<p>Colistin Plus Carbapenem versus Colistin Monotherapy in the Treatment of Carbapenem-Resistant <em>Acinetobacter baumannii</em> Pneumonia</p>

Abstract

Purpose: Colistin alone may not be sufficient for treating carbapenem-resistant Acinetobacter baumannii (CRAB); thus, efforts are needed to increase treatment success rates. We compared the effects of colistin plus carbapenem therapy versus colistin monotherapy in treating pneumonia caused by CRAB and attempted to identify specific populations or factors that could benefit from combination therapy. Methods: We retrospectively collected data on cases of CRAB pneumonia. The patients were divided into colistin plus carbapenem therapy and colistin monotherapy groups. The primary outcome was 14-day mortality. The secondary outcomes were in-hospital mortality, clinical improvement at days 2 and 14, and microbiological improvement at day 14.Results: Of 160 cases meeting criteria for CRAB pneumonia, 83 (52%) and 77 (48.0%) were treated with carbapenem combination therapy or colistin monotherapy, respectively. Among these patients, 50 (63.3%) in the combination group and 27 (39.7%) in the monotherapy group had Acute Physiologic Assessment and Chronic Health Evaluation (APACHE) II scores >24 points (p=0.010). Overall, there was no significant difference in 14-day mortality between the combination and monotherapy groups (24.1% vs 20.8%, p=0.616). Clinical improvement and sputum-negative conversion also showed no significant difference. After adjusting for disease severity according to APACHE II score, the 14-day mortality was significantly lower in the combination group than in the monotherapy group among patients with APACHE II scores of 25-29 points (9.1% vs 53.8%, P=0.020). Conclusion: Despite more severe conditions, compared with colistin monotherapy, colistin plus carbapenem combination therapy showed equivalent primary mortality outcome in treating CRAB pneumonia. Combination therapy was more effective in patients with APACHE II score ranging from 25 to 29 points.

A Comparison of Colistin versus Colistin Plus Meropenem for the Treatment of Carbapenem-Resistant Acinetobacter baumannii in Critically Ill Patients: A Propensity Score-Matched Analysis

“…Our findings showed that the maximal clinical benefit of combination therapy was observed in our patients with critical illness, which is consistent with data from a previous study [ 15 , 16 ]. A retrospective study comparing colistin monotherapy with colistin plus a carbapenem combination therapy on 160 cases of CRAB pneumonia showed no significant difference in 14-day mortality between the combination and monotherapy groups (24.1% vs. 20.8%, p = 0.616).…”

“…A retrospective study comparing colistin monotherapy with colistin plus a carbapenem combination therapy on 160 cases of CRAB pneumonia showed no significant difference in 14-day mortality between the combination and monotherapy groups (24.1% vs. 20.8%, p = 0.616). However, after adjusting for disease severity according to APACHE II score, the 14-day mortality was significantly lower in the combination group compared to the monotherapy group among patients with APACHE II scores of 25–29 points (9.1% vs. 53.8%, p = 0.020) [ 15 ]. In a previous retrospective study that evaluated data from 71 patients with CRAB bacteraemia treated with colistin monotherapy and colistin plus meropenem combination therapy, mortality tended to be higher in the monotherapy group, but the difference was not statistically significant (47.5% vs. 25.8%).…”

Insights into Acinetobacter baumannii: A Review of Microbiological, Virulence, and Resistance Traits in a Threatening Nosocomial Pathogen

“…Other combination regimens suggest increased efficacy of sulbactam with cefepime, meropenem, imipenem, amikacin, or rifampin [123]. Alternative combinations include colistin-tigecycline and colistin-carbapenem therapy, with the latter perhaps the most supported [36], and have been recommended in several trials [124][125][126]. Furthermore, a recent investigation has highlighted a remarkable synergistic interaction between colistin and vancomycin [127].…”

The effectiveness and nephrotoxicity of loading dose colistin combined with or without meropenem for the treatment of carbapenem-resistant A. baumannii

“…Data from some in-vitro studies have shown synergistic effects of colistin and meropenem combination therapy (Tängdén et al, 2017). On the other hand, another previous study reported no significant difference in antibacterial effect between colistin monotherapy and colistin plus meropenem combination (Shi et al, 2019). In addition, clinical data are very limited and have controversial results.…”