Inhalation with intravenous loading dose of colistin in critically ill patients with pneumonia caused by carbapenem-resistant gram-negative bacteria

Analysis and comparison of adverse events of colistin administered by different routes based on the FAERS database

OBJECTIVE

To analyze and compare the incidence of adverse events (AEs) associated with different administration routes of colistin, with the aim of providing a reference for its safe and effective clinical use.

METHODS

Adverse event (AE) reports related to colistin were retrieved from the FDA Adverse Event Reporting System (FAERS) database. The reporting trends were analyzed, and the Reporting Odds Ratio (ROR) and Proportional Reporting Ratio (PRR) for colistin-associated AEs were calculated. A comparative analysis was conducted to examine the occurrence of AEs under different administration routes of colistin.

RESULTS

A total of 13,043 AE reports were extracted from the FAERS database. Further analysis of 176 key AEs associated with colistin indicated a significant increase in the number of reports after 2021. The year and country of the reports showed heterogeneity across different administration routes. Intravenous (IV) administration of colistin was associated with the highest proportion of AEs, and heterogeneity was also observed in the types of AEs reported for inhaled and oral (PO) administration routes.

CONCLUSION

Compared to inhaled and PO administration routes, IV administration of colistin is more likely to result in AEs such as nephrotoxicity and drug ineffectiveness. Additionally, there are significant differences in the types of AEs associated with colistin across different administration routes.

Korean Guidelines for the Management and Antibiotic Therapy in Adult Patients with Hospital-Acquired Pneumonia

Hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) are correlated with high morbidity and mortality rates. Guidelines that consider local epidemiologic data are fundamental for identifying optimal treatment strategies. However, Korea has no HAP/VAP guidelines. This study was conducted by a committee of nine experts from the Korean Academy of Tuberculosis and Respiratory Diseases Respiratory Infection Study Group using the results of Korean HAP/VAP epidemiologic studies. Eleven key questions for HAP/VAP diagnosis and treatment were addressed. The Convergence of Opinion on Suggestions and Evidence (CORE) process was used to derive suggestions, and evidence levels and recommendation grades were in accordance with the Grading of Recommendations Assessment Development and Evaluation (GRADE) methodology. Suggestions were made for the 11 key questions pertinent to diagnosis, biomarkers, antibiotics, and treatment strategies for adult patients with HAP/VAP. Using the CORE process and GRADE methodology, the committee generated a series of recommendations for HAP/VAP diagnosis and treatment in the Korean context.

Efficacy and Safety of Aerosol Inhalation of Colistin Sulfate for the Treatment of Carbapenem-Resistant Klebsiella pneumoniae Infection in the Peri-Operative Period of Liver Transplantation: A Single-Center Retrospective Study

Objective: This study intended to evaluate the clinical efficacy and safety of colistin sulfate aerosol inhalation in combination with ceftazidime-avibactam for the treatment of pulmonary carbapenem-resistant Klebsiella pneumoniae (CRKP) infection during the peri-operative period of liver transplantation. Materials and Methods: A retrospective analysis was designed to investigate 52 patients who developed pulmonary CRKP infection after liver transplantation between December 1, 2019, and November 30, 2022. On the basis of whether they received colistin sulfate aerosol inhalation, the patients were divided into the treatment group (n = 29) and the control group (n = 23). The baseline information, infection status, CRKP enzyme type, inflammatory markers, liver and kidney function, and prognosis were compared and analyzed. Results: There were no significant differences in patient characteristics, infection status, and drug resistance enzyme type between the treatment group (treated with colistin sulfate aerosol inhalation and ceftazidime and avibactam sodium for injection) and the control group (treated with ceftazidime and avibactam sodium for injection alone). Colistin sulfate aerosol inhalation treatment reduced concentrations of inflammatory markers, with post-treatment white blood cell count, procalcitonin, and C-reactive protein significantly lower than pre-treatment levels (p < 0.05). Except for C-reactive protein at 14 days (p = 0.032), the two groups had no significant differences in other indicators. There were no significant differences in alanine aminotransferase, aspartate aminotransferase, total bilirubin, and glomerular filtration rate after treatment, indicating no discernible alteration in liver and kidney function. In addition, the treatment group took a significantly shorter time to normalize body temperature compared with the control group (p = 0.025), but there were no significant differences in the cure with no colonization rate and all-cause mortality rate between the two groups. Conclusions: The combination of colistin sulfate aerosol inhalation and ceftazidime and avibactam sodium for injection is effective in treating pulmonary CRKP infection during the peri-operative period of liver transplantation. It does not impose an additional burden on liver and kidney function, providing a new treatment option for this type of infection.

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.

Rapid evolution of colistin resistance in a bioreactor model of infection of Klebsiella pneumoniae

Colistin remains an important antibiotic for the therapeutic management of drug-resistant Klebsiella pneumoniae. Despite the numerous reports of colistin resistance in clinical strains, it remains unclear exactly when and how different mutational events arise resulting in reduced colistin susceptibility. Using a bioreactor model of infection, we modelled the emergence of colistin resistance in a susceptible isolate of K. pneumoniae. Genotypic, phenotypic and mathematical analyses of the antibiotic-challenged and un-challenged population indicates that after an initial decline, the population recovers within 24 h due to a small number of "founder cells" which have single point mutations mainly in the regulatory genes encoding crrB and pmrB that when mutated results in up to 100-fold reduction in colistin susceptibility. Our work underlines the rapid development of colistin resistance during treatment or exposure of susceptible K. pneumoniae infections having implications for the use of cationic antimicrobial peptides as a monotherapy.

Comparison of the clinical efficacy and toxicity of nebulized polymyxin monotherapy and combined intravenous and nebulized polymyxin for the treatment of ventilator-associated pneumonia caused by carbapenem-resistant gram-negative bacteria: a retrospective cohort study

Objective: To investigate the clinical efficacy and toxicity of nebulized polymyxin monotherapy and combined intravenous and nebulized polymyxin for the treatment of VAP caused by CR-GNB. Additionally, among patients treated with nebulized polymyxin monotherapy, we compared the clinical efficacy and toxicity of polymyxin B and polymyxin E. Methods: This study was a single-center, retrospective study. Included patients received aerosolized polymyxin for at least 72 h with or without intravenous polymyxin for the management of CR-GNB VAP. The primary endpoint was clinical cure at the end of polymyxin therapy. Secondary endpoints included AKI incidence, time of bacteria-negative conversion, duration of MV after inclusion, length of stay in ICU, and all-cause ICU mortality. Results: 39 patients treated with nebulized polymyxin monotherapy were assigned to the NL-polymyxin group. 39 patients treated with nebulized polymyxin combined with intravenous use of polymyxin were assigned to the IV-NL-polymyxin group. Among the NL-polymyxin group, 19 patients were treated with polymyxin B and 20 with polymyxin E. The clinical baseline characteristics before admission to the ICU and before nebulization of polymyxin were similar between the two groups. No differences were found between the two study groups in terms of microorganism distribution, VAP cure rate, time of bacteria-negative conversion, duration of MV after inclusion, length of stay in ICU and all-cause ICU mortality. Similarly, survival analysis did not differ between the two groups (χ2 = 3.539, p = 0.06). AKI incidence was higher in the IV-NL-polymyxin group. When comparing the clinical efficacy and toxicity to polymyxin B and polymyxin E, there was no difference between the two groups in terms of VAP cure rate, time of bacteria-negative conversion, duration of MV after inclusion, length of stay in ICU, SOFA score, CPIS, AKI incidence and all-cause ICU mortality. Conclusion: Our study found that nebulized polymyxin monotherapy was non-inferior to combination therapy with intravenous polymyxin in treating CR-GNB-VAP. Furthermore, we observed no differences in clinical efficacy or related toxic side effects between polymyxin B and polymyxin E during nebulized polymyxin therapy as monotherapy. However, future prospective studies with larger sample sizes are required to confirm these findings.

Guidelines for the diagnosis, treatment, prevention and control of infections caused by carbapenem-resistant gram-negative bacilli

The dissemination of carbapenem-resistant Gram-negative bacilli (CRGNB) is a global public health issue. CRGNB isolates are usually extensively drug-resistant or pandrug-resistant, resulting in limited antimicrobial treatment options and high mortality. A multidisciplinary guideline development group covering clinical infectious diseases, clinical microbiology, clinical pharmacology, infection control, and guideline methodology experts jointly developed the present clinical practice guidelines based on best available scientific evidence to address the clinical issues regarding laboratory testing, antimicrobial therapy, and prevention of CRGNB infections. This guideline focuses on carbapenem-resistant Enterobacteriales (CRE), carbapenem-resistant Acinetobacter baumannii (CRAB), and carbapenem-resistant Pseudomonas aeruginosa (CRPA). Sixteen clinical questions were proposed from the perspective of current clinical practice and translated into research questions using PICO (population, intervention, comparator, and outcomes) format to collect and synthesize relevant evidence to inform corresponding recommendations. The grading of recommendations, assessment, development and evaluation (GRADE) approach was used to evaluate the quality of evidence, benefit and risk profile of corresponding interventions and formulate recommendations or suggestions. Evidence extracted from systematic reviews and randomized controlled trials (RCTs) was considered preferentially for treatment-related clinical questions. Observational studies, non-controlled studies, and expert opinions were considered as supplementary evidence in the absence of RCTs. The strength of recommendations was classified as strong or conditional (weak). The evidence informing recommendations derives from studies worldwide, while the implementation suggestions combined the Chinese experience. The target audience of this guideline is clinician and related professionals involved in management of infectious diseases.

High-Dose Nebulized Colistin Methanesulfonate and the Role in Hospital-Acquired Pneumonia Caused by Gram-Negative Bacteria with Difficult-to-Treat Resistance: A Review

Hospital-acquired pneumonia, including ventilator-associated pneumonia (VAP) due to difficult-to-treat-resistant (DTR) Gram-negative bacteria, contributes significantly to morbidity and mortality in ICUs. In the era of COVID-19, the incidences of secondary nosocomial pneumonia and the demand for invasive mechanical ventilation have increased dramatically with extremely high attributable mortality. Treatment options for DTR pathogens are limited. Therefore, an increased interest in high-dose nebulized colistin methanesulfonate (CMS), defined as a nebulized dose above 6 million IU (MIU), has come into sight. Herein, the authors present the available modern knowledge regarding high-dose nebulized CMS and current information on pharmacokinetics, clinical studies, and toxicity issues. A brief report on types of nebulizers is also analyzed. High-dose nebulized CMS was administrated as an adjunctive and substitutive strategy. High-dose nebulized CMS up to 15 MIU was attributed with a clinical outcome of 63%. High-dose nebulized CMS administration offers advantages in terms of efficacy against DTR Gram-negative bacteria, a favorable safety profile, and improved pharmacokinetics in the treatment of VAP. However, due to the heterogeneity of studies and small sample population, the apparent benefit in clinical outcomes must be proven in large-scale trials to lead to the optimal use of high-dose nebulized CMS.

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.

Role of nebulized colistin as a substitutive strategy against nosocomial pneumonia caused by CR-GNB in intensive care units: a retrospective cohort study

BACKGROUND

Adverse reactions, especially nephrotoxicity, are great concerns of intravenous colistin treatment. The role of substitutive nebulized colistin in treating nosocomial pneumonia caused by carbapenem-resistant Gram-negative bacterial (CR-GNB) in critically ill patients remains unknown.

METHODS

This retrospective study enrolled patients with nosocomial pneumonia caused by colistin-susceptible CRGNB in the intensive care unit (ICU) without intravenous colistin treatment. Patients were categorized based on whether substitutive nebulized colistin was used alongside other intravenous antibiotics. Clinical responses and mortality rates were compared between the two groups in the original and propensity score (PS)-matched cohorts. This study aimed to investigate the clinical effectiveness of substitutive nebulized colistin in treatment outcomes of nosocomial pneumonia caused by CR-GNB. The impact of dosing strategy of nebulized colistin was also explored.

RESULTS

In total, 343 and 214 patients with and without substitutive nebulized colistin, respectively, were enrolled for analysis. In the PS-matched cohort, clinical failure rates on day 7 (22.6 vs. 42.6%, p = 0.001), day 14 (27.0 vs. 42.6%, p = 0.013), and day 28 (27.8 vs. 41.7%, p = 0.027) were significantly lower in patients with nebulized colistin. In multivariate analysis, nebulized colistin was an independent factor associated with lower day 14 clinical failure (Original cohort: adjusted odds ratio (aOR) 0.45, 95% confidence interval (CI) 0.30-0.67; PS-matched cohort: aOR 0.48, 95% CI 0.27-0.87). There were no differences in clinical failure rate and mortality rate between patients receiving high (> 6 MIU/day) and low (≤ 6 MIU/day) dose nebulized colistin in the PS-matched cohort.

CONCLUSIONS

In ICU-admitted patients with nosocomial pneumonia caused by colistin-susceptible CRGNB, substitutive nebulized colistin was associated with better clinical outcomes.

Prevalence of polymyxin-induced nephrotoxicity and its predictors in critically ill adult patients: A meta-analysis

BACKGROUND

Polymyxin-induced nephrotoxicity is a major safety concern in clinical practice due to long-term adverse outcomes and high mortality.

AIM

To conducted a systematic review and meta-analysis of the prevalence and potential predictors of polymyxin-induced nephrotoxicity in adult intensive care unit (ICU) patients.

METHODS

PubMed, EMBASE, the Cochrane Library and Reference Citation Analysis database were searched for relevant studies from inception through May 30, 2022. The pooled prevalence of polymyxin-induced nephrotoxicity and pooled risk ratios of associated factors were analysed using a random-effects or fixed-effects model by Stata SE ver. 12.1. Additionally, subgroup analyses and meta-regression were conducted to assess heterogeneity.

RESULTS

A total of 89 studies involving 12234 critically ill adult patients were included in the meta-analysis. The overall pooled incidence of polymyxin-induced nephrotoxicity was 34.8%. The pooled prevalence of colistin-induced nephrotoxicity was not higher than that of polymyxin B (PMB)-induced nephrotoxicity. The subgroup analyses showed that nephrotoxicity was significantly associated with dosing interval, nephrotoxicity criteria, age, publication year, study quality and sample size, which were confirmed in the univariable meta-regression analysis. Nephrotoxicity was significantly increased when the total daily dose was divided into 2 doses but not 3 or 4 doses. Furthermore, older age, the presence of sepsis or septic shock, hypoalbuminemia, and concomitant vancomycin or vasopressor use were independent risk factors for polymyxin-induced nephrotoxicity, while an elevated baseline glomerular filtration rate was a protective factor against colistin-induced nephrotoxicity.

CONCLUSION

Our findings indicated that the incidence of polymyxin-induced nephrotoxicity among ICU patients was high. It emphasizes the importance of additional efforts to manage ICU patients receiving polymyxins to decrease the risk of adverse outcomes.

The necessity of a loading dose when prescribing intravenous colistin in critically ill patients with CRGNB-associated pneumonia: a multi-center observational study

Background

The importance or necessity of a loading dose when prescribing intravenous colistin has not been well established in clinical practice, and approximate one-third to half of patients with carbapenem-resistant gram-negative bacteria (CRGNB) infection did not receive the administration of a loading dose. The aim of this study is to investigate the efficacy and risk of acute kidney injury when prescribing intravenous colistin for critically ill patients with nosocomial pneumonia caused by CRGNB.

Methods

This was a multicenter, retrospective study that recruited ICU-admitted patients who had CRGNB-associated nosocomial pneumonia and were treated with intravenous colistin. Then, we classified the patients into colistin loading dose (N = 85) and nonloading dose groups (N = 127). After propensity-score matching for important covariates, we compared the mortality rate, clinical outcome and microbiological eradication rates between the groups (N = 67).

Results

The loading group had higher percentages of patients with favorable clinical outcomes (55.2% and 35.8%, p = 0.037) and microbiological eradication rates (50% and 27.3%, p = 0.042) at day 14 than the nonloading group. The mortality rates at days 7, 14 and 28 and overall in-hospital mortality were not different between the two groups, but the Kaplan–Meier analysis showed that the loading group had a longer survival time than the nonloading group. Furthermore, the loading group had a shorter length of hospital stay than the nonloading group (52 and 60, p = 0.037). Regarding nephrotoxicity, there was no significant difference in the risk of developing acute kidney injury between the groups.

Conclusions

The administration of a loading dose is recommended when prescribing intravenous colistin for critically ill patients with nosocomial pneumonia caused by CRGNB.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-03947-9.

Infections Due to Acinetobacter baumannii-calcoaceticus Complex: Escalation of Antimicrobial Resistance and Evolving Treatment Options

Bacteria within the genus Acinetobacter (principally A. baumannii-calcoaceticus complex [ABC]) are gram-negative coccobacilli that most often cause infections in nosocomial settings. Community-acquired infections are rare, but may occur in patients with comorbidities, advanced age, diabetes mellitus, chronic lung or renal disease, malignancy, or impaired immunity. Most common sites of infections include blood stream, skin/soft-tissue/surgical wounds, ventilator-associated pneumonia, orthopaedic or neurosurgical procedures, and urinary tract. Acinetobacter species are intrinsically resistant to multiple antimicrobials, and have a remarkable ability to acquire new resistance determinants via plasmids, transposons, integrons, and resistance islands. Since the 1990s, antimicrobial resistance (AMR) has escalated dramatically among ABC. Global spread of multidrug-resistant (MDR)-ABC strains reflects dissemination of a few clones between hospitals, geographic regions, and continents; excessive antibiotic use amplifies this spread. Many isolates are resistant to all antimicrobials except colistimethate sodium and tetracyclines (minocycline or tigecycline); some infections are untreatable with existing antimicrobial agents. AMR poses a serious threat to effectively treat or prevent ABC infections. Strategies to curtail environmental colonization with MDR-ABC require aggressive infection-control efforts and cohorting of infected patients. Thoughtful antibiotic strategies are essential to limit the spread of MDR-ABC. Optimal therapy will likely require combination antimicrobial therapy with existing antibiotics as well as development of novel antibiotic classes.

Aerosolized antibiotics in the treatment of hospital-acquired pneumonia/ventilator-associated pneumonia

Aerosolized antibiotics are being increasingly used to treat respiratory infections, especially those caused by drug-resistant pathogens. Their use in the treatment of hospital-acquired pneumonia and ventilator-associated pneumonia in critically ill patients is especially significant. They are also used as an efficient alternative to overcome the issues caused by systemic administration of antibiotics, including the occurrence of drug-resistant strains, drug toxicity, and insufficient drug concentration at the target site. However, the rationale for the use of aerosolized antibiotics is limited owing to their insufficient efficacy and the potential for underestimated risks of developing side effects. Despite the lack of availability of high-quality evidence, the use of aerosolized antibiotics is considered as an attractive alternative treatment approach, especially in patients with multidrug-resistant pathogens. In this review, we have discussed the effectiveness and side effects of aerosolized antibiotics as well as the latest advancements in this field and usage in the Republic of Korea.

Investigation of Effect of the Colistin Loading Dosage on the clinical, Microbiological, and Laboratory Results in Acinetobacter baumannii Ventilator-Associated Pneumonia /Pneumonia

MATERIALS AND METHODS

Adult patients administered colistin with and without LD for MDR Acinetobacter baumannii VAP/pneumonia in intensive care units (ICUs) in a tertiary teaching hospital between 1 January 2018 and 31 December 2019 were included in this retrospective cohort study. The primary endpoint was an assessment of clinical and microbiological success between treatment groups. Secondary endpoints included 14- and 30-day mortality and development of nephrotoxicity.

RESULTS

A total of 101 patients were included (colistin with LD, n = 57; colistin without LD, n = 44). No significant difference in clinical success was observed between groups (73.7% versus 77.3%; p=0.670). In patients receiving colistin with LD, the microbiological success rate increased from 65.9% to 71.9%, but there was no statistically significantly difference (p=0.510). In terms of using combination therapies with carbapeneme and/or tigecycline, there was no significant difference between treatment groups (p=0.30). The rates of 14- and 30-day mortality were similar between groups. The colistin with LD group had a higher rate of nephrotoxicity compared to the other group (52.6% versus 20.5% p=0.001). The clinical and microbiological response times were found significantly higher in the colistin with LD group (p=0.001; p=0.017).

CONCLUSION

Colistin with LD was associated with a higher risk of nephrotoxicity and was not related to clinical success, microbiological success, and prolonged survival. Randomized comparative studies are needed to confirm the efficacy of LD colistin regimen on MDR Acinetobacter infection.

Colistin-Induced Acute Kidney Injury and the Effect on Survival in Patients with Multidrug-Resistant Gram-Negative Infections: Significance of Drug Doses Adjusted to Ideal Body Weight

Background

Colistin is a lifesaving treatment for multidrug-resistant Gram-negative bacterial (MDR-GNB) infections along with its well-known nephrotoxicity. The controversy of colistin-induced acute kidney injury (AKI) on mortality is noted. This study aimed to determine the risk factors and impact of AKI on the survival and significance of colistin dosage.

Methods

A retrospective cohort study was performed in adult patients who received intravenous colistin for MDR-GNB treatment between June 2015 and June 2017. Factors influencing colistin-induced AKI and survival were evaluated by Cox regression analysis. Cut-off levels of the colistin dose per ideal body weight (IBW) that significantly affected clinical outcomes were assessed with linearity trends and receiver operating characteristic analyses.

Results

AKI occurred in 68.5% of 412 enrolled patients with an incidence rate of 10.6 per 100 patients-days and a median time was 6 (3–13) days. Stages I–III of AKI were 38.3, 24.5, and 37.2%. Factors associated with colistin-induced AKI were advanced age, high serum bilirubin, AKI presented before colistin administration, increased daily colistin doses per IBW, and concomitant use of nephrotoxic drugs. Colistin-induced AKI was related to mortality (HR 1.74, 95% CI 1.06–2.86, p=0.028). In the non-AKI before colistin usage subgroup, the total dose and total dose/IBW were >1,500–2,000 mg and 30–35 mg/kg to benefit mortality reduction but were <2,500–3,000 mg and 45–50 mg/kg for risk reduction of AKI. A daily colistin dose/IBW >4.5 mg/kg/day also increased the risk of AKI. In the AKI developed before colistin subgroup, the cut-off values of total colistin dose >1250–1350 mg and total dose/IBW >23.5–24 mg/kg demonstrated significant risks of AKI.

Conclusion

The incidence of AKI after colistin administration was high and impacted mortality. Prevention and early correction of these related factors are mandatory. Careful use of colistin was also both beneficial in mortality and AKI reductions.

Population Pharmacokinetics of Colistin Methanesulfonate Sodium and Colistin in Critically Ill Patients: A Systematic Review

Understanding the pharmacokinetics parameter of colistin methanesulfonate sodium (CMS) and colistin is needed to optimize the dosage regimen in critically ill patients. However, there is a scarcity of pharmacokinetics parameters in this population. This review provides a comprehensive understanding of CMS and colistin pharmacokinetics parameters in this population. The relevant studies published in English that reported on the pharmacokinetics of CMS and colistin from 2000 until 2020 were systematically searched using the PubMed and Scopus electronic databases. Reference lists of articles were reviewed to identify additional studies. A total of 252 citation titles were identified, of which 101 potentially relevant abstracts were screened, and 25 full-text articles were selected for detailed analysis. Of those, 15 studies were included for the review. This review has demonstrated vast inter-study discrepancies in colistin plasma concentration and the pharmacokinetics parameter estimates. The discrepancies might be due to complex pathophysiological changes in the population studied, differences in CMS brand used, methodology, and study protocol. Application of loading dose of CMS and an additional dose of CMS after dialysis session was recommended by some studies. In view of inter-patient and intra-patient variability in colistin plasma concentration and pharmacokinetics parameters, personalized colistin dosing for this population is recommended.

Systematic review on estimated rates of nephrotoxicity and neurotoxicity in patients treated with polymyxins

BACKGROUND

Nephrotoxicity and neurotoxicity are commonly associated with polymyxin treatment; however, the emergence of multidrug-resistant Gram-negative bacteria with limited therapeutic options has resulted in increased use of polymyxins.

OBJECTIVES

To determine the rates of nephrotoxicity and neurotoxicity during polymyxin treatment and whether any factors influence these.

DATA SOURCES

Medline, Embase and Cochrane Library databases were searched on 2 January 2020.

STUDY ELIGIBILITY CRITERIA

Studies reporting nephrotoxicity and/or neurotoxicity rates in patients with infections treated with polymyxins were included. Reviews, meta-analyses and reports not in English were excluded.

PARTICIPANTS

Patients hospitalized with infections treated with systemic or inhaled polymyxins were included. For comparative analyses, patients treated with non-polymyxin-based regimens were also included.

METHODS

Meta-analyses were performed using a random-effects model; subgroup meta-analyses were conducted where data permitted using a mixed-effects model.

RESULTS

In total, 237 reports of randomized controlled trials, cohort and case-control studies were eligible for inclusion; most were single-arm observational studies. Nephrotoxic events in 35,569 patients receiving polymyxins were analysed. Overall nephrotoxicity rate was 0.282 (95% confidence interval (CI) 0.259-0.307). When excluding studies where >50% of patients received inhaled-only polymyxin treatment or nephrotoxicity assessment was by methods other than internationally recognized criteria (RIFLE, KDIGO or AKIN), the nephrotoxicity rate was 0.391 (95% CI 0.364-0.419). The odds of nephrotoxicity were greater with polymyxin therapies compared to non-polymyxin-based regimens (odds ratio 2.23 (95% CI 1.58-3.15); p < 0.001). Meta-analyses showed a significant effect of polymyxin type, dose, patient age, number of concomitant nephrotoxins and use of diuretics, glycopeptides or vasopressors on the rate of nephrotoxicity. Polymyxin therapies were not associated with a significantly different rate of neurotoxicity than non-polymyxin-based regimens (p 0.051). The overall rate of neurotoxicity during polymyxin therapy was 0.030 (95% CI 0.020-0.043).

CONCLUSIONS

Polymyxins are associated with a higher risk of nephrotoxicity than non-polymyxin-based regimens.

Colistin co-administration with other nephrotoxins: experience of teaching hospital of Latvia

Background Colistin is a potentially nephrotoxic antibiotic used for the management of multidrug-resistant bacterial infections in critically ill patients. Co-administration with other nephrotoxins was reported as a potentially modifiable risk factor of colistin acute kidney injury. Objective To establish the role of colistin dosing and co-medications in development of colistin kidney injury. Setting Community teaching hospital in Latvia. Method Adult patients from intensive care units with diagnosed Gram-negative bacterial infections, undergoing colistin treatment for longer than 72 h, and not receiving renal replacement therapy were included in this retrospective study. Main outcome measure Colistin nephrotoxicity was defined as an increase in the serum creatinine level by at least 50% from the baseline after ≥ 48 h. Results In 73 of 87 cases, Acinetobacter baumannii pneumonia was diagnosed. The nephrotoxicity rate was 27.6% with a median onset of 8 days. In 79% of the cases, colistin was co-administrated with at least one potentially nephrotoxic agent. The most used nephrotoxins were loop diuretics (44 cases), non-steroidal anti-inflammatory drugs (19 cases) and vancomycin (11 cases). The use of nephrotoxins was similar in patients with colistin nephrotoxicity (group-1) and without it (group-2). Carbapenems were more common in group-2 (37% vs 62%, p = 0.004) and a colistin loading dose of 9 MU in group-1 (87% vs 62%, p = 0.027). However, in the multifactor regression analysis, the protective role of carbapenems was not confirmed. Conclusion Potentially nephrotoxic agents are commonly co-administrated with colistin. This study failed to prove their role in the development of acute kidney injury.

Efficacy and safety of colistin loading dose: a meta-analysis

Objectives

Colistin represents a polypeptide used for the treatment of MDR microorganisms, although the optimal dosing strategy is under investigation. The present meta-analysis aims to determine whether the administration of a colistin loading dose in patients receiving high-dose maintenance regimens changes the rates of treatment success and the risk of nephrotoxicity.

Methods

Medline, Scopus, CENTRAL, Clinicaltrials.gov and Google Scholar were systematically searched from inception to 18 November 2019. Studies were considered eligible if they reported clinical outcomes among patients receiving high-dose colistin therapy with and without the administration of a loading dose. Meta-analysis was performed by fitting a random-effects model.

Results

Eight (three prospective and five retrospective cohort) studies were included, comprising 1115 patients. The administration of a colistin loading dose was associated with significantly higher microbiological [risk ratio (RR) = 1.23, 95% CI = 1.10–1.39] but not clinical (RR = 1.04, 95% CI = 0.87–1.24) success. No significant associations were calculated for nephrotoxicity (RR = 1.31, 95% CI = 0.90–1.91) and mortality (RR = 1.03, 95% CI = 0.82–1.29) risk. The results remained stable after adjustments for small sample size, credibility ceilings, publication bias and risk of bias.

Conclusions

Observational evidence suggests that the administration of a colistin loading dose in patients receiving high maintenance dosage regimens is significantly associated with higher rates of microbiological response, but does not change clinical cure, mortality or nephrotoxicity risk. The dosing regimen that would provide the optimal balance between treatment efficacy and safety needs to be determined by future randomized controlled trials.