Aerosolized plus intravenous colistin vs intravenous colistin alone for the treatment of nosocomial pneumonia due to multidrug-resistant Gram-negative bacteria: A retrospective cohort study

Ceftazidime-Avibactam Versus Colistin for the Treatment of Multidrug-Resistant Pseudomonas aeruginosa Infections: A Multicenter Cohort Study

Purpose: To evaluate the real-world evidence of ceftazidime-avibactam (CAZ-AVI) compared to intravenous colistin for the treatment of multidrug-resistant (MDR) P. aeruginosa infections. Method: This is a multicenter, retrospective cohort study conducted in the period between 2017 and 2023 at five institutions for patients who received either CAZ-AVI or colistin-based regimens for treating MDR P. aeruginosa infections. Outcomes were compared using multivariate logistic regression analysis. Result: Among the screened patients, 203 patients were included: 89 in the CAZ-AVI group and 114 in the colistin group. A total of 57% presented with pneumonia, 21% with bacteremia, and 61% were in the intensive care unit. The rate of clinical cure was significantly higher among patients who received CAZ-AVI (67% vs. 50%; OR, 2.07; 95% CI, 1.16-3.68). The rate of in-hospital mortality was numerically lower among patients who received CAZ-AVI (40% vs. 49%; OR, 0.58; 95% CI, 0.33-1.03). The rate of AKI was significantly lower among patients who received CAZ-AVI (15% vs. 43%; OR, 0.23; 95% CI, 0.11-0.45). Conclusion: CAZ-AVI was more effective in treating MDR P. aeruginosa infections and showed a better safety profile compared to colistin. Thus, CAZ-AVI could be a better alternative for treating MDR P. aeruginosa infections.

A systematic review and meta-analysis: rising prevalence of colistin resistance in ICU-acquired Gram-negative bacteria

Colistin is a last-resort treatment for multidrug-resistant Gram-negative bacterial infections, particularly in critically ill patients. Nevertheless, it remains a major threat to public health. We assessed the proportion of colistin-resistant Gram-negative isolates from intensive care unit (ICU) infections in different years, areas, pathogens, and antimicrobial susceptibility tests (AST). We searched the studies in PubMed, Scopus, Embase, and Web of Science (until November 2021). Statistical analyses were conducted using STATA software (ver. 14.0). The overall rate of colistin resistance was 5.18% (95% CI 2.70%-8.22%). The proportion of colistin resistance was 4% (95% CI 2%-7%) before 2015 and 6% (95% CI 4%-9%) in 2015-2019. The rates of colistin resistance in Europe, America, Asia, and Africa were 8.24%, 3.78%, 3.60%, and 0%, respectively. The proportion of colistin-resistant non-fermenting Gram-negative bacilli isolated from the ICU was 2.25% (Acinetobacter baumannii [1.68%] and Pseudomonas aeruginosa [3.30%]). A 4-fold increase in colistin resistance was observed when comparing EUCAST and CLSI. We described the global epidemiology of colistin resistance over time and shown the distribution of colistin-resistant strains in different countries. Robust antimicrobial stewardship programs can increase the success of ICU physicians in improving patient outcomes.

The challenges of difficult-to-treat Acinetobacter infections

SUMMARYInfections due to Acinetobacter spp. are among the most difficult to treat. Most are resistant to standard antibiotics, and there is difficulty in distinguishing colonizers from pathogens. This mini-review examines the available antibiotics that exhibit activity against these organisms and provides guidance as to which cultures are relevant and how to treat active infections. Antibiograms describing resistance mechanisms and the minimum inhibitory concentration (MIC) are essential to determine which agent or combination of agents should be used after confirmation of infection, utilizing clinical parameters and biomarkers such as procalcitonin. Directed therapy should be prompt as despite its reputation as a colonizer, the attributable mortality is high. However, although combination therapy is advised, no specific combination has definite evidence of superiority.

The efficacy and safety of inhaled antibiotics for pneumonia: A systematic review and meta-analysis

OBJECTIVES

The aim of this study was to evaluate the efficacy and safety of inhaled antibiotics for adults with pneumonia by meta-analysis.

METHODS

Literature retrieval was completed through five databases (PubMed, Embase, Cochrane Library, Web of Science and Scopus) by the deadline of May 31, 2024. The process of study selection and data extraction were performed independently by two reviewers. The quality of observational studies and randomized controlled trial (RCT) studies were evaluated by Newcastle Ottawa scale and Jadad scale, respectively. The primary outcomes included mortality, clinical cure, and microbiological cure. Secondary outcomes were recurrence and renal impairment.

RESULTS

There were 30 studies were analyzed, including 12 RCT studies and 18 observational studies. Inhaled antibiotics did not significantly reduce mortality in RCT studies (odds ratio (OR) = 1.06, 95 % confidence interval (CI): 0.80-1.41). Inhaled antibiotics were associated with higher rates of clinical cure (OR = 1.47 95%CI: 0.82-2.66 in RCT studies and OR = 2.09, 95%CI: 1.36-3.21 in observational studies) and microbiological cure (OR = 7.00 in RCT studies and OR = 2.20 in observational studies). Subgroup analysis showed patients received inhaled antibiotics combined with intravenous administration and inhaled amikacin had better improvements of mortality, clinical cure and microbiological cure. Inhaled antibiotics were not associated with recurrence. The pooled OR of renal impairment were 0.65 (95%CI: 0.27-1.13; I-squared = 43.5 %, P = 0.124) and 0.63(95%CI: 0.26-1.11; I-squared = 69.0 %, P = 0.110) in RCT studies and observational studies, respectively.

CONCLUSIONS

Inhaled antibiotics decreased risk of renal impairment and achieved significant improvements of clinical and microbiological cure in patients with pneumoniae.

Efficacy and safety of different polymyxin-containing regimens for the treatment of pneumonia caused by multidrug-resistant gram-negative bacteria: a systematic review and network meta-analysis

BACKGROUND

The optimal administration of polymyxins for treating multidrug-resistant gram-negative bacterial (MDR-GNB) pneumonia remains unclear. This study aimed to systematically assess the efficacy and safety of three polymyxin-containing regimens by conducting a comprehensive network meta-analysis.

METHODS

We comprehensively searched nine databases. Overall mortality was the primary outcome, whereas the secondary outcomes encompassed microbial eradication rate, clinical success, acute kidney injury, and incidence of bronchospasm. Extracted study data were analyzed by pairwise and network meta-analyses. Version 2 of the Cochrane risk-of-bias tool and the Risk of Bias in Nonrandomized Studies of Interventions (ROBINS-I) assessment tool were used to assess the risk of bias in randomized trials and cohort studies, respectively.

RESULTS

This study included 19 observational studies and 3 randomized controlled trials (RCTs), encompassing 3318 patients. Six studies with high risk of bias were excluded from the primary analysis. In the pairwise meta-analysis, compared to the intravenous (IV) polymyxin-containing regimen, the intravenous plus inhaled (IV + IH) polymyxin-containing regimen showed a significant decrease in overall mortality, while no statistically significant difference was found in the inhaled (IH) polymyxin-containing regimen. The network meta-analysis indicated that the IV + IH polymyxin-containing regimen had significantly lower overall mortality (OR 0.67; 95% confidence interval [CI] 0.50-0.88), higher clinical success rate (OR 1.90; 95% CI 1.20-3.00), better microbial eradication rate (OR 2.70; 95% CI 1.90-3.90) than the IV polymyxin-containing regimen, and significantly better microbial eradication rate when compared with the IH polymyxin-containing regimen (OR 2.30; 95% CI 1.30-4.20). Furthermore, compared with IV + IH and IV polymyxin-containing regimens, the IH polymyxin-containing regimen showed a significant reduction in acute kidney injury.

CONCLUSIONS

Our study indicates that among the three administration regimens, the IV + IH polymyxin-containing regimen may be the most effective for treating MDR-GNB pneumonia, with a significantly lower overall mortality compared to the IV regimen and a considerably higher microbial eradication rate compared to the IH regimen. The IH regimen may be considered superior to the IV regimen due to its substantially lower incidence of acute kidney injury, even though the reduction in overall mortality was not significant.

In Vitro Evaluation of Colistin Conjugated with Chitosan-Capped Gold Nanoparticles as a Possible Formulation Applied in a Metered-Dose Inhaler

Inhaled colistin is used to treat pneumonia and respiratory infections through nebulization or dry powder inhalers. Nevertheless, the development of a metered-dose inhaler (MDI) for colistin, which could enhance patient convenience and treatment efficacy, has not yet been developed. Colistin is known for its ability to induce cellular toxicity. Gold nanoparticles (AuNPs) can potentially mitigate colistin toxicity. Therefore, this study aimed to evaluate the antimicrobial effectiveness of colistin conjugated with chitosan-capped gold nanoparticles (Col-CS-AuNPs) and their potential formulation for use with MDIs to deliver the aerosol directly to the deep lung. Fourier-transform infrared spectroscopy, nuclear magnetic resonance, and elemental analysis were used to characterize the synthesized Col-CS-AuNPs. Drug release profiles fitted with the most suitable release kinetic model were evaluated. An MDI formulation containing 100 µg of colistin per puff was prepared. The aerosol properties used to determine the MDI performance included the fine particle fraction, mass median aerodynamic diameter, and geometric standard deviation, which were evaluated using the Andersen Cascade Impactor. The delivered dose uniformity was also determined. The antimicrobial efficacy of the Col-CS-AuNP formulation in the MDI was assessed. The chitosan-capped gold nanoparticles (CS-AuNPs) and Col-CS-AuNPs had particle sizes of 44.34 ± 1.02 and 174.50 ± 4.46 nm, respectively. CS-AuNPs effectively entrapped 76.4% of colistin. Col-CS-AuNPs exhibited an initial burst release of up to 60% colistin within the first 6 h. The release mechanism was accurately described by the Korsmeyer-Peppas model, with an R2 > 0.95. The aerosol properties of the Col-CS-AuNP formulation in the MDI revealed a high fine particle fraction of 61.08%, mass median aerodynamic diameter of 2.34 µm, and geometric standard deviation of 0.21, with a delivered dose uniformity within 75-125% of the labeled claim. The Col-CS-AuNP MDI formulation completely killed Escherichia coli at 5× and 10× minimum inhibitory concentrations after 6 and 12 h of incubation, respectively. The toxicity of CS-AuNP and Col-CS-AuNP MDI formulations in upper and lower respiratory tract cell lines was lower than that of free colistin. The stability of the Col-CS-AuNP MDI formulation was maintained for at least 3 months. The Col-CS-AuNP MDI formulation effectively eradicated bacteria over a 12-h period, showing promise for advancing lung infection treatments.

Narrative Review of the Epidemiology of Hospital-Acquired Pneumonia and Ventilator-Associated Pneumonia in Gulf Cooperation Council Countries

Hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) are the most common healthcare-associated infections, with rates varying between countries. Antimicrobial resistance (AMR) among common HAP/VAP pathogens has been reported, and multidrug resistance (MDR) is of further concern across Middle Eastern countries. This narrative review summarizes the incidence and pathogens associated with HAP/VAP in hospitals across Gulf Cooperation Council (GCC) countries. A PubMed literature search was limited to available data on HAP or VAP in patients of any age published within the past 10 years. Reviews, non-English language articles, and studies not reporting HAP/VAP data specific to a GCC country were excluded. Overall, 41 articles, a majority of which focused on VAP, were selected for inclusion after full-text screening. Studies conducted over multiple years showed a general reduction in VAP rates over time, with Gram-negative bacteria the most commonly reported pathogens. Gram-negative isolates reported across GCC countries included Acinetobacter baumannii, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Rates of AMR varied widely among studies, and MDR among A. baumannii, K. pneumoniae, Escherichia coli, P. aeruginosa, and Staphylococcus aureus isolates was commonly reported. In Saudi Arabia, between 2015 and 2019, rates of carbapenem resistance among Gram-negative bacteria were 19-25%; another study (2004-2009) reported antimicrobial resistance rates in Acinetobacter species (60-89%), P. aeruginosa (13-31%), and Klebsiella species (100% ampicillin, 0-13% other antimicrobials). Although limited genotype data were reported, OXA-48 was found in ≥ 68% of patients in Saudi Arabia with carbapenem-resistant Enterobacteriaceae infections. Ventilator utilization ratios varied across studies, with rates up to 0.9 reported in patients admitted to adult medical/surgical intensive care units in both Kuwait and Saudi Arabia. VAP remains a burden across GCC countries albeit with decreases in rates over time. Evaluation of prevention and treatment measures and implementation of a surveillance program could be useful for the management of HAP and VAP.

Efficacy and safety of intravenous combined with aerosolised polymyxin versus intravenous polymyxin alone in the treatment of multidrug-resistant gram-negative bacterial pneumonia: A systematic review and meta-analysis

Background

Previous studies have questioned the efficacy and safety of intravenous combined with aerosolised (IV + AS) polymyxin versus intravenous (IV) polymyxin alone in the treatment of patients with multidrug-resistant gram-negative bacterial (MDR-GNB) pneumonia. Therefore, we conducted a meta-analysis to evaluate the efficacy and safety of IV + AS polymyxin in the treatment of MDR-GNB pneumonia.

Methods

We identified all relevant studies by searching the PubMed, EMBASE and Cochrane library databases from their inception to May 31, 2022. All included studies were evaluated using the Newcastle Ottawa scale (NOS) checklist. The summary relative risk (RR) and 95% confidence interval (CI) were used to determine the outcome differences between the IV + AS and the IV groups. Subgroup analysis was performed based on population, polymyxin dose and kinds of polymyxin.

Results

A total of 16 studies were included in the meta-analysis. The IV + AS group had lower mortality (RR = 0.86, 95% CI: 0.77-0.97, P = 0.01) than the IV group. Subgroup analysis revealed that IV + AS polymyxin could reduce mortality only when used in low doses. Simultaneously, the IV + AS group outperformed the IV group in terms of clinical response rate, clinical cure rate, microbiological eradication and duration of mechanical ventilation. The duration of hospitalisation and the incidence of nephrotoxicity did not differ significantly between the two groups.

Conclusions

IV + AS polymyxin is beneficial in the treatment of MDR-GNB pneumonia. It could lower patient mortality and improve clinical and microbial outcomes without increasing the risk of nephrotoxicity. However, retrospective analysis in the majority of studies and heterogeneity between studies implies that our findings must be interpreted carefully.

Efficacy and safety of polymyxin E sulfate in the treatment of critically ill patients with carbapenem-resistant organism infections

Objective

Polymyxins are currently the last line of defense in the treatment of carbapenem-resistant organisms (CRO). As a kind of polymyxin available for clinical use in China, we aim to explore the efficacy and safety of colistin sulfate (Polymyxin E sulfate, PES) in this study.

Methods

This real-world retrospective study included 119 patients diagnosed with CRO infection and treated with PES for more than 72 h, from May 2020 to July 2022 at West China Hospital. The primary outcome was clinical efficacy at the end of treatment, and secondary outcomes included microbial response, in-hospital mortality and incidence of nephrotoxicity.

Results

The effective clinical and microbiological responses were 53.8% and 49.1%, respectively. And the in-hospital mortality was 27.7%. Only 9.2% of patients occurred with PES-related nephrotoxicity. Multivariate analysis revealed that duration of PES was an independent predictor of effective therapy, while age-adjusted Charlson comorbidity index (aCCI) and post-treatment PCT(p-PCT) were independent risk factors for poor outcome.

Conclusions

PES can be a salvage treatment for CRO-induced infections with favorable efficacy and low nephrotoxicity. The treatment duration of PES, aCCI and p-PCT were factors related to the clinical effectiveness of PES.

Treatments and Predictors of Mortality for Carbapenem-Resistant Gram-Negative Bacilli Infections in Malaysia: A Retrospective Cohort Study

This study evaluated the treatments, mortality rate and patient-related factors associated with mortality. This is a retrospective study involving hospitalised patients with infections caused by carbapenem-resistant Gram-negative bacilli (CR-GNB) in a tertiary hospital in Malaysia from January 2018 to June 2020. A clinical pharmacist reviewed patients' electronic records and collected the data according to a pre-designed form. Data were analysed using both descriptive and inferential tests. The study included 145 patients with CR-GNB infections including 77, 40 and 28 Acinetobacter baumannii, enterobacteriaceae and Pseudomonas aeruginosa, respectively. The mean age was 57.9 ± 15.8 years. Pneumonia (40.7%) and bacteremia (25.5%) were the most common infections. Meropenem (24.7%) and piperacillin-tazobactam (20.4%) were the most commonly used empiric antibiotics while colistin (63.3%) and amikacin (8.3%) were the most common definitive antibiotics. The mean duration before active antibiotics was 4.6 ± 3.3 days. Overall, the in-hospital mortality rate was 41.4%. Multivariate logistic regression analysis showed that intensive care unit (ICU) admission (adjusted odds ratio (AOR): 5.201; 95% confidence interval (CI): 1.603-16.872; p = 0.006), sepsis/septic shock (AOR: 3.430; 95% CI: 1.021-11.522; p = 0.049) and elevated serum creatinine (AOR: 2.752; 95% CI: 1.005-7.536; p = 0.049) were independently associated with mortality. The mortality rate among patients with CR-GNB infection is high. A high rate of inappropriate antibiotic use was observed, including combination antibiotic therapy and delays in starting active antibiotics. Mortality was significantly associated with ICU admission, sepsis/septic shock and elevated serum creatinine.

Ceftolozane-tazobactam versus colistin for the treatment of infections due to drug-resistant Pseudomonas aeruginosa. A multicenter cohort study

BACKGROUND

The aim of this study was to compare the safety and effectiveness of ceftolozane-tazobactam (C-T) to colistin-based regimen for treating infections caused by multidrug-resistant (MDR) P. aeruginosa.

METHOD

This was a retrospective, multicenter, observational cohort study of inpatients who received either C-T or intravenous colistin for treating infections caused by MDR P. aeruginosa. The study was conducted in 5 tertiary care hospitals in Saudi Arabia. Main study outcomes included clinical cure at end of treatment, in-hospital mortality, and acute kidney injury (AKI). Univariate analysis and multivariate logistic regression model were conducted to evaluate the independent effect of C-T on the clinical outcome.

RESULT

A total of 184 patients were included in the study: 82 patients received C-T and 102 patients received colistin-based regimen. Clinical cure (77% vs 57%; P = 0.005; OR, 2.52; 95% CI, 1.32-4.79) was significantly more common in patients who received C-T. After adjusting the difference between the two groups, treatment with C-T is independently associated with clinical cure (adjusted OR, 2.47; 95% CI, 1.16-5.27). In-hospital mortality (39% vs 49%; P = 0.175; OR, 0.67; 95% CI, 0.37-1.20) was lower in patients who received C-T but the difference was not significant. AKI (15% vs 41%; P < 0.001; OR, 0.25; 95% CI, 0.12-0.51) was significantly less common in patients who received C-T.

CONCLUSION

C-T is associated with higher rate of clinical cure and lower rate of AKI compared to colistin. Our findings support the preferential use of C-T over colistin-based regimen for treating these infections.

Ceftazidime-Avibactam versus Colistin for the Treatment of Infections Due to Carbapenem-Resistant Enterobacterales: A Multicenter Cohort Study

Background

The aim of this study was to compare the safety and effectiveness of ceftazidime-avibactam (CAZ-AVI) to colistin-based regimen in the treatment of infections caused by carbapenem-resistant Enterobacterales (CRE).

Methods

This was a retrospective, multicenter, observational cohort study of inpatients who received either CAZ-AVI or intravenous colistin for treatment of infections due to CRE. The study was conducted in 5 tertiary care hospitals in Saudi Arabia. Main study outcomes included in-hospital mortality, clinical cure at end of treatment, and acute kidney injury (AKI). Univariate analysis and multivariate logistic regression model were conducted to assess the independent impact of CAZ-AVI on the clinical outcome.

Results

A total of 230 patients were included in this study: 149 patients received CAZ-AVI and 81 patients received colistin-based regimen. Clinical cure (71% vs 52%; P = 0.004; OR, 2.29; 95% CI, 1.31–4.01) was significantly more common in patients who received CAZ-AVI. After adjusting the difference between the two groups, treatment with CAZ-AVI is independently associated with clinical cure (adjusted OR, 2.75; 95% CI, 1.28–5.91). In-hospital mortality (35% vs 44%; P = 0.156; OR, 0.67; 95% CI, 0.39–1.16) was lower in patients who received CAZ-AVI but the difference was not significant. AKI (15% vs 33%; P = 0.002; OR, 0.37; 95% CI, 0.19–0.69) was significantly less common in patients who received CAZ-AVI.

Conclusion

CAZ-AVI is associated with higher rate of clinical cure and lower rate of AKI compared to colistin. Our findings support the preferential use of CAZ-AVI over colistin-based regimen for treating these infections.