacycline: What is omadacycline, what are its approved indications, and what advantage does its oral formulation offer?

49. Extended-spectrum tetracyclines: What are tigecycline and eravacycline used for? Which important Gram-negatives do they NOT cover, and why are they poor choices for bacteremia and UTI?

Fosfomycin

50. Fosfomycin use: What is the main clinical use for fosfomycin in the outpatient setting?

 

Vancomycin

51. Vancomycin spectrum: What is the main Gram-positive coverage of vancomycin?

 

52. Vancomycin special use: What infection is oral vancomycin specifically used for, and why does it work by that route?

 

53. Vancomycin toxicities: Name two important toxicities or reactions of vancomycin.

 

Clindamycin

54. Clindamycin spectrum: What types of organisms does clindamycin cover well?

 

55. Clindamycin limitations: Why should clindamycin not be trusted for intra-abdominal infections anymore?

 

Metronidazole

56. Metronidazole spectrum: What organisms does metronidazole target especially well?

 

57. Metronidazole side effects: What reaction can occur if metronidazole is taken with alcohol?

 

58. Metronidazole special role: What is the role of metronidazole in combination regimens for anaerobic coverage?

 

Rifampin

59. Rifampin: Why is rifampin never used as monotherapy, and what is its most important clinical problem?

 

60. Rifampin toxicity and red urine: What is the most important organ toxicity of rifampin? What discoloration of urine and other body fluids does it cause, and what should patients be told about it (including contact lenses)?

 

Resistance Concepts

61. ESBL: What is an ESBL, and which drug class is the treatment of choice for serious ESBL infections?

 

62. AmpC: Which organisms carry chromosomal AmpC, and why can a third-generation cephalosporin fail during therapy?

 

63. VRE: What is VRE, and which two drugs are the main treatment options?

 

Stewardship and Safety

64. IV-to-PO switch: Name four antibiotics with excellent oral bioavailability that allow early switch from IV to oral therapy.

 

65. C. difficile risk: Which antibiotics carry the highest risk of C. difficile infection?

 

66. Pregnancy: Which common antibiotics are considered safe in pregnancy, and which should be avoided?

 

67. QT-prolonging drugs: Which antimicrobial classes prolong the QT interval, and what should be checked before starting them?

68. Pneumonia duration: What is the classic treatment duration for uncomplicated community-acquired pneumonia, and for hospital- or ventilator-associated pneumonia?

69. UTI duration: What are the classic treatment durations for uncomplicated cystitis with nitrofurantoin, Bactrim, and fosfomycin, and for pyelonephritis with a fluoroquinolone vs a beta-lactam?

Antifungals

70. Fluconazole vs echinocandins: Which Candida species are often resistant to fluconazole, and which drug class is preferred as initial therapy for candidemia?

 

71. Amphotericin B: What are the main toxicities of amphotericin B, and in which infections is it still first-line?

 

Antivirals

72. Acyclovir: What are the main indications for acyclovir, and what renal toxicity can occur with high-dose IV use? How is it prevented?

 

🧠🌀🦠💉🔬💊 NEUROSYPHILIS

A 46‑year‑old man with untreated HIV infection (CD4 = 180 cells/µL, HIV RNA = 75 000 copies/mL) is brought to the emergency department because of progressive memory loss, gait unsteadiness, and bilateral lower‑limb weakness over two months. He reports intermittent headaches and blurred vision.

• Vitals: T 37.4 °C, BP 126/72 mm Hg, HR 88 bpm.

• Neuro exam: wide‑based gait, positive Romberg, brisk patellar reflexes; pupils accommodate but are sluggish to light.

• Serum RPR: reactive 1 : 128 (prior documentation six months ago: non‑reactive).

• CSF: WBC 95 cells/µL (90 % lymphs), protein 110 mg/dL, VDRL reactive 1 : 16.

Question
Which antibiotic regimen is most appropriate to treat this patient’s infection?

A) Aqueous crystalline penicillin G 3 million units IV every 4 h for 14 days
B) Meropenem 2 g IV every 8 h for 14 days
C) Doxycycline 200 mg orally twice daily for 28 days
D) Ceftriaxone 2 g IV once daily for 14 days
E) Levofloxacin 750 mg IV once daily for 14 days

🫀🦠 MSSA Endocarditis

A 48‑year‑old man with poorly controlled type 2 diabetes and a history of intravenous heroin use presents with three days of fever, rigors, and pleuritic chest pain.

• Vitals: T 39.2 °C, HR 110 bpm, BP 118/66 mm Hg
• Exam: new holosystolic murmur at the left lower sternal border; several Janeway lesions on the palms; no focal neurological deficits.
• Investigations: Three blood‑culture sets grow methicillin‑susceptible Staphylococcus aureus (MSSA) within ten hours (oxacillin MIC ≤ 2 µg/mL). Transthoracic echo shows a 1.2 cm vegetation on the tricuspid valve with mild regurgitation. Renal and liver function are normal.
He has no β‑lactam allergy.

QUESTION
Which intravenous antibiotic regimen is most appropriate to start—and continue—for this infection?

A) Cefazolin 2 g IV every 8 h for at least six weeks
B) Vancomycin dosed to trough 15–20 mg/L for at least six weeks
C) Daptomycin 10 mg/kg IV once daily for at least six weeks
D) Linezolid 600 mg IV every 12 h for at least six weeks
E) Gentamicin 3 mg/kg IV once daily plus rifampicin 300 mg orally every 8 h

🦶🦠Diabetic foot infection

A 62‑year‑old man with poorly‑controlled type 2 diabetes (HbA1c 9.4 %) is admitted with a worsening plantar ulcer under the right first metatarsal head.

Two weeks ago his podiatrist prescribed trimethoprim–sulfamethoxazole (TMP‑SMX) for presumed mild cellulitis. The ulcer has enlarged, now draining malodorous pus.

Vitals: T 38.3 °C, HR 96 bpm, BP 132/78 mm Hg.
Exam: 3 × 2 cm ulcer, erythema extending 4 cm, no bone palpated. Peripheral pulses intact.
Labs: WBC 13 000/µL (85 % neutrophils), CRP 110 mg/L, Cr 1.0 mg/dL.
X‑ray: soft‑tissue swelling; no osteitis.

You plan empiric IV therapy while awaiting deep‑tissue culture.

Which regimen is most appropriate now?

A. Continue TMP‑SMX and add oral clindamycin
B. Vancomycin plus cefepime
C. Piperacillin–tazobactam (Zosyn)
D. Linezolid monotherapy
E. Ciprofloxacin plus metronidazole

⛰️ Fever after traveling to TN - "magical" antibiotic

A previously healthy 27-year-old male presents to the emergency department in mid-July with a 5-day history of fever, chills, severe frontal headache, diffuse muscle aches, and nausea. He returned from a camping trip in Tennessee approximately one week ago. Vital signs upon presentation show temperature 39.3°C (102.7°F), heart rate 112 bpm, blood pressure 98/64 mmHg, and respiratory rate 20/min. On physical examination, the patient appears acutely ill and has a diffuse maculopapular rash involving his palms and soles. There is no neck rigidity, and cardiopulmonary examination is normal. Laboratory studies reveal:

Laboratory Test	Result	Normal Range
WBC	3,400/mm³	(4,500–11,000/mm³)
Platelets	62,000/mm³	(150,000–400,000/mm³)
Hemoglobin	13.8 g/dL	(13.5–17.5 g/dL)
Sodium	130 mEq/L	(135–145 mEq/L)
AST	112 U/L	(10–40 U/L)
ALT	95 U/L	(10–40 U/L)
Creatinine	1.2 mg/dL	(0.6–1.2 mg/dL)

Given the clinical findings and lab abnormalities, immediate empiric antibiotic therapy is initiated pending confirmatory testing.

Which of the following antibiotics is the most appropriate initial therapy?

A. Ceftriaxone
B. Ciprofloxacin
C. Vancomycin
D. Doxycycline
E. Chloramphenicol

🫁🤒Community‑Acquired Pneumonia in a Young Adult

Scenario
A 45‑year‑old man with no significant past medical history presents with a 3‑day history of fever (38.5 °C), productive cough, pleuritic chest pain, and mild dyspnea. He is haemodynamically stable (BP 125/80, HR 95, RR 20, SpO₂ 94% on room air). Laboratory tests show WBC 12 × 10⁹/L. Chest X‑ray demonstrates a right lower‑lobe consolidation. His CURB‑65 score is 1 (age < 65 but BUN normal), indicating inpatient—or close outpatient—management.

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Question:

Which empiric antibiotic regimen is most appropriate for this patient?

A) IV ceftriaxone + IV azithromycin
B) IV ampicillin–sulbactam + IV azithromycin
C) IV levofloxacin monotherapy
D) IV ceftaroline + IV azithromycin

👊Human Bite (“Fight Bite”) to the Hand

Scenario
A 28‑year‑old man presents to the ED 12 hours after punching another person in the face and sustaining a 1 cm laceration over the dorsal aspect of his right third metacarpophalangeal joint. He cleaned it at home but now has:

• Increasing pain, swelling, and erythema over the joint

• Temperature 38.2 °C, pulse 100 bpm

• Mild crepitus when extending the finger

• No obvious abscess, but the wound is tender with a small serosanguineous discharge

He is otherwise healthy, with no penicillin allergy.

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Question

Which empiric oral antibiotic regimen is most appropriate for this patient?

A) Amoxicillin–clavulanate
B) Clindamycin monotherapy
C) Doxycycline + metronidazole
D) Cephalexin
E) Dicloxacillin

🧠‑🤒 Meningitis in a Young Adult (Weekend)

A 24‑year‑old woman with no significant medical history presents on a Saturday evening with a 12‑hour history of fever (39 °C), worsening headache, photophobia, and neck stiffness. She is alert but irritable, with a heart rate of 110 bpm and blood pressure 120/70 mmHg. A head CT is not immediately available, and lumbar puncture (LP) cannot be done until Monday. You draw blood cultures and decide to start empiric antibiotics without delay.

Which empiric IV regimen is most appropriate while awaiting LP and cultures?

A) Ceftriaxone + Vancomycin
B) Ampicillin + Gentamicin
C) Vancomycin + Acyclovir
D) Meropenem alone
E) Vancomycin + Cefepime

🦠 HAP in a Haemodialysis Patient - in shock

Scenario:
A 68‑year‑old man on thrice‑weekly haemodialysis, recently transferred from a nursing home, develops a new fever (38.8 °C), worsening dyspnoea on BiPAP, hypotension (BP 85/50 mmHg) and tachycardia (115 bpm) five days into his admission for heart failure. A chest X‑ray shows a new right lower‑lobe infiltrate. His WBC is 18 × 10⁹/L and procalcitonin is elevated. Blood and sputum cultures are pending.

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Question:
Which empiric IV regimen is most appropriate for this critically ill patient at high risk for ESBL‑producing organisms?

A) Vancomycin + Cefepime
B) Vancomycin + Piperacillin–Tazobactam
C) Vancomycin + Meropenem
D) Levofloxacin monotherapy

🤰Perforated Diverticulitis with Septic shock

Scenario:
A 63‑year‑old woman with recurrent diverticulitis presents with 24 hours of severe abdominal pain, fever (39 °C), rigors and hypotension (BP 85/50 mmHg). She appears "peritonitic" and is tachycardic at 120 bpm. CT scan shows free intraperitoneal air and colonic perforation. She has had three courses of broad‑spectrum antibiotics over the past year and now requires urgent laparotomy.

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Question:
Which empiric IV regimen is most appropriate in this critically unwell patient to cover broad Gram‑negatives, anaerobes and Candida?

A) Piperacillin–tazobactam + fluconazole
B) Meropenem + micafungin
C) Cefepime + metronidazole + fluconazole
D) Piperacillin–tazobactam + micafungin
E) Meropenem alone

🦠 Severe Diverticulitis Requiring Admission

Scenario:

A 55‑year‑old woman presents with 48 hours of severe left lower‑quadrant pain, fever (38.5 °C), and inability to tolerate oral intake. She reports nausea and has been unable to pass flatus. On examination she is tender in the left lower quadrant with guarding but no peritonism. Her white cell count is 16 × 10^9/L, and CRP is elevated. A CT scan confirms uncomplicated diverticulitis (no abscess or perforation) with marked pericolic fat stranding. Given her pain, systemic features and inability to eat, you admit her for IV antibiotic therapy.

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Question:
Which empiric IV regimen is most appropriate on admission?

A) Piperacillin–tazobactam
B) Ceftriaxone + metronidazole
C) Ertapenem
D) Meropenem
E) Ampicillin–sulbactam