From the Guidelines
Vancomycin is not recommended for Pseudomonas aeruginosa infections due to its intrinsic resistance to this antibiotic. Vancomycin is a glycopeptide antibiotic that targets the cell wall of gram-positive bacteria by inhibiting peptidoglycan synthesis, but it cannot penetrate the outer membrane of gram-negative bacteria like Pseudomonas 1. For Pseudomonas infections, appropriate antibiotic choices include:
- Antipseudomonal beta-lactams (piperacillin-tazobactam 4.5g IV q6h, cefepime 2g IV q8h, or meropenem 1g IV q8h)
- Fluoroquinolones (ciprofloxacin 400mg IV q8h or 750mg PO q12h)
- Aminoglycosides (tobramycin 5-7mg/kg IV daily) Severe Pseudomonas infections often require combination therapy with two different antibiotic classes for synergistic effect and to prevent resistance development, as suggested by the guidelines for hospital-acquired and ventilator-associated pneumonia 1. Treatment duration typically ranges from 7-14 days depending on infection site and severity. Antibiotic selection should ideally be guided by culture and susceptibility testing, as Pseudomonas is known for developing resistance to multiple antibiotics 1. If empiric therapy is necessary before culture results are available, local antibiogram data should guide the initial antibiotic choice.
From the Research
Vancomycin for Pseudomonas
- Vancomycin is not typically used to treat Pseudomonas infections, as it is a gram-positive antibiotic and Pseudomonas is a gram-negative bacterium 2.
- The most commonly used antipseudomonal agents are extended-spectrum penicillins, aminoglycosides, cephalosporins, fluoroquinolones, polymixins, and monobactams 2.
- Combination therapy with an aminoglycoside and a beta-lactam penicillin is usually considered the first line treatment for Pseudomonas infections 2, 3.
Alternative Treatment Options
- Cefepime, piperacillin/tazobactam, gentamicin, ciprofloxacin, and levofloxacin have been studied as alternative treatment options for Pseudomonas infections 3.
- A systematic review and meta-analysis found no evidence of clinical benefit differences among direct antibiotic comparisons for Pseudomonas infections, but all subgroup analyses were underpowered to detect significant differences 4.
- Novel fluoroquinolones, new combinations of β-lactams/β-lactamase inhibitors, and cefiderocol have shown promising results against Pseudomonas infections 5.
Combination Therapy
- Combination therapy with ceftazidime and tobramycin has been shown to be synergistic against hypermutable Pseudomonas aeruginosa isolates 6.
- High-dose combination regimens of ceftazidime and tobramycin provided significant initial killing and suppression of re-growth and resistance in a dynamic in vitro infection model 6.