Antibiogram

15 October 2022 by Shahriar Lahouti.

The following antibiogram is provided only as a rough concept. Whenever possible, local antimicrobial susceptibility patterns (antibiogram) should be considered for use.

👉First-line agents for common gram-positive pathogens

• MSSA: Cefazolin or, nafcillin.
• MRSA: Vancomycin , linezolid (not preferred for bacteremia), or daptomycin  (ineffective in pneumonia).
• Enterococcus faecalis: Ampicillin .
• Enterococcus faecium (VRE): Linezolid is first-line, daptomycin 2nd line.
• Enterococcus faecium (non-VRE): Vancomycin or linezolid.
• Streptococcus pyogenes (Group A strep) or Streptococcus agalactiae (Group B strep): Penicillin G is 1st line, cefazolin is 2nd line.
• Streptococcus pneumoniae (not meningitis): Ceftriaxone is 1st line, Vancomycin is 2nd line.
• Listeria spp. Ampicillin is 1st line, trimethoprim/sulfamethoxazole is 2nd line.

👉Antibiotics for gram-negatives coverage

• E. coli, Klebsiella pneumoniae:
  • No risk factors for ESBL species:  Ceftriaxone or cefepime.
  • Risk factors for ESBL species:  Carbapenem.
• Proteus species:  Piperacillin-tazobactam or cefepime.
• Enterobacter or Citrobacter:  Cefepime or carbapenem.
• Pseudomonas:  Piperacillin/tazobactam, ceftazidime , cefepime, or Meropenem.
  • If double-coverage for pseudomonas is considered, the following antibiotics may be added (to the antipseudomonal beta-lactam backbone antibiotics): 
    • Aminoglycoside (Gentamicin , Amikacin)
    • Fluoroquinolones ( Ciprofloxacin, Levofloxacin)

👉Anti-anaerobic coverage

• Metronidazole: Best anti-anaerobic agent.
  
  • Generally avoid adding it to piperacillin-tazobactam or meropenem (these agents have great anaerobic coverage).
• Clindamycin
  • Inferior to metronidazole for anaerobic coverage.
  • Increasing resistance seen among gut anaerobes (e.g. Bacteroides spp.).
  • Clindamycin can be useful for lung abscess, due to combined coverage of anaerobes and oral streptococcal spp.
• Carbapenem ( Meropenem; imipenem/cilastatin)
• Ampicillin/sulbactam
• Piperacillin/tazobactam
• Cefoxitin
• Cefoperazone / Sulbactam