Organism	Preferred regimens	Alternative regimens*
Anaerobes	Clindamycin, 600 mg IV every 6 hours Ticarcillin/clavulanate (Timentin), 3.1 g IV every 4 hours	Cefotetan (Cefotan), 2 g IV every 12 hours Metronidazole (Flagyl), 500 mg IV every 6 hours
Cutibacterium acnes (formerly known as Propionibacterium acnes)	Penicillin G, 2 to 4 million units IV every 4 hours	Ceftriaxone, 2 g IV every 24 hours
Enterobacteriaceae (e.g., Escherichia coli), quinolone resistant	Ticarcillin/clavulanate, 3.1 g IV every 4 hours Piperacillin/tazobactam (Zosyn), 3.375 g IV every 6 hours	Ceftriaxone (Rocephin), 2 g IV every 24 hours
Enterobacteriaceae, quinolone sensitive	Fluoroquinolone (e.g., ciprofloxacin, 400 mg IV every 8 to 12 hours)	Ceftriaxone, 2 g IV every 24 hours Ciprofloxacin, 750 mg orally every 12 hours Levofloxacin (Levaquin), 750 mg orally every 24 hours
Pseudomonas aeruginosa	Cefepime, 2 g IV every 8 to 12 hours, plus ciprofloxacin, 400 mg IV every 8 to 12 hours	Imipenem/cilastatin (Primaxin), 1 g IV every 8 hours, plus aminoglycoside
	Piperacillin/tazobactam, 3.375 g IV every 6 hours, plus ciprofloxacin, 400 mg IV every 12 hours
Staphylococcus aureus, methicillin resistant	Vancomycin, 15 to 20 mg per kg per dose IV every 8 to 12 hours For patients allergic to vancomycin: Linezolid (Zyvox), 600 mg IV every 12 hours  or Rifampin, 600 mg daily	Daptomycin (Cubicin), 6 mg per kg IV every 24 hours Linezolid, 600 mg IV or orally every 12 hours Clindamycin, 600 mg IV or orally every 8 hours Trimethoprim/sulfamethoxazole, 3.5 to 4.0 mg per kg per dose or 2 double-strength tablets (for an 80-kg [176-lb] adult) IV or orally every 8 to 12 hours
S. aureus, methicillin sensitive	Nafcillin or oxacillin, 1 to 2 g IV every 4 hours Cefazolin, 1 to 1.5 g IV every 6 hours	Ceftriaxone, 2 g IV every 24 hours Vancomycin, 1 g IV every 12 hours
Streptococcus species	Penicillin G, 2 to 4 million units IV every 4 hours	Ceftriaxone, 2 g IV every 24 hours Clindamycin, 600 mg IV every 6 hours