From the Guidelines
For multidrug-resistant (MDR) Acinetobacter pneumonia, colistin is generally preferred over tigecycline as first-line therapy, due to its better pulmonary penetration and clinical outcomes data in pneumonia, as supported by the most recent study from 2023 1.
Comparison of Tigecycline and Colistin
The comparison between tigecycline and colistin for the treatment of MDR Acinetobacter pneumonia is crucial in determining the most effective treatment approach.
- Colistin (polymyxin E) is typically administered at a loading dose of 9 million units followed by 4.5 million units every 12 hours intravenously, with dose adjustments needed for renal impairment.
- Tigecycline, while active against MDR Acinetobacter, achieves suboptimal lung concentrations at standard doses (100mg loading, then 50mg every 12 hours) and has been associated with higher mortality in severe infections, as reported in a study from 2022 1.
Clinical Outcomes and Recommendations
When using tigecycline for pneumonia, higher doses are often recommended (200mg loading, then 100mg every 12 hours).
- Combination therapy is frequently employed for severe MDR Acinetobacter pneumonia, with options including colistin plus a carbapenem (meropenem 2g every 8 hours as extended infusions) or colistin plus rifampin (600mg daily), as suggested by guidelines from 2016 1.
- Treatment duration typically ranges from 7-14 days depending on clinical response.
- Colistin's mechanism involves disrupting bacterial cell membranes, while tigecycline inhibits protein synthesis by binding to the 30S ribosomal subunit.
Considerations and Precautions
The preference for colistin stems from its better pulmonary penetration and clinical outcomes data in pneumonia, though nephrotoxicity remains a significant concern requiring close monitoring of renal function, as highlighted in a study from 2023 1.
- It is essential to consider local antimicrobial susceptibility and MIC, having patients’ renal and hepatic functions, and comorbidities, in deciding which regimen should be considered for use in combination with colistin to treat CRAB pneumonia, as recommended by guidelines from 2022 1.
From the Research
Comparison of Tigecycline and Colistin for MDR Acinetobacter baumannii Pneumonia
- The efficacy of tigecycline and colistin in treating multidrug-resistant (MDR) Acinetobacter baumannii pneumonia has been compared in several studies 2, 3, 4.
- A study published in 2016 found that tigecycline-based therapy had a comparable clinical success rate to colistin-based therapy (47% vs 48%, P = 0.95) 2.
- However, another study published in 2014 found that the tigecycline group had an excess mortality of 16.7% compared to the colistin group (60.7% vs 44%, P = 0.04) 3.
- A systematic review and meta-analysis published in 2023 found that the efficacy of tigecycline-based regimens was similar to that of colistin-based regimens, but with a higher mortality rate and lower rate of microbiological eradication 4.
- In vitro studies have shown that the combination of tigecycline and colistin may be an effective therapy to synergistically prevent the emergence of resistance during treatment of MDR Acinetobacter baumannii infections 5.
Clinical Outcomes
- Clinical success rates for tigecycline-based therapy have been reported to be around 47-58% 2, 4.
- Clinical success rates for colistin-based therapy have been reported to be around 48-53% 2, 4.
- Mortality rates for tigecycline-based therapy have been reported to be around 41-51% 6, 4.
- Mortality rates for colistin-based therapy have been reported to be around 34-44% 3, 4.
Microbiological Outcomes
- Microbiological eradication rates for tigecycline-based therapy have been reported to be around 32-85% 6, 5.
- Microbiological eradication rates for colistin-based therapy have been reported to be around 43% 4.
- The combination of tigecycline and colistin has been shown to achieve a greater reduction in bacterial density and area under the bactericidal curve (AUBC) compared to monotherapy 5.