Attributable Risk and Time Course of Colistin-Associated Acute Kidney Injury

Incidence of acute kidney injury (AKI) and its impact on patient outcomes among adult hospitalized patients with carbapenem-resistant Gram-negative infections who received targeted treatment with a newer β-lactam or β-lactam/β-lactamase inhibitor-, polymyxin- or aminoglycoside-containing regimen

BACKGROUND

Limited comparative data exist on acute kidney injury (AKI) risk and AKI-associated outcomes in hospitalized patients with carbapenem-resistant Gram-negative infections (CR-GNIs) treated with a newer β-lactam/β-lactam-β-lactamase inhibitor (BL/BL-BLI)-, polymyxin (PB)- or aminoglycoside (AG)-containing regimen. This study quantified the risk of AKI and AKI-related outcomes among patients with CR-GNIs treated with a newer BL/BL-BLI-, PB- or AG-containing regimen.

METHODS

A multicentre, retrospective, observational study was performed (2016-20). The study included adult hospitalized patients with (i) baseline estimated glomerular filtration rates ≥30 mL/min/1.73 m2; (ii) CR-GN pneumonia, complicated urinary tract infection or bloodstream infection; and (iii) receipt of newer BL/BL-BLI, PG or AG within 7 days of index CR-GN culture for ≥3 days. Outcomes included AKI, in-hospital mortality and hospital costs.

RESULTS

The study included 750 patients and most (48%) received a newer BL/BL-BLI. The median (IQR) treatment duration was 8 (5-11), 5 (4-8) and 7 (4-8) days in the newer BL/BL-BLI group, AG group and PB group, respectively. The PB group had the highest adjusted AKI incidence (95% CI) (PB: 25.1% (15.6%-34.6%) versus AG: 8.9% (5.7%-12.2%) versus newer BL/BL-BLI: 11.9% (8.1%-15.7%); P = 0.001). Patients with AKI had significantly higher in-hospital mortality (AKI: 18.5% versus 'No AKI': 5.6%; P = 0.001) and mean hospital costs (AKI: $49 192 versus 'No AKI': $38,763; P = 0.043).

CONCLUSIONS

The AKI incidence was highest among PB patients and patients with AKI had worse outcomes. Healthcare systems should consider minimizing the use of antibiotics that augment AKI risk as a measure to improve outcomes in patients with CR-GNIs.

Nephrotoxicity caused by colistin use in ICU: a single centre experience

BACKGROUND

We aimed to determine the risk factors that may be associated with colistin-induced acute kidney injury (AKI) to promote the safer use of colistin in the treatment of nosocomial infections caused by multidrug-resistant Gram-negative bacteria in intensive care units.

MATERIALS AND METHODS

This retrospective observational study was conducted among adult patients who received a minimum of 48 h of intravenous colistin from January 2020 to December 2020 at the intensive care unit of a tertiary care hospital. AKI diagnosis and staging were made based on the Kidney Disease Improving Global Outcome Criteria.

RESULTS

Of 148 patients who received intravenous colistin at a daily dose of 9 million IU, 54 (36%) developed AKI. In the univariate analysis, age, Charlson comorbidity index, APACHE II score, duration of colistin treatment, basal creatinine level, use of vasopressors, and vancomycin were significantly associated with AKI (p < 0.05). The multivariate analysis revealed that the independent predictor of AKI was the use of vasopressors (OR: 3.14; 95% confidence interval: 1.39-97.07; p = 0.06).

CONCLUSION

The use of vasopressors in critically ill patients was independently associated with AKI developing during colistin treatment.

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.

Detection of potential drug-drug interactions for risk of acute kidney injury: a population-based case-control study using interpretable machine-learning models

Background: Acute kidney injury (AKI), with an increase in serum creatinine, is a common adverse drug event. Although various clinical studies have investigated whether a combination of two nephrotoxic drugs has an increased risk of AKI using traditional statistical models such as multivariable logistic regression (MLR), the evaluation metrics have not been evaluated despite the fact that traditional statistical models may over-fit the data. The aim of the present study was to detect drug-drug interactions with an increased risk of AKI by interpreting machine-learning models to avoid overfitting. Methods: We developed six machine-learning models trained using electronic medical records: MLR, logistic least absolute shrinkage and selection operator regression (LLR), random forest, extreme gradient boosting (XGB) tree, and two support vector machine models (kernel = linear function and radial basis function). In order to detect drug-drug interactions, the XGB and LLR models that showed good predictive performance were interpreted by SHapley Additive exPlanations (SHAP) and relative excess risk due to interaction (RERI), respectively. Results: Among approximately 2.5 million patients, 65,667 patients were extracted from the electronic medical records, and assigned to case (N = 5,319) and control (N = 60,348) groups. In the XGB model, a combination of loop diuretic and histamine H₂ blocker [mean (|SHAP|) = 0.011] was identified as a relatively important risk factor for AKI. The combination of loop diuretic and H₂ blocker showed a significant synergistic interaction on an additive scale (RERI 1.289, 95% confidence interval 0.226-5.591) also in the LLR model. Conclusion: The present population-based case-control study using interpretable machine-learning models suggested that although the relative importance of the individual and combined effects of loop diuretics and H₂ blockers is lower than that of well-known risk factors such as older age and sex, concomitant use of a loop diuretic and histamine H₂ blocker is associated with increased risk of AKI.

Comprehensive Assessment of Colistin Induced Nephrotoxicity: Incidence, Risk Factors and Time Course

Purpose

In recent years, the emergence of multidrug-resistant (MDR) microorganisms had caused the resurgence of colistin use after it was previously abandoned due to its side effects, nephrotoxicity in particular. However, the specific incidence of colistin-induced nephrotoxicity varies in reports with different populations. This study aims to assess the incidence of colistin-associated nephrotoxicity and the associated risk factors.

Patients and Methods

This study was on 178 patients who received colistin for more than 48 hours during the years 2019-2022, who were followed up for 14 days after the initiation of colistin, and demographic and clinical data were gained from medical reports. Logistic regression was used to assess the relationship between nephrotoxicity and study variables.

Results

The incidence of nephrotoxicity was 44.9% (95% confidence interval (CI); 37% to 53%), and the overall mortality was 33%, with a significantly higher level among patients with nephrotoxicity. The significant risk factors for nephrotoxicity after adjustment were; higher weights (OR = 1.1, 95% CI; 0.03-1.2), P-value: 0.006, and the combination with carbapenem showed a significant protective effect (OR = 0.09, 95% CI; 0.01-0.8), P-value: 0.03. The severity, according to KDIGO classification, was stage 1 (47%), stage 2 (21%), and stage 3 (31%). Higher stages had earlier onset acute kidney injury, a lower percentage of returning to baseline, and exposure to a higher colistin dose.

Conclusion

Colistin-induced nephrotoxicity was a frequent issue associated with higher weights, mitigated by the combination with carbapenems. While higher colistin dosages, and earlier onset AKI, were linked to the progression to higher AKI stages and the need for dialysis.

Colistin- and amikacin-loaded lipid-based drug delivery systems for resistant gram-negative lung and wound bacterial infections

Antimicrobial resistance (AMR) is a global health issue, which needs to be tackled without further delay. The World Health Organization(WHO) has classified three gram-negative bacteria, Pseudomonas aeruginosa, Klebsiella pneumonia and Acinetobacter baumannii, as the principal responsible for AMR, mainly causing difficult to treat nosocomial lung and wound infections. In this regard, the need for colistin and amikacin, the re-emerged antibiotics of choice for resistant gram-negative infections, will be examined as well as their associated toxicity. Thus, current but ineffective clinical strategies designed to prevent toxicity related to colistin and amikacin will be reported, highlighting the importance of lipid-based drug delivery systems (LBDDSs), such as liposomes, solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs), as efficient delivery strategies for reducing antibiotic toxicity. This review reveals that colistin- and amikacin-NLCs are promising carriers with greater potential than liposomes and SLNs to safely tackle AMR, especially for lung and wound infections.

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.

Incidence and Risk Factors of Colistin-Induced Nephrotoxicity Associated with The International Consensus Guidelines for the Optimal Use of the Polymyxins: A Retrospective Study in a Tertiary Care Hospital, Saudi Arabia

Background: Colistin is an effective therapy against multidrug-resistant gram-negative bacteria. However, nephrotoxicity is a major issue with its use. Objective: We aimed to evaluate the incidence and the potential risk factors of nephrotoxicity in colistin-treated patients. Methods: A retrospective cohort study was conducted. All adult patients aged 18 years and older who received colistin for ≥72 h were included in the study, while end-stage kidney disease patients requiring dialysis or had renal transplants were excluded. The incidence and severity of acute kidney injury (AKI) were assessed based on the Kidney Disease Improving Global Outcomes (KDIGO). Result: Out of 128 patients who received colistin, 51.56% of them have experienced AKI. The incidence was increased among oldest patients (above 80) and those who did not receive the appropriate dose (p-value = 0.0003). In addition, the median time until the AKI occurred was 10 days after receiving the colistin treatment. Rates of AKI in patients with previous AKI (71.7%) were three times higher than patients who did not previously experience AKI (HR = 2.97, 95% CI [1.8-4.8]). Conclusions: Nephrotoxicity is a significant issue among patients who receive colistin in the hospital, especially among older patients and those who did not receive the appropriate dose. As a result, healthcare providers should play a major role in colistin dosing, especially among the older adult population.

Pharmacokinetics and Pharmacodynamics of Colistin Methanesulfonate in Healthy Chinese Subjects after Multi-Dose Regimen

Colistin methanesulfonate (CMS) is an important treatment option for infections caused by carbapenem-resistant Gram-negative organisms (CROs). This study evaluated the pharmacokinetic/pharmacodynamic (PK/PD) profiles and safety of CMS in Chinese subjects following a recommended dosage. A total of 12 healthy Chinese subjects received CMS injections at 2.5 mg/kg once every 12 h for 7 consecutive days. The PK/PD profiles of the active form of CMS, colistin, against CROs were analyzed with the Monte Carlo simulation method. No serious adverse events were observed. The average steady-state plasma concentrations of CMS and colistin were 4.41 ± 0.75 μg/mL and 1.27 ± 0.27 μg/mL, and the steady-state exposures (AUC0−12,ss) were 52.93 ± 9.05 h·μg/mL and 15.28 ± 3.29 h·μg/mL, respectively. Colistin, at its minimum inhibitory concentration (MIC) of 0.5 μg/mL, has >90% probability to reduce CROs by ≥1 log. The PK/PD breakpoints for the ≥1 log kill were ≥MIC90 for carbapenem-resistant Klebsiella pneumoniae and Pseudomonas aeruginosa, but were ≤MIC50 for carbapenem-resistant Acinetobacter baumannii. The recommended dose regimen of CMS for 7 consecutive days was safe in Chinese subjects. The systemic exposure of colistin showed a high probability of being sufficient for most CROs, but was not sufficient for some carbapenem-resistant A. baumannii.

Colistin Therapy, Survival and Renal Replacement Therapy in Burn Patients: A 10-Year Single-Center Cohort Study

Purpose

Patients and Methods

Results

Conclusion

Characteristics, Influencing Factors, Predictive Scoring System, and Outcomes of the Patients with Nephrotoxicity Associated with Administration of Intravenous Colistin

Multidrug-resistant Gram-negative infection is a major global public health threat. Currently, colistin is considered the last-resort treatment despite its nephrotoxicity. The purpose of this study was to estimate the incidence, characteristics, and influencing factors and to develop a prediction model for colistin-associated nephrotoxicity. A retrospective study was conducted in the university hospital in the South of Thailand from December 2015 to June 2019. A total of 381 patients (median age (IQR) of 64 (51–62) years) were analyzed. Overall, 282 (74%) had nephrotoxicity according to the Kidney Disease: Improving Global Outcomes (KDIGO) classification. In-hospital, 30-day mortality rates and cost of hospital admission were significantly higher among those with nephrotoxicity. Age > 60 years, comorbidities, serum albumin less than 3.5 g/dL, and concomitant nephrotoxic use were significantly associated with colistin-associated nephrotoxicity with adjusted OR (95% CI) 2.01 (1.23–2.45), 1.85 (1.18–3.6), 1.68 (1.09–2.99), and 1.77 (1.10–2.97), respectively. The prediction model for high-risk colistin-associated nephrotoxicity was identified with good overall performance (specificity of 79.6% (95% CI 70.3–87.1) and positive predictive value of 92.1% (95% CI 88.0–95.1)). In conclusion, the incidence of colistin-associated nephrotoxicity was high and incurred significant morbidity, mortality, and economic burden. Our predictive scoring system is relatively simple and useful for optimizing colistin therapy.

Utilization of Colistin Versus β-Lactam and β-Lactamase Inhibitor Agents in Relation to Acute Kidney Injury in Patients with Severe Gram-Negative Infections

Introduction

Colistin is used to treat severe antibiotic-resistant Gram-negative infections (GNIs). With the rise of antibiotic resistance, colistin has been used increasingly as a ‘last-line’ therapy for multidrug-resistant GNIs. We evaluated the incidence of acute kidney injury (AKI) and mortality among patients receiving colistin or one of the new β-lactam/β-lactamase inhibitors (βL + βLI) (ceftazidime/avibactam, ceftolozane/tazobactam, or meropenem/vaborbactam).

Methods

This retrospective cohort study used data from the Premier Healthcare Database. The cohort included propensity score-matched adults with an inpatient stay between January 2016 and December 2018. Patients given both colistin and BL + BLI as treatment for ≥ 72 h were excluded. AKI was defined as acute renal failure or dialysis during hospitalization with antibiotic administration. Propensity score matching was used to control for selection bias and confounding. Logistic regression evaluated associations between treatment, AKI, and in-hospital mortality.

Results

The total number of patients in the matched cohorts were 256 in each. Overall, 23.8% and 13.3% of patients receiving colistin or new βL + βLI agents, respectively, experienced AKI during hospitalization (p = 0.002); odds of AKI for colistin were 3.0 (95% CI 1.71, 5.21). Following propensity score-matching, patients without baseline renal disease experienced AKI during hospitalization to a higher degree in the colistin group compared to the βL + βLI group (17.1% vs. 6.8%); colistin use was associated with 3.7 times higher odds (95% CI 1.84, 7.42) of AKI compared to βL + βLI agents. The odds of mortality in patients on colistin developing AKI were more than three times that of patients receiving a BL + BLI agent who developed AKI. Among patients receiving colistin, incident AKI was associated with 6.1 times higher odds (95% CI 2.53, 14.71) of mortality.

Conclusions

Patients receiving colistin for GNIs had significantly higher odds of AKI and mortality than those receiving βL + βLI.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-021-00556-x.

Iron deficiency exacerbates cisplatin- or rhabdomyolysis-induced acute kidney injury through promoting iron-catalyzed oxidative damage

Iron deficiency is the most common micronutrient deficiency worldwide. While iron deficiency is known to suppress embryonic organogenesis, its effect on the adult organ in the context of clinically relevant damage has not been considered. Here we report that iron deficiency is a risk factor for nephrotoxic intrinsic acute kidney injury of the nephron (iAKI). Iron deficiency exacerbated cisplatin-induced iAKI by markedly increasing non-heme catalytic iron and Nox4 protein which together catalyze production of hydroxyl radicals followed by protein and DNA oxidation, apoptosis and ferroptosis. Crosstalk between non-heme catalytic iron/Nox4 and downstream oxidative damage generated a mutual amplification cycle that facilitated rapid progression of cisplatin-induced iAKI. Iron deficiency also exacerbated a second model of iAKI, rhabdomyolysis, via increasing catalytic heme-iron. Heme-iron induced lipid peroxidation and DNA oxidation by interacting with Nox4-independent mechanisms, promoting p53/p21 activity and cellular senescence. Our data suggests that correcting iron deficiency and/or targeting specific catalytic iron species are strategies to mitigate iAKI in a wide range of patients with diverse forms of kidney injury.

Risk factors and mortality of acute kidney injury within 1 month after lung transplantation

After lung transplantation (LT), some patients are at risk of acute kidney injury (AKI), which is associated with worse outcomes and increased mortality. Previous studies focused on AKI development from 72 h to 1 week within LT, and reported main risk factors for AKI such as intraoperative hypotension, need of ECMO support, ischemia time or longer time on waiting list. However, this period interval rarely reflects medical risk factors probably happen in longer post-operative period. So, in this study we aimed to describe the incidence and risk factor of AKI within post-operative 1 month, which is longer follow up duration. Among 161 patients who underwent LT at Severance hospital in Seoul, Korea from October 2012 to September 2017, 148 patients were retrospectively enrolled. Multivariable logistic regression and Cox proportional hazard models were utilized. Among 148 patients, 59 (39.8%) developed AKI within 1-month after LT. Stage I or II, and stage III AKI were recorded in 26 (17.5%) and 33 (22.2%), respectively. We also classified AKI according to occurrence time, within 1 week as early AKI, from 1 week within 1 month was defined as late AKI. AKI III usually occurred within 7 days after transplantation (early vs. late AKI III, 72.5% vs 21.1%). Risk factor for AKI development was pre-operative anemia, higher units of red blood cells transfused during surgery, colistin intravenous infusion for treating multi drug resistant pathogens were independent risk factors for AKI development. Post-operative bleeding, grade 3 PGD within 72 h, and sepsis were more common complication in the AKI group. Patients with AKI III ([24/33] 72.7%) had significantly higher 1-year mortality than the no-AKI ([18/89] 20.2%), and AKI I or II group ([9/26] 34.6%), log-rank test, P < 0.001). AKI was associated with worse post-operative outcome, 3-month, and 1-year mortality after LT. Severity of AKI was usually determined in early post op period (ex. within 7 days) after LT, so optimal post-operative management as well as recipients selection should be considered.

Comparison of colistin-induced nephrotoxicity between two different formulations of colistin in critically ill patients: a retrospective cohort study

Background

Colistin is widely used in the treatment of nosocomial infections caused by carbapenem-resistant gram-negative bacilli (CR-GNB). Colistin-induced nephrotoxicity is one of the major adverse reactions during colistin treatment. Comparisons of colistin-induced nephrotoxicity between different formulations of colistin are rarely reported.

Methods

In this retrospective cohort study, we enrolled intensive care unit–admitted patients if they had culture isolates of CR-GNB and underwent intravenous treatment with colistin. The occurrence of acute kidney injury (AKI) during intravenous treatment with colistin was recorded. The occurrence of colistin-induced nephrotoxicity was compared between two formulations of colistin, Locolin®, and Colimycin®. Treatment outcomes associated with the occurrence of colistin-induced nephrotoxicity were also investigated.

Results

Among 195 patients, 95 who were treated with Locolin® and 100 who were treated with Colimycin® were included for analysis. Patients treated with Locolin® had a higher rate of occurrence of stage 2 (46.3% vs. 32%, p = 0.040) and stage 3 (29.5% vs. 13%, p = 0.005) AKI than did those treated with Colimycin®. In multivariate analysis, the presence of septic shock (adjusted odds ratio [aOR] 2.17, 95% confidence interval [CI] 1.10–4.26) and inappropriate colistin dosage (aOR 2.52, 95% CI 1.00–6.33) were clinical factors associated with colistin-induced nephrotoxicity. Treatment with Colimycin® was an independent factor associated with a lower risk of colistin-induced nephrotoxicity (aOR 0.37, 95% CI 0.18–0.77). The mortality rate was comparable between patients with and without colistin-induced nephrotoxicity.

Conclusions

The risk of colistin-induced nephrotoxicity significantly varied in different formulations of colistin in critically ill patients. Colistin-induced nephrotoxicity was not associated with increased mortality rate.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13756-021-00977-w.

Effects of Lipidation on a Proline-Rich Antibacterial Peptide

The emergence of multidrug-resistant bacteria is a worldwide health problem. Antimicrobial peptides have been recognized as potential alternatives to conventional antibiotics, but still require optimization. The proline-rich antimicrobial peptide Bac7(1-16) is active against only a limited number of Gram-negative bacteria. It kills bacteria by inhibiting protein synthesis after its internalization, which is mainly supported by the bacterial transporter SbmA. In this study, we tested two different lipidated forms of Bac7(1-16) with the aim of extending its activity against those bacterial species that lack SbmA. We linked a C12-alkyl chain or an ultrashort cationic lipopeptide Lp-I to the C-terminus of Bac7(1-16). Both the lipidated Bac-C12 and Bac-Lp-I forms acquired activity at low micromolar MIC values against several Gram-positive and Gram-negative bacteria. Moreover, unlike Bac7(1-16), Bac-C12, and Bac-Lp-I did not select resistant mutants in E. coli after 14 times of exposure to sub-MIC concentrations of the respective peptide. We demonstrated that the extended spectrum of activity and absence of de novo resistance are likely related to the acquired capability of the peptides to permeabilize cell membranes. These results indicate that C-terminal lipidation of a short proline-rich peptide profoundly alters its function and mode of action and provides useful insights into the design of novel broad-spectrum antibacterial agents.

Colistin Dosing Regimens against Pseudomonas aeruginosa in Critically Ill Patients: An Application of Monte Carlo Simulation

Our aims are to assess various colistin dosing regimens against Pseudomonas aeruginosa (P. aeruginosa) infection in critically ill patients and to propose an appropriate regimen based on microbiological data. A Monte Carlo simulation was performed using the published colistin’s pharmacokinetic parameters of critically ill patients, the published pharmacodynamic target from a mouse thigh infection model, and the minimum inhibitory concentration (MIC) results from a Vietnamese hospital. The probability of target attainment (PTA) of 80% and cumulative fraction of response (CFR) of 90% were used to evaluate the efficacy of each regimen. Of 121 P. aeruginosa laboratory datasets, the carbapenem-resistant P. aeruginosa (CRPA) and the colistin-resistant P. aeruginosa rates were 29.8% and 0.8%, respectively. MIC_50,90 were both 0.5 mg/L. The simulated results showed that at MIC of 2 mg/L, most regimens could not reach the PTA target, particularly in patients with normal renal function (Creatinine clearance (CrCl) ≥ 80 mL/min). At MIC of 0.5 mg/L and 1 mg/L, current recommendations still worked well. On the basis of these results, aside from lung infection, our study recommends three regimens against P. aeruginosa infection at MIC of 0.5 mg/L, 1 mg/L, and 2 mg/L. In conclusion, higher total daily doses and fractionated colistin dosing regimens could be the strategy for difficult-to-acquire PTA cases, while a less aggressive dose might be appropriate for empirical treatment in settings with low MIC_50/90.

Evaluation of prognosis and nephrotoxicity in patients treated with colistin in intensive care unit

Introduction

Nephrotoxicity is the most important adverse effect of colistin therapy. We investigated the frequency of nephrotoxicity, risk factors related to nephrotoxicity, and its relationship with mortality in patients who received intravenous colistin in intensive care units (ICUs).

Materials and methods

We retrospectively reviewed the data of patients who received intravenous colistin in ICUs between 2011 and 2017. Acute kidney injury (AKI) diagnosis and staging were made based on the Kidney Disease Improving Global Outcome criteria.

Results

There were 149 patients included in the study with 61% being male. The mean age was 58.7 ± 20.3 years. AKI was detected in 96 (64.4%) patients. There were 25 patients with AKI stage 1 (16.8%) and 71 patients with AKI stage 2 or 3 (47.7%). Advanced age (65.0 vs. 47.4 years; p < .001), diabetes mellitus (p < .001), heart failure (p = .01), high APACHE II score (31.7 vs. 28.08, p = .019), and inotrope usage (p = .01) were found as risk factors for AKI. The 14-day mortality rate was higher in the AKI group (p = .027).

Discussion

Higher AKI and mortality rates are observed in patients with diabetes, heart failure, advanced age and the hemodynamically impaired. However, it is a fact that there are no alternative therapies other than colistin in the treatment of multidrug-resistant Gram-negative bacterial infections. Therefore, the development of AKI in this patient group should not be considered a sufficient reason for discontinuing colistin treatment. Understanding the risk factors in this potential nephrotoxic treatment can provide a more careful patient follow-up.

No increased acute kidney injury rate through giving an intravenous colistin loading dose in pediatric patients

OBJECTIVES

A colistin loading dose is required to achieve adequate drug exposure for the treatment of multidrug-resistant Gram-negative bacteria. However, data on acute kidney injury (AKI) rates associated with this approach in children have been unavailable. The aim of this study was to examine AKI rates in children who were prescribed a colistin loading dose.

METHODS

A retrospective study was conducted in patients aged 1 month to 18 years who had received intravenous colistin for ≥48 h. Loading dose (LD) was defined as colistin methanesulfonate at 4-5 mg of colistin base activity/kg/dose. AKI was defined according to KDIGO serum creatinine (SCr) criteria - SCr ≥ 1.5 times the baseline, measured 3-7 days after colistin initiation. Augmented renal clearance (ARC) was defined as an estimated glomerular filtration rate (eGFR) >150 mL/min/1.73 m². The rates of AKI were compared between children receiving or not receiving an LD, and between different eGFR groups.

RESULTS

In total, 181 children were enrolled. The mean age was 4.3 years (95% confidence interval [CI], 3.6-4.9 years). Ninety-five of the subjects (52.5%) were male. There were 157 children with a baseline eGFR of ≥ 80 mL/min/1.73 m². The overall AKI rate within the first week in this group was 20.4% (95% CI, 14.4-27.6%): LD, 16.1% vs no LD, 23.2% (p = 0.29). Subgroup analysis, excluding patients with ARC, showed a lower AKI rate of 12.8% (95% CI, 6.8-21.3%): LD, 9.7% vs no LD, 14.3% (p = 0.53).

CONCLUSIONS

AKI rate was not different among children who received an intravenous colistin loading dose. This approach should be implemented to ensure the necessary drug exposure required for good treatment outcomes.

Clinical Outcomes of Patient Subgroups in the TANGO II Study

Introduction

Meropenem–vaborbactam (M-V), a new approved antimicrobial, was developed specifically to be effective treatment for the increasingly prevalent and difficult to treat carbapenem-resistant Enterobacterales (CRE) infections. However, registration phase 3 clinical studies offer limited applicability to daily medical practice as they often focus on indications such as urinary tract infections or skin and soft tissue infections, which generally have patients with fewer comorbid conditions that the typical patients who develops infection with CRE. The more useful studies are pathogen-focused trials which do not exclude the more complicated subjects with conditions such as renal failure, immunocompromised status, or exposure to prior antibiotic therapy.

Methods

The TANGO II study was an open-label investigation of M-V compared with the best available treatment (BAT) in hospitalized adults with a confirmed infection that was known or suspected to be a CRE infection. TANGO II specifically included patients with comorbidities, prior antibiotic therapy, renal failure, and immunocompromised status that are typical in patients with a CRE infection. Interim data analysis indicated that a significant benefit was seen for those patients receiving M-V over BAT. This analysis reports on subsets of TANGO II study patients with multiple comorbidities and high severity of illness, specifically those with prior antibiotic therapy, renal failure, and immunocompromised status. A patient case that highlights particular complexities and challenges of treating patients with CRE infections in the real world is also presented.

Results

Subjects with comorbid conditions had better outcomes when given M-V rather than BAT.

Conclusion

M-V is a welcome addition to the antibiotic armamentarium for the treatment of severe CRE infections in complicated patients.

Trial Registration

ClinicalTrials.gov identifier NCT02168946.

Efficacy of adjunctive nebulized colistin in critically ill patients with nosocomial carbapenem-resistant Gram-negative bacterial pneumonia: a multi-centre observational study

OBJECTIVES

To investigate the association between adjunctive nebulized colistin and treatment outcomes in critically ill patients with nosocomial carbapenem-resistant Gram-negative bacterial (CR-GNB) pneumonia.

METHODS

This retrospective, multi-centre, cohort study included individuals admitted to the intensive care unit with nosocomial pneumonia caused by colistin-susceptible CR-GNB. Enrolled patients were divided into groups with/without nebulized colistin as adjunct to at least one effective intravenous antibiotic. Propensity score matching was performed in the original cohort (model 1) and a time-window bias-adjusted cohort (model 2). The association between adjunctive nebulized colistin and treatment outcomes was analysed.

RESULTS

In total, 181 and 326 patients treated with and without nebulized colistin, respectively, were enrolled for analysis. The day 14 clinical failure rate and mortality rate were 41.4% (75/181) versus 46% (150/326), and 14.9% (27/181) versus 21.8% (71/326), respectively. In the propensity score-matching analysis, patients with nebulized colistin had lower day 14 clinical failure rates (model 1: 41% (68/166) versus 54.2% (90/166), p 0.016; model 2: 35.3% (41/116) versus 56.9% (66/116), p 0.001). On multivariate analysis, nebulized colistin was an independent factor associated with fewer day 14 clinical failures (model 1: adjusted odds ratio (aOR) 0.59, 95% CI 0.37-0.92; model 2: aOR 0.37, 95% CI 0.21-0.65). Nebulized colistin was not associated independently with a lower 14-day mortality rate in the time-dependent analysis in both models 1 and 2.

CONCLUSIONS

Adjunctive nebulized colistin was associated with lower day 14 clinical failure rate, but not lower 14-day mortality rate, in critically ill patients with nosocomial pneumonia caused by colistin-susceptible CR-GNB.

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.

Is it time to move away from polymyxins?: evidence and alternatives

Increasing burden of carbapenem resistance and resultant difficult-to-treat infections are of particular concern due to the lack of effective and safe treatment options. More recently, several new agents with activity against certain multidrug-resistant (MDR) and extensive drug-resistant (XDR) Gram-negative pathogens have been approved for clinical use. These include ceftazidime-avibactam, meropenem-vaborbactam, imipenem-cilastatin-relebactam, plazomicin, and cefiderocol. For the management of MBL infections, clinically used triple combination comprising ceftazidime-avibactam and aztreonam is hindered due to non-availability of antimicrobial susceptibility testing methods and lack of information on potential drug-drug interaction leading to PK changes impacting its safety and efficacy. Moreover, in several countries including Indian subcontinent and developing countries, these new agents are yet to be made available. Under these circumstances, polymyxins are the only last resort for the treatment of carbapenem-resistant infections. With the recent evidence of suboptimal PK/PD particularly in lung environment, limited efficacy and increased nephrotoxicity associated with polymyxin use, the Clinical and Laboratory Standards Institute (CLSI) has revised both colistin and polymyxin B breakpoints. Thus, polymyxins 'intermediate' breakpoint for Enterobacterales, P. aeruginosa, and Acinetobacter spp. are now set at ≤ 2 mg/L, implying limited clinical efficacy even for isolates with the MIC value 2 mg/L. This change has questioned the dependency on polymyxins in treating XDR infections. In this context, recently approved cefiderocol and phase 3 stage combination drug cefepime-zidebactam assume greater significance due to their potential to act as polymyxin-supplanting therapies.

Schisantherin A attenuates sepsis-induced acute kidney injury by suppressing inflammation via regulating the NRF2 pathway

AIMS

Tubulointerstitial inflammation is recognized as a key determinant of progressive sepsis-induced acute kidney injury (AKI). Schisantherin A (SchA) has been shown to be capable of regulating inflammatory processes. In the present study, we explored the possibility of SchA in preventing lipopolysaccharide (LPS)-induced kidney inflammation and injury.

MATERIALS AND METHODS

AKI was induced by a single intraperitoneal injection of LPS in CD1 mice, administration of SchA was used for treatment. The protective effect of SchA on renal function and inflammation were analyzed respectively; the NRK-52E cell line was employed for the in vitro study and relative molecular mechanism was explored.

KEY FINDINGS

Administration with SchA markedly attenuated LPS-induced damage on renal function and histopathological changes of the kidney. Additionally, pretreatment with SchA could inhibit the expression of inflammatory factors in the kidneys. In NRK-52E cells, SchA treatment significantly inhibited LPS-induced NF-κB activation and pro-inflammatory cytokine expression. Moreover, SchA could promote NRF2 pathway activation, and further blockade of NRF2 activation reversed the SchA-induced inhibition of NF-κB activation.

SIGNIFICANCE

These presented results indicated that SchA may have great potential for protecting against sepsis-induced AKI.

Acute kidney injury following colistin treatment in critically-ill patients: may glucocorticoids protect?

Nephrotoxicity following colistin administration is common and factors alleviating nephrotoxicity are yet to be determined. We retrospectively evaluated outcomes of subjects who were treated with colistin (n = 133) and with antibiotics other than colistin (control, n = 133) in intensive care units. Acute kidney injury (AKI) occurred in 69.2% and 29.3% of patients in colistin and control groups, respectively (p < 0.001). In the colistin group, glucocorticoid exposure was more common in subjects who did not develop AKI (p < 0.001). This was not the case in the control group. In the colistin cohort, older age (per 10 years, odds ratio [OR] 1.41, 95% CI 1.05-1.91; p = 0.025), PPI use (OR 3.30, 95% CI 1.18-9.23; p = 0.023) and furosemide treatment (OR 2.66, 95% CI 1.01-6.98; p = 0.047) were independently associated with the development of AKI while glucocorticoid treatment (OR 0.23, 95% CI 0.10-0.53; p = 0.001) was independently associated with reduced risk of AKI. Mortality was observed in 74 patients in the colistin cohort (55.6%). A higher APACHE-II score (OR 1.17, 95% CI 1.08-1.26; p < 0.001) was independently associated with mortality while a higher serum albumin level (per 1 g/dL increase, OR 0.20, 95% CI 0.070-0.60; p = 0.004) was associated with a lower risk of mortality. In conclusion, glucocorticoid exposure is associated with a lower risk of AKI caused by colistin therapy in critically-ill patients. Prospective studies are needed to confirm these findings and determine the optimal type, dose and duration of glucocorticoid therapy.

Colistimethate sodium and acute kidney injury: Incidence, risk factors, outcome and prognosis of renal function

BACKGROUND

Colistimethate sodium (CMS) treatment has increased over the last years, being acute kidney injury (AKI) its main drug-related adverse event. Therefore, this study aimed to evaluate the incidence and risk factors associated with AKI, as well as identifying the factors that determine renal function (RF) outcomes at six months after discharge.

MATERIALS AND METHODS

This retrospective study included adult septic patients receiving intravenous CMS for at least 48h (January 2007-December 2014). AKI was assessed using KDIGO criteria. The glomerular filtration rate (GFR) was estimated by the 4-variable MDRD equation. Logistic and linear models were performed to evaluate the risk factors for AKI and chronic kidney disease (CKD).

RESULTS

Among 126 patients treated with CMS; the incidence of AKI was 48.4%. Sepsis-severe sepsis (OR 8.07, P=0.001), sepsis-septic shock (OR 42.9, P<0.001), and serum creatinine (SCr) at admission (OR 6.20, P=0.009) were independent predictors. Eighty-four patients survived; the main factors for RF evolution at the 6-month follow-up was baseline eGFR (0.58, P<0.001) and at discharge (0.34, P<0.001). Fifty-six percent (34/61) of the patients that developed AKI survived. At six months, 32% had CKD.

CONCLUSIONS

The development of AKI in septic patients with CMS treatment was associated with sepsis severity and SCr at admission. Baseline eGFR and eGFR at discharge were and important determinant of the RF at the 6-month follow-up. These predictors may assist in clinical decision making for this patient population.

Is colistin-associated acute kidney injury clinically important in adults? A systematic review and meta-analysis

Colistin is the last-resort antimicrobial agent against infections caused by multidrug-resistance Gram-negative bacteria (MDR-GNB). However, a differing risk of colistin-associated acute kidney injury (CA-AKI) has been demonstrated without affecting mortality, thus the association and its importance needs to be questioned. To assess the impact of this adverse effect, a meta-analysis comparing colistin with other antibiotics in treating MDR-GNB infections was conducted. The PubMed, Embase and Cochrane Library electronic databases were searched up to 31 December 2018 for cohort studies and randomised controlled trials with at least two arms with one arm containing colistin-based treatment. The primary endpoint was the incidence of AKI. The secondary endpoint was 30-day all-cause mortality. A total of 34 studies, including 26 regarding colistin-based therapy versus other antibiotics and 9 regarding colistin monotherapy versus combination therapy, were included. The incidence of CA-AKI was 32.3%. Colistin was associated with an 82% higher incidence of AKI than other antibiotics [odd ratio (OR) = 1.82, 95% confidence interval (CI) 1.13-2.92; P = 0.01]. Most CA-AKI events were mild and reversible without a higher rate of mortality or the requirement for renal replacement therapy (RRT). Only 1.0% of patients required RRT for > 4 weeks. Compared with colistin monotherapy, combination therapy was associated with a significantly lower incidence of AKI (OR = 1.46, 95% CI 1.10-1.94; P = 0.009), particularly in combination with a carbapenem (OR = 1.97, 95% CI 1.30-2.99; P = 0.001). In conclusion, CA-AKI might not be an important limitation of colistin in MDR-GNB therapy.

Clinical and subclinical acute kidney injury in multidrug-resistant septic patients treated with colistimethate sodium: Incidence and clinical outcomes

AIM

Colistimethate sodium (CMS) has been postulated as the principal cause of high incidence of clinical acute kidney injury (AKI) in multidrug-resistance (MDR) septic patients with normal baseline serum creatinine (sCr) who were treated with CMS. This prospective observational study was conducted to examine the incidence and clinical outcomes of clinical and subclinical AKI in MDR septic patients receiving CMS.

METHODS

Forty-two MDR septic patients with normal sCr who required CMS were included. Clinical AKI was diagnosed by increased sCr levels according to the KDIGO2012 criteria while subclinical AKI was identified by elevated levels of urinary neutrophil gelatinase-associated lipocalin (uNGAL > 150 ng/mL) or urinary liver-type fatty-acid-binding protein (uL-FABP > 10.5 ng/mL).

RESULTS

Clinical AKI was noted in 47.6% of patients on day 5 and 38.1% on day 7 after initiating CMS. By using uL-FABP, subclinical AKI was observed in 45.2% and 54.8% on day 5 and 7, respectively. At baseline prior to CMS treatment, subclinical AKI was already present in 90%. The baseline uL-FABP was superior to the baseline uNGAL in early prediction of clinical AKI on day 5. The subclinical AKI patients had comparable worse outcomes as clinical AKI patients.

CONCLUSION

The incidence of subclinical AKI in MDR septic patients before CMS treatment was extremely high. The baseline uL-FABP provided the best predictive capacity of clinical AKI. The causes of clinical AKI might include the persistence of sepsis process, subclinical AKI and CMS nephrotoxicity. Proper management of subclinical AKI patients before CMS initiation should be concerned to prevent further renal damage and improve patient and renal outcomes.

Basic Principles of Antibiotics Dosing in Patients with Sepsis and Acute Kidney Damage Treated with Continuous Venovenous Hemodiafiltration

Sepsis is the leading cause of acute kidney damage in patients in intensive care units. Pathophysiological mechanisms of the development of acute kidney damage in patients with sepsis may be hemodynamic and non-hemodynamic. Patients with severe sepsis, septic shock and acute kidney damage are treated with continuous venovenous hemodiafiltration. Sepsis, acute kidney damage, and continuous venovenous hemodiafiltration have a significant effect on the pharmacokinetics and pharmacodynamics of antibiotics. The impact dose of antibiotics is increased due to the increased volume of distribution (increased administration of crystalloids, hypoalbuminemia, increased capillary permeability syndrome toproteins). The dose of antibiotic maintenance depends on renal, non-renal and extracorporeal clearance. In the early stage of sepsis, there is an increased renal clearance of antibiotics, caused by glomerular hyperfiltration, while in the late stage of sepsis, as the consequence of the development of acute renal damage, renal clearance of antibiotics is reduced. The extracorporeal clearance of antibiotics depends on the hydrosolubility and pharmacokinetic characteristics of the antibiotic, but also on the type of continuous dialysis modality, dialysis dose, membrane type, blood flow rate, dialysis flow rate, net filtration rate, and effluent flow rate. Early detection of sepsis and acute kidney damage, early target therapy, early administration of antibiotics at an appropriate dose, and early extracorporeal therapy for kidney replacement and removal of the inflammatory mediators can improve the outcome of patients with sepsis in intensive care units.

Rat models of colistin nephrotoxicity: previous experimental researches and future perspectives

Colistin is an old antibiotic, which is abandoned decades ago because of high nephrotoxicity rates. However, it is reintroduced to clinical medicine due to lack of newly discovered antibiotics and is still widely used for the treatment of resistant gram-negative infections. Discovering mechanisms to reduce nephrotoxicity risk is of significant importance since exposed patients may have many other factors that alter kidney functions. Several agents were evaluated in animal models of colistin nephrotoxicity as a means to prevent kidney injury. Considerable heterogeneity exists in terms of reporting colistin dosing and experimental designs. This issue leads clinicians to face difficulties in designing studies and sometimes may lead to report dosing strategies inadequately. Here, we present a review according to animal models of colistin nephrotoxicity using data gathered from previous experiments to draw attention on possible complexities that researchers may encounter.

Polymyxin Acute Kidney Injury: Dosing and Other Strategies to Reduce Toxicity

Polymyxins are valuable antimicrobials for the management of multidrug-resistant Gram-negative bacteria; however, nephrotoxicity associated with these drugs is a very common side effect that occurs during treatment. This article briefly reviews nephrotoxic mechanisms and risk factors for polymyxin-associated acute kidney injury (AKI) and discusses dosing strategies that may mitigate kidney damage without compromising antimicrobial activity. Polymyxins have a very narrow therapeutic window and patients requiring treatment with these drugs are frequently severely ill and have multiple comorbidities, which increases the risk of AKI. Notably, there is a significant overlap between therapeutic and toxic plasma polymyxin concentrations that substantially complicates dose selection. Recent dosing protocols for both colistin and polymyxin B have been developed and may help fine tune dose adjustment of these antibiotics. Minimizing exposure to modifiable risk factors, such as other nephrotoxic agents, is strongly recommended. The dose should be carefully selected, particularly in high-risk patients. The administration of oxidative stress-reducing drugs is a promising strategy to ameliorate polymyxin-associated AKI, but still requires support from clinical studies.

Novel Glycopolymer Eradicates Antibiotic- and CCCP-Induced Persister Cells in Pseudomonas aeruginosa

Antibiotic treatments often fail to completely eradicate a bacterial infection, leaving behind an antibiotic-tolerant subpopulation of intact bacterial cells called persisters. Persisters are considered a major cause for treatment failure and are thought to greatly contribute to the recalcitrance of chronic infections. Pseudomonas aeruginosa infections are commonly associated with elevated levels of drug-tolerant persister cells, posing a serious threat to human health. This study represents the first time a novel large molecule polycationic glycopolymer, poly (acetyl, arginyl) glucosamine (PAAG), has been evaluated against antibiotic and carbonyl cyanide m-chlorophenylhydrazone induced P. aeruginosa persisters. PAAG eliminated eliminated persisters at concentrations that show no significant cytotoxicity on human lung epithelial cells. PAAG demonstrated rapid bactericidal activity against both forms of induced P. aeruginosa persister cells resulting in complete eradication of the in vitro persister cells within 24 h of treatment. PAAG demonstrated greater efficacy against persisters in vitro than antibiotics currently being used to treat persistent chronic infections such as tobramycin, colistin, azithromycin, aztreonam, and clarithromycin. PAAG caused rapid permeabilization of the cell membrane and caused significant membrane depolarization in persister cells. PAAG efficacy against these bacterial subpopulations suggests it may have substantial therapeutic potential for eliminating recurrent P. aeruginosa infections.