Continuous versus intermittent infusions of ceftazidime for treating exacerbation of cystic fibrosis

Prolonged Beta-Lactam Infusions in Children: A Systematic Review and Meta-Analysis

OBJECTIVE

To assess whether beta-lactam extended or continuous beta-lactam infusions (EI/CI) improve clinical outcomes in children with proven or suspected bacterial infections.

STUDY DESIGN

We included observational and interventional studies that compared beta-lactam EI or CI with standard infusions in children less than 18 years old, and reported on mortality, hospital or intensive care unit length of stay, microbiological cure, and/or clinical cure. Data sources included PubMed, Medline, EBM Reviews, EMBASE, and CINAHL and were searched from January 1, 1980, to November 3, 2023. Thirteen studies (2945 patients) were included: 5 randomized control trials and 8 observational studies. Indications for antimicrobial therapies and clinical severity varied, ranging from cystic fibrosis exacerbation to critically ill children with bacteriemia.

RESULTS

EI and CI were not associated with a reduction in mortality in randomized control trials (n = 1464; RR 0.93, 95% CI 0.71, 1.21), but were in observational studies (n = 833; RR 0.43, 95% CI 0.19, 0.96). We found no difference in hospital length of stay. Results for clinical and microbiological cures were heterogeneous and reported as narrative review. The included studies were highly heterogeneous, limiting the strength of our findings. The lack of shared definitions for clinical and microbiological cure outcomes precluded analysis.

CONCLUSIONS

EI and CI were not consistently associated with reduced mortality or length of stay in children. Results were conflicting regarding clinical and microbiological cures. More well-designed studies targeting high-risk populations are necessary to determine the efficacy of these alternative dosing strategies.

[CF Lung Disease - a German S3 Guideline: Pseudomonas aeruginosa]

Cystic Fibrosis (CF) is the most common autosomal recessive genetic multisystemic disease. In Germany, it affects at least 8000 people. The disease is caused by mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene leading to dysfunction of CFTR, a transmembrane chloride channel. This defect causes insufficient hydration of the airway epithelial lining fluid which leads to reduction of the mucociliary clearance.Even if highly effective, CFTR modulator therapy has been available for some years and people with CF are getting much older than before, recurrent and chronic infections of the airways as well as pulmonary exacerbations still occur. In adult CF life, Pseudomonas aeruginosa (PA) is the most relevant pathogen in colonisation and chronic infection of the lung, leading to further loss of lung function. There are many possibilities to treat PA-infection.This is a S3-clinical guideline which implements a definition for chronic PA-infection and demonstrates evidence-based diagnostic methods and medical treatment in order to give guidance for individual treatment options.

International consensus recommendations for the use of prolonged-infusion beta-lactam antibiotics: Endorsed by the American College of Clinical Pharmacy, British Society for Antimicrobial Chemotherapy, Cystic Fibrosis Foundation, European Society of Clinical Microbiology and Infectious Diseases, Infectious Diseases Society of America, Society of Critical Care Medicine, and Society of Infectious Diseases Pharmacists

Intravenous β-lactam antibiotics remain a cornerstone in the management of bacterial infections due to their broad spectrum of activity and excellent tolerability. β-lactams are well established to display time-dependent bactericidal activity, where reductions in bacterial burden are directly associated with the time that free drug concentrations remain above the minimum inhibitory concentration (MIC) of the pathogen during the dosing interval. In an effort to take advantage of these bactericidal characteristics, prolonged (extended and continuous) infusions (PIs) can be applied during the administration of intravenous β-lactams to increase time above the MIC. PI dosing regimens have been implemented worldwide, but implementation is inconsistent. We report consensus therapeutic recommendations for the use of PI β-lactams developed by an expert international panel with representation from clinical pharmacy and medicine. This consensus guideline provides recommendations regarding pharmacokinetic and pharmacodynamic targets, therapeutic drug-monitoring considerations, and the use of PI β-lactam therapy in the following patient populations: severely ill and nonseverely ill adult patients, pediatric patients, and obese patients. These recommendations provide the first consensus guidance for the use of β-lactam therapy administered as PIs and have been reviewed and endorsed by the American College of Clinical Pharmacy (ACCP), the British Society for Antimicrobial Chemotherapy (BSAC), the Cystic Fibrosis Foundation (CFF), the European Society of Clinical Microbiology and Infectious Diseases (ESCMID), the Infectious Diseases Society of America (IDSA), the Society of Critical Care Medicine (SCCM), and the Society of Infectious Diseases Pharmacists (SIDP).

Therapeutic drug monitoring-guided dosing for pediatric cystic fibrosis patients: recent advances and future outlooks

INTRODUCTION

Medicine use in children with cystic fibrosis (CF) is complicated by inconsistent pharmacokinetics at variance with the general population, a lack of research into this and its effects on clinical outcomes. In the absence of established dose regimens, therapeutic drug monitoring (TDM) is a clinically relevant tool to optimize drug exposure and maximize therapeutic effect by the bedside. In clinical practice though, use of this is variable and limited by a lack of expert recommendations.

AREAS COVERED

We aimed to review the use of TDM in children with CF to summarize recent developments, current recommendations, and opportunities for future directions. We searched PubMed for relevant publications using the broad search terms "cystic fibrosis" in combination with the specific terms "therapeutic drug monitoring (TDM)" and "children." Further searches were undertaken using the name of identified drugs combined with the term "TDM."

EXPERT OPINION

Further research into the use of Bayesian forecasting and the relationship between exposure and response is required to personalize dosing, with the opportunity for the development of expert recommendations in children with CF. Use of noninvasive methods of TDM has the potential to improve accessibility to TDM in this cohort.

Optimizing Betalactam Clinical Response by Using a Continuous Infusion: A Comprehensive Review

INTRODUCTION

Antimicrobial resistance is a major healthcare issue responsible for a large number of deaths. Many reviews identified that PKPD data are in favor of the use of continuous infusion, and we wanted to review clinical data results in order to optimize our clinical practice.

METHODOLOGY

We reviewed Medline for existing literature comparing continuous or extended infusion to intermittent infusion of betalactams.

RESULTS

In clinical studies, continuous infusion is as good as intermittent infusion. In the subset group of critically ill patients or those with an infection due to an organism with high MIC, a continuous infusion was associated with better clinical response.

CONCLUSIONS

Clinical data appear to confirm those of PK/PD to use a continuous infusion in severely ill patients or those infected by an organism with an elevated MIC, as it is associated with higher survival rates. In other cases, it may allow for a decrease in antibiotic daily dosage, thereby contributing to a decrease in overall costs.

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.

Evaluation of the safety of piperacillin-tazobactam extended infusion in pediatric cystic fibrosis patients

BACKGROUND

Patients with cystic fibrosis (CF) may be treated with piperacillin-tazobactam (PZT) for acute pulmonary exacerbations. Extending the infusion of PZT is one strategy to increase efficacy. Direct comparison, with respect to the incidence of acute kidney injury (AKI), between these two strategies has not been evaluated in pediatric patients with CF. The primary objective of this study was to compare the incidence of AKI in pediatric CF patients receiving extended infusion (EI) PZT versus traditional infusion (TI).

METHODS

This IRB-approved, retrospective analysis included patients ages 30 days to 18 years that received PZT for at least 48 h between January 1, 2008, and January 1, 2020. PZT was infused over 30 min (TI group) or 4 h (EI group).

RESULTS

Two hundred and four patients were included (TI: 109, EI: 95). Median age was 8 years (4-13) and 7 years (3-12) in the TI and EI groups (p = 0.15). The groups did not differ significantly in their baseline characteristics. There were 12 (11%) AKIs in the TI group and 8 (8.4%) in the EI group (p = 0.53). There was one occurrence of serum sickness in the TI group and none in the EI group. The incidence of thrombocytopenia was similar between the two groups. Median treatment duration was 8 days (5-11) and 9 days (5-13) for the TI and EI groups, respectively (p = 0.24).

CONCLUSIONS

There was no significant increase in AKI in pediatric patients with CF receiving PZT by EI compared with TI. EI may be utilized to optimize the pharmacokinetics of PZT in pediatric CF patients.

Activity of newest generation β-lactam/β-lactamase inhibitor combination therapies against multidrug resistant Pseudomonas aeruginosa

Multidrug resistant (MDR) P. aeruginosa accounts for 35% of all P. aeruginosa isolated from respiratory samples of patients with cystic fibrosis (CF). The usefulness of β-lactam antibiotics for treating CF, such as carbapenems and later generation cephalosporins, is limited by the development of antibacterial resistance. A proven treatment approach is the combination of a β-lactam antibiotic with a β-lactamase inhibitor. New β-lactam/β-lactamase inhibitor combinations are available, but data are lacking regarding the susceptibility of MDR CF-associated P. aeruginosa (CFPA) to these new combination therapies. In this study we determined MIC values for three new combinations; imipenem-relebactam (I-R), ceftazidime-avibactam (CZA), and ceftolozane-tazobactam (C/T) against MDR CFPA (n = 20). The MIC₉₀ of I-R, CZA, and C/T was 64/4, 32/4, and 16/8 (all µg/mL), respectively. The susceptibility of isolates to imipenem was not significantly improved with the addition of relebactam (p = 0.68). However, susceptibility to ceftazidime was significantly improved with the addition of avibactam (p < 0.01), and the susceptibility to C/T was improved compared to piperacillin/tazobactam (p < 0.05) These data provide in vitro evidence that I-R may not be any more effective than imipenem monotherapy against MDR CFPA. The pattern of susceptibility observed for CZA and C/T in the current study was similar to data previously reported for non-CF-associated MDR P. aeruginosa.

A Review of Extended and Continuous Infusion Beta-Lactams in Pediatric Patients

Intravenous beta-lactam antibiotics are the most prescribed antibiotic class in US hospitalized patients of all ages; therefore, optimizing their dosing is crucial. Bactericidal killing is best predicted by the time in which beta-lactam drug concentrations are maintained above the organism's minimum inhibitory concentration (MIC), rather than achievement of a high peak concentration. As such, administration of beta-lactam antibiotics via extended or continuous infusions over a minimum of 3 hours, rather than standard infusions over approximately 30 minutes, has been associated with improved achievement of pharmacodynamic targets and improved clinical outcomes in adult medical literature. This review summarizes the pediatric medical literature. Applicable studies include pharmacodynamic models, case series, retrospective analyses, and prospective studies on the use of extended infusion and continuous infusion penicillins, cephalosporins, carbapenems, and monobactams in neonates, infants, children, and adolescents. Specialized patient populations with unique pharmacokinetics and high-risk infections (neonates, critically ill, febrile neutropenia, cystic fibrosis) are also reviewed. While more studies are needed to confirm prospective clinical outcomes, the current body of evidence suggests extended and continuous infusions of beta-lactam antibiotics are well tolerated in children and improve achievement of pharmacokineticpharmacodynamic targets with similar or superior clinical outcomes, particularly in infections associated with high MICs.

Quantification of ceftazidime/avibactam in human plasma and dried blood spots: Implications on stability and sample transport

Ceftazidime is an established third-generation cephalosporin antibiotic frequently administered to intensive care patients. To overcome drug resistance of pathogens, it is combined with the newly developed non-ß-lactam ß-lactamase inhibitor avibactam under the brand name Zavicefta®. To facilitate therapeutic drug monitoring (TDM), we developed a method for the simultaneous quantification of these substances by LC-MS/MS. A problem for TDM is the low stability of the analytes in plasma, requiring transport times of less than 6 h at 23 °C. Thus, we evaluated dried blood spots (DBS) as matrix for better stability. For both analytes, stable isotope labelled internal standards were applied. Plasma samples were prepared by protein precipitation, DBS by liquid extraction. The chromatographic separation took place on a polar-modified C18 column, and detection was achieved by tandem mass spectrometry with ESI ionization in positive mode for ceftazidime and negative mode for avibactam. Calibration was linear in the ranges of 5 - 100 µg/mL for ceftazidime and 1.25 - 25 µg/mL for avibactam in plasma and 2.5 - 50 µg/mL and 0.625 - 12.5 µg/mL in DBS, respectively. Precision was better than 7 % and accuracy better than 10% for plasma as well as for DBS. The stability of ceftazidime and avibactam was better in DBS than in plasma or full blood, extending maximal transport times at 23 °C from 6 h in plasma or full blood to 24 h for DBS samples. However, robust estimation of plasma concentrations from DBS measurements requires validation by future clinical studies.

Liquid chromatographic method to follow-up ceftazidime and pyridine in portable elastomeric infusion pumps over 24 h

Portable infusion pumps are an interesting solution to continue outpatient parenteral antimicrobial therapy (OPAT) at the patient's home. However, the use of ceftazidime for such applications is challenging in view of its relatively poor stability in solution. In this study, elastomeric infusion pumps with 6 or 7 g of ceftazidime were deflated over 24 h in an oven at 33°C while ceftazidime and its degradation product, pyridine, were regularly monitored. Hereto, a fast and sensitive liquid chromatographic (LC) method has been developed using a Kinetex^® C18 (150 × 3 mm, 2.6 μm) column with gradient elution. Ammonium formate 20 mM and acetonitrile (ACN) were mixed in a ratio of 98:2 v/v for mobile phase A and 85:15 v/v for mobile phase B. Both were adjusted to pH 4.5 with formic acid. The flow rate was set at 0.4 mL/min. The solution with a starting dose of 6 g ceftazidime was found to be degraded 10% after an average of 19 h 11 min so that an administration of 6 g to the patient was not reached. For the solution with a starting dose of 7 g of ceftazidime, 10% degradation was observed after an average of 18 h 42 min. However, by starting from a higher dose, an average of 6.56 g of ceftazidime could be administered over 24 h. In addition, 1.0% of pyridine versus ceftazidime pentahydrate with sodium carbonate (=mixture for injection) was formed over 24 h.

Pharmacokinetics of Ceftazidime in Children and Adolescents with Obesity

PURPOSE

The aim of this study was to evaluate ceftazidime pharmacokinetics (PK) in a cohort that includes a predominate number of children and adolescents with obesity and assess the efficacy of competing dosing strategies.

METHODS

A population PK model was developed using opportunistically collected plasma samples. For each dosing strategy, model-based probability of target attainment (PTA) estimates were computed for study participants using empirical Bayes estimates. In addition, the effects of body size and renal function on PTA were evaluated using stochastic model simulations with virtually generated subjects.

RESULTS

Twenty-nine participants, 24 of whom were obese, contributed data towards the analysis. The median (range) age, body weight, and body mass index of participants were 12.2 years (2.3-20.6), 59.2 kg (8.4-121), and 25.2 kg/m2 (13.8-42.9), respectively. Administration of 50 mg/kg intravenously (IV) every 8 hours (q8h; max 6 g/day) or 40 mg/kg IV q6h (max 6 g/day) resulted in PTA values of ≥ 90% (minimum inhibitory concentration 8 mg/L) for the subset of obese participants with estimated glomerular filtration rates (GFR) ≥ ~ 80 mL/min/1.73 m2. However, for both regimens, stochastic model simulations denoted lower PTA values (< 90%) with increasing body weight for virtual subjects with GFR ≥ 120 mL/min/1.73 m2. Alternatively, permitting for a maximum daily dose of 8 g/day using a 40 mg/kg IV q6h regimen provided PTA values that were near or above target (90%) for virtual subjects between 10 to 120 kg with GFR ≥ 80 mL/min/1.73 m2.

CONCLUSION

Our analysis suggests administration of 40 mg/kg IV q6h (max 8 g/day) maximizes PTA in children and adolescents with obesity and GFR ≥ 80 mL/min/1.73 m2.

TRIAL REGISTRATION

Clinicaltrials.gov Identifier: NCT01431326.

Single versus combination intravenous anti-pseudomonal antibiotic therapy for people with cystic fibrosis

BACKGROUND

The choice of antibiotic, and the use of single or combined therapy are controversial areas in the treatment of respiratory infection due to Pseudomonas aeruginosa in cystic fibrosis (CF). Advantages of combination therapy include wider range of modes of action, possible synergy and reduction of resistant organisms; advantages of monotherapy include lower cost, ease of administration and reduction of drug-related toxicity. Current evidence does not provide a clear answer and the use of intravenous antibiotic therapy in CF requires further evaluation. This is an update of a previously published review.

OBJECTIVES

To assess the effectiveness of single compared to combination intravenous anti-pseudomonal antibiotic therapy for treating people with CF.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register, comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. Most recent search of the Group's Trials Register: 07 October 2020. We also searched online trials registries on 16 November 2020.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing a single intravenous anti-pseudomonal antibiotic with a combination of that antibiotic plus a second anti-pseudomonal antibiotic in people with CF.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. We assessed the certainty of the data using GRADE.

MAIN RESULTS

We identified 59 trials, of which we included eight trials (356 participants) comparing a single anti-pseudomonal agent to a combination of the same antibiotic and one other. There was a wide variation in the individual antibiotics used in each trial. In total, the trials included seven comparisons of a beta-lactam antibiotic (penicillin-related or third generation cephalosporin) with a beta-lactam-aminoglycoside combination and three comparisons of an aminoglycoside with a beta-lactam-aminoglycoside combination.  There was considerable heterogeneity amongst these trials, leading to difficulties in performing the review and interpreting the results. These results should be interpreted cautiously. Six of the included trials were published between 1977 and 1988; these were single-centre trials with flaws in the randomisation process and small sample size. Overall, the methodological quality was poor and the certainty of the evidence ranged from low to moderate. The review did not find any differences between monotherapy and combination therapy in either the short term or in the long term for the outcomes of different lung function measures, bacteriological outcome measures, need for additional treatment, adverse effects, quality of life or symptom scores.

AUTHORS' CONCLUSIONS

The results of this review are inconclusive. The review raises important methodological issues. There is a need for an RCT which needs to be well-designed in terms of adequate randomisation allocation, blinding, power and long-term follow-up. Results need to be standardised to a consistent method of reporting, in order to validate the pooling of results from multiple trials.

Pharmacokinetic and Pharmacodynamic Optimization of Antibiotic Therapy in Cystic Fibrosis Patients: Current Evidences, Gaps in Knowledge and Future Directions

Antibiotic therapy is one of the main treatments for cystic fibrosis (CF). It aims to eradicate bacteria during early infection, calms down the inflammatory process, and leads to symptom resolution of pulmonary exacerbations. CF can modify both the pharmacokinetic (PK) and pharmacodynamic (PD) profiles of antibiotics, therefore specific PK/PD endpoints should be determined in the context of CF. Currently available data suggest that optimal PK/PD targets cannot be attained in sputum with intravenous aminoglycosides. Continuous infusion appears preferable for β-lactam antibiotics, but optimal concentrations in sputum are unlikely to be reached, with some possible exceptions such as meropenem and ceftolozane. Usual doses are likely suboptimal for fluoroquinolones and linezolid, whereas daily doses of 45-60 mg/kg and 200 mg could be convenient for vancomycin and doxycycline, respectively. Weekly azithromycin doses of 22-30 mg/kg could also be appropriate for its anti-inflammatory effect. The difficulty with achieving optimal concentrations supports the use of combined treatments and the inhaled administration route, as very high local concentrations, concomitantly with low systemic exposure, can be obtained with the inhaled route for aminoglycosides, colistin, and fluoroquinolones, thus minimizing the risk of toxicity.

The pharmacokinetics of antibiotics in cystic fibrosis

INTRODUCTION

Dosing of antibiotics in people with cystic fibrosis (CF) is challenging, due to altered pharmacokinetics, difficulty of lung tissue penetration, and increasing presence of antimicrobial resistance.

AREAS COVERED

The purpose of this work is to critically review original data as well as previous reviews and guidelines on pharmacokinetics of systemic and inhaled antibiotics in CF, with the aim to propose strategies for optimization of antibacterial therapy in both children and adults with CF.

EXPERT OPINION

For systemic antibiotics, absorption is comparable in CF patients and non-CF controls. The volume of distribution (Vd) of most antibiotics is similar between people with CF with normal body composition and healthy individuals. However, there are a few exceptions, like cefotiam and tobramycin. Many antibiotic class-dependent changes in drug metabolism and excretion are reported, with an increased total body clearance for ß-lactam antibiotics, aminoglycosides, fluoroquinolones, and trimethoprim. We, therefore, recommend following class-specific guidelines for CF, mostly resulting in higher dosages per kg bodyweight in CF compared to non-CF controls. Higher local antibiotic concentrations in the airways can be obtained by inhalation therapy, with which eradication of bacteria may be achieved while minimizing systemic exposure and risk of toxicity.

Outcomes and endpoints reported in studies of pulmonary exacerbations in people with cystic fibrosis: A systematic review

BACKGROUND

There is no consensus about which outcomes should be evaluated in studies of pulmonary exacerbations in people with cystic fibrosis (CF). Outcomes used for evaluation should be meaningful; that is, they should capture how people feel, function or survive and be acknowledged as important to people with CF, or should be reliable surrogates of those outcomes. We aimed to summarise the outcomes and corresponding endpoints which have been reported in studies of pulmonary exacerbations, and to identify those which are most likely to be meaningful.

METHODS

A PROSPERO registered systematic review (CRD42020151785) was conducted in Medline, Embase and Cochrane from inception until July 2020. Registered trials were also included.

RESULTS

144 studies met the inclusion criteria. A wide range of outcomes and corresponding endpoints were reported. Death, QoL and many patient-reported outcomes are likely to be meaningful as they directly capture how people feel, function or survive. Forced expiratory volume in 1-second [FEV₁] is a validated surrogate of risk of death and reduced QoL. The extent of structural lung disease has also been correlated with lung function, pulmonary exacerbations and risk of death. Since no evidence of a correlation between airway microbiology or biomarkers with clinically meaningful outcomes was found, the value of these as surrogates was unclear.

CONCLUSIONS

Death, QoL, patient-reported outcomes, FEV₁, and structural lung changes were identified as outcomes that are most likely to be meaningful. Development of a core outcome set in collaboration with stakeholders including people with CF is recommended.

Population pharmacokinetics of ceftazidime in critically ill children: impact of cystic fibrosis

BACKGROUND

Pharmacokinetics data on ceftazidime are sparse for the paediatric population, particularly for children with cystic fibrosis (CF) or severe infections.

OBJECTIVES

To characterize the population pharmacokinetics of ceftazidime in critically ill children, identify covariates that affect drug disposition and evaluate the current dosing regimens.

METHODS

The study was registered with Clinicaltrials.gov (NCT01344512). Children receiving ceftazidime were selected in 13 French hospitals. Plasma concentrations were determined by UPLC-MS/MS. Population pharmacokinetic analyses were performed using NONMEN software.

RESULTS

One hundred and eight patients, aged 28 days to 12 years, with CF (n = 32), haematology and/or oncology disorders (n = 47) or severe infection (n = 29) were included. Ceftazidime was administered by continuous or intermittent infusions; 271 samples were available for analysis. A two-compartment model with first-order elimination and allometric scaling was developed and covariate analysis showed that ceftazidime pharmacokinetics were also significantly affected by CLCR and CF. Ceftazidime clearance was 82% higher in CF than in non-CF patients. Monte Carlo simulations showed that the percentage of target attainment (PTA) for the target of T>MIC = 65% was (i) lower in CF than in non-CF children with intermittent infusions and (ii) higher with continuous than intermittent infusion in all children.

CONCLUSIONS

The population pharmacokinetics model for ceftazidime in children was influenced by body weight, CLCR and CF. A higher PTA was obtained with continuous versus intermittent infusions. Further studies should explore the benefits of continuous versus intermittent infusion of ceftazidime, including current versus increased doses in CF children.

Optimizing Antibiotic Treatment Strategies for Neonates and Children: Does Implementing Extended or Prolonged Infusion Provide any Advantage?

Optimizing the use of antibiotics has become mandatory, particularly for the pediatric population where limited options are currently available. Selecting the dosing strategy may improve overall outcomes and limit the further development of antimicrobial resistance. Time-dependent antibiotics optimize their free concentration above the minimal inhibitory concentration (MIC) when administered by continuous infusion, however evidences from literature are still insufficient to recommend its widespread adoption. The aim of this review is to assess the state-of-the-art of intermittent versus prolonged intravenous administration of antibiotics in children and neonates with bacterial infections. We identified and reviewed relevant literature by searching PubMed, from 1 January 1 2000 to 15 April 2020. We included studies comparing intermittent versus prolonged/continuous antibiotic infusion, among the pediatric population. Nine relevant articles were selected, including RCTs, prospective and retrospective studies focusing on different infusion strategies of vancomycin, piperacillin/tazobactam, ceftazidime, cefepime and meropenem in the pediatric population. Prolonged and continuous infusions of antibiotics showed a greater probability of target attainment as compared to intermittent infusion regimens, with generally good clinical outcomes and safety profiles, however its impact in terms on efficacy, feasibility and toxicity is still open, with few studies led on children and adult data not being fully extendable.

Acute Pulmonary Exacerbations in Cystic Fibrosis

With the improving survival of cystic fibrosis (CF) patients and the advent of highly effective cystic fibrosis transmembrane conductance regulator 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 an acute pulmonary exacerbation. Clinical and microbial epidemiology studies of CF pulmonary exacerbations continue to provide important insight into the disease course, prognosis, and complications. This work has now led to a number of large scale clinical trials with the goal of improving the treatment paradigm for CF pulmonary exacerbation. The primary goal of this review is to provide a summary of the pathophysiology, the clinical epidemiology, microbial epidemiology, outcome and the treatment of CF pulmonary exacerbation.

Duration of intravenous antibiotic therapy in people with cystic fibrosis

BACKGROUND

Progressive lung damage from recurrent exacerbations is the major cause of mortality and morbidity in cystic fibrosis. Life expectancy of people with cystic fibrosis has increased dramatically in the last 40 years. One of the major reasons for this increase is the mounting use of antibiotics to treat chest exacerbations caused by bacterial infections. The optimal duration of intravenous antibiotic therapy is not clearly defined. Individuals usually receive intravenous antibiotics for 14 days, but treatment may range from 10 to 21 days. A shorter duration of antibiotic treatment risks inadequate clearance of infection which could lead to further lung damage. Prolonged courses of intravenous antibiotics are expensive and inconvenient. The risk of systemic side effects such as allergic reactions to antibiotics also increases with prolonged courses and the use of aminoglycosides requires frequent monitoring to minimise some of their side effects. However, some organisms which infect people with cystic fibrosis are known to be multi-resistant to antibiotics, and may require a longer course of treatment. This is an update of previously published reviews.

OBJECTIVES

To assess the optimal duration of intravenous antibiotic therapy for treating chest exacerbations in people with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises references identified from comprehensive electronic database searches, handsearches of relevant journals, abstract books and conference proceedings. Most recent search of the Group's Cystic Fibrosis Trials Register: 30 May 2019.We also searched online trials registries. Most recent search of the ClinicalTrials.gov and WHO International Clinical Trials Registry Platform (ICTRP) portal: 06 January 2019.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials comparing different durations of intravenous antibiotic courses for acute respiratory exacerbations in people with CF, either with the same drugs at the same dosage, the same drugs at a different dosage or frequency or different antibiotics altogether, including studies with additional therapeutic agents.

DATA COLLECTION AND ANALYSIS

No eligible trials were identified for inclusion. A trial looking at the standardised treatment of pulmonary exacerbations is currently ongoing and will be included when the results are published.  MAIN RESULTS: No eligible trials were included.

AUTHORS' CONCLUSIONS

There are no clear guidelines on the optimum duration of intravenous antibiotic treatment. Duration of treatment is currently based on unit policies and response to treatment. Shorter duration of treatment should improve quality of life and adherence, result in a reduced incidence of drug reactions and be less costly. However, the shorter duration may not be sufficient to clear a chest infection and may result in an early recurrence of an exacerbation. This systematic review identifies the need for a multicentre, randomised controlled trial comparing different durations of intravenous antibiotic treatment as it has important clinical and financial implications. The currently ongoing STOP2 trial is expected to provide some guidance on these questions when published.

In vitro Interactions of Pseudomonas aeruginosa With Scedosporium Species Frequently Associated With Cystic Fibrosis

Members of the Scedosporium apiospermum species complex are the second most frequently isolated pathogens after Aspergillus fumigatus from cystic fibrosis (CF) patients with fungal pulmonary infections. Even so, the main risk factors for the infection are unrevealed. According to previous studies, bacterial infections might reduce the risk of a fungal infection, but an antibacterial therapy may contribute to the airway colonization by several fungal pathogens. Furthermore, corticosteroids, which are often used to reduce lung inflammation in children and adults with CF, are also proved to enhance the growth of A. fumigatus in vitro. Considering all the above discussed points, we aimed to test how Pseudomonas aeruginosa influences the growth of scedosporia and to investigate the potential effect of commonly applied antibacterial agents and corticosteroids on Scedosporium species. Direct interactions between fungal and bacterial strains were tested using the disk inhibition method. Indirect interactions via volatile compounds were investigated by the plate-in-plate method, while the effect of bacterial media-soluble molecules was tested using a modified cellophane assay and also in liquid culture media conditioned by P. aeruginosa. To test the effect of bacterial signal molecules, antibacterial agents and corticosteroids on the fungal growth, the broth microdilution method was used. We also investigated the germination ability of Scedosporium conidia in the presence of pyocyanin and diffusible signal factor by microscopy. According to our results, P. aeruginosa either inhibited or enhanced the growth of scedosporia depending on the culture conditions and the mode of interactions. When the two pathogens were cultured physically separately from each other in the plate-in-plate tests, the presence of the bacteria was able to stimulate the growth of several fungal isolates. While in direct physical contact, bacterial strains inhibited the fungal growth. This effect might be attributed to bacterial signal molecules, which also proved to inhibit the germination and growth of scedosporia. In addition, antibacterial agents showed growth-promoting, while corticosteroids exhibited growth inhibitory effect on several Scedosporium isolates. These data raise the possibility that a P. aeruginosa infection or a previously administered antibacterial therapy might be able to increase the chance of a Scedosporium colonization in a CF lung.

Antimicrobial susceptibility testing (AST) and associated clinical outcomes in individuals with cystic fibrosis: A systematic review

BACKGROUND

Antimicrobial susceptibility testing (AST) is a cornerstone of infection management. Cystic fibrosis (CF) treatment guidelines recommend AST to select antimicrobial treatments for CF airway infection but its utility in this setting has never been objectively demonstrated.

METHODS

We conducted a systematic review of primary published articles designed to address two PICO (patient, intervention, comparator, outcome) questions: 1) "For individuals with CF, is clinical response to antimicrobial treatment of bacterial airways infection predictable from AST results available at treatment initiation?" and 2) "For individuals with CF, is clinical response to antimicrobial treatment of bacterial airways infection affected by the method used to guide antimicrobial selection?" Relationships between AST results and clinical response (changes in pulmonary function, weight, signs and symptoms of respiratory tract infection, and time to next event) were assessed for each article and results were compared across articles when possible.

RESULTS

Twenty-five articles describing the results of 20 separate studies, most of which described Pseudomonas aeruginosa treatment, were identified. Thirteen studies described pulmonary exacerbation (PEx) treatment and seven described 'maintenance' of chronic bacterial airways infection. In only three of 16 studies addressing PICO question #1 was there a suggestion that baseline bacterial isolate antimicrobial susceptibility was associated with clinical response to treatment. None of the four studies addressing PICO question #2 suggested that antimicrobial selection methods influenced clinical outcomes.

CONCLUSIONS

There is little evidence that AST predicts the clinical outcome of CF antimicrobial treatment, suggesting a need for careful consideration of current AST use by the CF community.

Pharmacokinetics of Continuous Infusion Beta-lactams in the Treatment of Acute Pulmonary Exacerbations in Adult Patients With Cystic Fibrosis

BACKGROUND

Several clinical trials have shown the efficacy of continuous infusion beta-lactam (BL) antibiotics in patients with cystic fibrosis (CF); however, little is known about pharmacokinetic changes during the treatment of an acute pulmonary exacerbation (APE). Identifying and understanding these changes may assist in optimizing antibiotic dosing during APE treatment.

METHODS

This study was a retrospective cohort study of 162 adult patients with CF admitted to the University of Utah Hospital between January 1, 2008, and May 15, 2014, for treatment of an APE with both a continuous infusion BL and IV tobramycin. We extracted the administered doses of continuous infusion BLs and tobramycin along with serum drug concentrations and calculated medication clearance rates. The primary outcome was change in clearance rates of continuous infusion BLs between day 2 and day 7 of APE treatment.

RESULTS

The BL clearance rate increased 20.7% (95% CI, 11.42 to 32.49; P < .001), whereas the tobramycin clearance rate decreased 6.3% (95% CI, -12.29 to -4.45; P < .001). The mean percent predicted FEV1 increased between admission and discharge by 12.2% (95% CI, -13.81 to -10.55; P < .001).

CONCLUSIONS

Clinicians should monitor BL levels along with aminoglycoside levels and make dose adjustments to maximize the chance of optimal antibiotic treatment. Continuous infusion BL and tobramycin clearance can change dramatically during the treatment of an APE, which may necessitate significant changes in dosing to achieve optimal antibiotic levels. Clearance rates of these antibiotics may change in opposite directions, requiring specific monitoring of each medication.

Ceftazidime-avibactam has potent sterilizing activity against highly drug-resistant tuberculosis

There are currently many patients with multidrug-resistant and extensively drug-resistant tuberculosis. Ongoing transmission of the highly drug-resistant strains and high mortality despite treatment remain problematic. The current strategy of drug discovery and development takes up to a decade to bring a new drug to clinical use. We embarked on a strategy to screen all antibiotics in current use and examined them for use in tuberculosis. We found that ceftazidime-avibactam, which is already used in the clinic for multidrug-resistant Gram-negative bacillary infections, markedly killed rapidly growing, intracellular, and semidormant Mycobacterium tuberculosis in the hollow fiber system model. Moreover, multidrug-resistant and extensively drug-resistant clinical isolates demonstrated good ceftazidime-avibactam susceptibility profiles and were inhibited by clinically achievable concentrations. Resistance arose because of mutations in the transpeptidase domain of the penicillin-binding protein PonA1, suggesting that the drug kills M. tuberculosis bacilli via interference with cell wall remodeling. We identified concentrations (exposure targets) for optimal effect in tuberculosis, which we used with susceptibility results in computer-aided clinical trial simulations to identify doses for immediate clinical use as salvage therapy for adults and young children. Moreover, this work provides a roadmap for efficient and timely evaluation of antibiotics and optimization of clinically relevant dosing regimens.

Single versus combination intravenous anti-pseudomonal antibiotic therapy for people with cystic fibrosis

BACKGROUND

Choice of antibiotic, and the use of single or combined therapy are controversial areas in the treatment of respiratory infection due to Pseudomonas aeruginosa in cystic fibrosis (CF). Advantages of combination therapy include wider range of modes of action, possible synergy and reduction of resistant organisms; advantages of monotherapy include lower cost, ease of administration and reduction of drug-related toxicity. Current evidence does not provide a clear answer and the use of intravenous antibiotic therapy in cystic fibrosis requires further evaluation. This is an update of a previously published review.

OBJECTIVES

To assess the effectiveness of single compared to combination intravenous anti-pseudomonal antibiotic therapy for treating people with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register, comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.Most recent search of the Group's Trials Register: 14 October 2016.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing a single intravenous anti-pseudomonal antibiotic with a combination of that antibiotic plus a second anti-pseudomonal antibiotic in people with CF.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data.

MAIN RESULTS

We identified 45 trials, of which eight trials (356 participants) comparing a single anti-pseudomonal agent to a combination of the same antibiotic and one other, were included.There was a wide variation in the individual antibiotics used in each trial. In total, the trials included seven comparisons of a beta-lactam antibiotic (penicillin-related or third generation cephalosporin) with a beta-lactam-aminoglycoside combination and three comparisons of an aminoglycoside with a beta-lactam-aminoglycoside combination. These two groups of trials were analysed as separate subgroups.There was considerable heterogeneity amongst these trials, leading to difficulties in performing the review and interpreting the results. The meta-analysis did not demonstrate any significant differences between monotherapy and combination therapy, in terms of lung function; symptom scores; adverse effects; and bacteriological outcome measures.These results should be interpreted cautiously. Six of the included trials were published between 1977 and 1988; these were single-centre trials with flaws in the randomisation process and small sample size. Overall, the methodological quality was poor.

AUTHORS' CONCLUSIONS

The results of this review are inconclusive. The review raises important methodological issues. There is a need for an RCT which needs to be well-designed in terms of adequate randomisation allocation, blinding, power and long-term follow up. Results need to be standardised to a consistent method of reporting, in order to validate the pooling of results from multiple trials.

Duration of intravenous antibiotic therapy in people with cystic fibrosis

BACKGROUND

Respiratory disease is the major cause of mortality and morbidity in cystic fibrosis. Life expectancy of people with cystic fibrosis has increased dramatically in the last 40 years. One of the major reasons for this increase is the mounting use of antibiotics to treat chest exacerbations caused by bacterial infections. The optimal duration of intravenous antibiotic therapy is not clearly defined. Individuals usually receive intravenous antibiotics for 14 days, but treatment may range from 10 to 21 days. A shorter duration of antibiotic treatment risks inadequate clearance of infection which could lead to further lung damage. Prolonged courses of intravenous antibiotics are expensive and inconvenient and the incidence of allergic reactions to antibiotics also increases with prolonged courses. The use of aminoglycosides requires frequent monitoring to avoid some of their side effects. However, some organisms which infect people with cystic fibrosis are known to be multi-resistant to antibiotics, and may require a longer course of treatment. This is an update of previously published reviews.

OBJECTIVES

To assess the optimal duration of intravenous antibiotic therapy for treating chest exacerbations in people with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises references identified from comprehensive electronic database searches, handsearches of relevant journals, abstract books and conference proceedings.Most recent search of the Group's Cystic Fibrosis Trials Register: 05 May 2016.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials comparing different durations of intravenous antibiotic courses for acute respiratory exacerbations in people with CF, either with the same drugs at the same dosage, the same drugs at a different dosage or frequency or different antibiotics altogether, including studies with additional therapeutic agents.

DATA COLLECTION AND ANALYSIS

No eligible trials were identified.

MAIN RESULTS

No eligible trials were identified.

AUTHORS' CONCLUSIONS

There are no clear guidelines on the optimum duration of intravenous antibiotic treatment. Duration of treatment is currently based on unit policies and response to treatment. Shorter duration of treatment should improve quality of life and compliance; result in a reduced incidence of drug reactions; and be less costly. However, this may not be sufficient to clear a chest infection and may result in an early recurrence of an exacerbation. This systematic review identifies the need for a multicentre, randomised controlled trial comparing different durations of intravenous antibiotic treatment as it has important clinical and financial implications.

Infectious Diseases Pharmacotherapy for Children With Cystic Fibrosis

Cystic fibrosis (CF) affects several organs, most notably the lungs, which become predisposed to infections with potentially severe consequences. Because of physiologic changes and infection characteristics, unique approaches to antimicrobial agent selection, dosing, and administration are needed. To provide optimal acute and long-term care, pediatric health care providers must be aware of these patient features and common approaches to antimicrobial therapy in CF, which can differ significantly from those of other infectious diseases. The purpose of this article is to review common respiratory pathogens, pharmacology of commonly used antimicrobial agents, and unique pharmacokinetics and dosing strategies often used when treating children with CF.

Population pharmacokinetics of meropenem administered as a prolonged infusion in children with cystic fibrosis

OBJECTIVES

Meropenem is frequently used to treat pulmonary exacerbations in children with cystic fibrosis (CF) in the USA. Prolonged-infusion meropenem improves the time that free drug concentrations remain above the MIC (fT> MIC) in adults, but data in CF children are sparse. We describe the population pharmacokinetics, tolerability and treatment burden of prolonged-infusion meropenem in CF children.

METHODS

Thirty children aged 6-17 years with a pulmonary exacerbation received 40 mg/kg meropenem every 8 h; each dose was administered as a 3 h infusion. Pharmacokinetics were determined using population methods in Pmetrics. Monte Carlo simulation was employed to compare 0.5 with 3 h infusions to estimate the probability of pharmacodynamic target attainment (PTA) at 40% fT> MIC. NCT#01429259.

RESULTS

A two-compartment model fitted the data best with clearance and volume predicted by body weight. Clearance and volume of the central compartment were 0.41 ± 0.23 L/h/kg and 0.30 ± 0.17 L/kg, respectively. Half-life was 1.11 ± 0.38 h. At MICs of 1, 2 and 4 mg/L, PTAs for the 0.5 h infusion were 87.6%, 70.1% and 35.4%, respectively. The prolonged infusion increased PTAs to >99% for these MICs and achieved 82.8% at 8 mg/L. Of the 30 children, 18 (60%) completed treatment with prolonged infusion; 5 did so at home without any reported burden. Nine patients were changed to a 0.5 h infusion when discharged home.

CONCLUSIONS

In these CF children, meropenem clearance was greater compared with published values from non-CF children. Prolonged infusion provided an exposure benefit against pathogens with MICs ≥1 mg/L, was well tolerated and was feasible to administer in the hospital and home settings, the latter depending on perception and family schedule.

Intravenous antibiotics for pulmonary exacerbations in people with cystic fibrosis

BACKGROUND

Cystic fibrosis is a multi-system disease characterised by the production of thick secretions causing recurrent pulmonary infection, often with unusual bacteria. Intravenous antibiotics are commonly used in the treatment of acute deteriorations in symptoms (pulmonary exacerbations); however, recently the assumption that exacerbations are due to increases in bacterial burden has been questioned.

OBJECTIVES

To establish if intravenous antibiotics for the treatment of pulmonary exacerbations in people with cystic fibrosis improve short- and long-term clinical outcomes.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched the reference lists of relevant articles and reviews and ongoing trials registers.Date of last search of Cochrane trials register: 27 July 2015.

SELECTION CRITERIA

Randomised controlled trials and the first treatment cycle of cross-over studies comparing intravenous antibiotics (given alone or in an antibiotic combination) with placebo, inhaled or oral antibiotics for people with cystic fibrosis experiencing a pulmonary exacerbation.

DATA COLLECTION AND ANALYSIS

The authors assessed studies for eligibility and risk of bias and extracted data.

MAIN RESULTS

We included 40 studies involving 1717 participants. The quality of the included studies was largely poor and, with a few exceptions, these comprised of mainly small, inadequately reported studies.When comparing treatment with a single antibiotic to a combined antibiotic regimen, those participants receiving a combination of antibiotics experienced a greater improvement in lung function when considered as a whole group across a number of different measurements of lung function, but with very low quality evidence. When limited to the four placebo-controlled studies (n = 214), no difference was observed, again with very low quality evidence. With regard to the review's remaining primary outcomes, there was no effect upon time to next exacerbation and no studies in any comparison reported on quality of life. There were no effects on the secondary outcomes weight or adverse effects. When comparing specific antibiotic combinations there were no significant differences between groups on any measure. In the comparisons between intravenous and nebulised antibiotic or oral antibiotic (low quality evidence), there were no significant differences between groups on any measure. No studies in any comparison reported on quality of life.

AUTHORS' CONCLUSIONS

The quality of evidence comparing intravenous antibiotics with placebo is poor. No specific antibiotic combination can be considered to be superior to any other, and neither is there evidence showing that the intravenous route is superior to the inhaled or oral routes. There remains a need to understand host-bacteria interactions and in particular to understand why many people fail to fully respond to treatment.

Good practice recommendations for paediatric outpatient parenteral antibiotic therapy (p-OPAT) in the UK: a consensus statement

There is compelling evidence to support the rationale for managing children on intravenous antimicrobial therapy at home whenever possible, including parent and patient satisfaction, psychological well-being, return to school/employment, reductions in healthcare-associated infection and cost savings. As a joint collaboration between the BSAC and the British Paediatric Allergy, Immunity and Infection Group, we have developed good practice recommendations to highlight good clinical practice and governance within paediatric outpatient parenteral antibiotic therapy (p-OPAT) services across the UK. These guidelines provide a practical approach for safely delivering a p-OPAT service in both secondary care and tertiary care settings, in terms of the roles and responsibilities of members of the p-OPAT team, the structure required to deliver the service, identifying patients and pathologies that are suitable for p-OPAT, ensuring appropriate vascular access, antimicrobial choice and delivery and the clinical governance aspects of delivering a p-OPAT service. The process of writing a business case to support the introduction of a p-OPAT service is also addressed.

Single versus combination intravenous antibiotic therapy for people with cystic fibrosis

BACKGROUND

Choice of antibiotic, and the use of single or combined therapy are controversial areas in the treatment of respiratory infection in cystic fibrosis (CF). Advantages of combination therapy include wider range of modes of action, possible synergy and reduction of resistant organisms; advantages of monotherapy include lower cost, ease of administration and reduction of drug-related toxicity. Current evidence does not provide a clear answer and the use of intravenous antibiotic therapy in CF requires further evaluation.

OBJECTIVES

To assess the effectiveness of single compared to combination intravenous antibiotic therapy for treating people with CF.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register, comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.Most recent search of the Group's Trials Register: 22 August 2013.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing a single intravenous antibiotic with a combination of that antibiotic plus a second antibiotic in people with CF.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data.

MAIN RESULTS

We identified 43 trials, of which eight trials (356 participants) comparing a single agent to a combination of the same antibiotic and one other, were included.There was a wide variation in the individual antibiotics used in each trial. In total, the trials included seven comparisons of a beta-lactam antibiotic (penicillin-related or third generation cephalosporin) with a beta-lactam-aminoglycoside combination and three comparisons of an aminoglycoside with a beta-lactam-aminoglycoside combination. These two groups of trials were analysed as separate subgroups.There was considerable heterogeneity amongst these trials, leading to difficulties in performing the review and interpreting the results. The meta-analysis did not demonstrate any significant differences between monotherapy and combination therapy, in terms of lung function; symptom scores; adverse effects; and bacteriological outcome measures.These results should be interpreted cautiously. Six of the included trials were published between 1977 and 1988; these were single-centre trials with flaws in the randomisation process and small sample size. Overall, the methodological quality was poor.

AUTHORS' CONCLUSIONS

The results of this review are inconclusive. The review raises important methodological issues. There is a need for an RCT which needs to be well-designed in terms of adequate randomisation allocation, blinding, power and long-term follow up. Results need to be standardised to a consistent method of reporting, in order to validate the pooling of results from multiple trials.

How to minimize toxic exposure to pyridine during continuous infusion of ceftazidime in patients with cystic fibrosis?

Ceftazidime is particularly efficient against Pseudomonas aeruginosa in cystic fibrosis patients. Thus, the spontaneous production of pyridine, which is a toxic product, raises some concern. Our aim was to examine the kinetics of degradation of ceftazidime in portable infusion pumps either at 4°C, 22°C, or 33°C and to propose some recommendations in order to reduce the pyridine exposure. Two administration models were studied in vitro. In model 1, we administered 12 g of ceftazidime infused over 23 h (once-daily infusion) compared to 6 g infused over 11.5 h in model 2 (twice-daily regimen). Samples were collected at 0 h and then every 4 and 2 h after the shaping of portable infusion pumps in models 1 and 2, respectively. Both ceftazidime and pyridine were analyzed using an ultraviolet high-performance liquid chromatograph. Production of pyridine is highly depending on the temperature. The in situ production of pyridine per day of treatment decreases at a ratio close to 1/6 and 1/3 between 33°C and 4°C in models 1 and 2, respectively. Regardless of the conditions, the production of pyridine is significantly lower in model 2, whereas the total delivery amount of ceftazidime is significantly higher at 4°C and 33°C compared to that in model 1. According to a the precautionary principle, these findings lead to three major recommendations: (i) exposing a solution of ceftazidime to over 22°C should be strictly avoided, (ii) a divided dose of 6 g over 11.5 h instead of a once-daily administration is preferred, and (iii) infusion should be administered immediately after reconstitution.

Continuous infusion meropenem and ticarcillin-clavulanate in pediatric cystic fibrosis patients

Aztreonam, cefepime, and ceftazidime are anti-pseudomonal beta-lactam antibiotics which have been previously reported to be administered by continuous infusion (CI) in pediatric CF patients. We present two cases administering intravenous (IV) meropenem and ticarcillin-clavulanate by CI in pediatric CF patients. The delivery of beta-lactam antibiotics via CI should be considered in order to optimize the pharmacodynamics (PD) of beta-lactams in the treatment of acute pulmonary exacerbations (APE).

Small airway deposition of dornase alfa during exacerbations in cystic fibrosis; a randomized controlled clinical trial

INTRODUCTION

Small airway obstruction is important in the pathophysiology of cystic fibrosis (CF) lung disease. Additionally, many CF patients lose lung function in the long term as a result of respiratory tract exacerbations (RTEs). No trials have been performed to optimize mucolytic therapy during a RTE. We investigated whether specifically targeting dornase alfa to the small airways improves small airway obstruction during RTEs.

METHODS

In a multi-center, double-blind, randomized controlled trial CF patients hospitalized for a RTE and on maintenance treatment with dornase alfa were switched to a smart nebulizer. Patients were randomized to small airway deposition (n = 19) or large airway deposition (n = 19) of dornase alfa for at least 7 days. Primary endpoint was forced expiratory flow at 75% of forced vital capacity (FEF75 ).

MAIN RESULTS

Spirometry parameters improved significantly during admission, but the difference in mean change in FEF75 between treatment groups was not significant: 0.7 SD, P = 0.30. FEF25-75 , FEV1 , nocturnal oxygen saturation and diary symptom scores also did not differ between groups.

CONCLUSIONS

This study did not detect a difference if inhaled dornase alfa was targeted to small versus large airways during a RTE. However, the 95% confidence interval for the change in FEF75 was wide. Further studies are needed to improve the effectiveness of RTE treatment in CF.

Oral, inhaled, and intravenous antibiotic choice for treating pulmonary exacerbations in cystic fibrosis

RATIONALE

Patients with cystic fibrosis (CF) experience frequent pulmonary exacerbations (PExs). Clinicians manage these episodes of worsening signs and symptoms in a variety of ways.

OBJECTIVES

To characterize the antibiotic management and associated change in lung function following PExs.

METHODS

We used 2003-2005 data from the Epidemiologic Study of Cystic Fibrosis to examine antibiotic treatment and the immediate and long-term lung function change associated with clinician reported PExs.

RESULTS

A total of 45,374 PExs were reported in 13,194 unique patients. Most PExs (73%) were treated with oral antibiotics, while 39% were treated IV and 24% were treated with inhaled antibiotics. The likelihood of non-IV versus IV antibiotic treatment was associated with the patient's age, stage of lung disease, and magnitude of lung function drop prior to the PEx. Following treatment, the average improvement in the FEV1 was 3.4 ± 12.2% predicted with a greater (5.1 ± 12.7% predicted) improvement following IV antibiotic treatment than with non-IV treatment (2.0 ± 11.6% predicted). When the best FEV1 from the year before was compared with 180 days following the PEx there was an average fall of 3.8 ± 10.5% predicted with little difference observed between antibiotic treatment routes. Patients with only one exacerbation during the 3-year study had a similar loss of lung function to patients with no reported exacerbations.

CONCLUSION

Clinicians treat the majority of PExs with oral antibiotics, particularly in younger, healthier patients. Pulmonary function improves with antibiotic therapy, however, PExs are associated with lung function deterioration over time.

Optimization of anti-pseudomonal antibiotics for cystic fibrosis pulmonary exacerbations: VI. Executive summary

Acute pulmonary exacerbations (APE) are well-described complications of cystic fibrosis (CF) and are associated with progressive morbidity and mortality. Despite aggressive management with two or more intravenous anti-pseudomonal agents, approximately 25% of exacerbations will result in a loss of lung function. The aim of this review is to provide an overview of the classes of intravenous anti-pseudomonal antibiotics, the findings of anti-pseudomonal antibiotic utilization surveys, the current antibiotic dosing recommendations from the U.S. and Europe, and the pharmacokinetic (PK) and pharmacodynamic (PD) differences between CF and non-CF individuals. Anti-pseudomonal antibiotic classes include beta-lactams, aminoglycosides, fluoroquinolones, and colistimethate sodium. Recent surveys of antibiotic utilization in CF Foundation-accredited care centers have shown that a large number of centers are not following recommended dosing strategies despite published recommendations in the U.S. and Europe. The recommended doses for anti-pseudomonal antibiotics may be higher than FDA-approved doses due to PK and PD differences. As a large portion of CF patients will not regain their lung function following an APE, it seems possible that currently available anti-pseudomonal agents are being used sub-optimally. As new anti-pseudomonal agents are not currently available, we suggest the need to optimize antibiotic dosing and dosing regimens used to treat pulmonary exacerbations in an effort to improve outcomes for CF patients infected with Pseudomonas aeruginosa.

Duration of intravenous antibiotic therapy in people with cystic fibrosis

BACKGROUND

Respiratory disease is the major cause of mortality and morbidity in cystic fibrosis (CF). Life expectancy of people with CF has increased dramatically in the last 40 years. One of the major reasons for this increase is the mounting use of antibiotics to treat chest exacerbations caused by bacterial infections. The optimal duration of intravenous antibiotic therapy is not clearly defined. Individuals usually receive intravenous antibiotics for 14 days, but treatment may range from 10 to 21 days. A shorter duration of antibiotic treatment risks inadequate clearance of infection which could lead to further lung damage. Prolonged courses of intravenous antibiotics are expensive and inconvenient and the incidence of allergic reactions to antibiotics also increases with prolonged courses. The use of aminoglycosides requires frequent monitoring to avoid some of their side effects. However, some organisms which infect people with CF are known to be multi-resistant to antibiotics, and may require a longer course of treatment.

OBJECTIVES

To assess the optimal duration of intravenous antibiotic therapy for treating chest exacerbations in people with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises references identified from comprehensive electronic database searches, handsearches of relevant journals, abstract books and conference proceedings.Most recent search of the Group's Cystic Fibrosis Trials Register: 15 November 2012.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials comparing different durations of intravenous antibiotic courses for acute respiratory exacerbations in people with CF, either with the same drugs at the same dosage, the same drugs at a different dosage or frequency or different antibiotics altogether, including studies with additional therapeutic agents.

DATA COLLECTION AND ANALYSIS

No eligible trials were identified.

MAIN RESULTS

No eligible trials were identified.

AUTHORS' CONCLUSIONS

There are no clear guidelines on the optimum duration of intravenous antibiotic treatment. Duration of treatment is currently based on unit policies and response to treatment. Shorter duration of treatment should improve quality of life and compliance; result in a reduced incidence of drug reactions; and be less costly. However, this may not be sufficient to clear a chest infection and may result in an early recurrence of an exacerbation. This systematic review identifies the need for a multicentre, randomised controlled trial comparing different durations of intravenous antibiotic treatment as it has important clinical and financial implications.

Optimization of anti-pseudomonal antibiotics for cystic fibrosis pulmonary exacerbations: II. cephalosporins and penicillins

Acute pulmonary exacerbations (APE) are well-described complications of cystic fibrosis (CF) and are associated with progressive morbidity and mortality. Despite aggressive management with two or more intravenous anti-pseudomonal agents, approximately 25% of exacerbations will result in a loss of lung function. The aim of this review is to provide an evidence-based summary of pharmacokinetic/pharmacodynamic (PK/PD), tolerability, and efficacy studies utilizing anti-pseudomonal cephalosporins (i.e., ceftazidime and cefepime) and penicillins (i.e., piperacillin-tazobactam and ticarcillin-clavulanate) in the treatment of APE and to identify areas where further study is warranted. The ceftazidime and cefepime dosing ranges from the literature are 200-400 mg/kg/day divided every 6-8 hr, maximum 8-12 g/day, and 150-200 mg/kg/day divided every 6-8 hr, up to 6-8 g/day, respectively. The literature supported dosing ranges for piperacillin and ticarcillin are 350-600 mg/kg/day divided every 4 hr, maximum 18-24 g/day of piperacillin component, and 400-750 mg/kg/day divided every 6 hr, up to 24-30 g/day of ticarcillin component, respectively. As a large portion of CF patients will not regain their lung function following an APE, we suggest the need to optimize antibiotic dosing and dosing regimens used to treat an APE in efforts to improve outcomes for CF patients infected with Pseudomonas aeruginosa. Future studies are needed to determine the clinical efficacy of higher than FDA-approved doses of ceftazidime, cefepime, and ticarcillin-clavulanate in APE. The usefulness of high dose piperacillin (>600 mg/kg/day) may be limited due to treatment-related adverse effects. Further understanding of these adverse effects in CF patients is needed.

Optimization of anti-pseudomonal antibiotics for cystic fibrosis pulmonary exacerbations: I. aztreonam and carbapenems

Acute pulmonary exacerbations (APE) in cystic fibrosis (CF) are associated with loss of lung function that may require aggressive management with intravenous antibiotics. The aim of this review is to provide an evidence-based summary of pharmacokinetic/pharmacodynamic (PK/PD), tolerability, and efficacy studies utilizing aztreonam and anti-pseudomonal carbapenems (i.e., doripenem, imipenem-cilastatin, and meropenem) in the treatment of an APE, and to identify areas where further study is warranted. The current dosing recommendations in the United States and Europe for aztreonam are lower than the literature supported dosing range of 200-300 mg/kg/day divided every 6 hr, maximum 8-12 g/day. In vitro, PK/PD, and tolerability studies show the potential of doripenem 90 mg/kg/day divided every 8 hr, infused over 4 hr, maximum 6 g/day in the treatment of APE. Imipenem-cilastatin 100 mg/kg/day divided every 6 hr, maximum 4 g/day and meropenem 120 mg/kg/day divided every 8 hr, maximum 6 g/day have been shown to be tolerable and effective in the treatment of APE. With availability issues of new anti-pseudomonal agents and a large percentage of CF patients will not regain their lung function following an APE, we suggest the need to determine optimization of aztreonam and meropenem dosing in CF, as well as to determine the clinical efficacy of doripenem in the treatment of APE. The usefulness of imipenem-cilastatin may be limited due to the rapid development of resistance.

Continuous beta-lactam infusion in critically ill patients: the clinical evidence

There is controversy over whether traditional intermittent bolus dosing or continuous infusion of beta-lactam antibiotics is preferable in critically ill patients. No significant difference between these two dosing strategies in terms of patient outcomes has been shown yet. This is despite compelling in vitro and in vivo pharmacokinetic/pharmacodynamic (PK/PD) data. A lack of significance in clinical outcome studies may be due to several methodological flaws potentially masking the benefits of continuous infusion observed in preclinical studies. In this review, we explore the methodological shortcomings of the published clinical studies and describe the criteria that should be considered for performing a definitive clinical trial. We found that most trials utilized inconsistent antibiotic doses and recruited only small numbers of heterogeneous patient groups. The results of these trials suggest that continuous infusion of beta-lactam antibiotics may have variable efficacy in different patient groups. Patients who may benefit from continuous infusion are critically ill patients with a high level of illness severity. Thus, future trials should test the potential clinical advantages of continuous infusion in this patient population. To further ascertain whether benefits of continuous infusion in critically ill patients do exist, a large-scale, prospective, multinational trial with a robust design is required.

Continuous-infusion antipseudomonal Beta-lactam therapy in patients with cystic fibrosis

OBJECTIVE

We sought to evaluate the pharmacokinetics, efficacy, safety, stability, pharmacoeconomics, and quality-of-life effects of continuous-infusion antipseudomonal beta-lactam therapy in patients with cystic fibrosis (CF).

DATA SOURCES

Literature retrieval was accessed through Medline (from 1950 to December 2010) using the following terms: cystic fibrosis; beta-lactams or piperacillin or ticarcillin or cefepime or ceftazidime or doripenem or meropenem or imipenem/cilastin or aztreonam; continuous infusion or constant infusion; drug stability; economics, pharmaceutical; and quality of life. In addition, reference citations from identified publications were reviewed.

STUDY SELECTION AND DATA EXTRACTION

We evaluated all articles in English identified from the data sources.

DATA SYNTHESIS

Patients with CF often harbor colonies of multidrug-resistant organisms, increasing the risk of suboptimal dosing and failure to meet the time above the minimum inhibitory concentration (T > MIC) pharmacodynamic targets. The pharmacokinetics of continuous-infusion antipseudomonal beta-lactam therapy in CF maintains serum concentrations above the MIC of susceptible strains and is more likely than intermittent infusion to achieve optimal T > MIC targets for some intermediate and resistant strains of Pseudomonas aeruginosa. Three noncomparative and four comparative studies have assessed the efficacy and safety of continuous-infusion antipseudomonal beta-lactam therapy during CF pulmonary exacerbations. Ceftazidime, the most extensively studied antibiotic for continuous infusion in CF, has been shown to improve forced expiratory volume in 1 second (FEV(1)), to improve forced vital capacity (FVC), and to extend the time between pulmonary exacerbations. Continuous-infusion cefepime has been studied in a small number of patients, and a trend toward improved pulmonary function has been observed. Continuous-infusion antipseudomonal beta-lactam therapy appears to be well tolerated, although most of the data pertain to ceftazidime. Because continuous infusion may necessitate that patients wear a portable pump in close proximity to the body, the stability of the antibiotic at body temperature must be considered. Several beta-lactams have good stability at body temperature (piperacillin/tazobactam, ticarcillin/clavulanate, and aztreonam) or acceptable if the medication cartridge is changed twice daily (cefepime and doripenem), whereas other beta-lactams have acceptable 24-hour stability only at lower temperatures (cefepime, ceftazidime, doripenem, and meropenem). Although no pharmacoeconomic studies have evaluated the cost-benefit of continuous infusion versus intermittent infusion in patients with CF, the potential medication cost reduction appears to be considerable. There is little information regarding the impact of continuous infusion on quality of life in patients with CF.

CONCLUSION

Efficacy and safety studies suggest that ceftazidime, administered as a continuous infusion for the treatment of CF pulmonary exacerbations, is safe and effective; has the potential to reduce the costs of treatment; and is preferred to intermittent infusion among patients treated at home. Continuous-infusion ceftazidime may therefore be an alternative to traditional dosing on a case-by-case basis, such as for patients with multidrug-resistant isolates of P. aeruginosa. Treatment with continuous-infusion ceftazidime at home may be considered in such a case, assuming resources and support equivalent to the hospital setting can be ensured. Additional studies assessing the safety and efficacy of other antipseudomonal beta-lactams, when administered as a continuous infusion, during CF pulmonary exacerbations are needed.

A survey of the utilization of anti-pseudomonal beta-lactam therapy in cystic fibrosis patients

The purpose of this study was to characterize the utilization of anti-pseudomonal beta-lactam antibiotics in the treatment of acute pulmonary exacerbations (APE) among Cystic Fibrosis Foundation (CFF)-accredited care centers. An anonymous national cross-sectional survey of CFF-accredited care centers was performed using an electronic survey tool (SurveyMonkey.com®). One hundred and twenty-one of 261 centers completed the survey (46%) representing 56% (14,856/26,740) of patients in the CFF Patient Registry. One hundred and nineteen of 121 (98%) respondents reported using beta-lactams for the treatment of APE. Intermittent dosing regimens constituted 155/167 (93%) reported regimens, while extended infusions were 12/167 (7%). Ceftazidime was the most commonly utilized beta-lactam comprising 74/167 (44%) of all infusions (intermittent and extended) of which 70/74 (95%) were intermittent infusions. The majority of intermittent ceftazidime regimens (56/70; 80%) were at doses lower than CFF and European guidelines recommended doses. In conclusion, a great majority of respondents use intermittent anti-pseudomonal beta-lactam antibiotics, with over half of respondents utilizing lower than guidelines recommended doses. While this is of concern, it is not known if optimization of dosing strategies according to guidelines recommendations will result in clinical benefit.

Antibiotic treatment of CF lung disease: from bench to bedside

Chronic infection of the respiratory tract is a hallmark of cystic fibrosis (CF). Antibiotic treatment has been used as one of the mainstays of therapy and together with other treatment modalities has resulted in increased survival of CF patients. Increasing resistance of CF-specific pathogens to various classes of antibiotics explains the need for novel antibiotic strategies. This review focuses on the future development of new antibiotic therapies, including: (1) New targets, (2) novel antibiotic regimens in CF, (3) new antibiotics, and (4) other investigational therapies. In addition, we briefly summarize developments in the area of microbial diagnostics and discuss interactions between the complex pulmonary microflora.

Eradication of Pseudomonas aeruginosa in an adult patient with cystic fibrosis

PURPOSE

The use of a continuous infusion of a β-lactam antibiotic in combination with high-dose, extended-interval amino-glycoside therapy for eradication of Pseudomonas aeruginosa in an adult patient with cystic fibrosis (CF) is reported.

SUMMARY

Testing of an expectorated sputum sample taken during routine evaluation of a 32-year-old woman with CF isolated P. aeruginosa; the patient's medical record indicated no prior episodes of P. aeruginosa colonization. In an initial attempt to eradicate the organism, the woman received outpatient therapy with oral ciprofloxacin twice daily combined with an aminoglycoside (tobramycin solution) by nebulization twice daily. After a culture four weeks later again isolated P. aeruginosa, the patient was hospitalized, and i.v. antimicrobial therapy was initiated. The inpatient treatment regimen consisted of continuous-infusion cefepime 6 g (100 mg/kg/24 hr) and i.v. tobramycin 700 mg (12 mg/kg/24 hr), with both drugs administered via a peripherally inserted central catheter, for two weeks. A bronchoalveolar lavage fluid culture performed two months after completion of the i.v. antimicrobial regimen, as well as several sputum cultures obtained during the subsequent three years, tested negative for P. aeruginosa.

CONCLUSION

The administration of continuous-infusion cefepime and high-dose, extended-interval tobramycin led to the successful eradication of P. aeruginosa in an adult patient with CF.