Table 3.

Antimicrobial spectrum for tobramycin and vancomycin

Organism (tobramycin)	MIC range (µg/ml) (tobramycin)	Organism (vancomycin)	MIC range (µg/ml) (vancomycin)
Enterococcus faecalis	8–32	Enterococci	4.0
Escherichia coli	0.25–1.0	MSSA	< 2.0
Pseudomonas aeruginosa	0.25–1.0	MRSA	< 2.0
Staphylococcus aureus	0.12–1.0	Coagulase-negative Staphylococci	4.0
NA	NA	Streptococci other than S. pneumonia	≤ 1.0

Vancomycin is primarily effective against gram-positive cocci. S. aureus and S. epidermidis, both methicillin-susceptible (MSSA and MSSE) or resistant-species (MRSA and MRSE), are typically sensitive to vancomycin with MICs < 1.5 µg/ml. Most strains of streptococcus are sensitive to vancomycin. Vancomycin is considered bactericidal (MBC/MIC < 4 µg/ml) except with enterococci and some tolerant staphylococci (MBC/MIC > 32 µg/ml)

NA not applicable, MIC minimum inhibitory concentration, MBC MIC minimum bactericidal concentration, MSSA methicillin-sensitive S. aureus, MRSA methicillin-resistant S. aureus