[Comparison of 2 administration protocols (continuous or discontinuous) of a time-dependent antibiotic, Tazocin]

Infective endocarditis caused by Enterococcus faecalis treated with continuous infusion of ampicillin without adjunctive aminoglycosides

Aminoglycosides are useful antimicrobial agents for treating infective endocarditis; however, they occasionally cause troublesome side effects, such as nephrotoxicity and ototoxicity. We herein report a case of infective endocarditis caused by Enterococcus faecalis that was treated successfully with continuous infusion of ampicillin without adjunctive aminoglycosides. The serum ampicillin concentrations were higher than the minimal inhibitory concentration for the target strain. Although the use of ampicillin monotherapy is currently avoided because double β-lactam therapy is reportedly more effective, continuous penicillin administration remains an effective therapeutic choice for treating infective endocarditis.

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 of antibiotics in the critically ill: The new holy grail for beta-lactams and vancomycin?

The alarming global rise of antimicrobial resistance combined with the lack of new antimicrobial agents has led to a renewed interest in optimization of our current antibiotics. Continuous infusion (CI) of time-dependent antibiotics has certain theoretical advantages toward efficacy based on pharmacokinetic/pharmacodynamic principles. We reviewed the available clinical studies concerning continuous infusion of beta-lactam antibiotics and vancomycin in critically ill patients. We conclude that CI of beta-lactam antibiotics is not necessarily more advantageous for all patients. Continuous infusion is only likely to have clinical benefits in subpopulations of patients where intermittent infusion is unable to achieve an adequate time above the minimal inhibitory concentration (T > MIC). For example, in patients with infections caused by organisms with elevated MICs, patients with altered pharmacokinetics (such as the critically ill) and possibly also immunocompromised patients. For vancomycin CI can be chosen, not always for better clinical efficacy, but because it is practical, cheaper, associated with less AUC_24h (area under the curve >24 h)-variability, and easier to monitor.

Continuous versus intermittent administration of piperacillin-tazobactam in intensive care unit patients with ventilator-associated pneumonia

BACKGROUND AND AIMS

Ventilator-associated pneumonia (VAP) is one of the most common Intensive Care Unit (ICU)-acquired infection. The aim of this study was to compare the clinical outcome of continuous and intermittent administration of piperacillin-tazobactam by serial measurements of the Clinical Pulmonary Infection Score (CPIS).

SUBJECTS AND METHODS

Groups were designed as parallel and the study was designed as quasi-experimental and conducted at a semi-closed ICU between September 2008 and May 2010. Patients received 3.375 g (piperacillin 3 g/tazobactam 0.375 g) either through intermittent infusion every 6 h for 30 min [Intermittent Infusion (II) group; n = 30] or through continuous infusion every 8 h for 4 h [Continuous Infusion (CI) group; n = 31]. CPIS was used to assess the clinical diagnosis and outcome of VAP patients.

RESULTS

Sex, age, Acute Physiology and Chronic Health Evaluation II II score on ICU admission, diagnosis and underlying disease of VAP patients were not significantly different in the CI (n = 31) and II (n = 30) groups. Duration of mechanical ventilation, length of stay, total number of antibiotics used per patient and duration of piperacillin/tazobactam treatment were similar in both groups. Mortality rates of VAP patients were similar between both groups during hospitalization.

CONCLUSION

There was no significant difference in clinical outcomes of patients receiving piperacillin-tazobactam via CI or II when measured by serial CPIS score.

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.

[Monitoring of antibiotic treatment of patient with a severe bacterial infection]

OBJECTIVES

To provide a summary of useful up-to-date knowledge regarding experimental and clinical bacteriology, pharmacokinetics and pharmacodynamics in order to optimise efficacy of antibiotic treatment of hospital patients with serious bacterial infections.

DATA SOURCES

Record of references from national and international journals in Medline.

STUDY SELECTION

Extraction of the most relevant theoretical and practical data from studies published over the last 5 years.

DATA SYNTHESIS

Changes in resistance to antibiotics, as well as the limited number of new antibacterial drugs available and the cost of therapeutic failure all militate in favour of a more elaborate approach to therapeutic strategies involving antibiotics, particularly regarding hospitalised patients. The efficacy of antibiotic therapy can be optimised through the utilization of bacteriological, pharmacokinetic and pharmacodynamic data, thereby increasing the likelihood of a successful outcome. While the antibiogram constitutes the fundamental analytical tool for evaluating the activity of antibiotics, the minimum inhibitory concentration (MIC) is of value in selecting appropriate drugs and dosages, particularly for bacterial strains having lower susceptibility. Screening for genes of resistance to antibiotics provides more accurate analysis of bacterial resistance. In recent years, the efficacy of antibiotics has been improved through the use of a number of pharmacodynamic parameters: inhibitory quotient (IQ), area under the serum concentration-time curve to MIC ratio (AUC/MIC) and the time the serum concentration is greater than the MIC (T > MIC). In standard practice, data readily available to the clinician comprise the MIC and serum antibiotic concentrations. There is some discussion concerning optimisation of antibiotic efficacy through the use of these parameters.

CONCLUSION

Close collaboration between clinicians and microbiologists results in improved quality of antibiotic therapy and better management of antibiotics.