Colistin versus Colistin Combined with Ampicillin-Sulbactam for Multiresistant Acinetobacter baumannii Ventilator-associated Pneumonia Treatment: An Open-label Prospective Study

Clinical Outcomes Of Colistin In Combination With Either 6-G Sulbactam Or Carbapenems For The Treatment Of Extensively Drug-Resistant Acinetobacter Baumannii Pneumonia With High MIC To Sulbactam, A Prospective Cohort Study

Purpose

Extensively drug-resistant Acinetobacter baumannii (XDRAB) is an important cause of nosocomial pneumonia with limited therapeutic options. Colistin-based regimen is the recommended treatment. Which drugs should be combined with colistin remains uncertain. The aim of this study was to investigate the clinical outcomes of patients with XDRAB pneumonia who were treated with colistin, combined with either 6-g sulbactam or carbapenems, in the setting of high MIC to sulbactam.

Patients and methods

In this prospective cohort study, hospitalized patients diagnosed with XDRAB pneumonia in Phramongkutklao Hospital were enrolled. The primary outcome was 28-day mortality. Secondary outcomes were 7- and 14-day mortality, length of stay, ventilator days and factors associated with mortality.

Results

From 1 July 2016 to 30 September 2017, 182 patients were included; 92 received colistin plus sulbactam and 90 received colistin plus carbapenems. Most of the patients were males diagnosed with ventilator-associated pneumonia in medical intensive care unit. Overall mortality rates at 7, 14, 28 days were 24.2%, 37.4%, and 53.3%, respectively. Mortality rates did not differ between sulbactam group and carbapenem groups at 7 days (19.6% vs 28.9%, p-value 0.424, adjusted HR 1.277; 95% CI = 0.702–2.322), 14 days (34.8% vs 40%, p = 0.658, adjusted HR 1.109; 95% CI = 0.703–1.749) and 28 days (51.1% vs 55.6%, p = 0.857, adjusted HR 1.038; 95% CI = 0.690–1.562). Length of stay, ICU days and ventilator days did not differ. Complications of treatment including acute kidney injury were not statistically different.

Conclusion

In XDRAB pneumonia with high MIC to sulbactam, differences in mortality rates were not statistically significant between colistin plus 6-g sulbactam and colistin plus carbapenems.

Management of ventilator-associated pneumonia (VAP) caused by resistant gram-negative bacteria: which is the best strategy to treat?

Introduction: Treatment of ventilator-associated pneumonia (VAP) is a major challenge. The increase in multi-drug resistant bacteria has not been accompanied by the validation of new drugs, or by any new antimicrobial strategies to exploit the available agents. VAP due to Gram-negative bacteria has increased mortality, both due to the resistant pathogens themselves and due to inappropriate treatment. Local epidemiology, patients' characteristics and clinical responses provide the most important information for therapeutic decision-making. Moreover, data on VAP therapy due to resistant bacteria are lacking, and the choice of treatment is often based on clinical practice and individual experience. Areas covered: This review summarizes the strategies available for treating the three most prevalent resistant Gram-negative organisms causing VAP: Pseudomonas aeruginosa, Acinetobacter baumannii and Enterobacteriaceae. The review covers the results of a Pubmed search, clinical practice guidelines and reviews, and the authors' experience. Expert opinion: The existing evidence focuses on bloodstream infections or other sites rather than pneumonia and there are no recommendations for the treatment of VAP by multi-drug resistant Gram-negative bacteria, especially for combination regimens. The approval of new drugs is needed to provide effective and safe alternatives for treating carbapenemase-producing strains. Precision medicine and personalized approach are also fundamental in future research.

Rationalizing antimicrobial therapy in the ICU: a narrative review

The massive consumption of antibiotics in the ICU is responsible for substantial ecological side effects that promote the dissemination of multidrug-resistant bacteria (MDRB) in this environment. Strikingly, up to half of ICU patients receiving empirical antibiotic therapy have no definitively confirmed infection, while de-escalation and shortened treatment duration are insufficiently considered in those with documented sepsis, highlighting the potential benefit of implementing antibiotic stewardship programs (ASP) and other quality improvement initiatives. The objective of this narrative review is to summarize the available evidence, emerging options, and unsolved controversies for the optimization of antibiotic therapy in the ICU. Published data notably support the need for better identification of patients at risk of MDRB infection, more accurate diagnostic tools enabling a rule-in/rule-out approach for bacterial sepsis, an individualized reasoning for the selection of single-drug or combination empirical regimen, the use of adequate dosing and administration schemes to ensure the attainment of pharmacokinetics/pharmacodynamics targets, concomitant source control when appropriate, and a systematic reappraisal of initial therapy in an attempt to minimize collateral damage on commensal ecosystems through de-escalation and treatment-shortening whenever conceivable. This narrative review also aims at compiling arguments for the elaboration of actionable ASP in the ICU, including improved patient outcomes and a reduction in antibiotic-related selection pressure that may help to control the dissemination of MDRB in this healthcare setting.

Safety and efficacy of colistin alone or in combination in adults with Acinetobacter baumannii infection: A systematic review and meta-analysis

This review comprehensively assessed the safety and efficacy of colistin alone or in combination in adults with Acinetobacter baumannii infection. PubMed, Embase and the Cochrane Library were searched from inception to March 2018 for studies evaluating colistin monotherapy compared with other antibiotic therapy or colistin-based combination therapy for the treatment of A. baumannii infection in adults. Efficacy outcomes were clinical response and microbiological cure. Safety outcomes were mortality and nephrotoxic adverse events. A total of 4 randomised controlled trials (RCTs) and 14 observational studies were identified, including 7 reporting colistin versus other antibiotics and 12 reporting colistin monotherapy versus colistin-based combination therapy. Overall clinical response, microbiological response and mortality did not differ significantly between colistin monotherapy versus other antibiotics. However, the incidence of nephrotoxicity was significantly higher in colistin monotherapy (OR = 2.50, 95% CI 1.05-5.98; P = 0.04). No significant differences were detected in clinical response and >28-day mortality between colistin monotherapy and combination therapy. However, colistin-based combination therapy showed an increased microbiological response (OR = 0.49, 95% CI 0.32-0.74; P = 0.0009) and decreased incidence of nephrotoxicity (OR = 1.66, 95% CI 0.99-2.78; P =0.05). In conclusion, colistin alone is as effective as other antibiotics for the treatment of A. baumannii infection but has a higher risk of nephrotoxicity. Colistin-based combination therapy demonstrated a microbiological benefit and no higher risk of nephrotoxicity compared with monotherapy. High-quality RCTs are still needed to confirm the beneficial role of colistin-based combination therapy.

Intravenous Colistin Monotherapy versus Combination Therapy against Carbapenem-Resistant Gram-Negative Bacteria Infections: Meta-Analysis of Randomized Controlled Trials

This meta-analysis aims to compare intravenous colistin monotherapy and colistin-based combination therapy against carbapenem-resistant gram-negative bacteria (GNB) infections. PubMed, Embase, and Cochrane databases were searched up to July 2018. Only randomized controlled trials (RCTs) evaluating colistin alone and colistin-based combination therapy in the treatment of carbapenem-resistant GNB infections were included. The primary outcome was all-cause mortality. Five RCTs including 791 patients were included. Overall, colistin monotherapy was associated with a risk ratio (RR) of 1.03 (95% confidence interval (CI), 0.89–1.20, I² = 0%) for all-cause mortality compared with colistin-based combination therapy. The non-significant difference was also detected in infection-related mortality (RR, 1.23, 95% CI, 0.91–1.67, I² = 0%) and microbiologic response (RR, 0.86, 95% CI, 0.72–1.04, I² = 62%). In addition, no significant difference was observed in the subgroup analysis—high or low dose, with or without a loading dose, carbapenem-resistant Acinetobacter baumannii infections, and in combination with rifampicin. Finally, colistin monotherapy was not associated with lower nephrotoxicity than colistin combination therapy (RR, 0.98; 95% CI, 0.84–1.21, I² = 0%). Based on the analysis of the five RCTs, no differences were found between colistin monotherapy and colistin-based combination therapy against carbapenem-resistant GNB infections, especially for A. baumannii infections.