[Duration of antibiotic therapy for ventilator-associated pneumonia: comparison of 7 and 10 days. A pilot study]

Evaluating antibiotic therapy for ventilator-associated pneumonia caused by gram-negative bacilli

Introduction

Ventilator-associated pneumonias (VAPs) are a complication of mechanical ventilation in the intensive care unit (ICU) that increase length of stay, morbidity, and mortality. While identifying and treating infections early is paramount to improving patient outcomes, more and more data demonstrate limited courses of antibiotics improve outcomes. Prolonged (10-14 day) courses of antibiotics have remained the standard of care for pneumonia due to gram-negative bacilli (GNR). We aimed to review our GNR VAPs to assess risk factors for recurrent GNR infections.

Methods

We reviewed trauma patients who developed VAP from 02/2019 through 05/2022. Demographics, injury characteristics, and outcomes were reviewed with a focus on pneumonia details including the cultured pathogen(s), antibiotic(s) used, treatment duration, and presence of recurrent infections. We then compared single episode VAPs to multiple episode VAPs among patients infected by GNRs.

Results

Eleven of the fifty trauma patients admitted to the ICU suffered a VAP caused by a GNR. Of these eleven patients, six experienced a recurrent infection, four of which were caused by Pseudomonas aeruginosa and two of which were caused by Enterobacter aerogenes. Among the patients who received ten days of antibiotic treatment, half suffered a recurrence. Although, there was no difference in the microbiology or antibiotic duration between the recurrences and single episodes.

Conclusion

Despite prolonged use of antibiotics, we found that the risk of recurrent or persistent infections was high among patients with VAP due to GNB. Further study is needed to determine optimal treatment to minimize the risk of these recurrences.

Key message

Ventilator-associated pneumonia due to gram-negative bacilli is a rare but high morbidity complication in intensive care units. Despite prolonged duration of therapy, these infections still appear to account for many recurrent infections and further study into optimal therapy is warranted.

Short-course versus prolonged-course antibiotic regimens for ventilator-associated pneumonia: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Current guidelines recommend short-duration antibiotic therapy for non-fermenting gram-negative bacilli (NF-GNB) ventilator-associated pneumonia (VAP) which may be associated with a higher recurrence of pneumonia. In this meta-analysis, we aimed to compare short- versus prolonged-course antibiotic regimens for VAP.

METHODS

We searched several databases for randomized controlled trials (RCTs) that compared the effectiveness of a short- versus long-course of antibiotic treatment in patients with VAP. Data analysis was performed using RevMan 5.4.

RESULTS

Our pooled analysis consisted of six RCTs. For 28-day mortality, no significant difference was found between the prolonged course and the short course. Administration of a short course of antibiotics increased the risk of recurrence of pneumonia in patients with VAP due to NF-GNB (RR 1.73; 95% CI: 1.17-2.54). Secondary outcomes, such as clinical resolution, duration of ICU stay, and duration of mechanical ventilation, revealed no significant difference between the two regimens. The quality of evidence was low for most outcomes.

CONCLUSIONS

Low-quality evidence suggests that a short course of antibiotics is associated with a higher recurrence of pneumonia in NF-GNB VAP with no difference in mortality as compared to a prolonged course. For definitive conclusions, large-scale and blinded RCTs are required.

Major Publications in the Critical Care Pharmacotherapy Literature: 2022

OBJECTIVES

A number of trials related to critical care pharmacotherapy were published in 2022. We aimed to summarize the most influential publications related to the pharmacotherapeutic care of critically ill patients in 2022.

DATA SOURCES

PubMed/Medical Literature Analysis and Retrieval System Online and the Clinical Pharmacy and Pharmacology Pharmacotherapy Literature Update.

STUDY SELECTION

Randomized controlled trials, prospective studies, or systematic review/meta-analyses of adult critically ill patients assessing a pharmacotherapeutic intervention and reporting clinical endpoints published between January 1, 2022, and December 31, 2022, were included in this article.

DATA EXTRACTION

Articles from a systematic search and the Clinical Pharmacy and Pharmacology Pharmacotherapy Literature Update were included and stratified into clinical domains based upon consistent themes. Consensus was obtained on the most influential publication within each clinical domain utilizing an a priori defined three-round modified Delphi process with the following considerations: 1) overall contribution to scientific knowledge and 2) novelty to the literature.

DATA SYNTHESIS

The systematic search and Clinical Pharmacy and Pharmacology Pharmacotherapy Literature Update yielded a total of 704 articles, of which 660 were excluded. The remaining 44 articles were stratified into the following clinical domains: emergency/neurology, cardiovascular, gastroenterology/fluids/nutrition, hematology, infectious diseases/immunomodulation, and endocrine/metabolic. The final article selected from each clinical domain was summarized following a three-round modified Delphi process and included three randomized controlled trials and three systematic review/meta-analyses. Article topics summarized included dexmedetomidine versus other sedatives during mechanical ventilation, beta-blocker treatment in the critically ill, restriction of IV fluids in septic shock, venous thromboembolism prophylaxis in critically ill adults, duration of antibiotic therapy for Pseudomonas aeruginosa ventilator-associated pneumonia, and low-dose methylprednisolone treatment in severe community-acquired pneumonia.

CONCLUSIONS

This concise review provides a perspective on articles published in 2022 that are relevant to the pharmacotherapeutic care of critically ill patients and their potential impact on clinical practice.

Comparison of a short versus long-course antibiotic therapy for ventilator-associated pneumonia: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

For ventilator-associated pneumonia (VAP), the safety of short-course versus long-course antibiotic therapy is still debated, especially regarding documented VAP due to non-fermenting Gram-negative bacilli (NF-GNB). The aim of this meta-analysis was to assess the rates of recurrence and relapse of VAP in patients receiving short-course (≤8 days) and long-course (≥10-15 days) of antibiotic therapy.

METHODS

The protocol for this study was registered in the PROSPERO database (ID: CRD42022365138). We performed an electronic search of the relevant literature and limited our search to data published from 2000 until September 1, 2022. We searched for randomized controlled trials (RCTs) in the United States National Library of Medicine, Cochrane Database of Systematic Reviews (CDSR) and the Cochrane Central Register of Controlled Trials (CENTRAL), Embase, National Institutes of Health PubMed/MEDLINE, web of science and Google Scholar databases. The primary endpoint was the recurrence and relapses of VAP, secondary endpoints were 28-day mortality, mechanical ventilation duration, number of extra-pulmonary infections and length of ICU stay.

FINDINGS

We identified five relevant studies involving 1069 patients (530 patients in the short-course group and 539 patients in the long-course group). The meta-analysis did not reveal any significant difference between short and long-course antibiotic therapy for recurrence and relapses of VAP (odd ratio "OR" = 1.48, 95% confidence intervals (CI) [0.96, 2.28], p = 0.08 and OR = 1.45, 95% CI [0.94, 2.22], p = 0.09, respectively), including those due to NF-GNB (OR = 1.90, 95% CI [0.93, 3.33], p = 0.05 and OR = 1.76, 95% CI [0.93, 3.33], p = 0.08, respectively). No difference was found for 28 days-mortality (OR = 1.24, 95% CI [0.92, 1.67], p = 0.16), mechanical ventilation duration, number of extra-pulmonary infections and length of ICU stay. However, short-course therapy significantly increased the number of antibiotic-free days.

INTERPRETATION

Our meta-analysis showed that short-course antibiotic therapy did not result in increased number of recurence and relapses of VAP, suggesting that short-course should be preferred to reduce the exposure to antibiotics.

FUNDING

None.

Less Is More? Antibiotic Treatment Duration in Pseudomonas aeruginosa Ventilator-Associated Pneumonia

Recommended antimicrobial treatment durations for ventilator-associated pneumonia (VAP) caused by Pseudomonas aeruginosa have evolved over the past few decades. In this Viewpoint, we provide a narrative review of landmark trials investigating antimicrobial treatment durations for VAP caused by P. aeruginosa, and appraise iterations of expert consensus guidelines based on these data. We highlight strengths and weaknesses of existing data on this topic and provide recommendations for future avenues of study.

Comparison of 8 versus 15 days of antibiotic therapy for Pseudomonas aeruginosa ventilator-associated pneumonia in adults: a randomized, controlled, open-label trial

PURPOSE

Compared to long duration of antibiotic therapy, a short duration has a comparable clinical efficacy for ventilator-associated pneumonia (VAP), with the exception of documented VAP of non-fermenting Gram-negative bacilli (NF-GNB), including Pseudomonas aeruginosa (PA). We aimed to assess the non-inferiority of a short duration of antibiotics (8 days) vs. prolonged antibiotic therapy (15 days) in VAP due to PA (PA-VAP).

METHODS

We conducted a nationwide, randomized, open-labeled, multicenter, non-inferiority trial to evaluate optimal duration of antibiotic treatment in PA-VAP. Eligible patients were adults with diagnosis of PA-VAP and randomly assigned in 1:1 ratio to receive a short-duration treatment (8 days) or a long-duration treatment (15 days). A pre-specified analysis was used to assess a composite endpoint combining mortality and PA-VAP recurrence rate during hospitalization in the intensive care unit (ICU) within 90 days.

RESULTS

In intention-to-treat population (n = 186), the percentage of patients who reached the composite endpoint was 25.5% (N = 25/98) in the 15-day group versus 35.2% (N = 31/88) in the 8-day group (difference 9.7%, 90% confidence interval (CI) 0.0-21.2%). The percentage of recurrence of PA-VAP during the ICU stay was 9.2% in the 15-day group versus 17% in the 8-day group. The two groups had similar median days of mechanical ventilation, of ICU stay, number of extra pulmonary infections and acquisition of multidrug-resistant (MDR) pathogens during ICU stay.

CONCLUSIONS

Our study showed no differences in the composite or separate outcomes (90-day mortality or VAP recurrence) between short- and long-duration treatments for PA-VAP. However, the lack of power limits the interpretation of this study.

Effect of Antibiotic Discontinuation Strategies on Mortality and Infectious Complications in Critically Ill Septic Patients: A Meta-Analysis and Trial Sequential Analysis

OBJECTIVE

To investigate methods of antibiotic duration minimization and their effect on mortality and infectious complications in critically ill patients.

DATA SOURCES

A systematic search of PubMed, Embase (via Ovid), clinicaltrials.gov, and the Cochrane Central Register of Controlled Trials (via Wiley) (CENTRAL, Issue 2, 2015).

STUDY SELECTION

Randomized clinical trials comparing strategies to minimize antibiotic duration (days) for patients with infections or sepsis in intensive care.

DATA EXTRACTION

A systematic review with meta-analyses and trial sequential analyses of randomized clinical trials. Dichotomous data are presented as relative risk (95% CIs) and p value, and continuous data are presented as mean difference (CI) and p value.

DATA SYNTHESIS

We included 22 randomized clinical trials (6,046 patients). Strategies to minimize antibiotic use included procalcitonin (14 randomized clinical trials), clinical algorithms (two randomized clinical trials), and fixed-antibiotic duration (six randomized clinical trials). Procalcitonin (-1.23 [-1.61 to -0.85]; p < 0.001), but not clinical algorithm-guided antibiotic therapy (-7.41 [-18.18 to 3.37]; p = 0.18), was associated with shorter duration of antibiotic therapy. The intended reduction in antibiotic duration ranged from 3 to 7 days in fixed-duration antibiotic therapy randomized clinical trials. Neither procalcitonin-guided antibiotic treatment (0.91 [0.82-1.01]; p = 0.09), clinical algorithm-guided antibiotic treatment (0.67 [0.30-1.54]; p = 0.35), nor fixed-duration antibiotics (1.21 [0.90-1.63]; p = 0.20) were associated with reduction in mortality. Z-curve for trial sequential analyses of mortality associated with procalcitonin-guided therapy did not reach the trial sequential monitoring boundaries for benefit, harm, or futility (adjusted CI, 0.72-1.10). Trial sequential analyses for mortality associated with clinical algorithm and fixed-duration treatment accumulated less than 5% of the required information size. Despite shorter antibiotic duration, neither procalcitonin-guided therapy (0.93 [0.84-1.03]; p = 0.15) nor fixed-duration antibiotic therapy (1.06 [0.74-1.53]; p = 0.75) was associated with treatment failure.

CONCLUSIONS

Although the duration of antibiotic therapy is reduced with procalcitonin-guided therapy or prespecified limited duration, meta-analysis and trial sequential analyses are inconclusive for mortality benefit. Data on clinical algorithms to guide antibiotic cessation are limited.

Short- vs long-course antibiotic therapy for pneumonia: a comparison of systematic reviews and guidelines for the SIMI Choosing Wisely Campaign

Reduction of the inappropriate use of antibiotics in clinical practice is one of the main goals of the Società Italiana di Medicina Interna (SIMI) choosing wisely campaign. We conducted a systematic review of secondary studies (systematic reviews and guidelines) to verify what evidence is available on the duration of antibiotic treatment in Pneumonia. A literature systematic search was performed to identify all systematic reviews and the three most cited and recent guidelines that address the duration of antibiotic therapy in pneumonia. Moreover, a meta-analysis of non-duplicate data from randomized controlled trials (RCTs) considered in the enrolled systematic reviews was performed together with a trial sequential analysis to identify the need for further studies. Two systematic reviews on antibiotic duration in community-acquired pneumonia (CAP) for a total of 17 RCTs (2764 patients) were enrolled in our study. Meta-analysis of non-duplicate RCTs show a non-significant difference in rate of treatment failure between short (≤ 7 days) and long (> 7 days) antibiotic treatment course: RR 1.05 (95% CI, 0.82-1.36). The trial sequential analysis suggests that further data would not affect current evidence or become clinically relevant. Selected guidelines suggest consideration of a short course, with a low grade of evidence and without citing the already published systematic reviews. Antibiotic treatment of CAP for ≤ 7 days is not associated with a higher rate of treatment failure than longer courses and should thus be taken in consideration. Guidelines should upgrade the evidence on this topic.

Resistance Trends and Treatment Options in Gram-Negative Ventilator-Associated Pneumonia

PURPOSE OF REVIEW

Hospital-acquired and ventilator-associated pneumonia (VAP) are frequent causes of infection among critically ill patients. VAP is the most common hospital-acquired bacterial infection among mechanically ventilated patients. Unfortunately, many of the nosocomial Gram-negative bacteria that cause VAP are increasingly difficult to treat. Additionally, the evolution and dissemination of multi- and pan-drug resistant strains leave clinicians with few treatment options. VAP patients represent a dynamic population at risk for antibiotic failure and under-dosing due to altered antibiotic pharmacokinetic parameters. Since few antibiotic agents have been approved within the last 15 years, and no new agents specifically targeting VAP have been approved to date, it is anticipated that this problem will worsen. Given the public health crisis posed by resistant Gram-negative bacteria, it is essential to establish a firm understanding of the current epidemiology of VAP, the changing trends in Gram-negative resistance in VAP, and the current issues in drug development for Gram-negative bacteria that cause VAP.

RECENT FINDINGS

Rapid identification technologies and phenotypic methods, new therapeutic strategies, and novel treatment paradigms have evolved in an attempt to improve treatment outcomes for VAP; however, clinical data supporting alternative treatment strategies and adjunctive therapies remain sparse. Importantly, new classes of antimicrobials, novel virulence factor inhibitors, and beta-lactam/beta-lactamase inhibitor combinations are currently in development. Conscientious stewardship of new and emerging therapeutic agents will be needed to ensure they remain effective well into the future.

Individualized antibiotic therapy in patients with ventilator-associated pneumonia

The optimal duration of the treatment of ventilator-associated pneumonia (VAP) is still the subject of debate. While 1 week treatment has been reported as possibly sufficient, patients generally receive antibiotic therapy for 10 to 14 days. The purpose of our study was to investigate whether length of treatment in patients with VAP can be reduced with an individualized therapeutic strategy. The study was performed prospectively with patients diagnosed with VAP in our hospital's intensive care units between 1 January and 31 December 2015. Duration of antibiotic therapy was determined with 5 day clinical evaluation according to previously established criteria. Patients were divided into two groups depending on length of treatment, short (7-10 days) and long treatment (>10 days). Nineteen patients received 7 to 10 day antibiotic therapy, and 30 received >10 day antibiotic therapy. Demographic and clinical characteristics, Glasgow Coma Scale score, CPIS and the PaO2/FiO2 ratio at the time of diagnosis of VAP were statistically similar between the two groups (P>0.05). A second VAP attack occurred post-treatment in three patients receiving short-term treatment and in four receiving long-term treatment (P=0.561). The numbers of antibiotic-free days were 15.6±6.2 in the short-term treatment group and 8.3±7.5 in the long-term group (P<0.0001). One of the patients receiving short-term treatment died within 28 days after treatment, and four of the patients receiving long-term treatment (P=0.348) did so. The most commonly observed micro-organisms in both groups were Acinetobacterbaumannii and Pseudomonasaeruginosa. Short-term treatment can be administered in cases with early clinical and laboratory response started on VAP treatment by considering individual characteristics and monitoring fever, CPIS, the PaO2/FiO2 ratio, C-reactive protein and procalcitonin values.

Impact of the duration of antibiotics on clinical events in patients with Pseudomonas aeruginosa ventilator-associated pneumonia: study protocol for a randomized controlled study

Background

Ventilator-associated pneumonia (VAP) accounts for 25% of infections in intensive care units. Compared to a long duration (LD) of antibiotic therapy, a short duration (SD) has a comparable clinical efficacy with less antibiotic use and less multidrug-resistant (MDR) pathogen emergence, with the exception of documented VAP of non-fermenting Gram-negative bacilli (NF-GNB), including Pseudomonas aeruginosa (PA). These results have led the American Thoracic Society to recommend SD therapy for VAP, except for PA-VAP. Thus the beneficial effect of SD therapy in PA-VAP is still a matter of debate. We aimed to assess the non-inferiority of a short duration of antibiotics (8 days) versus prolonged antibiotic therapy (15 days) in PA-VAP.

Methods/design

The impact of the duration of antibiotics on clinical events in patients with Pseudomonas aeruginosa ventilator-associated pneumonia (iDIAPASON) trial is a randomized, open-labeled non-inferiority controlled trial, conducted in 34 French intensive care units (ICUs), comparing two groups of patients with PA-VAP according to the duration (8 days or 15 days) of effective antibiotic therapy against PA. The primary outcome is a composite endpoint combining day 90 mortality and PA-VAP recurrence rate during hospitalization in the ICU. Furthermore, durations of mechanical ventilation and hospitalization, as well as number and types of extrapulmonary infections or acquisition of MDR pathogens during the hospitalization in the ICU will be recorded. Recurrence with predefined criteria (clinical suspicion of VAP associated with a positive quantitative culture of a respiratory sample) will be evaluated by two independent experts.

Discussion

Demonstrating that an SD (8 days) versus LD (15 days) therapy strategy in PA-VAP treatment is safe and not associated with an increased mortality or recurrence rate could lead to a change in practices and guidelines in the management of antibiotic therapy of this frequent ICU complication. This strategy could lead to decreased antibiotic exposure during hospitalization in the ICU and in turn reduce the acquisition and the spread of MDR pathogens.

Trial registration

ClinicalTrials.gov: NCT02634411. Registered on 19 November 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-1780-3) contains supplementary material, which is available to authorized users.

Management of Adults With Hospital-acquired and Ventilator-associated Pneumonia: 2016 Clinical Practice Guidelines by the Infectious Diseases Society of America and the American Thoracic Society

It is important to realize that guidelines cannot always account for individual variation among patients. They are not intended to supplant physician judgment with respect to particular patients or special clinical situations. IDSA considers adherence to these guidelines to be voluntary, with the ultimate determination regarding their application to be made by the physician in the light of each patient's individual circumstances.These guidelines are intended for use by healthcare professionals who care for patients at risk for hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP), including specialists in infectious diseases, pulmonary diseases, critical care, and surgeons, anesthesiologists, hospitalists, and any clinicians and healthcare providers caring for hospitalized patients with nosocomial pneumonia. The panel's recommendations for the diagnosis and treatment of HAP and VAP are based upon evidence derived from topic-specific systematic literature reviews.

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.

Emerging and resistant infections

The lungs are a major target for infection and a key battleground in the fight against the development of antimicrobial drug-resistant pathogens. Ventilator-associated pneumonia (VAP) is associated with mortality rates of 24-50%. The optimal duration of antibiotic therapy against VAP is unknown, but prolonged courses are associated with the emergence of bacterial resistance. De-escalation strategies in which treatment is discontinued based on signs of clinical resolution, fixed durations of therapy (generally 7-8 d), or serum procalcitonin responses have been shown to decrease antibiotic consumption. Outcomes are comparable to longer treatment courses, with the possible exception of VAP due to nonfermenting, gram-negative bacilli such as Pseudomonas aeruginosa. Staphylococcus aureus is a leading cause of VAP and other infections. Outcomes after S. aureus infection are shaped by the interplay between environmental, bacterial, and host genetic factors. It is increasingly clear that mechanisms of pathogenesis vary in different types of S. aureus infections. Genome-scale studies of S. aureus strains, host responses, and host genetics are redefining our understanding of the pathogenic mechanisms underlying VAP. Genome-sequencing technologies are also revolutionizing our understanding of the molecular epidemiology, evolution, and transmission of influenza. Deep sequencing using next-generation technology platforms is defining the remarkable genetic diversity of influenza strains within infected hosts. Investigators have demonstrated that antiviral drug-resistant influenza may be present prior to the initiation of treatment. Moreover, drug-resistant minor variant influenza strains can be transmitted from person to person in the absence of selection pressure. Studies of lung infections and the causative pathogens will remain at the cutting edge of clinical and basic medical research.

Impact of antibiotic exposure on occurrence of nosocomial carbapenem-resistant Acinetobacter baumannii infection: a case control study

Carbapenem-resistant Acinetobacter baumannii (CRAB) infection is one of the most important healthcare associated diseases worldwide. Although antibiotic use is recognized as a risk factor for CRAB infection, the impact of antibiotic class and length of use on CRAB infection is still unclear. A case-control study was conducted in adult intensive care units and general wards of Songklanagarind Hospital, a tertiary-care hospital in southern Thailand, to investigate the effect of different antibiotic exposure and the duration of use on the risk of developing CRAB infection. Cases were defined as patients with carbapenem-susceptible A. baumannii (CSAB) or CRAB infection. Controls were randomly selected from patients and matched 1:1 with cases using ward and date of admission. Multinomial logistic regression was used to compute relative risk ratios (RRR) and 95% confidence intervals (CI) for CRAB infection. Of 197 cases with A. baumannii infection, there were 139 with CRAB infection and 58 with CSAB infection. Compared to the control group, use of fluoroquinolones, broad-spectrum cephalosporins and carbapenems for more than three days increased the risk of CRAB infection with RRR (95% CI) of 81.2 (38.1-862.7), 31.3 (9.9-98.7) and 112.1 (7.1-1770.6), respectively. The RRR (95% CI) for one to three day treatment of fluoroquinolones, broad-spectrum cephalosporins and carbapenems were 5.4 (0.8-38.7), 6.2 (0.1-353.2) and 63.3 (15.6-256.9), respectively. Long-term use of certain antibiotics and even short term use of carbapenems increased the risk of CRAB infection. In this setting, use of these antibiotics, especially carbapenems, should be limited to reduce CRAB infection.

Optimal duration of antimicrobial therapy in ventilator-associated pneumonia: What is the role for procalcitonin?

Hospital-acquired pneumonia (HAP) is the major cause of hospital-acquired infections in critically ill patients. Up to 90% of intensive care unit episodes of HAP occur in mechanically ventilated patients, who may develop what is termed ventilator-associated pneumonia (VAP). An appropriate duration of antimicrobial therapy is crucial in the management of HAP: on the one hand, delay in administration of proper therapy has been associated with an increased risk of treatment failure and mortality; on the other hand, unnecessary prolongation of antimicrobial treatment may favour the emergence of multidrug-resistant bacteria and increase healthcare costs. In this review, we discuss the evidence and recommendations from international guidelines for the management of VAP and focus on randomised controlled trials comparing the clinical efficacy of a short-course vs. an extended-course antimicrobial regimen for the treatment of VAP in adults. In these trials, short-course regimens were as effective and safe as long-course regimens for the treatment of VAP, provided that infection was not due to difficult-to-treat micro-organisms such as non-fermenting Gram-negative bacilli. In addition, strategies incorporating individualised stop-points for antibiotics, i.e. clinical features or biomarkers such as procalcitonin, were shown to reduce antibiotic exposure, healthcare costs and the risk of developing antimicrobial resistance, without negatively affecting other outcomes.

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.

Duration of antibiotic therapy for bacteremia: a systematic review and meta-analysis

Introduction

The optimal duration of antibiotic therapy for bloodstream infections is unknown. Shorter durations of therapy have been demonstrated to be as effective as longer durations for many common infections; similar findings in bacteremia could enable hospitals to reduce antibiotic utilization, adverse events, resistance and costs.

Methods

A search of the MEDLINE, EMBASE and COCHRANE databases was conducted for the years 1947-2010. Controlled trials were identified that randomized patients to shorter versus longer durations of treatment for bacteremia, or the infectious foci most commonly causing bacteremia in critically ill patients (catheter-related bloodstream infections (CRBSI), intra-abdominal infections, pneumonia, pyelonephritis and skin and soft-tissue infections (SSTI)).

Results

Twenty-four eligible trials were identified, including one trial focusing exclusively on bacteremia, zero in catheter related bloodstream infection, three in intra-abdominal infection, six in pyelonephritis, thirteen in pneumonia and one in skin and soft tissue infection. Thirteen studies reported on 227 patients with bacteremia allocated to 'shorter' or 'longer' durations of treatment. Outcome data were available for 155 bacteremic patients: neonatal bacteremia (n = 66); intra-abdominal infection (40); pyelonephritis (9); and pneumonia (40). Among bacteremic patients receiving shorter (5-7 days) versus longer (7-21 days) antibiotic therapy, no significant difference was detected with respect to rates of clinical cure (45/52 versus 47/49, risk ratio 0.88, 95% confidence interval [CI] 0.77-1.01), microbiologic cure (28/28 versus 30/32, risk ratio 1.05, 95% CI 0.91-1.21), and survival (15/17 versus 26/29, risk ratio 0.97, 95% CI 0.76-1.23).

Conclusions

No significant differences in clinical cure, microbiologic cure and survival were detected among bacteremic patients receiving shorter versus longer duration antibiotic therapy. An adequately powered randomized trial of bacteremic patients is needed to confirm these findings.

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, the optimal duration of antibiotic therapy for hospital-acquired pneumonia (HAP) is uncertain.

OBJECTIVES

To assess the effectiveness of short versus prolonged-course antibiotic administration for HAP in critically ill adults, including patients with ventilator-associated pneumonia (VAP).

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 1), which includes the Cochrane Acute Respiratory Infections Group's Specialised Register, MEDLINE (1950 to February week 4, 2011), EMBASE (1974 to March 2011), LILACS (1985 to March 2011) and Web of Science (1985 to March 2011).

SELECTION CRITERIA

We considered all randomised controlled trials (RCTs) comparing fixed durations of antibiotic therapy, or comparing a protocol intended to limit duration of therapy with standard care, 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

Eight studies (1703 patients) were included. Methodology varied considerably and we found little evidence regarding patients with a high probability of HAP who were not mechanically ventilated. For patients with VAP, a short seven to eight-day course of antibiotics compared with a prolonged 10 to 15-day course (three studies, N = 508) increased 28-day antibiotic-free days (odds ratio (OR) 4.02; 95% confidence interval (CI) 2.26 to 5.78) and reduced recurrence of VAP due to multi-resistant organisms (OR 0.44; 95% CI 0.21 to 0.95), without adversely affecting other outcomes. However, for cases of VAP due to non-fermenting Gram-negative bacilli (NF-GNB), recurrence was greater after short-course therapy (OR 2.18; 95% CI 1.14 to 4.16; two studies, N = 176), though other outcome measures did not significantly differ. Discontinuation strategies utilising clinical features (one study; N = 302) or procalcitonin (three studies; N = 323) led to a reduction in duration of therapy and, in the procalcitonin studies, increased 28-day antibiotic-free days (mean difference (MD) 2.80; 95% CI 1.39 to 4.21) without negatively affecting other outcomes.

AUTHORS' CONCLUSIONS

We conclude that for patients with VAP not due to NF-GNB, a short fixed-course (seven or eight days) antibiotic therapy may be more appropriate than a prolonged course (10 to 15 days). Use of an individualised strategy (incorporating clinical features or serum procalcitonin) appears to safely reduce duration of antibiotic therapy for VAP.