Why is vancomycin (Vancomycin) considered a last resort antibiotic?

From the Guidelines

Vancomycin is considered a last resort antibiotic because it is reserved for treating serious infections caused by gram-positive bacteria that are resistant to other antibiotics, particularly methicillin-resistant Staphylococcus aureus (MRSA) and other multidrug-resistant organisms. This glycopeptide antibiotic works by inhibiting cell wall synthesis in bacteria, but its use comes with significant considerations. Vancomycin requires careful administration, typically intravenous for serious infections at doses of 15-20 mg/kg every 8-12 hours (adjusted for renal function), with therapeutic drug monitoring to maintain effective blood levels while avoiding toxicity, as recommended by the Infectious Diseases Society of America 1. The medication can cause serious adverse effects including nephrotoxicity, ototoxicity, and infusion-related reactions like "red man syndrome." Additionally, inappropriate or overuse of vancomycin contributes to the development of vancomycin-resistant organisms, such as vancomycin-resistant enterococci (VRE) and vancomycin-intermediate or resistant Staphylococcus aureus (VISA/VRSA), which further limits treatment options for severe infections, as noted in studies 1.

Some key points to consider when using vancomycin include:

• Vancomycin trough concentrations of 15–20 lg/mL are recommended for serious infections, such as bacteremia, infective endocarditis, osteomyelitis, meningitis, pneumonia, and severe SSTI (eg, necrotizing fasciitis) due to MRSA 1.
• Trough vancomycin monitoring is recommended for serious infections and patients who are morbidly obese, have renal dysfunction (including those receiving dialysis), or have fluctuating volumes of distribution 1.
• Vancomycin doses of 15–20 mg/kg/day every 8–12 h are recommended for adult patients on the basis of actual body weight and are adjusted for the patient’s estimated creatinine clearance, not to exceed 2 g per dose 1.
• The pharmacodynamic parameter that best predicts efficacy of vancomycin is the ratio of the area under the curve (AUC) to the MIC (AUC/MIC), with a target AUC/MIC >400 1.

Overall, preserving vancomycin's effectiveness through judicious use is essential for maintaining our ability to treat life-threatening resistant infections when other antibiotics fail, as emphasized in guidelines and studies 1. The use of vancomycin should be guided by clinical practice guidelines and susceptibility testing results, with careful consideration of the potential risks and benefits.

From the Research

Vancomycin as a Last Resort Antibiotic

Vancomycin is considered a last resort antibiotic due to several factors, including:

• Its potential to cause adverse effects, such as nephrotoxicity, ototoxicity, and hypersensitivity reactions 2
• The risk of increasing minimum inhibitory concentrations (MICs) and treatment failures with inadequate doses and prolonged therapy 2
• The emergence of vancomycin-resistant strains, including vancomycin-resistant enterococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA) 3, 4

Mechanisms of Resistance

The mechanisms of vancomycin resistance are complex and involve various strategies, including:

• Alterations in cell wall structure and function 4
• Production of enzymes that modify or degrade vancomycin 4
• Development of alternative metabolic pathways that bypass the inhibitory effects of vancomycin 4

Alternative Treatment Options

Several alternative treatment options are available for infections caused by vancomycin-resistant strains, including:

• Linezolid, which has shown efficacy against MRSA and VRE 5, 6
• Daptomycin, which has shown non-inferiority to vancomycin in the treatment of MRSA bacteremia 5, 6
• Newer cephalosporins, such as ceftaroline and ceftobiprole, which have activity against MRSA 3
• Novel glycopeptides, such as dalvavancin, telavancin, and oritavancin, which have shown promise in clinical trials 3