Optimizing ceftazidime pharmacodynamics in patients with acute exacerbation of severe chronic bronchitis

Benefits of prolonged infusion of beta-lactam antibiotics in patients with sepsis: personal perspectives

INTRODUCTION

In the current era of relatively scarce antibiotic production and significant levels of antimicrobial resistance, optimization of pharmacokinetics and pharmacodynamics of antibiotic therapy is mandatory. Prolonged infusion of beta-lactam antibiotics in comparison to the intermittent infusion has the theoretical advantage of better patient outcomes. Apparently, conflicting data in the literature possibly underestimate the benefits of prolonged infusion of antibiotic treatment.

AREAS COVERED

We provide our perspective on the subject based on our experience and by critically evaluating literature data.

EXPERT OPINION COMMENTARY

In our opinion, the available data are suggestive of the beneficial role of prolonged infusion of beta-lactams in regard to piperacillin/tazobactam and carbapenems after administering a loading dose. While more data from randomized controlled trials are necessary to solidify or negate the evident benefits of prolonged infusion of the aforementioned antibiotics, clinicians should strongly consider this mode of administration of relevant antibiotics, especially in patients with severe infections.

Continuous and Prolonged Intravenous β-Lactam Dosing: Implications for the Clinical Laboratory

Beta-lactam antibiotics serve as a cornerstone in the management of bacterial infections because of their wide spectrum of activity and low toxicity. Since resistance rates among bacteria are continuously on the rise and the pipeline for new antibiotics does not meet this trend, an optimization of current beta-lactam treatment is needed. This review provides an overview of optimization through use of prolonged- and continuous-infusion dosing strategies compared with more traditional intermittent infusions. Included is an overview of the scientific basis for using these nontraditional prolonged- and continuous-infusion-based regimens, with a focus on major areas in which the clinical laboratory can support the clinical use of these regimens.

Beta-Lactam Infusion in Severe Sepsis (BLISS): a prospective, two-centre, open-labelled randomised controlled trial of continuous versus intermittent beta-lactam infusion in critically ill patients with severe sepsis

PURPOSE

This study aims to determine if continuous infusion (CI) is associated with better clinical and pharmacokinetic/pharmacodynamic (PK/PD) outcomes compared to intermittent bolus (IB) dosing in critically ill patients with severe sepsis.

METHODS

This was a two-centre randomised controlled trial of CI versus IB dosing of beta-lactam antibiotics, which enrolled critically ill participants with severe sepsis who were not on renal replacement therapy (RRT). The primary outcome was clinical cure at 14 days after antibiotic cessation. Secondary outcomes were PK/PD target attainment, ICU-free days and ventilator-free days at day 28 post-randomisation, 14- and 30-day survival, and time to white cell count normalisation.

RESULTS

A total of 140 participants were enrolled with 70 participants each allocated to CI and IB dosing. CI participants had higher clinical cure rates (56 versus 34 %, p = 0.011) and higher median ventilator-free days (22 versus 14 days, p < 0.043) than IB participants. PK/PD target attainment rates were higher in the CI arm at 100 % fT >MIC than the IB arm on day 1 (97 versus 70 %, p < 0.001) and day 3 (97 versus 68 %, p < 0.001) post-randomisation. There was no difference in 14-day or 30-day survival between the treatment arms.

CONCLUSIONS

In critically ill patients with severe sepsis not receiving RRT, CI demonstrated higher clinical cure rates and had better PK/PD target attainment compared to IB dosing of beta-lactam antibiotics. Continuous beta-lactam infusion may be mostly advantageous for critically ill patients with high levels of illness severity and not receiving RRT. Malaysian National Medical Research Register ID: NMRR-12-1013-14017.

Prolonged infusion versus intermittent boluses of β-lactam antibiotics for treatment of acute infections: a meta-analysis

The clinical advantages of prolonged (extended/continuous) infusion remain controversial. Previous studies and reviews have failed to show consistent clinical benefits of extending the infusion time. This meta-analysis sought to determine whether prolonged β-lactam infusions were associated with a reduction in mortality and improvement in clinical success. A search of PubMed, EMBASE and The Cochrane Library for randomised controlled trials (RCTs) and observational studies comparing prolonged infusion with intermittent bolus administration of the same antibiotic in hospitalised adult patients was conducted. Primary outcomes evaluated were mortality and clinical success. A total of 29 studies with 2206 patients (18 RCTs and 11 observational studies) were included in the meta-analysis. Compared with intermittent boluses, use of prolonged infusion appeared to be associated with a significant reduction in mortality [pooled relative risk (RR) = 0.66, 95% confidence interval (CI) 0.53-0.83] and improvement in clinical success (RR = 1.12, 95% CI 1.03-1.21). Statistically significant benefit was supported by non-randomised studies (mortality, RR = 0.57, 95% CI 0.43-0.76; clinical success, RR = 1.34, 95% CI 1.02-1.76) but not by RCTs (mortality, RR = 0.83, 95% CI 0.57-1.21; clinical success, RR = 1.05, 95% CI 0.99-1.12). The positive results from observational studies, especially in the face of increasing antibiotic resistance, serve to justify the imperative need to conduct a large-scale, well-designed, multicentre RCT involving critically ill patients infected with high minimum inhibitory concentration pathogens to clearly substantiate this benefit.

Continuous versus intermittent infusions of antibiotics for the treatment of severe acute infections

BACKGROUND

Intravenous broad-spectrum antibiotics are indicated for the treatment of severe infections. However, the emergence of infections caused by multi-drug resistant organisms in conjunction with a lack of novel antibiotics has prompted the investigation of alternative dosing strategies to improve clinical efficacy and tolerability. To optimise pharmacokinetic and pharmacodynamic antibiotic parameters, continuous antibiotic infusions have been compared to traditional intermittent antibiotic infusions.

OBJECTIVES

To compare the clinical efficacy and safety of continuous intravenous administration of concentration-dependent and time-dependent antibiotics to traditional intermittent intravenous administration in adults with severe acute bacterial infections.

SEARCH METHODS

The following electronic databases were searched in September 2012: The Cochrane Injuries Group Specialised Register, Cochrane Central Register of Controlled Trials (The Cochrane Library), MEDLINE (OvidSP), EMBASE (OvidSP), CINAHL, ISI Web of Science: Science Citation Index Expanded (SCI-EXPANDED), ISI Web of Science: Conference Proceedings Citation Index-Science (CPCI-S). The reference lists of all relevant material, the Internet and the trials registry www.clinicaltrials.gov for completed and ongoing trials were also searched.

SELECTION CRITERIA

Randomized controlled trials in adults with a bacterial infection requiring intravenous antibiotic therapy comparing continuous versus intermittent infusions of antibiotics were included. Both time-dependent and concentration-dependent antibiotics were considered.

DATA COLLECTION AND ANALYSIS

Three independent authors performed data extraction for the included studies. All data was cross-checked and disagreements resolved by consensus. An intention to treat analysis was conducted using a random-effects model.

MAIN RESULTS

Twenty-nine studies met inclusion criteria with a combined total of over 1,600 patients. The majority of included studies were judged to be at unclear or high risk of bias with regard to randomisation sequence generation, allocation concealment, blinding, management of incomplete outcome data, selective outcome reporting, and other potential threats to validity. No studies were judged to be at low risk of bias for all methodological quality items assessed. There were no differences in all-cause mortality (n=1241, RR 0.89, 95% CI 0.67 - 1.20, p=0.45), infection recurrence (n=398, RR 1.22, 95% CI 0.35 - 4.19, p=0.76), clinical cure (n=975, RR 1.00, 95% CI 0.93 - 1.08, p=0.98), and superinfection post-therapy (n=813, RR 1.08, 95% CI 0.60 - 1.94, p=0.79). There were no differences in safety outcomes including adverse events (n=575, RR 1.02, 95% CI 0.94 - 1.12, p=0.63), serious adverse events (n=871, RR 1.36, 95% CI 0.80 - 2.30, p=0.26), and withdrawal due to adverse events (n=871, RR 2.03, 95% CI 0.52 - 7.95, p=0.31). A difference was observed in the subgroup analyses of clinical cure in septic versus non-septic patients, where intermittent antibiotic infusions were favoured for clinical cure in septic patients. However, this effect was not consistent between random-effects and fixed-effects analyses. No differences were found in sensitivity analyses conducted.

AUTHORS' CONCLUSIONS

There were no differences in mortality, infection recurrence, clinical cure, superinfection post-therapy, and safety outcomes when comparing continuous infusions of intravenous antibiotics to traditional intermittent infusions of antibiotics. However, the wide confidence intervals suggest that beneficial or harmful effects cannot be ruled out for all outcomes. Therefore, the current evidence is insufficient to recommend the widespread adoption of continuous infusion antibiotics in the place of intermittent infusions of antibiotics. Further large prospective randomised trials, with consistent and complete reporting of clinical outcome measures, conducted with concurrent pharmacokinetic and pharmacodynamic studies in special populations are required to determine whether adoption of continuous antibiotic infusions is warranted in specific circumstances.

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.

Clinical and microbiological efficacy of continuous versus intermittent application of meropenem in critically ill patients: a randomized open-label controlled trial

Introduction

Meropenem bactericidal activity depends on the time when the free drug concentrations remain above the minimum inhibitory concentration of pathogens. The goal of this study was to compare clinical and bacteriological efficacy of continuous meropenem infusion versus bolus administration in critically ill patients with severe infection, and to evaluate the safety of both dosing regimens.

Methods

Patients admitted to the interdisciplinary Intensive Care Unit (ICU) who suffered from severe infections and received meropenem were randomized either in the Infusion group (n = 120) or in the Bolus group (n = 120). Patients in the Infusion group received a loading dose of 2 g of meropenem followed by a continuous infusion of 4 g of meropenem over 24 hours. Patients in the Bolus group were given 2 g of meropenem over 30 minutes every 8 hours. Clinical and microbiological outcome, safety, meropenem-related length of ICU and hospital stay, meropenem-related length of mechanical ventilation, duration of meropenem treatment, total dose of meropenem, and ICU and in-hospital mortality were assessed.

Results

Clinical cure at the end of meropenem therapy was comparable between both groups (83.0% patients in the Infusion vs. 75.0% patients in the Bolus group; P = 0.180). Microbiological success rate was higher in the Infusion group as opposed to the Bolus group (90.6% vs. 78.4%; P = 0.020). Multivariate logistic regression identified continuous administration of meropenem as an independent predictor of microbiological success (OR = 2.977; 95% CI = 1.050 to 8.443; P = 0.040). Meropenem-related ICU stay was shorter in the Infusion group compared to the Bolus group (10 (7 to 14) days vs. 12 (7 to 19) days; P = 0.044) as well as shorter duration of meropenem therapy (7 (6 to 8) days vs. 8 (7 to 10) days; P = 0.035) and lower total dose of meropenem (24 (21 to 32) grams vs. 48 (42 to 60) grams; P < 0.0001). No severe adverse events related to meropenem administration in either group were observed.

Conclusions

Continuous infusion of meropenem is safe and, in comparison with higher intermittent dosage, provides equal clinical outcome, generates superior bacteriological efficacy and offers encouraging alternative of antimicrobial therapy in critically ill patients.

Does prolonged β-lactam infusions improve clinical outcomes compared to intermittent infusions? A meta-analysis and systematic review of randomized, controlled trials

Background

The emergence of multi-drug resistant Gram-negatives (MDRGNs) coupled with an alarming scarcity of new antibiotics has forced the optimization of the therapeutic potential of available antibiotics. To exploit the time above the minimum inhibitory concentration mechanism of β-lactams, prolonging their infusion may improve outcomes. The primary objective of this meta-analysis was to determine if prolonged β-lactam infusion resulted in decreased mortality and improved clinical cure compared to intermittent β-lactam infusion.

Methods

Relevant studies were identified from searches of MEDLINE, EMBASE, and CENTRAL. Heterogeneity was assessed qualitatively, in addition to I² and Chi-square statistics. Pooled relative risks (RR) and 95% confidence intervals (CI) were calculated using Mantel-Haenszel random-effects models.

Results

Fourteen randomized controlled trials (RCTs) were included. Prolonged infusion β-lactams were not associated with decreased mortality (n= 982; RR 0.92; 95% CI:0.61-1.37) or clinical cure (n = 1380; RR 1.00 95% CI:0.94-1.06) compared to intermittent infusions. Subgroup analysis for β-lactam subclasses and equivalent total daily β-lactam doses yielded similar results. Most studies had notable methodological flaws.

Conclusions

No clinical advantage was observed for prolonged infusion β-lactams. The limited number of studies with MDRGNs precluded evaluation of prolonged infusion of β-lactams for this subgroup. A large, multicenter RCT with critically ill patients infected with MDRGNs is needed.

Interspecies effects in a ceftazidime-treated mixed culture of Pseudomonas aeruginosa, Burkholderia cepacia and Staphylococcus aureus: analysis at the single-species level

OBJECTIVES

in vitro studies commonly use single bacterial isolates for testing antibiotic susceptibilities. However, interspecies effects that may arise when mixed infections are treated with antibiotics can obviously not be investigated by this approach. In the study presented here, the effect of ceftazidime against a model microbial community consisting of Pseudomonas aeruginosa, Burkholderia cepacia and Staphylococcus aureus was studied in order to reveal effects that only may appear in a ceftazidime-treated mixed culture.

METHODS

time-kill experiments were conducted with mixed and pure cultures in a defined medium containing 30 mg/L ceftazidime. Interspecies effects were revealed by comparing growth and kill dynamics from time-kill experiments with results from untreated mixed and pure cultures. For species-specific cell enumeration, a quantitative terminal restriction fragment length polymorphism was used. Ceftazidime was measured by HPLC.

RESULTS

P. aeruginosa showed only a lytic phase in the ceftazidime-treated mixed culture, but not in the untreated mixed culture nor in the ceftazidime-treated pure culture. On the other hand, S. aureus did not lyse in the ceftazidime-treated mixed culture, while it did in the untreated mixed culture.

CONCLUSIONS

this finding suggests that the efficacy of ceftazidime against P. aeruginosa was increased by an interspecies effect during co-cultivation with B. cepacia and S. aureus. The latter seemed to be negatively affected by interspecies effects in mixed culture without ceftazidime. The same effect was nullified when ceftazidime was applied to the mixed culture. Further studies are required to reveal the underlying mechanisms.

Prospective determination of serum ceftazidime concentrations in intensive care units

INTRODUCTION

The purpose of this study was to assess the value of a serum assay for ceftazidime (CAZ) in patients in the intensive care unit (ICU) of the Saint-Etienne University Teaching Hospital and in other ICUs in the region to optimize therapy.

MATERIAL AND METHODS

Between November 1, 2005, and February 29, 2008, for patients hospitalized in ICUs not on dialysis and undergoing continuous CAZ infusion, serum assay of the antibiotic was performed 36 to 48 hours after the start of treatment using a single serum sample. The target serum CAZ concentration was 40 +/- 10 mg/L with a concentration/minimum inhibitory concentration ratio of 5 or greater x minimum inhibitory concentration of CAZ when a strain was isolated.

RESULTS

Serum CAZ concentration was determined in 92 patients (28 females, 64 males) receiving CAZ by continuous infusion. The mean age was 66 years (range, 19-89 years) and the mean weight was 73 kg (range, 33-122 kg). The CAZ dose was between 1 g and 6 g/24 hours. The mean serum CAZ concentration was 46.9 mg/L (range, 7.4-162.3 mg/L). Serum CAZ concentrations were as follows: 30 to 50 mg/L in 35.9% of patients, less than 30 mg/L in 36.9%, and greater than 50 mg/L in 27.2%. Infection was documented in 51 patients, with 42 strains of Pseudomonas aeruginosa being detected. The serum concentration/minimum inhibitory concentration ratio was 5 or greater for 84.3%. Antibiotic dosage was adjusted based on the CAZ assay results.

CONCLUSION

Our study suggests that CAZ measurement is needed in ICUs to achieve adequate CAZ concentrations to avoid treatment toxicity and to achieve efficacy as rapidly as possible, particularly in strains having limited susceptibility to antibiotics.

Continuous vs. intermittent cefotaxime administration in patients with chronic obstructive pulmonary disease and respiratory tract infections: pharmacokinetics/pharmacodynamics, bacterial susceptibility and clinical efficacy

AIM

To compare the pharmacokinetics/pharmacodynamics, antibiotic resistance and clinical efficacy of continuous (CA) vs. intermittent administration (IA) of cefotaxime in patients with obstructive pulmonary disease and respiratory infections.

METHODS

A randomized controlled prospective nonblinded study was performed in 93 consecutive hospitalized patients requiring antibiotics for acute exacerbations of chronic obstructive pulmonary disease. Forty-seven patients received 2 g of cefotaxime intravenously over 24 h plus a loading dose of 1 g, and 46 patients were given the drug intermittently (1 g three times daily).

RESULTS

Similar pathogens were identified in both groups, being mostly Haemophilus influenzae (51%), Streptococcus pneumoniae (21%) and Moraxella catharralis (18%). Mean minimal inhibitory concentration (MIC) values were also similar before and after treatment in both groups. Clinical cure was achieved in 37/40 (93%) (CA) vs. 40/43 (93%) (IA) of patients (P = 0.93). In microbiologically evaluable patients, criteria such as 70% of treatment time with antibiotic concentrations > or = MIC (CA 100%vs. IA 60% of patients) and/or > or = 5 x MIC (CA 100%vs. IA 55% of patients) were significantly better following continuous administration (P < 0.01). Samples with suboptimal antibiotic concentrations were found in 0% of CA vs. 65% of IA patients (P < 0.01).

CONCLUSIONS

Although clinical cure rates were comparable, continuous cefotaxime administration led to significantly greater proportions of concentrations > MIC and > 5 x MIC compared with intermittent dosing. Continuous administration of cefotaxime at a lower dose [2 g (CA) vs. 3 g (CI)] is equally effective pharmacodynamically and microbiologically, may be more cost-effective and offers at least the same clinical efficacy. Based on these observations, we recommend continuous administration of cefotaxime as the preferred mode of administration.

Clinical efficacy of continuous infusion of piperacillin compared with intermittent dosing in septic critically ill patients

Since the bactericidal effects of beta-lactam antibiotics are time dependent, the optimum strategy for their administration could be continuous infusion. In this prospective, randomised controlled trial to evaluate the clinical efficacy of continuous infusion therapy, we evaluated the outcomes for 40 septic critically ill patients who received piperacillin either continuously (2 g intravenously (i.v.) over 0.5 h as a loading dose followed by 8 g i.v. daily over 24 h (n=20)) or as an intermittent infusion (3 g i.v. every 6h over 0.5 h (n=20)). Results from our study demonstrated that the clinical efficacy of piperacillin as a continuous infusion is superior to intermittent administration in critically ill patients. Change in APACHE II scores from baseline at the end of the second, third and fourth days, respectively, were 4.1, 5.1 and 5.2 for continuous infusion and 2.0, 2.6 and 2.8 for intermittent infusion (P< or =0.04). Considering minimum inhibitory concentrations (MICs) of 16 microg/mL and 32 microg/mL, the percentage of time for which piperacillin plasma concentrations were higher than the MIC (%T>MIC) was calculated for each patient in the two groups. For MICs of 16 microg/mL and 32 microg/mL, %T>MIC in the continuous infusion group was 100% and 65% of the dosing interval, respectively; in the intermittent infusion group, %T>MIC was only 62% and 39% of the dosing interval. There was a significant relationship between clinical results and laboratory data. It was shown that the superiority of the clinical efficacy of continuous infusion could be related to piperacillin pharmacodynamics. Continuous infusion significantly reduced the severity of illness as demonstrated by APACHE II scores during therapy.