Antibiotic Coverage

INFECTIOUS DISEASES, Pharmacy and Therapeutics

When doing empiric abx coverage, you want to think of covering the following as needed.

Also, see risk factors for Multi-drug Resistant Pathogens.

Antibiotics that Cover Pseudomonas Aeruginosa

  1. Zosyn (piperacillin & tazobactam); Piperacillin; Timentin (Ticarcillin & clavulanate); Ticarcillin; Carbenicillin — these are the Antipseudomonal Penicillins alone and combined with beta-lactamase inhibitors.
  2. Ceftazidime (3rd Gen Cephalosporin). Also, Cefoperazone (no longer made in the U.S.) ***Ceftriaxone does NOT cover Pseudomonas!
  3. Cefepime (4th Gen Cephalosporin). ** Ceftaroline (5th Gen) does NOT cover Pseudomonas. 
  4. Imipenem; Meropenem, Doripenem (Carbapenems).  Note: Ertapenem, a new carbapenem doesn’t cover pseudomonas. All carbapenems are resistant to Beta-lactamases, including Extended Spectrum Bata-Lactamases (ESBL).
  5. Aztreonam (a monobactam)
  6. Ciprofloxacin (Resistance is increasing) & Levofloxacin. ** Cipro and levofloxacin still provide excellent coverage for Pseudomonas, especially after I.D. and sensitivities are back. You can use them po. Even so, the IDSA 2016 HAP/HAV guidelines recommend using them to cover pseudomonas.
  7. Aminoglycosides – Amikacin, Gentamicin, Tobramycin
  8. Polymixins

*Fluoroquinolones are the only class of antibiotics which has an oral formulation that is reliably active against Pseudomonas aeruginosa. Use Ciprofloxacin 750mg q12h or Levofloxacin 750mg QD.

Antibiotics that Cover the Anaerobes (including Bacteroides fragilis)

  1. Zosyn (piperacillin & tazobactam); Augmentin (Amoxicillin & Clavulanate); Unasyn (Ampicillin & Sulbactam); Timentin (Ticarcillin & clavulanate) —  Penicillins with beta-lactamase inhibitor*
  2. Cefoxitin; Cefotetan; Cefmetazole (2nd Gen. cephalosporins)
  3. Imipenem, Meropenem, Doripenem, and Ertapenem (Carbapenems)
  4. Chloramphenicol
  5. Clindamycin
  6. Metronidazole
  7. Moxifloxacin
  8. Tigecycline

*Penicillins were used to treat anaerobic infections in the past but these organisms developed resistance to PCNs by producing beta-lactamases. We outwit them by combining PCNs with beta-lactamase inhibitors.

Options for covering both Pseudomonas and anaerobes:
1) Pip/Tazo (Zosyn), OR
2) Aztreonam + Metronizadole, OR——- This is on DRMC’s guidelines recommend this combination in pts. with allergies to PCN who can’t take Pip/Tazo
3) Imipenem or Meropenem or Doripenem

Antibiotics that cover the difficult to kill gram-positive bacteria

Methicillin-Resistant Staph Aureus (MRSA)

  1. Vancomycin
  2. Linezolid
  3. Daptomycin
  4. Telavancin
  5. Quinupristin / Dalfopristin
  6. Tigecycline
  7. Ceftaroline

Vancomycin-Resistant Enterococci (VRE)

  1. Linezolid
  2. Daptomycin
  3. Tigecycline

Oral Antibiotics for MRSA

  1. Bactrim
  2. Clindamycin
  3. Doxycycline

More on oral MRSA treatment here.

Empiric antibiotic therapy for gram negatives and anaerobes

Regimen Dose (Adult)*  Comments
First choice
Monotherapy with a beta-lactam/beta-lactamase inhibitor:
Ampicillin-sulbactam
[Amoxicillin Clav po at d/c]		 3 g IV every six hours E. coli resistance to Ampicillin-sulbactam is emerging in some areas; check local susceptibility data.
Piperacillin-tazobactam 3.375 or 4.5 g IV every six hours
Ticarcillin-clavulanate 3.1 g IV every four hours
Combination third-generation cephalosporin PLUS metronidazole:
Ceftriaxone plus 1 g IV every 24 hours or 2 g IV every 12 hours for CNS infections
Metronidazole 500 mg IV every eight hours
Alternative empiric regimens
Combination fluoroquinolone PLUS metronidazole:
Ciprofloxacin or 400 mg IV every 12 hours Fluoroquinolones are generally avoided in pregnant women due to potential fetal toxicity.
Levofloxacin plus 500 or 750 mg IV once daily
Metronidazole 500 mg IV every eight hours
Monotherapy with a carbapenem:
Imipenem-cilastatin 500 mg IV every six hours
Meropenem 1 g IV every eight hours
Doripenem 500 mg IV every eight hours
Ertapenem 1 g IV once daily

Antibiotic doses should be adjusted appropriately for patients with renal insufficiency or other dose-related consideration.

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