OnlineMedEd: Infectious Disease - "Antibiotic Ladder"

Question 1

Go through the antibiotic ladder for Gram-positive coverage.

Answer 1

1) Methicillin family (nafcillin, oxacillin, dicloxacillin)
2) Vancomycin (for MRSA coverage)
3) Linezolid (for MRSA coverage in those with contraindications to vancomycin)

Question 2

The amino beta-lactams have what coverage?

Answer 2

Positive and negative (the amine group lets them penetrate the outer cell wall)

Question 3

Adding ___________ to the amino beta-lactams makes them broad spectrum.

Answer 3

beta-lactamase inhibitors

Though amoxicillin by itself is actually broad spectrum.

Question 4

Go through the antibiotic ladder for Gram-negative coverage.

Answer 4

1) Amoxicillin or ampicillin (same but just oral vs. IV)
2) Amoxicillin/clavulanate or ampicillin/sulbactam (ditto)
3) Piperacillin/tazobactam (for Pseudomonas)
4) Carbapenems (for those with contraindications to Zosyn)

Question 5

Review the cephalosporins by generation and what they cover.

Answer 5

1st: Gram-positive
2nd: Gram-positive
3rd: Gram-positive and Gram-negative equally
4th: Gram-negative

Disclaimer: there is actually a huge amount of overlap in each. They are all broad spectrum. This is just a representation of their relative strengths.

Question 6

Review the generations of fluoroquinolones.

Answer 6

1st: ciprofloxacin
2nd: levofloxacin
3rd: moxifloxacin

As they progress, they retain the properties of the preceding generations. Cipro is best at GN, levo gas GN and some GP, and moxi has definitive GN and GP.

Notice the alphabetical order: C, L, M.

This is why cipro is the “urinary” fluoroquinolone, while moxi is the “respiratory” fluoroquinolone.

Question 7

For anaerobic coverage, go through when to use what.

Answer 7

• Abdomen and groin: metronidazole

* Everywhere else:

Question 8

Give the three equivalent regimens for CAP.

Answer 8

• Moxifloxacin (wrong on the test because it’s too broad spectrum)
• Azithromycin (good for ambulatory patients because it’s oral)
• Azithromycin and ceftriaxone (good for hospitalized patients because can be given IV)

Question 9

Give the regimen for HCAP.

Answer 9

Vancomycin (for MRSA) and Zosyn (for Pseudomonas) until culture proves otherwise

Question 10

What drugs are used for meningitis in adults?

Answer 10

• Vancomycin
• Ceftriaxone
• Ampicillin for the immunocompromised
• Steroids

Question 11

List the drugs that can be used to treat UTI.

Answer 11

• Amoxicillin (pregnant)
• Nitrofurantoin ( woman)
• Bactrim (only if no renal failure)
• Ceftriaxone (only IV for hospitalized)
• Ciprofloxacin (ambulatory pyelonephritis)