Effect of Aminoglycoside and β‐Lactam Combination Therapy versus β‐Lactam Monotherapy on the Emergence of Antimicrobial Resistance: A Meta‐analysis of Randomized, Controlled Trials

Development and application of a risk nomogram for the prediction of risk of carbapenem-resistant Acinetobacter baumannii infections in neuro-intensive care unit: a mixed method study

OBJECTIVE

This study aimed to develop and apply a nomogram with good accuracy to predict the risk of CRAB infections in neuro-critically ill patients. In addition, the difficulties and expectations of application such a tool in clinical practice was investigated.

METHODS

A mixed methods sequential explanatory study design was utilized. We first conducted a retrospective study to identify the risk factors for the development of CRAB infections in neuro-critically ill patients; and further develop and validate a nomogram predictive model. Then, based on the developed predictive tool, medical staff in the neuro-ICU were received an in-depth interview to investigate their opinions and barriers in using the prediction tool during clinical practice. The model development and validation is carried out by R. The transcripts of the interviews were analyzed by Maxqda.

RESULTS

In our cohort, the occurrence of CRAB infections was 8.63% (47/544). Multivariate regression analysis showed that the length of neuro-ICU stay, male, diabetes, low red blood cell (RBC) count, high levels of procalcitonin (PCT), and number of antibiotics ≥ 2 were independent risk factors for CRAB infections in neuro-ICU patients. Our nomogram model demonstrated a good calibration and discrimination in both training and validation sets, with AUC values of 0.816 and 0.875. Additionally, the model demonstrated good clinical utility. The significant barriers identified in the interview include "skepticism about the accuracy of the model", "delay in early prediction by the indicator of length of neuro-ICU stay", and "lack of a proper protocol for clinical application".

CONCLUSIONS

We established and validated a nomogram incorporating six easily accessed indicators during clinical practice (the length of neuro-ICU stay, male, diabetes, RBC, PCT level, and the number of antibiotics used) to predict the risk of CRAB infections in neuro-ICU patients. Medical staff are generally interested in using the tool to predict the risk of CRAB, however delivering clinical prediction tools in routine clinical practice remains challenging.

Single-drug versus combination antimicrobial therapy in critically ill patients with hospital-acquired pneumonia and ventilator-associated pneumonia due to Gram-negative pathogens: a multicenter retrospective cohort study

KEY MESSAGES

In this study including 391 critically ill patients with nosocomial pneumonia due to Gram-negative pathogens, combination therapy was not associated with a reduced hazard of death at Day 28 or a greater likelihood of clinical cure at Day 14. No over-risk of AKI was observed in patients receiving combination therapy.

BACKGROUND

The benefits and harms of combination antimicrobial therapy remain controversial in critically ill patients with hospital-acquired pneumonia (HAP), ventilated HAP (vHAP) or ventilator-associated pneumonia (VAP) involving Gram-negative bacteria.

METHODS

We included all patients in the prospective multicenter OutcomeRea database with a first HAP, vHAP or VAP due to a single Gram-negative bacterium and treated with initial adequate single-drug or combination therapy. The primary endpoint was Day-28 all-cause mortality. Secondary endpoints were clinical cure rate at Day 14 and a composite outcome of death or treatment-emergent acute kidney injury (AKI) at Day 7. The average effects of combination therapy on the study endpoints were investigated through inverse probability of treatment-weighted regression and multivariable regression models. Subgroups analyses were performed according to the resistance phenotype of the causative pathogens (multidrug-resistant or not), the pivotal (carbapenems or others) and companion (aminoglycosides/polymyxins or others) drug classes, the duration of combination therapy (< 3 or ≥ 3 days), the SOFA score value at pneumonia onset (< 7 or ≥ 7 points), and in patients with pneumonia due to non-fermenting Gram-negative bacteria, pneumonia-related bloodstream infection, or septic shock.

RESULTS

Among the 391 included patients, 151 (38.6%) received single-drug therapy and 240 (61.4%) received combination therapy. VAP (overall, 67.3%), vHAP (16.4%) and HAP (16.4%) were equally distributed in the two groups. All-cause mortality rates at Day 28 (overall, 31.2%), clinical cure rate at Day 14 (43.7%) and the rate of death or AKI at Day 7 (41.2%) did not significantly differ between the groups. In inverse probability of treatment-weighted analyses, combination therapy was not independently associated with the likelihood of all-cause death at Day 28 (adjusted odd ratio [aOR], 1.14; 95% confidence interval [CI] 0.73-1.77; P = 0.56), clinical cure at Day 14 (aOR, 0.79; 95% CI 0.53-1.20; P = 0.27) or death or AKI at Day 7 (aOR, 1.07; 95% CI 0.71-1.63; P = 0.73). Multivariable regression models and subgroup analyses provided similar results.

CONCLUSIONS

Initial combination therapy exerts no independent impact on Day-28 mortality, clinical cure rate at Day 14, and the hazard of death or AKI at Day 7 in critically ill patients with mono-bacterial HAP, vHAP or VAP due to Gram-negative bacteria.

A metagenomic analysis for combination therapy of multiple classes of antibiotics on the prevention of the spread of antibiotic-resistant genes

Antibiotics used systemically to treat infections may have off-target effects on the gut microbiome, potentially resulting in the emergence of drug-resistant bacteria or selection of pathogenic species. These organisms may present a risk to the host and spread to the environment with a risk of transmission in the community. To investigate the risk of emergent antibiotic resistance in the gut microbiome following systemic treatment with antibiotics, this metagenomic analysis project used next-generation sequencing, a custom-built metagenomics pipeline, and differential abundance analysis to study the effect of antibiotics (ampicillin, ciprofloxacin, and fosfomycin) in monotherapy and different combinations at high and low doses, to determine the effect on resistome and taxonomic composition in the gut of Balb/c mice. The results showed that low-dose monotherapy treatments showed little change in microbiome composition but did show an increase in expression of many antibiotic-resistant genes (ARGs) posttreatment. Dual combination treatments allowed the emergence of some conditionally pathogenic bacteria and some increase in the abundance of ARGs despite a general decrease in microbiota diversity. Triple combination treatment was the most successful in inhibiting emergence of relevant opportunistic pathogens and completely suppressed all ARGs after 72 h of treatment. The relative abundances of mobile genetic elements that can enhance transmission of antibiotic resistance either decreased or remained the same for combination therapy while increasing for low-dose monotherapy. Combination therapy prevented the emergence of ARGs and decreased bacterial diversity, while low-dose monotherapy treatment increased ARGs and did not greatly change bacterial diversity.

Comparative Investigation into the Roles of Imipenem:Cyclodextrin Complexation and Antibiotic Combination in Combatting Antimicrobial Resistance in Gram-Negative Bacteria

Extensively drug-resistant (XDR), multidrug-resistant (MDR) and pandrug-resistant (PDR) Gram-negative microorganisms (GNBs) are considered a significant global threat. β-lactam and aminoglycoside combinations and imipenem:cyclodextrin inclusion complexes were studied for the treatment of lethal GNBs. This is because of the broad empiric coverage of the two drugs and their possession of different spectra of activity. Two cyclodextrins (β- and hydroxy propyl β-cyclodextrins) were utilized for inclusion complex formation with imipenem using the physical and kneading methods. In silico investigation using the molecular docking and Fourier-infrared spectroscopy (FTIR) were employed to estimate binding constant and confirm complex formation, respectively. The in vitro effects of amikacin and imipenem combination in comparison to the effect of imipenem-β- and hydroxy propyl β-cyclodextrin (CD) complexes against Klebsiella spp. and Acinetobacter baumannii were studied. The isolated microorganisms' antimicrobial responsiveness to various antibiotics (19 antibiotics) was evaluated. It was found that piperacillin/tazobactam and gentamycin (resistance rates were 33.3% and 34%, respectively) were the most effective antimicrobials. The in vitro studies have been performed by the checkerboard technique and time-killing assay. The studied combination of amikacin and imipenem showed a substantial drop in bacterial count (p < 0.05). The in vitro studies demonstrated a synergism for the investigated combination. Conventional PCR was used in molecular studies to identify the resistance genes bla IMP and aac (6')-Ib. The blaIMP and aac (6')-Ib were recorded in 38.2% and 3.6% of the studied isolates, respectively. The in vitro studies showed synergistic effects among the tested antibiotics with FICIs of ≤0.5. Finally, the study compared the reduction in bacterial count between the tested antibiotic combinations and imipenem:CD physical and kneaded mixtures. Imipenem:CD inclusion complexes demonstrated a significant bacterial count reduction over the antibiotic combination. These results highlight the emerging role of CDs as safe biofunctional excipients in the combat against superbug bacterial resistance.

The effect of combining antibiotics on resistance: A systematic review and meta-analysis

When and under which conditions antibiotic combination therapy decelerates rather than accelerates resistance evolution is not well understood. We examined the effect of combining antibiotics on within-patient resistance development across various bacterial pathogens and antibiotics. We searched CENTRAL, EMBASE and PubMed for (quasi)-randomised controlled trials (RCTs) published from database inception to November 24th, 2022. Trials comparing antibiotic treatments with different numbers of antibiotics were included. A patient was considered to have acquired resistance if, at the follow-up culture, a resistant bacterium was detected that had not been present in the baseline culture. We combined results using a random effects model and performed meta-regression and stratified analyses. The trials' risk of bias was assessed with the Cochrane tool. 42 trials were eligible and 29, including 5054 patients, were qualified for statistical analysis. In most trials, resistance development was not the primary outcome and studies lacked power. The combined odds ratio (OR) for the acquisition of resistance comparing the group with the higher number of antibiotics with the comparison group was 1.23 (95% CI 0.68-2.25), with substantial between-study heterogeneity (I2 =77%). We identified tentative evidence for potential beneficial or detrimental effects of antibiotic combination therapy for specific pathogens or medical conditions. The evidence for combining a higher number of antibiotics compared to fewer from RCTs is scarce and overall, is compatible with both benefit or harm. Trials powered to detect differences in resistance development or well-designed observational studies are required to clarify the impact of combination therapy on resistance.

Addition of aminoglycosides reduces recurrence of infections with multidrug-resistant Gram-negative bacilli in patients with sepsis and septic shock

OBJECTIVES

Aminoglycosides and β-lactams have been recommended for treatment of sepsis/septic shock despite a lack of mortality benefit. Previous studies have examined resistance emergence for the same bacterial isolate using old dosing regimens and during a narrow follow-up window. We hypothesised that combination regimens employing aminoglycosides will decrease the cumulative incidence of infections due to multidrug-resistant (MDR) Gram-negative bacilli (GNB) compared with β-lactams alone.

METHODS

All adult patients admitted to Barnes Jewish Hospital between 2010 and 2017 with a diagnosis of sepsis/septic shock were included in this retrospective cohort study. Patients were divided into two treatment groups, with and without aminoglycosides. Patient demographics, severity of presentation, administered antibiotics, follow-up cultures with susceptibility results for a period of 4-60 days, and mortality were extracted. After propensity score matching, a Fine-Gray subdistribution proportional hazards model summarised the estimated incidence of subsequent infections with MDR-GNB in the presence of all-cause death as a competing risk.

RESULTS

A total of 10 212 septic patients were included, with 1996 (19.5%) treated with at least two antimicrobials including one aminoglycoside. After propensity score matching, the cumulative incidence of MDR-GNB infections between 4-60 days was lower in the combination group (incidence at 60 days 0.073, 95% CI 0.062-0.085) versus patients not receiving aminoglycosides (0.116, 95% CI 0.102-0.130). Patients aged ≤65 years and with haematological malignancies had a larger treatment effect in subgroup analyses.

CONCLUSION

Addition of aminoglycosides to β-lactams may protect against subsequent infections due to MDR-GNB in patients with sepsis/septic shock.

Effect of Broad-Spectrum Antibiotic De-escalation on Critically Ill Patient Outcomes: A Retrospective Cohort Study

PURPOSE

Antibiotic de-escalation (ADE) in critically ill patients is controversial. Previous studies mainly focused on mortality; however, data are lacking about superinfection. Therefore, we aimed to identify the impact of ADE versus continuation of therapy on superinfections rate and other outcomes in critically ill patients.

METHODS

This was a two-center retrospective cohort study of adults initiated on broad-spectrum antibiotics in the intensive care unit (ICU) for ≥ 48 h. The primary outcome was the superinfection rate. Secondary outcomes included 30-day infection recurrence, ICU and hospital length of stay, and mortality.

RESULTS

250 patients were included, 125 in each group (ADE group and continuation group). Broad spectrum antibiotic discontinuation occurred at a mean of 7.2 ± 5.2 days in the ADE arm vs. 10.3 ± 7.7 in the continuation arm (P value = 0.001). Superinfection was numerically lower in the ADE group (6.4% vs. 10.4%; P = 0.254), but the difference was not significant. Additionally, the ADE group had shorter days to infection recurrence (P = 0.045) but a longer hospital stay (26 (14-46) vs. 21 (10-36) days; P = 0.016) and a longer ICU stay (14 (6-23) vs. 8 (4-16) days; P = 0.002).

CONCLUSION

No significant differences were found in superinfection rates among ICU patients whose broad-spectrum antibiotics were de-escalated versus patients whose antibiotics were continued. Future research into the association between rapid diagnostics with antibiotic de-escalation in the setting of high resistance is warranted.

Penicillin-Binding Protein 5/6 Acting as a Decoy Target in Pseudomonas aeruginosa Identified by Whole-Cell Receptor Binding and Quantitative Systems Pharmacology

The β-lactam antibiotics have been successfully used for decades to combat susceptible Pseudomonas aeruginosa, which has a notoriously difficult to penetrate outer membrane (OM). However, there is a dearth of data on target site penetration and covalent binding of penicillin-binding proteins (PBP) for β-lactams and β-lactamase inhibitors in intact bacteria. We aimed to determine the time course of PBP binding in intact and lysed cells and estimate the target site penetration and PBP access for 15 compounds in P. aeruginosa PAO1. All β-lactams (at 2 × MIC) considerably bound PBPs 1 to 4 in lysed bacteria. However, PBP binding in intact bacteria was substantially attenuated for slow but not for rapid penetrating β-lactams. Imipenem yielded 1.5 ± 0.11 log10 killing at 1h compared to <0.5 log10 killing for all other drugs. Relative to imipenem, the rate of net influx and PBP access was ~ 2-fold slower for doripenem and meropenem, 7.6-fold for avibactam, 14-fold for ceftazidime, 45-fold for cefepime, 50-fold for sulbactam, 72-fold for ertapenem, ~ 249-fold for piperacillin and aztreonam, 358-fold for tazobactam, ~547-fold for carbenicillin and ticarcillin, and 1,019-fold for cefoxitin. At 2 × MIC, the extent of PBP5/6 binding was highly correlated (r2 = 0.96) with the rate of net influx and PBP access, suggesting that PBP5/6 acted as a decoy target that should be avoided by slowly penetrating, future β-lactams. This first comprehensive assessment of the time course of PBP binding in intact and lysed P. aeruginosa explained why only imipenem killed rapidly. The developed novel covalent binding assay in intact bacteria accounts for all expressed resistance mechanisms.

Association between combination antibiotic therapy as opposed as monotherapy and outcomes of ICU patients with Pseudomonas aeruginosa ventilator-associated pneumonia: an ancillary study of the iDIAPASON trial

BACKGROUND

The optimal treatment duration and the nature of regimen of antibiotics (monotherapy or combination therapy) for Pseudomonas aeruginosa ventilator‑associated pneumonia (PA-VAP) remain debated. The aim of this study was to evaluate whether a combination antibiotic therapy is superior to a monotherapy in patients with PA-VAP in terms of reduction in recurrence and death, based on the 186 patients included in the iDIAPASON trial, a multicenter, randomized controlled trial comparing 8 versus 15 days of antibiotic therapy for PA-VAP.

METHODS

Patients with PA-VAP randomized in the iDIAPASON trial (short-duration-8 days vs. long-duration-15 days) and who received appropriate antibiotic therapy were eligible in the present study. The main objective is to compare mortality at day 90 according to the antibiotic therapy received by the patient: monotherapy versus combination therapy. The primary outcome was the mortality rate at day 90. The primary outcome was compared between groups using a Chi-square test. Time from appropriate antibiotic therapy to death in ICU or to censure at day 90 was represented using Kaplan-Meier survival curves and compared between groups using a Log-rank test.

RESULTS

A total of 169 patients were included in the analysis. The median duration of appropriate antibiotic therapy was 14 days. At day 90, among 37 patients (21.9%) who died, 17 received monotherapy and 20 received a combination therapy (P = 0.180). Monotherapy and combination antibiotic therapy were similar for the recurrence rate of VAP, the number of extra pulmonary infections, or the acquisition of multidrug-resistant (MDR) bacteria during the ICU stay. Patients in combination therapy were exposed to mechanical ventilation for 28 ± 12 days, as compared with 23 ± 11 days for those receiving monotherapy (P = 0.0243). Results remain similar after adjustment for randomization arm of iDIAPASON trial and SOFA score at ICU admission.

CONCLUSIONS

Except longer durations of antibiotic therapy and mechanical ventilation, potentially related to increased difficulty in achieving clinical cure, the patients in the combination therapy group had similar outcomes to those in the monotherapy group.

TRIAL REGISTRATION

NCT02634411 , Registered 15 December 2015.

Aminoglycosides for the Treatment of Severe Infection Due to Resistant Gram-Negative Pathogens

Aminoglycosides are a family of rapidly bactericidal antibiotics that often remain active against resistant Gram-negative bacterial infections. Over the past decade, their use in critically ill patients has been refined; however, due to their renal and cochleovestibular toxicity, their indications in the treatment of sepsis and septic shock have been gradually reduced. This article reviews the spectrum of activity, mode of action, and methods for optimizing the efficacy of aminoglycosides. We discuss the current indications for aminoglycosides, with an emphasis on multidrug-resistant Gram-negative bacteria, such as extended-spectrum β-lactamase-producing Enterobacterales, carbapenemase-producing Enterobacterales, multidrug-resistant Pseudomonas aeruginosa, and carbapenem-resistant Acinetobacter baumannii. Additionally, we review the evidence for the use of nebulized aminoglycosides.

Navigating Available Treatment Options for Carbapenem-Resistant Acinetobacter baumannii-calcoaceticus Complex Infections

Carbapenem-resistant Acinetobacter baumannii-calcoaceticus complex (CRAB) is one of the top-priority pathogens for new antibiotic development. Unlike other antibiotic-resistant threats, none of the available therapies have been shown to consistently reduce mortality or improve patient outcomes in clinical trials. Antibiotic combination therapy is routinely used in clinical practice; however, the preferred combination has not been defined. This narrative review focuses on evidence-based solutions for the treatment of invasive CRAB infections. We dissect the promise and perils of traditional agents used in combination, such as colistin, sulbactam, and the tetracyclines, and offer clinical pearls based on our interpretation of the available data. Next, we investigate the merits of newly developed β-lactam agents like cefiderocol and sulbactam-durlobactam, which have demonstrated contrasting results in recent randomized clinical trials. The review concludes with the authors' perspective on the evolving treatment landscape for CRAB infections, which is complicated by limited clinical data, imperfect treatment options, and a need for future clinical trials. We propose that effective treatment for CRAB infections requires a personalized approach that incorporates host factors, the site of infection, pharmacokinetic-pharmacodynamic principles, local molecular epidemiology of CRAB isolates, and careful interpretation of antibiotic susceptibility testing results. In most clinical scenarios, a dose-optimized, sulbactam-based regimen is recommended with the addition of at least one other in vitro active agent. Should sulbactam-durlobactam receive regulatory approval, recommendations will need to be re-evaluated with the most recent evidence.

Diagnosis and Management of Cystic Fibrosis Exacerbations

With the improving survival of cystic fibrosis (CF) patients and the advent of highly effective cystic fibrosis transmembrane conductance regulator (CFTR) therapy, the clinical spectrum of this complex multisystem disease continues to evolve. One of the most important clinical events for patients with CF in the course of this disease is acute pulmonary exacerbation (PEx). Clinical and microbial epidemiology studies of CF PEx continue to provide important insight into the disease course, prognosis, and complications. This work has now led to several large-scale clinical trials designed to clarify the treatment paradigm for CF PEx. The primary goal of this review is to provide a summary and update of the pathophysiology, clinical and microbial epidemiology, outcome and treatment of CF PEx, biomarkers for exacerbation, and the impact of highly effective modulator therapy on these events moving forward.

Study protocol for a randomized clinical trial to assess 7 versus 14-days of treatment for Pseudomonas aeruginosa bloodstream infections (SHORTEN-2 trial)

BACKGROUND

Research priorities in Antimicrobial Stewardship (AMS) have rapidly evolved in the last decade. The need for a more efficient use of antimicrobials have fueled plenty of studies to define the optimal duration for antibiotic treatments, and yet, there still are large areas of uncertainty in common clinical scenarios. Pseudomonas aeruginosa has been pointed as a priority for clinical research, but it has been unattended by most randomized trials tackling the effectiveness of short treatments. The study protocol of the SHORTEN-2 trial is presented as a practical example of new ways to approach common obstacles for clinical research in AMS.

OBJECTIVE

To determine whether a 7-day course of antibiotics is superior to 14-day schemes for treating bloodstream infections by P. aeruginosa (BSI-PA).

METHODS

A superiority, open-label, randomized controlled trial will be performed across 30 Spanish hospitals. Adult patients with uncomplicated BSI-PA will be randomized to receive a 7 versus 14-day course of any active antibiotic. The primary endpoint will be the probability for the 7-day group of achieving better outcomes than the control group, assessing altogether clinical effectiveness, severe adverse events, and antibiotic exposure through a DOOR/RADAR analysis. Main secondary endpoints include treatment failure, BSI-PA relapses, and mortality. A superiority design was set for the primary endpoint and non-inferiority for treatment failure, resulting in a sample size of 304 patients.

CONCLUSIONS

SHORTEN-2 trial aligns with some of the priorities for clinical research in AMS. The implementation of several methodological innovations allowed overcoming common obstacles, like feasible sample sizes or measuring the clinical impact and unintended effects.

TRIAL REGISTRATION

EudraCt: 2021-003847-10; ClinicalTrials.gov: NCT05210439.

Exposure to World Health Organization's AWaRe antibiotics and isolation of multidrug resistant bacteria: a systematic review and meta-analysis

BACKGROUND

Antibiotic use drives antibiotic resistance.

OBJECTIVES

To systematically review the literature and estimate associations between prior exposure to antibiotics across World Health Organization's (WHO) AWaRe categories (Access, Watch, Reserve) and isolation of critical and high-priority multidrug resistant organisms (MDROs) on the WHO priority pathogen list.

DATA SOURCES

Embase, Ovid Medline, Scopus, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov (from inception to 20/08/2020).

STUDY ELIGIBILITY CRITERIA

Case-control, cohort, or experimental studies that assessed the risk of infection/colonization with MDROs.

PARTICIPANTS

Inpatients or outpatients of any age and sex.

INTERVENTIONS

Prior exposure to antibiotics that could be categorized into the AWaRe framework.

DATA ANALYSIS

Tailored design-specific checklists applied to each included study. For each antibiotic/class, crude odds ratios (ORs) were pooled through random-effects meta-analyses, both overall and by MDRO. Heterogeneity was examined.

RESULTS

We identified 349 eligible studies. All were observational, prone to bias due to design and lack of adjustment for confounding, and not primarily designed to compare associations across AWaRe categories. We found statistically significant associations between prior exposure to almost all antibiotics/classes across AWaRe categories and colonization/infection with any MDRO. We observed higher ORs for Watch and Reserve antibiotics than with Access antibiotics. First generation cephalosporins (Access) had the least association with any MDRO colonization/infection (58 studies; OR = 1.2 [95% CI: 1.0-1.4]), whereas strongest associations were estimated for linezolid (Reserve) (22 studies; OR = 2.6 [95% CI: 2.1-3.1]), followed by carbapenems (Watch) (237 studies; OR = 2.3 [95% CI: 2.1-2.5]). There was high heterogeneity for all antibiotic/MDRO associations.

CONCLUSIONS

Optimising use of Access antibiotics is likely to reduce the selection of MDROs and global antibiotic resistance. Despite data limitations, our study offers a strong rationale for further adoption of AWaRe as an important tool to improve antibiotic use globally.

Antibiotic treatment protocols revisited: the challenges of a conclusive assessment by mathematical modelling

Hospital-acquired bacterial infections lead to prolonged hospital stays and increased mortality. The problem is exacerbated by antibiotic-resistant strains that delay or impede effective treatment. To ensure successful therapy and to manage antibiotic resistance, treatment protocols that draw on several different antibiotics might be used. This includes the administration of drug cocktails to individual patients (combination therapy) but also the random assignment of drugs to different patients (mixing) and a regular switch in the default drug used in the hospital from drug A to drug B and back (cycling). For more than 20 years, mathematical models have been used to assess the prospects of antibiotic combination therapy, mixing and cycling. But while tendencies in their ranking across studies have emerged, the picture remains surprisingly inconclusive and incomplete. In this article, we review existing modelling studies and demonstrate by means of examples how methodological factors complicate the emergence of a consistent picture. These factors include the choice of the criterion by which the effects of the protocols are compared, the model implementation and its analysis. We thereafter discuss how progress can be made and suggest future modelling directions.

Compatibility of Evolutionary Responses to Constituent Antibiotics Drive Resistance Evolution to Drug Pairs

Antibiotic combinations are considered a relevant strategy to tackle the global antibiotic resistance crisis since they are believed to increase treatment efficacy and reduce resistance evolution (WHO treatment guidelines for drug-resistant tuberculosis: 2016 update.). However, studies of the evolution of bacterial resistance to combination therapy have focused on a limited number of drugs and have provided contradictory results (Lipsitch, Levin BR. 1997; Hegreness et al. 2008; Munck et al. 2014). To address this gap in our understanding, we performed a large-scale laboratory evolution experiment, adapting eight replicate lineages of Escherichia coli to a diverse set of 22 different antibiotics and 33 antibiotic pairs. We found that combination therapy significantly limits the evolution of de novode novo resistance in E. coli, yet different drug combinations vary substantially in their propensity to select for resistance. In contrast to current theories, the phenotypic features of drug pairs are weak predictors of resistance evolution. Instead, the resistance evolution is driven by the relationship between the evolutionary trajectories that lead to resistance to a drug combination and those that lead to resistance to the component drugs. Drug combinations requiring a novel genetic response from target bacteria compared with the individual component drugs significantly reduce resistance evolution. These data support combination therapy as a treatment option to decelerate resistance evolution and provide a novel framework for selecting optimized drug combinations based on bacterial evolutionary responses.

The potential impact of the COVID-19 pandemic on global antimicrobial and biocide resistance: an AMR Insights global perspective

The COVID-19 pandemic presents a serious public health challenge in all countries. However, repercussions of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections on future global health are still being investigated, including the pandemic’s potential effect on the emergence and spread of global antimicrobial resistance (AMR). Critically ill COVID-19 patients may develop severe complications, which may predispose patients to infection with nosocomial bacterial and/or fungal pathogens, requiring the extensive use of antibiotics. However, antibiotics may also be inappropriately used in milder cases of COVID-19 infection. Further, concerns such as increased biocide use, antimicrobial stewardship/infection control, AMR awareness, the need for diagnostics (including rapid and point-of-care diagnostics) and the usefulness of vaccination could all be components shaping the influence of the COVID-19 pandemic. In this publication, the authors present a brief overview of the COVID-19 pandemic and associated issues that could influence the pandemic’s effect on global AMR.

Comparing treatment strategies to reduce antibiotic resistance in an in vitro epidemiological setting

The rapid rise of antibiotic resistance, combined with the increasing cost and difficulties to develop new antibiotics, calls for treatment strategies that enable more sustainable antibiotic use. The development of such strategies, however, is impeded by the lack of suitable experimental approaches that allow testing their effects under realistic epidemiological conditions. Here, we present an approach to compare the effect of alternative multidrug treatment strategies in vitro using a robotic liquid-handling platform. We use this framework to study resistance evolution and spread implementing epidemiological population dynamics for treatment, transmission, and patient admission and discharge, as may be observed in hospitals. We perform massively parallel experimental evolution over up to 40 d and complement this with a computational model to infer the underlying population-dynamical parameters. We find that in our study, combination therapy outperforms monotherapies, as well as cycling and mixing, in minimizing resistance evolution and maximizing uninfecteds, as long as there is no influx of double resistance into the focal treated community.

Superinfection rate among the patients treated with carbapenem versus piperacillin/tazobactam: Retrospective observational study

BACKGROUND

Superinfection is a new isolate pathogen after 48 h of antibiotic treatment or within one week of treatment discontinuation. In many studies carbapenem and piperacillin-tazobactam were associated with high risk of superinfection.

AIM

To evaluate the rate of superinfections during carbapenem and piperacillin/tazobactam treatment. Also, to identify risk factors for superinfections.

METHODS

A Retrospective observational study was conducted in King Abdulaziz Medical City. Approval from the institutional Review Board was obtained. The study included all adult patient treated with carbapenem or piperacillin/tazobactam for more than 72 h. Univariate and multivariate analysis was conducted to compare piperacillin/tazobactam versus carbapenems and to identify the associated risk factor to develop superinfection.

FINDING

507 patients were included in this study. The mean age of the patients was 61 years ± 19.33. Of these, 278 received carbapenems and 229 received piperacillin/tazobactam. In univariate analysis superinfections were significantly higher with carbapenems compared with piperacillin-tazobactam (28.77% versus 20.96%; P value = 0.044). After adjustment of cofounders in multivariate analysis, presence of tracheostomy, endotracheal ventilation, foley catheter and duration of antibiotic were associated with higher risk to developed superinfection adjusted odd ratio (aOR) 3.23 (95% CI,1.39-7.52) P < 0.01, aOR 2.556 (95% CI,1.30-5.02) P < 0.01, aOR 2.20 (95% CI,1.35-3.61) P < 0.001, aOR 1.051(95% CI,1.02-1.08) P < 0.001 respectively, but not carbapenems use aOR 1.052 (95% CI,0.657-1.685).

CONCLUSIONS

The use of carbapenems were not associated with higher risk to developed superinfection. The most important risk factors associated with superinfection were presence of tracheostomy, endotracheal mechanical ventilation, Foley catheter and the duration of antibiotics.

An inventory of 44 qPCR assays using hydrolysis probes operating with a unique amplification condition for the detection and quantification of antibiotic resistance genes

Early antibiotic resistance determinants (ARDs) detection in humans or animals is crucial to counteract their propagation. The ARDs quantification is fundamental to understand the perturbation caused by disruptors, such as antibiotics, during therapies. Forty-three qPCRs on the most diffused ARDs and integrons among human and animal Enterobacterales, and one on the 16S rDNA for bacteria quantification, were developed. The qPCRs, using hydrolysis probes, operated with a unique amplification condition and were tested analytically and diagnostically performing 435 reactions on five positive and negative controls for each qPCR. Diagnostic sensitivity and specificity were confirmed by PCR and genome sequencing of control isolates, demonstrating 100% performance for all qPCRs. An easy and rapid discrimination method for the epidemiologically relevant bla_CTX-Ms is provided. This large, noncommercial qPCRs inventory could serve for precise quantification of ARDs, but also as a rapid screening tool for surveillance purposes, providing the basis for further high-throughput developments.

Individualized antibiotic therapy in the treatment of severe infections

Introduction: Sepsis is a frequent and life-threatening clinical entity and antibiotic treatment is one of the most important interventions, together with source control and hemodynamic resuscitation. Guidelines have highlighted the importance of an early (i.e. within 1-3 h from recognition) and appropriate (i.e. the pathogen is sensitive in vitro to the administered drug) antimicrobial therapy in this setting.Areas covered: Antibiotic therapy should be individualized according to several issues, including early pathogen identification, optimal drug regimens based on pharmacokinetic/pharmacodynamics (PK/PD) and adequate duration using both clinical and biological biomarkers. This narrative review has considered the most relevant studies evaluating these issues.Expert opinion: Rapid identification pathogen resistance profile (i.e. the minimal inhibitory concentration for the available antimicrobials), real-time measurement of drug concentrations with regimen adjustment on MIC and daily measurement of procalcitonin to guide duration of therapy are the main issues to individualize the antibiotic management in critically ill patients.

Synergistic Antibacterial Activity of Designed Trp-Containing Antibacterial Peptides in Combination With Antibiotics Against Multidrug-Resistant Staphylococcus epidermidis

Multidrug resistance among various bacterial strains is leading to worldwide resistance to a wide range of antibiotics. Combination therapy involving current antibiotics and other biological or chemical molecules represents an attractive novel strategy. In this study, we investigated the synergistic antibacterial activity of a series of Trp-containing antimicrobial peptides (AMPs) with four classes of traditional chemical antibiotics that are inactive against multidrug-resistant Staphylococcus epidermidis (MRSE) in vitro and in vivo. Among the antibiotics that we studied, penicillin, ampicillin and erythromycin showed a distinct synergistic effect in combination with all of the Trp-containing AMPs, represented by a fractional inhibitory concentration index (FICI) of <0.5. The antibacterial activities were noticeably improved, with 32-to 64-fold reductions in the MIC values for ampicillin and 16- to 32-fold reductions in the MIC values for erythromycin and penicillin. Tetracycline showed synergistic activity with only I1WL5W but additive activity with L11W, L12W, and I4WL5W. Ceftazidime exhibited additive activity with the Trp-containing peptides. In addition, the antibiotics in combination with the peptide significantly inhibited biofilm formation by MRSE 1208. A mechanistic study demonstrated that the Trp-containing peptides, especially I1WL5W and I4WL5W, which contain two tryptophan residues, disrupted bacterial inner and outer membranes, which promoted antibiotic delivery into the cytoplasm and access to cytoplasmic targets; however, L11W and L12W may have increased intracellular antibiotic concentrations by decreasing blaZ, tet(m) and msrA expression. Importantly, strong synergistic activity against the MRSE 1208 strain was observed for the combination of I1WL5W and penicillin in a mouse infection model. Thus, the combination of AMPs and traditional antibiotics could be a promising option for the prevention of acute and chronic infections caused by MRSE.

Occurrence of diverse aminoglycoside modifying enzymes with co-existing extended-spectrum-β-lactamases within Enterobacteriaceae isolated in India

OBJECTIVE

The present study describes aminoglycoside modifying enzymes (AMEs) among clinical isolates with coexisting extended spectrum beta-lactamases.

METHODOLOGY

A total of 227 non duplicate enterobacterial isolates were collected and identified from patients who were admitted to different wards or attended OPD of a tertiary referral hospital of North-East India. Isolates were initially screened for antimicrobial susceptibility testing followed by PCR based screening of aminoglycosides modifying enzymes and co-existing ESBLs and carbapenemases. Horizontal transferability, incompatibility typing and stability of plasmids were also analyzed.

RESULTS

Diverse types of AMEs were observed namely; ant(3″)-I, ant(4')-Ia, aac(3)-IIc, ant(3')-I, aac(6')-Ib, ant(2″)-Ia and aac(6'). Majority of the AME positive isolates harboured bla_TEM followed by bla_CTX-M-15 and a combination of bla_TEM and bla_CTX-M-15 were also observed. Nine isolates were found to harbour carbapenemases genes. AME genes were found to be located within a self conjugative plasmid of Inc FIA, IncY, IncN, IncFIB and IncA/C incompatibility types. It was observed that most AME genes were stable over 50 days of serial passages whereas aph(3')-Via and aph(3')-IIb were completely lost within 50 days.

CONCLUSION

This study underscores the co-existence of AMEs and ESBLs within enterobacteriaceae which emphasize a reassessment of combination therapy in the health settings.

Functional insights into the Streptococcus pneumoniae HicBA toxin-antitoxin system based on a structural study

Streptococcus pneumonia has attracted increasing attention due to its resistance to existing antibiotics. TA systems are essential for bacterial persistence under stressful conditions such as nutrient deprivation, antibiotic treatment, and immune system attacks. In particular, S. pneumoniae expresses the HicBA TA gene, which encodes the stable HicA toxin and the labile HicB antitoxin. These proteins interact to form a non-toxic TA complex under normal conditions, but the toxin is activated by release from the antitoxin in response to unfavorable growth conditions. Here, we present the first crystal structure showing the complete conformation of the HicBA complex from S. pneumonia. The structure reveals that the HicA toxin contains a double-stranded RNA-binding domain that is essential for RNA recognition and that the C-terminus of the HicB antitoxin folds into a ribbon-helix-helix DNA-binding motif. The active site of HicA is sterically blocked by the N-terminal region of HicB. RNase activity assays show that His36 is essential for the ribonuclease activity of HicA, and nuclear magnetic resonance (NMR) spectra show that several residues of HicB participate in binding to the promoter DNA of the HicBA operon. A toxin-mimicking peptide that inhibits TA complex formation and thereby increases toxin activity was designed, providing a novel approach to the development of new antibiotics.

Antibiotic use in critical illness

OBJECTIVE

To provide a review on the current use of antimicrobials with a discussion on the pharmacokinetic and pharmacodynamic profiles of antimicrobials in critically ill patients, the challenges of drug resistance, the use of diagnostic testing to direct therapy, and the selection of the most likely efficacious antimicrobial protocol.

ETIOLOGY

Patients in the intensive care unit often possess profound pathophysiologic changes that can complicate antimicrobial therapy. Although many antimicrobials have known pharmacodynamic profiles, critical illness can cause wide variations in their pharmacokinetics. The two principal factors affecting pharmacokinetics are volume of distribution and drug clearance. Understanding the interplay between critical illness, drug pharmacokinetics, and antimicrobial characteristics (ie, time-dependent vs concentration-dependent) may improve antimicrobial efficacy and patient outcome.

DIAGNOSIS

Utilizing bacterial culture and susceptibility can aid in identifying drug resistant infections, selecting the most appropriate antimicrobials, and hindering the future development of drug resistance.

THERAPY

Having a basic knowledge of antimicrobial function and how to use diagnostics to direct therapeutic treatment is paramount in managing this patient population. Diagnostic testing is not always available at the time of initiation of antimicrobial therapy, so empiric selections are often necessary. These empiric choices should be made based on the location of the infection and the most likely infecting bacteria.

PROGNOSIS

Studies have demonstrated the importance of moving away from a "one dose fits all" approach to antimicrobial therapy. Instead there has been a move toward an individualized approach that takes into consideration the pharmacokinetic and pharmacodynamic variabilities that can occur in critically ill patients.

Individualising Therapy to Minimize Bacterial Multidrug Resistance

The scourge of antibiotic resistance threatens modern healthcare delivery. A contributing factor to this significant issue may be antibiotic dosing, whereby standard antibiotic regimens are unable to suppress the emergence of antibiotic resistance. This article aims to review the role of pharmacokinetic and pharmacodynamic (PK/PD) measures for optimising antibiotic therapy to minimise resistance emergence. It also seeks to describe the utility of combination antibiotic therapy for suppression of resistance and summarise the role of biomarkers in individualising antibiotic therapy. Scientific journals indexed in PubMed and Web of Science were searched to identify relevant articles and summarise existing evidence. Studies suggest that optimising antibiotic dosing to attain defined PK/PD ratios may limit the emergence of resistance. A maximum aminoglycoside concentration to minimum inhibitory concentration (MIC) ratio of > 20, a fluoroquinolone area under the concentration-time curve to MIC ratio of > 285 and a β-lactam trough concentration of > 6 × MIC are likely required for resistance suppression. In vitro studies demonstrate a clear advantage for some antibiotic combinations. However, clinical evidence is limited, suggesting that the use of combination regimens should be assessed on an individual patient basis. Biomarkers, such as procalcitonin, may help to individualise and reduce the duration of antibiotic treatment, which may minimise antibiotic resistance emergence during therapy. Future studies should translate laboratory-based studies into clinical trials and validate the appropriate clinical PK/PD predictors required for resistance suppression in vivo. Other adjunct strategies, such as biomarker-guided therapy or the use of antibiotic combinations require further investigation.

Antibiotic therapy in the critically ill - expert opinion of the Intensive Care Medicine Scientific Subcommittee of the European Society of Anaesthesiology

Antimicrobial treatment is the cornerstone of infection treatment, and the selection of appropriate antibiotic treatment for critically ill patients is challenging. Clinicians working with critically ill patients usually feel a greater obligation towards their patient than towards maintenance of the delicate ecological balance of prevalent microbiological threats and their resistance patterns. Although antibiotic overtreatment is a frequent phenomenon, patient outcomes need not be compromised when antibiotic treatment is driven by informed decision-making.At the 2016 Euro Anaesthesia Conference (London, UK), the European Society of Anaesthesia Intensive Care Scientific Subcommittee convened an expert panel on antibiotic therapy. This article summarises the main conclusions of the panel, namely the principles of antibiotic therapy that all physicians working with critically ill patients must know.

Antimicrobial stewardship for acute-care hospitals: An Asian perspective

Inappropriate use of antibiotics is contributing to a serious antimicrobial resistance problem in Asian hospitals. Despite resource constraints in the region, all Asian hospitals should implement antimicrobial stewardship (AMS) programs to optimize antibiotic treatment, improve patient outcomes, and minimize antimicrobial resistance. This document describes a consensus statement from a panel of regional experts to help multidisciplinary AMS teams design programs that suit the needs and resources of their hospitals. In general, AMS teams must decide on appropriate interventions (eg, prospective audit and/or formulary restriction) for their hospital, focusing on the most misused antibiotics and problematic multidrug-resistant organisms. This focus is likely to include carbapenem use with the goal to reduce carbapenem-resistant gram-negative bacteria. Rather than initially trying to introduce a comprehensive, hospital-wide AMS program, it would be practical to begin by pilot testing a simple program based on 1 achievable core intervention for the hospital. AMS team members must work together to determine the most suitable AMS interventions to implement in their hospitals and how best to put them into practice. Continuous monitoring and feedback of outcomes to the AMS teams, hospital administration, and prescribers will enhance sustainability of the AMS programs.

Impact of carbapenem versus non-carbapenem treatment on the rates of superinfection: A meta-analysis of randomized controlled trials

Imipenem and meropenem are the recommended antipseudomonal carbapenems for nosocomial pneumonia per clinical practice guidelines. However, these agents have a relatively broader spectrum of activity than other antibiotics and need to be reserved. Carbapenems might cause higher rate of superinfection. The aim of this study was to compare the rate of superinfection between patients who received imipenem or meropenem versus those who received non-carbapenem treatment. PubMed, EMBASE, Cochrane Library databases and two trial registries were searched for relevant randomized controlled trials of hospitalized adults with pneumonia through February 24, 2017 without date or language restrictions. Risk ratios (RRs) with 95% confidence intervals (CIs) were estimated using random-effects models. The primary outcome was based on the intention-to-treat analysis while clinically evaluable patients were analyzed as secondary outcome. Eight RCTs were included in this meta-analysis. A statistically higher risk of superinfection with low heterogeneity (RR = 1.690, 95% CI 1.247-2.291, p = 0.001, I² = 0%) was associated with the two carbapenems compared to non-carbapenems. However, in comparison with non-carbapenems, superinfection with imipenem was significantly higher (RR = 1.694, 95% CI 1.234-2.325, p = 0.001, I² = 0%), while it was non-significant with meropenem (RR = 1.647, 95% CI 0.552-4.919, p = 0.371, I² = 0%). Superinfection was statistically higher in both double-blind and open-label studies and when carbapenems were compared to other antipseudomonal beta-lactams. This meta-analysis identified significantly higher superinfection with imipenem compared to non-carbapenems. The findings confirm the theory of higher superinfections with broader spectrum agents and provide additional support for reserving carbapenems for the treatment of infections caused by multidrug-resistant organisms.

Visible light active nanofibrous membrane for antibacterial wound dressing

Chronic wound infections, especially due to the emergence of multidrug resistance in bacteria, require the urgent development of alternative antibacterial therapies. Here, we developed a new class of hydrogel nanofibrous membranes that show visible light-induced disinfection. The presented photocatalytic disinfection is based on the generation of reactive singlet oxygen from a conjugated microporous polymer upon visible light irradiation. Therefore, sustained protection of the wound area can be provided in the presence of visible light. Fabrication of the photoactive wound dressing consists of first synthesizing photoactive conjugated microporous polymer nanoparticles by miniemulsion polymerization and subsequently embedding the nanoparticles in polyvinyl alcohol hydrogel nanofibers by colloid-electrospinning. The fibers were then crosslinked in glutaraldehyde/HCl vapor to be water-insoluble. This nanoparticle-in-nanofiber structure allows for a flexible combination of the properties of the nanoparticles and supporting nanofibers. The disinfecting properties of the membranes were evaluated with the inactivation of Escherichia coli K-12 and Bacillus subtilis as model systems of Gram-negative and Gram-positive bacteria, as well as the inhibition of biofilm growth under irradiation of visible light. Cytotoxicity tests on fibroblast cells revealed a high cytocompatibility of the membranes. Furthermore, the good mechanical properties of the membranes allow for their facile removal after use and prevent the leakage of the embedded nanoparticles into the wound, making the photoactive hydrogel membranes a promising candidate for active wound dressing materials.

Summary of the international clinical guidelines for the management of hospital-acquired and ventilator-acquired pneumonia

A summary of the evidence and recommendations made in the ERS/ESICM/ESCMID/ALAT guidelines for the management of hospital-acquired pneumonia and ventilator-associated pneumonia http://ow.ly/S3zA30iZfLa.

Empiric Antibiotics for Sepsis

BACKGROUND

Sepsis is life-threatening organ dysfunction caused by a dysregulated host response to infection. Early recognition and treatment are the cornerstones of management.

METHODS

Review of the English-language literature.

RESULTS

For both sepsis and septic shock "antimicrobials [should be] be initiated as soon as possible and within one hour" (Surviving Sepsis Campaign). The risk of progression from severe sepsis to septic shock increases 8% for each hour before antibiotics are started. Selection of antimicrobial agents is based on a combination of patient factors, predicted infecting organism(s), and local microbial resistance patterns. The initial drugs should have activity against typical gram-positive and gram-negative causative micro-organisms. Anaerobic coverage should be provided for intra-abdominal infections or others where anaerobes are significant pathogens. Empiric antifungal or antiviral therapy may be warranted. For patients with healthcare-associated infections, resistant micro-organisms will further complicate the choice of empiric antimicrobials. Recommendations are given for specific infections.

CONCLUSION

Early administration of broad-spectrum antimicrobial drugs is one of the most important, if not the most important, treatment for patients with sepsis or septic shock. Drugs should be initiated as soon as possible, and the choice of should take into account patient factors, common local pathogens, hospital antibiograms and resistance patterns, and the suspected source of infection. Antimicrobial agent therapy should be de-escalated as soon as possible.

Macropis fulvipes Venom component Macropin Exerts its Antibacterial and Anti-Biofilm Properties by Damaging the Plasma Membranes of Drug Resistant Bacteria

The abuse of antibiotics for disease treatment has led to the emergence of multidrug resistant bacteria. Antimicrobial peptides, found naturally in various organisms, have received increasing interest as alternatives to conventional antibiotics because of their broad spectrum antimicrobial activity and low cytotoxicity. In a previous report, Macropin, isolated from bee venom, exhibited antimicrobial activity against both gram-positive and negative bacteria. In the present study, Macropin was synthesized and its antibacterial and anti-biofilm activities were tested against bacterial strains, including gram-positive and negative bacteria, and drug resistant bacteria. Moreover, Macropin did not exhibit hemolytic activity and cytotoxicity to keratinocytes, whereas Melittin, as a positive control, showed very high toxicity. Circular dichroism assays showed that Macropin has an α-helical structure in membrane mimic environments. Macropin binds to peptidoglycan and lipopolysaccharide and kills the bacteria by disrupting their membranes. Moreover, the fractional inhibitory concentration index indicated that Macropin has additive and partially synergistic effects with conventional antibiotics against drug resistant bacteria. Thus, our study suggested that Macropin has potential for use of an antimicrobial agent for infectious bacteria, including drug resistant bacteria.

Clinical and Pathophysiological Overview of Acinetobacter Infections: a Century of Challenges

Acinetobacter is a complex genus, and historically, there has been confusion about the existence of multiple species. The species commonly cause nosocomial infections, predominantly aspiration pneumonia and catheter-associated bacteremia, but can also cause soft tissue and urinary tract infections. Community-acquired infections by Acinetobacter spp. are increasingly reported. Transmission of Acinetobacter and subsequent disease is facilitated by the organism's environmental tenacity, resistance to desiccation, and evasion of host immunity. The virulence properties demonstrated by Acinetobacter spp. primarily stem from evasion of rapid clearance by the innate immune system, effectively enabling high bacterial density that triggers lipopolysaccharide (LPS)-Toll-like receptor 4 (TLR4)-mediated sepsis. Capsular polysaccharide is a critical virulence factor that enables immune evasion, while LPS triggers septic shock. However, the primary driver of clinical outcome is antibiotic resistance. Administration of initially effective therapy is key to improving survival, reducing 30-day mortality threefold. Regrettably, due to the high frequency of this organism having an extreme drug resistance (XDR) phenotype, early initiation of effective therapy is a major clinical challenge. Given its high rate of antibiotic resistance and abysmal outcomes (up to 70% mortality rate from infections caused by XDR strains in some case series), new preventative and therapeutic options for Acinetobacter spp. are desperately needed.

Antimicrobial drug use in food-producing animals and associated human health risks: what, and how strong, is the evidence?

BACKGROUND

Antimicrobial resistance is a public health threat. Because antimicrobial consumption in food-producing animals contributes to the problem, policies restricting the inappropriate or unnecessary agricultural use of antimicrobial drugs are important. However, this link between agricultural antibiotic use and antibiotic resistance has remained contested by some, with potentially disruptive effects on efforts to move towards the judicious or prudent use of these drugs.

MAIN TEXT

The goal of this review is to systematically evaluate the types of evidence available for each step in the causal pathway from antimicrobial use on farms to human public health risk, and to evaluate the strength of evidence within a 'Grades of Recommendations Assessment, Development and Evaluation'(GRADE) framework. The review clearly demonstrates that there is compelling scientific evidence available to support each step in the causal pathway, from antimicrobial use on farms to a public health burden caused by infections with resistant pathogens. Importantly, the pathogen, antimicrobial drug and treatment regimen, and general setting (e.g., feed type) can have significant impacts on how quickly resistance emerges or spreads, for how long resistance may persist after antimicrobial exposures cease, and what public health impacts may be associated with antimicrobial use on farms. Therefore an exact quantification of the public health burden attributable to antimicrobial drug use in animal agriculture compared to other sources remains challenging.

CONCLUSIONS

Even though more research is needed to close existing data gaps, obtain a better understanding of how antimicrobial drugs are actually used on farms or feedlots, and quantify the risk associated with antimicrobial use in animal agriculture, these findings reinforce the need to act now and restrict antibiotic use in animal agriculture to those instances necessary to ensure the health and well-being of the animals.

Use of nebulized antimicrobials for the treatment of respiratory infections in invasively mechanically ventilated adults: a position paper from the European Society of Clinical Microbiology and Infectious Diseases

With an established role in cystic fibrosis and bronchiectasis, nebulized antibiotics are increasingly being used to treat respiratory infections in critically ill invasively mechanically ventilated adult patients. Although there is limited evidence describing their efficacy and safety, in an era when there is a need for new strategies to enhance antibiotic effectiveness because of a shortage of new agents and increases in antibiotic resistance, the potential of nebulization of antibiotics to optimize therapy is considered of high interest, particularly in patients infected with multidrug-resistant pathogens. This Position Paper of the European Society of Clinical Microbiology and Infectious Diseases provides recommendations based on the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology regarding the use of nebulized antibiotics in invasively mechanically ventilated adults, based on a systematic review and meta-analysis of the existing literature (last search July 2016). Overall, the panel recommends avoiding the use of nebulized antibiotics in clinical practice, due to a weak level of evidence of their efficacy and the high potential for underestimated risks of adverse events (particularly, respiratory complications). Higher-quality evidence is urgently needed to inform clinical practice. Priorities of future research are detailed in the second part of the Position Paper as guidance for researchers in this field. In particular, the panel identified an urgent need for randomized clinical trials of nebulized antibiotic therapy as part of a substitution approach to treatment of pneumonia due to multidrug-resistant pathogens.

The Immaculate Carbapenemase Study

Carbapenemase-producing organisms, or CPOs, are Gram-negative pathogens that produce a transmissible carbapenemase and are typically resistant to most (sometimes all) antibiotics. We now face a global CPO pandemic of high mortality. In this issue of the Journal of Clinical Microbiology, Karlowsky et al. (J Clin Microbiol 55:1638-1649, 2017, https://doi.org/10.1128/JCM.02316-16) report the results of an extensive global surveillance study that provide much-needed information that enhances our understanding of carbapenemase-producing Enterobacteriaceae (CPE) and which will be valuable for the development of improved strategies for CPE control and therapy of infections.

Bacteraemia in Intensive Care Unit: Clinical, Bacteriological, and Prognostic Prospective Study

Objectives. We conducted a one-year observational study from December 2012 to November 2013 to describe the epidemiology of bacteraemia in intensive care units (ICU) of Mohammed V Military Teaching Hospital of Rabat (Morocco). Methods. The study consisted of monitoring all blood cultures coming from intensive care units and studying the bacteriological profile of positive blood cultures as well as their clinical significance. Results. During this period, a total of 46 episodes of bacteraemia occurred, which corresponds to a rate of 15,4/1000 patients. The rate of nosocomial infections was 97% versus 3% for community infections. The most common source of bacteraemia was the lungs in 33%, but no source was identified in 52% of the episodes. Gram negative organisms were isolated in 83,6% of the cases with Acinetobacter baumannii being the most frequent. Antibiotic resistance was very high with 42,5% of extended-spectrum beta-lactamases (ESBLs) in Enterobacteriaceae and 100% of carbapenemase in Acinetobacter baumannii. The antibiotherapy introduced in the first 24 hours was adequate in 72% of the cases. Conclusions. Bloodstream infections in ICU occur most often in patients over 55 years, with hypertension and diabetes. The bacteria involved are mainly Gram negative bacteria multiresistant to antibiotics. Early administration of antibiotics significantly reduces patients mortality.

Strategies to enhance rational use of antibiotics in hospital: a guideline by the German Society for Infectious Diseases

Introduction

In the time of increasing resistance and paucity of new drug development there is a growing need for strategies to enhance rational use of antibiotics in German and Austrian hospitals. An evidence-based guideline on recommendations for implementation of antibiotic stewardship (ABS) programmes was developed by the German Society for Infectious Diseases in association with the following societies, associations and institutions: German Society of Hospital Pharmacists, German Society for Hygiene and Microbiology, Paul Ehrlich Society for Chemotherapy, The Austrian Association of Hospital Pharmacists, Austrian Society for Infectious Diseases and Tropical Medicine, Austrian Society for Antimicrobial Chemotherapy, Robert Koch Institute.

Materials and methods

A structured literature research was performed in the databases EMBASE, BIOSIS, MEDLINE and The Cochrane Library from January 2006 to November 2010 with an update to April 2012 (MEDLINE and The Cochrane Library). The grading of recommendations in relation to their evidence is according to the AWMF Guidance Manual and Rules for Guideline Development.

Conclusion

The guideline provides the grounds for rational use of antibiotics in hospital to counteract antimicrobial resistance and to improve the quality of care of patients with infections by maximising clinical outcomes while minimising toxicity. Requirements for a successful implementation of ABS programmes as well as core and supplemental ABS strategies are outlined. The German version of the guideline was published by the German Association of the Scientific Medical Societies (AWMF) in December 2013.

Individualized antibiotic strategies

PURPOSE OF REVIEW

Infections are common complications in critically ill patients and are frequently treated with antibiotics. Unfortunately, delivery of optimal therapy is complicated because efficacy of antimicrobials is influenced by the timing of treatment initiation, the use of combination therapy, and the optimization of drug dosing.

RECENT FINDINGS

Early diagnosis of infection is mandatory to provide a rapid and appropriate antibiotic therapy. The presence of less susceptible strains, in particular for hospital-acquired infections, or patients with severe disease, such as the presence of septic shock, may need combination antibiotic therapy. Antibiotic pharmacokinetics, notably volume of distribution and total body clearance, are significantly altered in these critically ill patients and can influence the attainment of adequate circulating levels when standard dosage regimens are administered. Higher dosing should be considered in such patients, although in case of renal impairment and reduced clearance, drug accumulation could also result in some side-effects. Nebulized antibiotics may provide a better clinical response than systemic antibiotics in ventilator-associated pneumonia because of multidrug-resistant pathogens.

SUMMARY

The optimal use of antibiotics in the management of severe infections is an important challenge for ICU physicians. Antimicrobial therapy needs to be individualized according to specific patient characteristics, infecting organisms, and susceptibility patterns.

Efficient Nanofibrous Membranes for Antibacterial Wound Dressing and UV Protection

Materials with a hierarchical structure often demonstrate superior properties with combined and even synergistic effects of multiple functions. Herein, we report the design of a new class of material with a multicompartment nanofibrous structure as a promising candidate for antibacterial wound dressing and functional textile applications. The design consists in first synthesizing nanocapsules loaded with functional payloads and subsequently embedding the nanocapsules into polymer nanofibers by using the colloid-electrospinning technique. The nanocontainer-in-nanofiber structure allows for a selective and separate loading of different functional agents with different polarities, and it offers a flexible combination of the properties of nanocontainers and nanofibers. An example of the potential for these multicompartment materials is demonstrated here, in which the synergistic antibacterial effect against E. coli K-12 and B. Subtilis combined with anti-UV property is shown.

Acute Pneumonia

Acute pneumonia is an active infection of the lungs that results when an individual at risk gets exposed to a particular microbiological pathogen. Acute pneumonia is the leading cause of death in the United States that is attributable to an infection. The risk factors, pathogenesis, and microbiological organisms involved differ if the pneumonia develops in the community versus health care-associated environment. The development of concise and comprehensive guidelines has led to an improvement in the management of the problem. However, the emergence of multidrug-resistant organisms and the increase in the percentage of elderly population keep mortality risk very substantial.

An update on the management of urinary tract infections in the era of antimicrobial resistance

Urinary tract infections (UTIs) caused by antibiotic-resistant Gram-negative bacteria are a growing concern due to limited therapeutic options. Gram-negative bacteria, specifically Enterobacteriaceae, are common causes of both community-acquired and hospital acquired UTIs. These organisms can acquire genes that encode for multiple antibiotic resistance mechanisms, including extended-spectrum-lactamases (ESBLs), AmpC- β -lactamase, and carbapenemases. The assessment of suspected UTI includes identification of characteristic symptoms or signs, urinalysis, dipstick or microscopic tests, and urine culture if indicated. UTIs are categorized according to location (upper versus lower urinary tract) and severity (uncomplicated versus complicated). Increasing rates of antibiotic resistance necessitate judicious use of antibiotics through the application of antimicrobial stewardship principles. Knowledge of the common causative pathogens of UTIs including local susceptibility patterns are essential in determining appropriate empiric therapy. The recommended first-line empiric therapies for acute uncomplicated bacterial cystitis in otherwise healthy adult nonpregnant females is a 5-day course of nitrofurantion or a 3-g single dose of fosfomycin tromethamine. Second-line options include fluoroquinolones and β-lactams, such as amoxicillin-clavulanate. Current treatment options for UTIs due to AmpC- β -lactamase-producing organisms include fosfomycin, nitrofurantion, fluoroquinolones, cefepime, piperacillin-tazobactam and carbapenems. In addition, treatment options for UTIs due to ESBLs-producing Enterobacteriaceae include nitrofurantion, fosfomycin, fluoroquinolones, cefoxitin, piperacillin-tazobactam, carbapenems, ceftazidime-avibactam, ceftolozane-tazobactam, and aminoglycosides. Based on identification and susceptibility results, alternatives to carbapenems may be used to treat mild-moderate UTIs caused by ESBL-producing Enterobacteriaceae. Ceftazidime-avibactam, colistin, polymixin B, fosfomycin, aztreonam, aminoglycosides, and tigecycline are treatment options for UTIs caused by carbapenem-resistant Enterobacteriaceae (CRE). Treatment options for UTIs caused by multidrug resistant (MDR)-Pseudomonas spp. include fluoroquinolones, ceftazidime, cefepime, piperacillin-tazobactam, carbapenems, aminoglycosides, colistin, ceftazidime-avibactam, and ceftolozane-tazobactam. The use of fluoroquinolones for empiric treatment of UTIs should be restricted due to increased rates of resistance. Aminoglycosides, colistin, and tigecycline are considered alternatives in the setting of MDR Gram-negative infections in patients with limited therapeutic options.