Table 4.

Treatment options for infections caused by reduced vancomycin susceptibility—listed by generic (and commercial) names

	Linezolid (Zyvox)50–54	Quinupristine/dalfopristine (Synercid)55–57	Daptomycin (Cubicin)58–62	Tigecycline (Tygacil)63–68
Class	Oxazolidinone (fermentation byproduct of Streptomyces roseosporus)	Streptogramin (isolated from Streptomyces pristinaespiralis)	Cyclic lipopeptide	Glycylcycline (a derivative of minocycline)
Mechanism of action	Inhibits initiation of protein synthesis by binding 23S rRNA of the 50S subunit of bacterial ribosome	Inhibits bacterial protein synthesis by interfering with function of 23S RNA (quinidine: dalfopristine=3:7)	Terminates bacterial DNA, RNA and protein synthesis and cell death by forming transmembrane channels in cell membrane and depolarisation of membrane potential	Inhibits bacterial protein synthesis by irreversibly binding to 30 S ribosomal unit
Route and dose	Oral—600 mg twice daily Intravenous—600 mg twice daily Intravitreal—300 mg/0.1 mL (rabbits) Topical—2 mg/mL (rabbits)	Intravenous—7.5 mg/kg 8 hourly Intravitreal—0.4 mg/0.1 mL In vitro—MIC90 0.5–2 mg/L	Intravenous—4–6 mg/kg per day Intravitreal—200 mg/0.05 mL (rabbits) Topical—1% (rabbits)	Intravenous—100 mg/100 ml over 30–60 min followed by 50 mg twice daily Intravitreal—0.5–1 mg/0.1 mL (rabbits) Topical—10–50 mg/mL (rabbits)
Side effects with systemic dose	Reversible myelosuppression, irreversible peripheral neuropathy, optic neuropathy (when used for >14 days)	Arthralgia, myalgia, pain and Periphlebitis at injection site	Not significant Minor gastrointestinal disturbances	Hypersensitivity-like reaction
Spectrum of activity	GPO, MRSA, VRSA, VISA, VRE, CNS, GNO, mycobacteria	MRSA, VISA, VRSA, Streptococcus species, CNS	VRSA, VRE, Staphylococcus, Streptococcus, Enterococcus species	MSSA, MRSA, VISA, VRE, Escherichia coli and Klebsiella pneumonia
Others	First pharmacologically active oxazolidinone (fermentation byproduct of Streptomyces roseosporus). Good intraocular availability after intravenous and oral administration	First intravitreal (0.4 mg/0.1 mL) use of quinupristin/dalfopristin acute postoperative endophthalmitis in 2011	Pharmacokinetics are linear at dose of 4–12 mg/kg/day. Available only in intravenous formulation	Minimum inhibitory concentration 90 (MIC90) of MDR bacteria range from 0.12–4 μg/mL

CNS, coagulase-negative staphylococci; FDA, US Food and Drug Administration; GNO, Gram-negative organism; GPO, Gram-positive organisms; MDR, multidrug resistant bacteria; MRSA, methicillin-resistant Staphylococcus aureus; VISA, vancomycin intermediate sensitive Staphylococcus aureus; VRE, vancomycin resistant Enterococcus; VRSA, vancomycin-resistant Staphylococcus aureus.