A randomized trial of 7-day doripenem versus 10-day imipenem-cilastatin for ventilator-associated pneumonia

Characteristics of an ideal nebulized antibiotic for the treatment of pneumonia in the intubated patient

Gram-negative pneumonia in patients who are intubated and mechanically ventilated is associated with increased morbidity and mortality as well as higher healthcare costs compared with those who do not have the disease. Intravenous antibiotics are currently the standard of care for pneumonia; however, increasing rates of multidrug resistance and limited penetration of some classes of antimicrobials into the lungs reduce the effectiveness of this treatment option, and current clinical cure rates are variable, while recurrence rates remain high. Inhaled antibiotics may have the potential to improve outcomes in this patient population, but their use is currently restricted by a lack of specifically formulated solutions for inhalation and a limited number of devices designed for the nebulization of antibiotics. In this article, we review the challenges clinicians face in the treatment of pneumonia and discuss the characteristics that would constitute an ideal inhaled drug/device combination. We also review inhaled antibiotic options currently in development for the treatment of pneumonia in patients who are intubated and mechanically ventilated.

Treatment of Gram-negative pneumonia in the critical care setting: is the beta-lactam antibiotic backbone broken beyond repair?

Beta-lactam antibiotics form the backbone of treatment for Gram-negative pneumonia in mechanically ventilated patients in the intensive care unit. However, this beta-lactam antibiotic backbone is increasingly under pressure from emerging resistance across all geographical regions, and health-care professionals in many countries are rapidly running out of effective treatment options. Even in regions that currently have only low levels of resistance, the effects of globalization are likely to increase local pressures on the beta-lactam antibiotic backbone in the near future. Therefore, clinicians are increasingly faced with a difficult balancing act: the need to prescribe adequate and appropriate antibiotic therapy while reducing the emergence of resistance and the overuse of antibiotics. In this review, we explore the burden of Gram-negative pneumonia in the critical care setting and the pressure that antibiotic resistance places on current empiric therapy regimens (and the beta-lactam antibiotic backbone) in this patient population. New treatment approaches, such as systemic and inhaled antibiotic alternatives, are on the horizon and are likely to help tackle the rising levels of beta-lactam antibiotic resistance. In the meantime, it is imperative that the beta-lactam antibiotic backbone of currently available antibiotics be supported through stringent antibiotic stewardship programs.

Population Pharmacokinetics of Doripenem in Critically Ill Patients with Sepsis in a Malaysian Intensive Care Unit

Doripenem has been recently introduced in Malaysia and is used for severe infections in the intensive care unit. However, limited data currently exist to guide optimal dosing in this scenario. We aimed to describe the population pharmacokinetics of doripenem in Malaysian critically ill patients with sepsis and use Monte Carlo dosing simulations to develop clinically relevant dosing guidelines for these patients. In this pharmacokinetic study, 12 critically ill adult patients with sepsis receiving 500 mg of doripenem every 8 h as a 1-hour infusion were enrolled. Serial blood samples were collected on 2 different days, and population pharmacokinetic analysis was performed using a nonlinear mixed-effects modeling approach. A two-compartment linear model with between-subject and between-occasion variability on clearance was adequate in describing the data. The typical volume of distribution and clearance of doripenem in this cohort were 0.47 liters/kg and 0.14 liters/kg/h, respectively. Doripenem clearance was significantly influenced by patients' creatinine clearance (CL(CR)), such that a 30-ml/min increase in the estimated CL(CR) would increase doripenem CL by 52%. Monte Carlo dosing simulations suggested that, for pathogens with a MIC of 8 mg/liter, a dose of 1,000 mg every 8 h as a 4-h infusion is optimal for patients with a CL(CR) of 30 to 100 ml/min, while a dose of 2,000 mg every 8 h as a 4-h infusion is best for patients manifesting a CL(CR) of >100 ml/min. Findings from this study suggest that, for doripenem usage in Malaysian critically ill patients, an alternative dosing approach may be meritorious, particularly when multidrug resistance pathogens are involved.

Pneumonia Pathogen Characterization Is an Independent Determinant of Hospital Readmission

BACKGROUND

Hospital readmissions for pneumonia occur often and are difficult to predict. For fiscal year 2013, the Centers for Medicare & Medicaid Services readmission penalties have been applied to acute myocardial infarction, heart failure, and pneumonia. However, the overall impact of pneumonia pathogen characterization on hospital readmission is undefined.

METHODS

This was a retrospective 6-year cohort study (August 2007 to September 2013).

RESULTS

We evaluated 9,624 patients with a discharge diagnosis of pneumonia. Among these patients, 4,432 (46.1%) were classified as having culture-negative pneumonia, 1,940 (20.2%) as having pneumonia caused by antibiotic-susceptible bacteria, 2,991 (31.1%) as having pneumonia caused by potentially antibiotic-resistant bacteria, and 261 (2.7%) as having viral pneumonia. The 90-day hospital readmission rate for survivors (n = 7,637, 79.4%) was greatest for patients with pneumonia attributed to potentially antibiotic-resistant bacteria (11.4%) followed by viral pneumonia (8.3%), pneumonia attributed to antibiotic-susceptible bacteria (6.6%), and culture-negative pneumonia (5.8%) (P < .001). Multiple logistic regression analysis identified pneumonia attributed to potentially antibiotic-resistant bacteria to be independently associated with 90-day readmission (OR, 1.75; 95% CI, 1.56-1.97; P < .001). Other independent predictors of 90-day readmission were Charlson comorbidity score > 4, cirrhosis, and chronic kidney disease. Culture-negative pneumonia was independently associated with lower risk for 90-day readmission.

CONCLUSIONS

Readmission after hospitalization for pneumonia is relatively common and is related to pneumonia pathogen characterization. Pneumonia attributed to potentially antibiotic-resistant bacteria is associated with an increased risk for 90-day readmission, whereas culture-negative pneumonia is associated with lower risk for 90-day readmission.

Short-course versus prolonged-course antibiotic therapy for hospital-acquired pneumonia in critically ill adults

BACKGROUND

Pneumonia is the most common hospital-acquired infection affecting patients in the intensive care unit (ICU). However, current national guidelines for the treatment of hospital-acquired pneumonia (HAP) are several years old and the diagnosis of pneumonia in mechanically ventilated patients (VAP) has been subject to considerable recent attention. The optimal duration of antibiotic therapy for HAP in the critically ill is uncertain.

OBJECTIVES

To assess the effectiveness of short versus prolonged-course antibiotics for HAP in critically ill adults, including patients with VAP.

SEARCH METHODS

We searched CENTRAL (2015, Issue 5), MEDLINE (1946 to June 2015), MEDLINE in-process and other non-indexed citations (5 June 2015), EMBASE (2010 to June 2015), LILACS (1982 to June 2015) and Web of Science (1955 to June 2015).

SELECTION CRITERIA

We considered all randomised controlled trials (RCTs) comparing a fixed 'short' duration of antibiotic therapy with a 'prolonged' course for HAP (including patients with VAP) in critically ill adults.

DATA COLLECTION AND ANALYSIS

Two review authors conducted data extraction and assessment of risk of bias. We contacted trial authors for additional information.

MAIN RESULTS

We identified six relevant studies involving 1088 participants. This included two new studies published after the date of our previous review (2011). There was substantial variation in participants, in the diagnostic criteria used to define an episode of pneumonia, in the interventions and in the reported outcomes. We found no evidence relating to patients with a high probability of HAP who were not mechanically ventilated. For patients with VAP, overall a short seven- or eight-day course of antibiotics compared with a prolonged 10- to 15-day course increased 28-day antibiotic-free days (two studies; N = 431; mean difference (MD) 4.02 days; 95% confidence interval (CI) 2.26 to 5.78) and reduced recurrence of VAP due to multi-resistant organisms (one study; N = 110; odds ratio (OR) 0.44; 95% CI 0.21 to 0.95), without adversely affecting mortality and other recurrence outcomes. However, for cases of VAP specifically due to non-fermenting Gram-negative bacilli (NF-GNB), recurrence was greater after short-course therapy (two studies, N = 176; OR 2.18; 95% CI 1.14 to 4.16), though mortality outcomes were not significantly different. One study found that a three-day course of antibiotic therapy for patients with suspected HAP but a low Clinical Pulmonary Infection Score (CPIS) was associated with a significantly lower risk of superinfection or emergence of antimicrobial resistance, compared with standard (prolonged) course therapy.

AUTHORS' CONCLUSIONS

On the basis of a small number of studies and appreciating the lack of uniform definition of pneumonia, we conclude that for patients with VAP not due to NF-GNB a short, fixed course (seven or eight days) of antibiotic therapy appears not to increase the risk of adverse clinical outcomes, and may reduce the emergence of resistant organisms, compared with a prolonged course (10 to 15 days). However, for patients with VAP due to NF-GNB, there appears to be a higher risk of recurrence following short-course therapy. These findings do not differ from those of our previous review and are broadly consistent with current guidelines. There are few data from RCTs comparing durations of therapy in non-ventilated patients with HAP, but on the basis of a single study, short-course (three-day) therapy for HAP appears not to be associated with worse clinical outcome, and may reduce the risk of subsequent infection or the emergence of resistant organisms when there is low probability of pneumonia according to the CPIS.

Pseudomonas aeruginosa nosocomial pneumonia: impact of pneumonia classification

OBJECTIVE

To describe and compare the mortality associated with nosocomial pneumonia due to Pseudomonas aeruginosa (Pa-NP) according to pneumonia classification (community-onset pneumonia [COP], hospital-acquired pneumonia [(HAP], and ventilator-associated pneumonia [VAP]).

DESIGN

We conducted a retrospective cohort study of adults with Pa-NP. We compared mortality for Pa-NP among patients with COP, HAP, and VAP and used logistic regression to identify risk factors for hospital mortality and inappropriate initial antibiotic therapy (IIAT).

SETTING

Twelve acute care hospitals in 5 countries (United States, 3; France, 2; Germany, 2; Italy, 2; and Spain, 3).

PATIENTS/PARTICIPANTS

A total of 742 patients with Pa-NP.

RESULTS

Hospital mortality was greater for those with VAP (41.9%) and HAP (40.1%) compared with COP (24.5%) (P<.001). In multivariate analyses, independent predictors of hospital mortality differed by pneumonia classification (COP: need for mechanical ventilation and intensive care; HAP: multidrug-resistant isolate; VAP: IIAT, increasing age, increasing Charlson comorbidity score, bacteremia, and use of vasopressors). Presence of multidrug resistance was identified as an independent predictor of IIAT for patients with COP and HAP, whereas recent antibiotic administration was protective in patients with VAP.

CONCLUSIONS

Among patients with Pa-NP, pneumonia classification identified patients with different risks for hospital mortality. Specific risk factors for hospital mortality also differed by pneumonia classification and multidrug resistance appeared to be an important risk factor for IIAT. These findings suggest that pneumonia classification for P. aeruginosa identifies patients with different mortality risks and specific risk factors for outcome and IIAT.

Ventilator associated pneumonia in the ICU: where has it gone?

PURPOSE OF REVIEW

To highlight the clinical importance of ventilator-associated pneumonia (VAP) in an era of escalating antimicrobial resistance.

RECENT FINDINGS

VAP continues to be an important infection in the critically ill. The development of rapid microbiologic diagnostics and new antimicrobial agents offer opportunities for improved treatment strategies for VAP balancing the need to treat effectively in a timely manner and antimicrobial stewardship. Additionally, the new surveillance definitions for assessing the quality of care in critically ill patients (ventilator-associated events, ventilator-associated conditions, and infection-related ventilator-associated conditions) do not appear to be adequate surrogates for the identification of VAP.

SUMMARY

Clinicians caring for critically ill patients should be aware of the importance of correctly treating VAP. As new diagnostic technologies and antimicrobials become available for VAP, their incorporation into routine patient management should occur in a way that optimizes patient outcomes wherein minimizing further emergence of antimicrobial resistance.

Ventilator-Associated Pneumonia (VAP) with Multidrug-Resistant (MDR) Pathogens: Optimal Treatment?

Ventilator-associated pneumonia (VAP) due to multidrug-resistant bacteria (MDR) is an emerging problem worldwide. Both gram-negative and gram-positive microorganisms are associated with VAP. We first describe the magnitude of the problem of MDR VAP followed by its clinical impact on survival outcomes, with the primary aim to review the optimal antibiotic choices to treat patients with MDR VAP. We discuss the challenges of intravenous and inhaled antibiotic treatments, as well as of monotherapy and combination antimicrobial therapies.

Strategies to reduce curative antibiotic therapy in intensive care units (adult and paediatric)

Emerging resistance to antibiotics shows no signs of decline. At the same time, few new antibacterials are being discovered. There is a worldwide recognition regarding the danger of this situation. The urgency of the situation and the conviction that practices should change led the Société de Réanimation de Langue Française (SRLF) and the Société Française d'Anesthésie et de Réanimation (SFAR) to set up a panel of experts from various disciplines. These experts met for the first time at the end of 2012 and have since met regularly to issue the following 67 recommendations, according to the rigorous GRADE methodology. Five fields were explored: i) the link between the resistance of bacteria and the use of antibiotics in intensive care; ii) which microbiological data and how to use them to reduce antibiotic consumption; iii) how should antibiotic therapy be chosen to limit consumption of antibiotics; iv) how can antibiotic administration be optimized; v) review and duration of antibiotic treatments. In each institution, the appropriation of these recommendations should arouse multidisciplinary discussions resulting in better knowledge of local epidemiology, rate of antibiotic use, and finally protocols for improving the stewardship of antibiotics. These efforts should contribute to limit the emergence of resistant bacteria.

Clinical evaluation of the need for carbapenems to treat community-acquired and healthcare-associated pneumonia

Carbapenems have an overall broad antibacterial spectrum and should be protected against from the acquisition of drug resistance. The clinical advantages of carbapenem in cases of pneumonia have not been certified and the need for antipseudomonal antimicrobial agents to treat healthcare-associated pneumonia (HCAP) remains controversial. We introduced an antimicrobial stewardship program for carbapenem and tazobactam/piperacillin use and investigated the effects of this program on the clinical outcomes of 591 pneumonia cases that did not require intensive care unit management, mechanical ventilation or treatment with vasopressor agents [221 patients with community-acquired pneumonia (CAP) and 370 patients with HCAP]. Compared with the pre-intervention period, age, comorbidities and the severity and etiology of pneumonia did not differ during the intervention period. Carbapenems were rarely used during the intervention period in cases of pneumonia (CAP: 12% vs. 1%, HCAP: 13% vs. 1%), while antipseudomonal beta-lactam use was reduced from 33% to 8% among cases with HCAP. This reduction in the rate of carbapenem administration did not have an impact on the prognosis in the cases of CAP, and the in-hospital mortality was lower among the patients with HCAP during the intervention period (15% vs. 5%, p = 0.013). The causes of death in the cases of HCAP were not directly related to pneumonia during the intervention period. The current study shows that carbapenem use can be avoided in cases of CAP or HCAP that are not in a critical condition. The frequent use of antipseudomonal beta-lactams does not improve the clinical outcomes of HCAP.

An international multicenter retrospective study of Pseudomonas aeruginosa nosocomial pneumonia: impact of multidrug resistance

INTRODUCTION

Pseudomonas aeruginosa nosocomial pneumonia (Pa-NP) is associated with considerable morbidity, prolonged hospitalization, increased costs, and mortality.

METHODS

We conducted a retrospective cohort study of adult patients with Pa-NP to determine 1) risk factors for multidrug-resistant (MDR) strains and 2) whether MDR increases the risk for hospital death. Twelve hospitals in 5 countries (United States, n = 3; France, n = 2; Germany, n = 2; Italy, n = 2; and Spain, n = 3) participated. We compared characteristics of patients who had MDR strains to those who did not and derived regression models to identify predictors of MDR and hospital mortality.

RESULTS

Of 740 patients with Pa-NP, 226 patients (30.5%) were infected with MDR strains. In multivariable analyses, independent predictors of multidrug-resistance included decreasing age (adjusted odds ratio [AOR] 0.91, 95% confidence interval [CI] 0.96-0.98), diabetes mellitus (AOR 1.90, 95% CI 1.21-3.00) and ICU admission (AOR 1.73, 95% CI 1.06-2.81). Multidrug-resistance, heart failure, increasing age, mechanical ventilation, and bacteremia were independently associated with in-hospital mortality in the Cox Proportional Hazards Model analysis.

CONCLUSIONS

Among patients with Pa-NP the presence of infection with a MDR strain is associated with increased in-hospital mortality. Identification of patients at risk of MDR Pa-NP could facilitate appropriate empiric antibiotic decisions that in turn could lead to improved hospital survival.

Participation of elderly adults in randomized controlled trials addressing antibiotic treatment of pneumonia

OBJECTIVES

To examine how relevant current evidence on antibiotic treatment of pneumonia is for elderly adults.

DESIGN

Systematic review.

SETTING

Randomized controlled trials (RCTs; N = 43) comparing different antibiotics and prospective observational studies (N = 182) published since 2005.

PARTICIPANTS

Adults with community-acquired (CAP), healthcare-associated (HCAP), hospital-acquired (HAP), or ventilator-associated (VAP) pneumonia.

MEASUREMENTS

Exclusion criteria that could preferentially limit participation of elderly adults were examined, subgroup or other adjusted analyses were searched for according to age, and treatment effects in participants younger than 65 in RCTs were compared with those in participants aged 65 and older. Mean participant ages in RCTs and observational studies were compared. Risk ratios (RRs) with 95% confidence intervals (CIs) for differences between older and younger adults were pooled using a fixed effect metaanalysis.

RESULTS

No RCT reported exclusion based on an upper age limit; 100% of community CAP trials, 90% of hospitalized CAP trials, and 76% of HAP and VAP trials excluded individuals based on comorbidities. None of the RCTs reported a subgroup analysis for mortality according to age. The RR for the pooled difference in treatment failure rates between participants younger than 65 and those aged 65 and older was 1.25 (95% CI = 0.94-1.65, 12 RCTs) and between participants younger than 75 and aged 75 and older was 1.43 (95% CI = 0.98-2.09, 7 RCTs). RCT participants were significantly younger (54.0 ± 9.6) than those in observational studies of CAP (66.2 ± 8.1, P < .001). Age differences were not significant for HCAP, HAP, and VAP.

CONCLUSION

Elderly adults are often excluded from RCTs of bacterial pneumonia. No data were found on the comparative efficacy of antibiotic treatment in elderly adults and the general population.

A meta-analysis of efficacy and safety of doripenem for treating bacterial infections

Objective

Methods

Results

Conclusion

Ventilator-associated pneumonia: present understanding and ongoing debates

INTRODUCTION

Ventilator-associated pneumonia (VAP) is a common cause of nosocomial infection, and is related to significant utilization of health-care resources. In the past decade, new data have emerged about VAP epidemiology, diagnosis, treatment and prevention.

RESULTS

Classifying VAP strictly based on time since hospitalization (early- and late-onset VAP) can potentially result in undertreatment of drug-resistant organisms in ICUs with a high rate of drug resistance, and overtreatment for patients not infected with resistant pathogens. A combined strategy incorporating diagnostic scoring systems, such as the Clinical Pulmonary Infection Score (CPIS), and either a quantitative or qualitative microbiological specimen, plus serial measurement of biomarkers, leads to responsible antimicrobial stewardship. The newly proposed ventilator-associated events (VAE) surveillance definition, endorsed by the Centers for Disease Control and Prevention, has low sensitivity and specificity for diagnosing VAP and the ability to prevent VAE is uncertain, making it a questionable surrogate for the quality of ICU care. The use of adjunctive aerosolized antibiotic treatment can provide high pulmonary concentrations of the drug and may facilitate shorter durations of therapy for multi-drug-resistant pathogens. A group of preventive strategies grouped as a 'ventilator bundle' can decrease VAP rates, but not to zero, and several recent studies show that there are potential barriers to implementation of these prevention strategies.

CONCLUSION

The morbidity and mortality related to VAP remain high and, in the absence of a gold standard test for diagnosis, suspected VAP patients should be started on antibiotics based on recommendations per the 2005 ATS guidelines and knowledge of local antibiotic susceptibility patterns. Using a combination of clinical severity scores, biomarkers, and cultures might help with reducing the duration of therapy and achieving antibiotic de-escalation.

Treatment of bloodstream infections in ICUs

Bloodstream infections (BSIs) are frequent in ICU and is a prognostic factor of severe sepsis. Community acquired BSIs usually due to susceptible bacteria should be clearly differentiated from healthcare associated BSIs frequently due to resistant hospital strains. Early adequate treatment is key and should use guidelines and direct examination of samples performed from the infectious source. Previous antibiotic therapy knowledge, history of multi-drug resistant organism (MDRO) carriage are other major determinants of first choice antimicrobials in heathcare-associated and nosocomial BSIs. Initial antimicrobial dose should be adapted to pharmacokinetic knowledge. In general, a high dose is recommended at the beginning of treatment.

If MDRO is suspected combination antibiotic therapy is mandatory because it increase the spectrum of treatment. Most of time, combination should be pursued no more than 2 to 5 days.

Given the negative impact of useless antimicrobials, maximal effort should be done to decrease the antibiotic selection pressure. De-escalation from a broad spectrum to a narrow spectrum antimicrobial decreases the antibiotic selection pressure without negative impact on mortality. Duration of therapy should be shortened as often as possible especially when organism is susceptible, when the infection source has been totally controlled.

How to treat VAP due to MDR pathogens in ICU patients

Background

The increasing occurrence of multidrug resistant (MDR) bacteria arises at a time when there is a lack of antibiotics active against these pathogens and few new antimicrobials are in the pipelines of the pharmaceutical industry. Treatment of ventilator-associated pneumonia (VAP) caused especially by MDR Gram-negative bacilli (GNB) represents a real challenge due to the dearth of treatment options.

Methods

We searched the medical literature relevant about management of ventilator-associated pneumonia caused by multi-drug resistant pathogens including GNB and methicillin-resistant S. aureus.

Results

Empirical therapy should be prescribed based on the local pattern of susceptibilities. Colistin and tigecycline are in many cases the unique options for the treatment of many episodes of VAP caused by MDR-GNB. Tigecyline (not licensed for treatment of pneumonia) should be used with an initial bolus of 200 mg followed by 100 mg every 12 h. The need for a loading dose and the administration of high doses of colistin (9 million IU/day in two or three doses) is currently accepted. Vancomycin has been considered the treatment of choice for pneumonia due to MRSA although linezolid may provide higher rate of clinical cure for MRSA VAP with a good safety profile. The initial antibiotic treatment must be reassessed and simplify in accordance of culture results.

Conclusions

Empirical treatment of VAP due to MDR pathogens should be based on knowledge of local ecology. A strategy combining early high doses of effective agents with subsequent simplification in the light of microbiologic information is recommended.

The doripenem serum concentrations in intensive care patients suffering from acute kidney injury, sepsis, and multi organ dysfunction syndrome undergoing continuous renal replacement therapy slow low-efficiency dialysis

Doripenem is a novel wide-spectrum antibiotic, and a derivate of carbapenems. It is an ideal antibiotic for treatment of serious nosocomial infections and severe sepsis for its exceptionally high efficiency and broad antibacterial spectrum of action. Doripenem is eliminated mainly by the kidneys. In cases of acute kidney injury, dosing of doripenem depends on creatinine clearance and requires adjustments. Doripenem is eliminated during hemodialysis because its molecular weight is 300–400 Da. The aim of this study was to establish the impact of continuous renal replacement therapy (CRRT) slow low-efficiency dialysis (SLED) on doripenem serum concentrations in a population of intensive-therapy patients with life-threatening infections and severe sepsis. Ten patients were enrolled in this observational study. Twelve blood samples were collected during the first administration of doripenem in a 1-hour continuous infusion while CRRT SLED was provided. Fluid chromatography was used for measurement of the concentration of doripenem in serum. In all collected samples, concentration of doripenem was above the minimum inhibition concentration of this antibiotic. Based on these results, we can draw the conclusion that doripenem concentration is above the minimum inhibition concentration throughout all of CRRT. The dosing pattern proposed by the manufacturer can be used in patients receiving CRRT SLED without necessary modifications.

Antibiotic stewardship in the intensive care unit

The rapid emergence and dissemination of antimicrobial-resistant microorganisms in ICUs worldwide constitute a problem of crisis dimensions. The root causes of this problem are multifactorial, but the core issues are clear. The emergence of antibiotic resistance is highly correlated with selective pressure resulting from inappropriate use of these drugs. Appropriate antibiotic stewardship in ICUs includes not only rapid identification and optimal treatment of bacterial infections in these critically ill patients, based on pharmacokinetic-pharmacodynamic characteristics, but also improving our ability to avoid administering unnecessary broad-spectrum antibiotics, shortening the duration of their administration, and reducing the numbers of patients receiving undue antibiotic therapy. Either we will be able to implement such a policy or we and our patients will face an uncontrollable surge of very difficult-to-treat pathogens.

High dose of tigecycline for extremely resistant Gram-negative pneumonia: yes, we can

Few antimicrobials are currently active to treat infections caused by extremely resistant Gram-negative bacilli (ERGNB), which represent a serious global public health concern. Tigecycline, which covers the majority of these ERGNB (with the exception of Pseudomonas aeruginosa), is not currently approved for hospital-acquired pneumonia, and several meta-analyses have suggested an increased risk of death in patients receiving this antibiotic. Other studies suggest that the use of high-dose tigecycline may represent an alternative in daily practice. De Pascale and colleagues report that the clinical cure rate in patients with ventilator-associated pneumonia is significantly higher with a high dose of tigecycline than with the conventional dose, although mortality was unaffected. This high dose is safe; no patients required discontinuation or dose reduction.

Significant publications on infectious diseases pharmacotherapy in 2012

PURPOSE

The most important articles pertaining to infectious diseases (ID) pharmacotherapy published in 2012, as nominated and ranked by panels of pharmacists and physicians with ID expertise, are summarized.

SUMMARY

Members of the Houston Infectious Diseases Network were asked to nominate articles on ID research published in prominent peer-reviewed journals during the period January 1-December 31, 2012, with a major impact in the field of ID pharmacotherapy. A list of 42 nominated articles on general ID-related topics and 8 articles pertaining to human immunodeficiency virus (HIV) infection or acquired immunodeficiency syndrome (AIDS) was compiled. In a survey conducted in January 2013, members of the Society of Infectious Diseases Pharmacists (SIDP) were asked to select from the list 10 general ID articles and 1 HIV/AIDS-related article that they considered to be the most important. Of the 180 SIDP members surveyed, 100 (55%) and 44 (24%) participated in ranking the general ID and HIV/AIDS-related articles, respectively. Summaries of the highest-ranked articles in both categories are presented here.

CONCLUSION

With the volume of published ID-related research growing each year, both ID specialists and nonspecialists are challenged to stay current with the literature. Key ID-related publications in 2012 included updated recommendations on management of diabetic foot infections, articles on promising approaches to prevention and early treatment of HIV disease, and reports on developments in research on pharmacotherapies for methicillin-resistant Staphylococcus aureus bacteremia and Klebsiella pneumoniae infections.

Doripenem population pharmacokinetics and dosing requirements for critically ill patients receiving continuous venovenous haemodiafiltration

OBJECTIVES

Doripenem is a newer carbapenem with little data available to guide effective dosing during renal replacement therapy in critically ill patients. The objective of this study was to determine the population pharmacokinetics of doripenem in critically ill patients undergoing continuous venovenous haemodiafiltration (CVVHDF) for acute kidney injury (AKI).

METHODS

This was an observational pharmacokinetic study in 12 infected critically ill adult patients with AKI undergoing CVVHDF and receiving 500 mg of doripenem intravenously every 8 h as a 60 min infusion. Serial blood samples were taken on 2 days of treatment and used for population pharmacokinetic analysis with S-ADAPT.

RESULTS

The median (IQR) age was 62 (53-71) years, the median (IQR) weight was 77 (67-96) kg and the median (IQR) APACHE II score was 29 (19-32). The median blood, dialysate and replacement fluid rates were 200, 1000 and 1000 mL/h, respectively. A two-compartment linear model with doripenem clearance described by CVVHDF, renal or non-renal mechanisms was most appropriate. The mean value for total doripenem clearance was 4.46 L/h and volume of distribution was 38.0 L. Doripenem clearance by CVVHDF was significantly correlated with the replacement fluid flow rate and accounted for ∼30%-37% of total clearance. A dose of 500 mg intravenously every 8 h achieved favourable pharmacokinetic/pharmacodynamics for all patients up to an MIC of 4 mg/L.

CONCLUSIONS

This is the first paper describing the pharmacokinetics/pharmacodynamics of doripenem in critically ill patients with AKI receiving CVVHDF. A dose of 500 mg intravenously every 8 h was appropriate for our CVVHDF settings for infections caused by susceptible bacteria.

The risk of seizures among the carbapenems: a meta-analysis

OBJECTIVES

A consensus exists among clinicians that imipenem/cilastatin is the most epileptogenic carbapenem, despite inconsistencies in the literature.

METHODS

We conducted a meta-analysis of all randomized controlled trials comparing carbapenems with each other or with non-carbapenem antibiotics to assess the risk of seizures for imipenem, meropenem, ertapenem and doripenem.

RESULTS

In the risk difference (RD) analysis, there were increased patients with seizure (2 per 1000 persons, 95% CI 0.001, 0.004) among recipients of carbapenems versus non-carbapenem antibiotics. This difference was largely attributed to imipenem as its use was associated with an additional 4 patients per 1000 with seizure (95% CI 0.002, 0.007) compared with non-carbapenem antibiotics, whereas none of the other carbapenems was associated with increased seizure. Similarly, in the pooled OR analysis, carbapenems were associated with a significant increase in the risk of seizures relative to non-carbapenem comparator antibiotics (OR 1.87, 95% CI 1.35, 2.59). The ORs for risk of seizures from imipenem, meropenem, ertapenem and doripenem compared with other antibiotics were 3.50 (95% CI 2.23, 5.49), 1.04 (95% CI 0.61, 1.77), 1.32 (95% CI 0.22, 7.74) and 0.44 (95% CI 0.13, 1.53), respectively. In studies directly comparing imipenem and meropenem, there was no difference in epileptogenicity in either RD or pooled OR analyses.

CONCLUSIONS

The absolute risk of seizures with carbapenems was low, albeit higher than with non-carbapenem antibiotics. Although imipenem was more epileptogenic than non-carbapenem antibiotics, there was no statistically significant difference in the imipenem versus meropenem head-to-head comparison.

Short- vs long-duration antibiotic regimens for ventilator-associated pneumonia: a systematic review and meta-analysis

BACKGROUND

We performed a systematic review and meta-analysis of short- vs long-duration antibiotic regimens for ventilator-associated pneumonia (VAP).

METHODS

We searched PubMed and Cochrane Central Registry of Controlled Trials. Four randomized controlled trials (RCTs) comparing short (7-8 days) with long (10-15 days) regimens were identified. Primary outcomes included mortality, antibiotic-free days, and clinical and microbiologic relapses. Secondary outcomes included mechanical ventilation-free days, duration of mechanical ventilation, and length of ICU stay.

RESULTS

All RCTs included mortality data, whereas data on relapse and antibiotic-free days were provided in three and two out of four RCTs, respectively. No difference in mortality was found between the compared arms (fixed effect model [FEM]: OR = 1.20; 95% CI, 0.84-1.72; P = .32). There was an increase in antibiotic-free days in favor of the short-course treatment with a pooled weighted mean difference of 3.40 days (random effects model: 95% CI, 1.43-5.37; P &lt; .001). There was no difference in relapses between the compared arms, although a strong trend to lower relapses in the long-course treatment was observed (FEM: OR = 1.67; 95% CI, 0.99-2.83; P = .06). No difference was found between the two arms regarding the remaining outcomes. Sensitivity analyses yielded similar results.

CONCLUSIONS

Short-course treatment of VAP was associated with more antibiotic-free days. No difference was found regarding mortality and relapses; however, a strong trend for fewer relapses was observed in favor of the long-course treatment, being mostly driven by one study in which the observed relapses were probably more microbiologic than clinical. Additional research is required to elucidate the issue.

Imipenem, meropenem, or doripenem to treat patients with Pseudomonas aeruginosa ventilator-associated pneumonia

Only limited data exist on Pseudomonas aeruginosa ventilator-associated pneumonia (VAP) treated with imipenem, meropenem, or doripenem. Therefore, we conducted a prospective observational study in 169 patients who developed Pseudomonas aeruginosa VAP. Imipenem, meropenem, and doripenem MICs for Pseudomonas aeruginosa isolates were determined using Etests and compared according to the carbapenem received. Among the 169 isolates responsible for the first VAP episode, doripenem MICs were lower (P<0.0001) than those of imipenem and meropenem (MIC50s, 0.25, 2, and 0.38, respectively); 61%, 64%, and 70% were susceptible to imipenem, meropenem, and doripenem, respectively (P was not statistically significant). Factors independently associated with carbapenem resistance were previous carbapenem use (within 15 days) and mechanical ventilation duration before VAP onset. Fifty-six (33%) patients had at least one VAP recurrence, and 56 (33%) died. Factors independently associated with an unfavorable outcome (recurrence or death) were a high day 7 sequential organ failure assessment score and mechanical ventilation dependency on day 7. Physicians freely prescribed a carbapenem to 88 patients: imipenem for 32, meropenem for 24, and doripenem for 32. The remaining 81 patients were treated with various antibiotics. Imipenem-, meropenem-, and doripenem-treated patients had similar VAP recurrence rates (41%, 25%, and 22%, respectively; P=0.15) and mortality rates (47%, 25%, and 22%, respectively; P=0.07). Carbapenem resistance emerged similarly among patients treated with any carbapenem. No carbapenem was superior to another for preventing carbapenem resistance emergence.

Optimal dosing of antibiotics in critically ill patients by using continuous/extended infusions: a systematic review and meta-analysis

Introduction

The aim of this study was to determine whether using pharmacodynamic-based dosing of antimicrobials, such as extended/continuous infusions, in critically ill patients is associated with improved outcomes as compared with traditional dosing methods.

Methods

We searched Medline, HealthStar, EMBASE, Cochrane Clinical Trial Registry, and CINAHL from inception to September 2013 without language restrictions for studies comparing the use of extended/continuous infusions with traditional dosing. Two authors independently selected studies, extracted data on methodology and outcomes, and performed quality assessment. Meta-analyses were performed by using random-effects models.

Results

Of 1,319 citations, 13 randomized controlled trials (RCTs) (n = 782 patients) and 13 cohort studies (n = 2,117 patients) met the inclusion criteria. Compared with traditional non-pharmacodynamic-based dosing, RCTs of continuous/extended infusions significantly reduced clinical failure rates (relative risk (RR) 0.68; 95% confidence interval (CI) 0.49 to 0.94, P = 0.02) and intensive care unit length of stay (mean difference, −1.5; 95% CI, −2.8 to −0.2 days, P = 0.02), but not mortality (RR, 0.87; 95% CI, 0.64 to 1.19; P = 0.38). No significant between-trial heterogeneity was found for these analyses (I² = 0). Reduced mortality rates almost achieved statistical significance when the results of all included studies (RCTs and cohort studies) were pooled (RR, 0.83; 95% CI, 0.69 to 1.00; P = 0.054).

Conclusions

Pooled results from small RCTs suggest reduced clinical failure rates and intensive care unit length-of-stay when using continuous/extended infusions of antibiotics in critically ill patients. Reduced mortality rates almost achieved statistical significance when the results of RCTs were combined with cohort studies. These results support the conduct of adequately powered RCTs to define better the utility of continuous/extended infusions in the era of antibiotic resistance.

Prolonging β-lactam infusion: a review of the rationale and evidence, and guidance for implementation

Given the sparse antibiotic pipeline and the increasing prevalence of resistant organisms, efforts should be made to optimise the pharmacodynamic exposure of currently available agents. Prolonging the infusion duration is a strategy used to increase the percentage of the dosing interval that free drug concentrations remain above the minimum inhibitory concentration (fT>MIC), the pharmacodynamic efficacy driver for time-dependent antibiotics such as β-lactams. β-Lactams, the most commonly prescribed class of antibiotics owing to their efficacy and safety profile, have been the mainstay of therapy since the discovery of penicillin over 60 years ago. Mounting evidence, including the use of population pharmacokinetic modelling and Monte Carlo simulation, suggests that prolonging the infusion time of β-lactam antibiotics may have advantages over standard infusion techniques, including an enhanced probability of achieving requisite fT>MIC exposures, lower mortality and potentially reductions in infection/antibiotic-related costs. As a result of these favourable attributes, clinical practice guidelines support the use of prolonged-infusion β-lactams in the treatment of many severe infections. This article discusses the rationale and evidence for prolonging the infusion of β-lactam antibiotics and provides guidance for the implementation of a prolonged-infusion programme.

Year in review 2012: Critical Care--respiratory infections

Over the last two decades, considerable progress has been made in the understanding of disease mechanisms and infection control strategies related to infections, particularly pneumonia, in critically ill patients. Patient-centered and preventative strategies assume paramount importance in this era of limited health-care resources, in which effective targeted therapy is required to achieve the best outcomes. Risk stratification using severity scores and inflammatory biomarkers is a promising strategy for identifying sick patients early during their hospital stay. The emergence of multidrug-resistant pathogens is becoming a major hurdle in intensive care units. Cooperation, education, and interaction between multiple disciplines in the intensive care unit are required to limit the spread of resistant pathogens and to improve care. In this review, we summarize findings from major publications over the last year in the field of respiratory infections in critically ill patients, putting an emphasis on a newer understanding of pathogenesis, use of biomarkers, and antibiotic stewardship and examining new treatment options and preventive strategies.

An alternate pathophysiologic paradigm of sepsis and septic shock: implications for optimizing antimicrobial therapy

The advent of modern antimicrobial therapy following the discovery of penicillin during the 1940s yielded remarkable improvements in case fatality rate of serious infections including septic shock. Since then, pathogens have continuously evolved under selective antimicrobial pressure resulting in a lack of significant improvement in clinical effectiveness in the antimicrobial therapy of septic shock despite ever more broad-spectrum and potent drugs. In addition, although substantial effort and money has been expended on the development novel non-antimicrobial therapies of sepsis in the past 30 years, clinical progress in this regard has been limited. This review explores the possibility that the current pathophysiologic paradigm of septic shock fails to appropriately consider the primacy of the microbial burden of infection as the primary driver of septic organ dysfunction. An alternate paradigm is offered that suggests that has substantial implications for optimizing antimicrobial therapy in septic shock. This model of disease progression suggests the key to significant improvement in the outcome of septic shock may lie, in great part, with improvements in delivery of existing antimicrobials and other anti-infectious strategies. Recognition of the role of delays in administration of antimicrobial therapy in the poor outcomes of septic shock is central to this effort. However, therapeutic strategies that improve the degree of antimicrobial cidality likely also have a crucial role.

Standard Versus Prolonged Doripenem Infusion for Treatment of Gram-Negative Infections

BACKGROUND

Doripenem is the most recently introduced carbapenem, with a broad spectrum of antimicrobial activity. Preliminary data indicated that activity is optimized by maximizing the time that serum concentration remains above the minimum inhibitory concentration; however, limited clinical data are available to support this approach.

OBJECTIVE

To compare clinical outcomes before and after implementation of a hospital-wide initiative extending the duration of infusion for doripenem from 1 hour (standard) to 4 hours (prolonged).

METHODS

This retrospective, quasi-experimental study compared clinical outcomes associated with doripenem administered as a 1-hour infusion versus a 4-hour infusion for treatment of suspected or documented infections caused by gram-negative organisms. Outcomes were assessed for the entire cohort, as well as for the subpopulation of patients admitted to the intensive care unit.

RESULTS

Two hundred patients were included; 106 patients received doripenem via standard infusion and 94 patients via prolonged infusion. No significant differences were noted between the treatment groups in clinical success, length of stay, or duration of treatment when the entire cohort was evaluated. In the critically ill subgroup, pneumonia, standard-infusion doripenem, and concomitant bacteremia were independent predictors of clinical failure (adjusted odds ratio [95% CI] 7.8 [2.4–25.6], 5.5 [1.6–18.7], and 7.0 [1.6–31.3], respectively). Additionally, critically ill patients who received doripenem via standard infusion were significantly more likely to experience recurrence of infection or death within 90 days. No significant differences were noted in length of stay or duration of bacteremia.

CONCLUSIONS

The duration of infusion did not significantly impact outcomes when the entire cohort was compared; however, prolonged infusion of doripenem was associated with significantly improved clinical outcomes among critically ill patients. These findings support the use of prolonged infusion of doripenem for critically ill patients.

Antibiotics for the critically ill: more than just selecting appropriate initial therapy

Critically ill patients with infection provide a number of challenges to clinicians in terms of optimizing their antimicrobial treatment. Of foremost importance, initial antibiotic treatment should be selected as to provide coverage for the causative pathogens. However, the administration of those antibiotics (dosing, interval of administration, duration of infusion, route of administration) should be prescribed in a manner to ensure optimal drug delivery to the site of infection. This is a challenge given the characteristics of many infected critically ill patients (shock, elevated cardiac output in the resuscitated state, supranormal creatinine clearance, increased volume of distribution). Intensive care unit practitioners should utilize treatment strategies that strive to deliver antibiotics in an individualized manner aimed at attaining desired pharmacokinetic/pharmacodynamic targets. The goal of such a treatment strategy is to maximize the likelihood of curing the infection and allowing the critically ill patient the best opportunity for recovery. Effective implementation of antimicrobial optimization delivery strategies will likely require a multi-disciplinary approach including intensivists, pharmacists, and infectious disease specialists.

Pharmacokinetics of Doripenem in Infected Patients Treated Within and Outside the Intensive Care Unit

BACKGROUND

Doripenem often is used in the intensive care unit (ICU) to treat serious infections. However, pharmacokinetics in this population often are altered by various physiologic changes. Current pharmacokinetic data in critically ill patients receiving doripenem are limited.

OBJECTIVE

To determine the pharmacokinetics of doripenem in patients treated in the ICU versus outside the ICU.

METHODS

A total of 3–4 serum samples were collected from 25 infected patients receiving doripenem. A 2-compartment model was fit to serum pharmacokinetic data with nonparametric adaptive grid with adaptive γ. In the structural pharmacokinetic model, clearance (Cl) was made proportional to creatinine clearance (CrCl) and an intercept term. Bayesian pharmacokinetic parameters were compared between the 2 populations. A 5000-patient Monte Carlo simulation was performed for various CrCl ranges. The probability of pharmacodynamic target attainment was calculated over a range of minimum inhibitory concentrations (MICs), assuming a target of 35% of the dosing interval that unbound drug concentrations remain above the MIC.

RESULTS

Mean (range) age, body mass index, and CrCl were 61 (31–90) years, 31.2 (15.1–55.5) kg/m2, and 86 (15–221) mL/min, respectively. After the Bayesian step, r2, bias, and precision were 0.97, 0.04, and 1.44 μg/mL, respectively. Mean (SD) parameters for ICU (n = 13) and non-ICU (n = 12) patients were not significantly different (p > 0.05): volume of central compartment (17.3 [11.2] vs 18.5 [11.7] L), Cl (10.1 [10.2] vs 15.5 [16.9] L/h), k12 (4.7 [4.7] vs 4.7 [4.8] h−1), and k21 (7.1 [5.5] vs 5.7 [5.3] h−1), respectively. Optimal target attainments were obtained for patients with normal renal function up to MICs of 2 μg/mL with a dose of 500 mg every 8 hours as 1-hour and 4-hour infusions.

CONCLUSIONS

Doripenem pharmacokinetics were similar between ICU and non-ICU patients in this population. Optimal dosing regimens should be selected based on underlying renal function and suspected MIC of the infecting pathogen.

A week seems to be weak: tailoring duration of antibiotic treatment in Gram-negative ventilator-associated pneumonia

The optimal length of antimicrobial therapy has not been extensively studied for a great majority of infections and, in critically ill patients affected by ventilator-associated pneumonia, is a persisting and unsolved issue confronting clinicians. The integration of biomarkers, clinical judgment, and microbiologic eradication might help to define a shorter duration for some ventilator-associated pneumonia episodes due to non-fermenting Gram-negative bacilli, but until these strategies are implemented in clinical practice for individualizing antibiotic treatment, a short-course duration does not seem to tailor a long benefit.