Attributable mortality of ventilator-associated pneumonia

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.

Metagenomics for the microbiological diagnosis of hospital-acquired pneumonia and ventilator-associated pneumonia (HAP/VAP) in intensive care unit (ICU): a proof-of-concept study

BACKGROUND

Hospital-acquired and ventilator-associated-pneumonia (HAP/VAP) are one of the most prevalent health-care associated infections in the intensive care unit (ICU). Culture-independent methods were therefore developed to provide faster route to diagnosis and treatment. Among these, metagenomic next-generation sequencing (mNGS) has shown considerable promise.

METHODS

This proof-of-concept study describes the technical feasibility and evaluates the clinical validity of the mNGS for the detection and characterization of the etiologic agents causing hospital-acquired and ventilator-associated pneumonia. We performed a prospective study of all patients with HAP/VAP hospitalized in our intensive care unit for whom a bronchoalveolar lavage (BAL) was performed between July 2017 and November 2018. We compared BAL fluid culture and mNGS results of these patients.

RESULTS

A total of 32 BAL fluids were fully analyzed. Of these, 22 (69%) were positive by culture and all pathogens identified were also reported by mNGS. Among the culture-positive BAL samples, additional bacterial species were revealed by mNGS for 12 patients, raising the issue of their pathogenic role (colonization versus coinfection). Among BALF with culture-negative test, 5 were positive in mNGS test.

CONCLUSIONS

This study revealed concordant results for pneumonia panel pathogens between mNGS and culture-positive tests and identified additional pathogens potentially implicated in pneumonia without etiologic diagnosis by culture. mNGS has emerged as a promising methodology for infectious disease diagnoses to support conventional methods. Prospective studies with real-time mNGS are warranted to examine the impact on antimicrobial decision-making and clinical outcome.

Ventilator-Associated Pneumonia in Immunosuppressed Patients

Immunocompromised patients-including patients with cancer, hematological malignancies, solid organ transplants and individuals receiving immunosuppressive therapies for autoimmune diseases-account for an increasing proportion of critically-ill patients. While their prognosis has improved markedly in the last decades, they remain at increased risk of healthcare- and intensive care unit (ICU)-acquired infections. The most frequent of these are ventilator-associated lower respiratory tract infections (VA-LTRI), which include ventilator-associated pneumonia (VAP) and tracheobronchitis (VAT). Recent studies have shed light on some of the specific features of VAP and VAT in immunocompromised patients, which is the subject of this narrative review. Contrary to previous belief, the incidence of VAP and VAT might actually be lower in immunocompromised than non-immunocompromised patients. Further, the relationship between immunosuppression and the incidence of VAP and VAT related to multidrug-resistant (MDR) bacteria has also been challenged recently. Etiological diagnosis is essential to select the most appropriate treatment, and the role of invasive sampling, specifically bronchoscopy with bronchoalveolar lavage, as well as new molecular syndromic diagnostic tools will be discussed. While bacteria-especially gram negative bacteria-are the most commonly isolated pathogens in VAP and VAT, several opportunistic pathogens are a special concern among immunocompromised patients, and must be included in the diagnostic workup. Finally, the impact of immunosuppression on VAP and VAT outcomes will be examined in view of recent papers using improved statistical methodologies and treatment options-more specifically empirical antibiotic regimens-will be discussed in light of recent findings on the epidemiology of MDR bacteria in this population.

Ventilator-Associated Pneumonia in COVID-19 Patients Admitted in Intensive Care Units: Relapse, Therapeutic Failure and Attributable Mortality-A Multicentric Observational Study from the OutcomeRea Network

Introduction: Ventilator-associated pneumonia (VAP) incidence is high among critically ill COVID-19 patients. Its attributable mortality remains underestimated, especially for unresolved episodes. Indeed, the impact of therapeutic failures and the determinants that potentially affect mortality are poorly evaluated. We assessed the prognosis of VAP in severe COVID-19 cases and the impact of relapse, superinfection, and treatment failure on 60-day mortality. Methods: We evaluated the incidence of VAP in a multicenter prospective cohort that included adult patients with severe COVID-19, who required mechanical ventilation for ≥48 h between March 2020 and June 2021. We investigated the risk factors for 30-day and 60-day mortality, and the factors associated with relapse, superinfection, and treatment failure. Results: Among 1424 patients admitted to eleven centers, 540 were invasively ventilated for 48 h or more, and 231 had VAP episodes, which were caused by Enterobacterales (49.8%), P. aeruginosa (24.8%), and S. aureus (22%). The VAP incidence rate was 45.6/1000 ventilator days, and the cumulative incidence at Day 30 was 60%. VAP increased the duration of mechanical ventilation without modifying the crude 60-day death rate (47.6% vs. 44.7% without VAP) and resulted in a 36% increase in death hazard. Late-onset pneumonia represented 179 episodes (78.2%) and was responsible for a 56% increase in death hazard. The cumulative incidence rates of relapse and superinfection were 45% and 39.5%, respectively, but did not impact death hazard. Superinfection was more frequently related to ECMO and first episode of VAP caused by non-fermenting bacteria. The risk factors for treatment failure were an absence of highly susceptible microorganisms and vasopressor need at VAP onset. Conclusions: The incidence of VAP, mainly late-onset episodes, is high in COVID-19 patients and associated with an increased risk of death, similar to that observed in other mechanically ventilated patients. The high rate of VAP due to difficult-to-treat microorganisms, pharmacokinetic alterations induced by renal replacement therapy, shock, and ECMO likely explains the high cumulative risk of relapse, superinfection, and treatment failure.

Attributable Mortality of Ventilator-associated Pneumonia Among Patients with COVID-19

Rationale: Patients with a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are at higher risk of ventilator-associated pneumonia (VAP) and may have an increased attributable mortality (increased or decreased risk of death if VAP occurs in a patient) and attributable fraction (proportion of deaths that are attributable to an exposure) of VAP-related mortality compared with subjects without coronavirus disease (COVID-19). Objectives: Estimation of the attributable mortality of the VAP among patients with COVID-19. Methods: Using the REA-REZO surveillance network, three groups of adult medical ICU patients were computed: control group (patients admitted between 2016 and 2019; prepandemic patients), pandemic COVID-19 group (PandeCOV⁺), and pandemic non-COVID-19 group (PandeCOV^-) admitted during 2020. The primary outcome was the estimation of attributable mortality and attributable fraction related to VAP in these patients. Using multistate modeling with causal inference, the outcomes related to VAP were also evaluated. Measurements and Main Results: A total of 64,816 patients were included in the control group, 7,442 in the PandeCOV^- group, and 1,687 in the PandeCOV⁺ group. The incidence of VAP was 14.2 (95% confidence interval [CI], 13.9 to 14.6), 18.3 (95% CI, 17.3 to 19.4), and 31.9 (95% CI, 29.8 to 34.2) per 1,000 ventilation-days in each group, respectively. Attributable mortality at 90 days was 3.15% (95%, CI, 2.04% to 3.43%), 2.91% (95% CI, -0.21% to 5.02%), and 8.13% (95% CI, 3.54% to 12.24%), and attributable fraction of mortality at 90 days was 1.22% (95% CI, 0.83 to 1.63), 1.42% (95% CI, -0.11% to 2.61%), and 9.17% (95% CI, 3.54% to 12.24%) for the control, PandeCOV^-, and PandeCOV⁺ groups, respectively. Except for the higher risk of developing VAP, the PandeCOV^- group shared similar VAP characteristics with the control group. PandeCOV⁺ patients were at lower risk of death without VAP (hazard ratio, 0.62; 95% CI, 0.52 to 0.74) than the control group. Conclusions: VAP-attributable mortality was higher for patients with COVID-19, with more than 9% of the overall mortality related to VAP.

Knowledge of intensive care nurses’ towards prevention of ventilator-associated pneumonia in North West Ethiopia referral hospitals, 2021: A multicenter, cross-sectional study

Introduction

Ventilator-associated pneumonia is a common nosocomial infection that occurs in critically ill patients who are on intubation and mechanical ventilation. Nurses' lack of knowledge may be a barrier to adherence to evidence-based guidelines for preventing ventilator-associated pneumonia. This study aimed to assess the knowledge of intensive care nurses’ towards the prevention of ventilator-associated pneumonia.

Methods

A multicenter cross-sectional study was conducted among nurses working in the intensive care unit from April to July 2021. A pre-tested and structured questionnaire was used to collect data. All intensive care nurses working in the study area were included in the study. Data was entered into Epi-data 4.1 version (EpiData Association, Denmark) and transferred to STATA version 14 (College Station, Texas 77845-4512 USA) statistical software for analysis. Both bi-variable and multivariable binary logistic regression analysis was used to identify factors associated with knowledge of intensive care unit nurse. Variables with a p-value less than <0.2 in the bi-variable analysis were fitted into the multivariable logistic regression analysis. Both Crude and Adjusted Odds Ratio with the corresponding 95% Confidence Interval was calculated to show the strength of association. In multivariable analysis, variables with a p-value of <0.05 were considered statistically significant.

Result

A total of 213 intensive care nurses were included in the study, with a response rate of 204(95.77%). The mean knowledge score of intensive care nurses regarding the prevention of ventilator-associated pneumonia out of 20 questions is (10.1 ± 2.41). There are 98 (48.04%) of the participants have been found to have good knowledge and 106 (51.96%) of them are rendered poor knowledge about the overall knowledge related to the prevention of ventilator-associated pneumonia. Higher academic qualifications and taking intensive care unit training were significantly associated with good knowledge of ventilator-associated pneumonia prevention in multi-variable logistic regression.

Conclusion

Our study indicates that the knowledge of intensive care nurses about ventilator-associated pneumonia prevention is not sufficient. Higher academic qualifications and taking intensive care unit training are significantly associated with a good level of knowledge. Therefore it shows the necessity for thorough training and education.

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The knowledge of intensive care nurses about ventilator-associated pneumonia prevention is not sufficient.

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Only 98 (48.04%) of the participants have been found to have good knowledge.

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Higher academic qualifications and taking intensive care unit training are significantly associated with a good level of knowledge.

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This study shows the necessity of in-service training and continuing education for intensive care nurses about the prevention of ventilator-associated pneumonia.

Ventilator -associated Pneumonia and Lung Ultrasound: Finally, What is between the Ears Matters

How to cite this article: Gopaldas JA, Kumar AKA. Ventilator-associatedPneumonia and Lung Ultrasound: Finally, What is between the EarsMatters. Indian J Crit Care Med 2021;25(9):1075-1076.

An automated retrospective VAE-surveillance tool for future quality improvement studies

Ventilator-associated pneumonia (VAP) is a frequent complication of mechanical ventilation and is associated with substantial morbidity and mortality. Accurate diagnosis of VAP relies in part on subjective diagnostic criteria. Surveillance according to ventilator-associated event (VAE) criteria may allow quick and objective benchmarking. Our objective was to create an automated surveillance tool for VAE tiers I and II on a large data collection, evaluate its diagnostic accuracy and retrospectively determine the yearly baseline VAE incidence. We included all consecutive intensive care unit admissions of patients with mechanical ventilation at Bern University Hospital, a tertiary referral center, from January 2008 to July 2016. Data was automatically extracted from the patient data management system and automatically processed. We created and implemented an application able to automatically analyze respiratory and relevant medication data according to the Centers for Disease Control protocol for VAE-surveillance. In a subset of patients, we compared the accuracy of automated VAE surveillance according to CDC criteria to a gold standard (a composite of automated and manual evaluation with mediation for discrepancies) and evaluated the evolution of the baseline incidence. The study included 22'442 ventilated admissions with a total of 37'221 ventilator days. 592 ventilator-associated events (tier I) occurred; of these 194 (34%) were of potentially infectious origin (tier II). In our validation sample, automated surveillance had a sensitivity of 98% and specificity of 100% in detecting VAE compared to the gold standard. The yearly VAE incidence rate ranged from 10.1-22.1 per 1000 device days and trend showed a decrease in the yearly incidence rate ratio of 0.96 (95% CI, 0.93-1.00, p = 0.03). This study demonstrated that automated VAE detection is feasible, accurate and reliable and may be applied on a large, retrospective sample and provided insight into long-term institutional VAE incidences. The surveillance tool can be extended to other centres and provides VAE incidences for performing quality control and intervention studies.

Attributable Mortality of Ventilator-associated Pneumonia. Replicating Findings, Revisiting Methods

Rationale: Estimating the impact of ventilator-associated pneumonia (VAP) from routinely collected intensive care unit (ICU) data is methodologically challenging.

Objectives: We aim to replicate earlier findings of limited VAP-attributable ICU mortality in an independent cohort. By refining statistical analyses, we gradually tackle different sources of bias.

Methods: Records of 2,720 adult patients admitted to Ghent University Hospital ICUs (2013–2017) and receiving mechanical ventilation within 48 hours after admission were extracted from linked Intensive Care Information System and Computer-based Surveillance and Alerting of Nosocomial Infections, Antimicrobial Resistance, and Antibiotic Consumption in the ICU databases. The VAP-attributable fraction of ICU mortality was estimated using a competing risk analysis that is restricted to VAP-free patients (approach 1), accounts for VAP onset by treating it as either a competing (approach 2) or censoring event (approach 3), or additionally adjusts for time-dependent confounding via inverse probability weighting (approach 4).

Results: A total of 210 patients (7.7%) acquired VAP. Based on benchmark approach 4, we estimated that (compared with current preventive measures) hypothetical eradication of VAP would lead to a relative ICU mortality reduction of 1.7% (95% confidence interval, −1.3 to 4.6) by Day 10 and of 3.6% (95% confidence interval, 0.7 to 6.5) by Day 60. Approaches 1–3 produced estimates ranging from −0.7% to 2.5% by Day 10 and from 5.2% to 5.5% by Day 60.

Conclusions: In line with previous studies using appropriate methodology, we found limited VAP-attributable ICU mortality given current state-of-the-art VAP prevention measures. Our study illustrates that inappropriate accounting of the time dependency of exposure and confounding of its effects may misleadingly suggest protective effects of early-onset VAP and systematically overestimate attributable mortality.

Association between mortality and highly antimicrobial-resistant bacteria in intensive care unit-acquired pneumonia

Data on the relationship between antimicrobial resistance and mortality remain scarce, and this relationship needs to be investigated in intensive care units (ICUs). The aim of this study was to compare the ICU mortality rates between patients with ICU-acquired pneumonia due to highly antimicrobial-resistant (HAMR) bacteria and those with ICU-acquired pneumonia due to non-HAMR bacteria. We conducted a multicenter, retrospective cohort study using the French National Surveillance Network for Healthcare Associated Infection in ICUs ("REA-Raisin") database, gathering data from 200 ICUs from January 2007 to December 2016. We assessed all adult patients who were hospitalized for at least 48 h and presented with ICU-acquired pneumonia caused by S. aureus, Enterobacteriaceae, P. aeruginosa, or A. baumannii. The association between pneumonia caused by HAMR bacteria and ICU mortality was analyzed using the whole sample and using a 1:2 matched sample. Among the 18,497 patients with at least one documented case of ICU-acquired pneumonia caused by S. aureus, Enterobacteriaceae, P. aeruginosa, or A. baumannii, 3081 (16.4%) had HAMR bacteria. The HAMR group was associated with increased ICU mortality (40.3% vs. 30%, odds ratio (OR) 95%, CI 1.57 [1.45-1.70], P < 0.001). This association was confirmed in the matched sample (3006 HAMR and 5640 non-HAMR, OR 95%, CI 1.39 [1.27-1.52], P < 0.001) and after adjusting for confounding factors (OR ranged from 1.34 to 1.39, all P < 0.001). Our findings suggest that ICU-acquired pneumonia due to HAMR bacteria is associated with an increased ICU mortality rate, ICU length of stay, and mechanical ventilation duration.

Attributable mortality of ICU acquired bloodstream infections: a propensity-score matched analysis

The mortality attributable to ICU-acquired bloodstream infection (BSI) differs between studies due to statistical methods used for cohort matching. Propensity-score matching has never been used to avoid eventual bias when studying BSI attributable mortality in the ICU. We conducted an observational prospective study over a 4-year period, on patients admitted for at least 48 h in 2 intensive care units. Based on risk factors for death in the ICU and for BSI, each patient with BSI was matched with 3 patients without BSI using propensity-score matching. We performed a competitive risk analysis to study BSI mortality attributable fraction. Of 2464 included patients, 71 (2.9%) had a BSI. Propensity-score matching was highly effective and group characteristics were fully balanced. Crude mortality was 36.6% in patients with BSI and 21.6% in propensity-score matched patients (p=0.018). Attributable mortality of BSI was 2.3% [1.2-4.0] and number needed to harm was 6.7. With Fine and Gray model, a higher risk for death was observed in patients with BSI than in propensity-score matched patients (sub distribution Hazard Ratio (sdHR) = 2.11; 95% CI [1.32-3.37] p = 0.002). Patients with BSI had a higher risk for death and BSI attributable mortality fraction was 2.3%.

Mortality review as a tool to assess the contribution of healthcare-associated infections to death: results of a multicentre validity and reproducibility study, 11 European Union countries, 2017 to 2018

IntroductionThe contribution of healthcare-associated infections (HAI) to mortality can be estimated using statistical methods, but mortality review (MR) is better suited for routine use in clinical settings. The European Centre for Disease Prevention and Control recently introduced MR into its HAI surveillance.AimWe evaluate validity and reproducibility of three MR measures.MethodsThe on-site investigator, usually an infection prevention and control doctor, and the clinician in charge of the patient independently reviewed records of deceased patients with bloodstream infection (BSI), pneumonia, Clostridioides difficile infection (CDI) or surgical site infection (SSI), and assessed the contribution to death using 3CAT: definitely/possibly/no contribution to death; WHOCAT: sole cause/part of causal sequence but not sufficient on its own/contributory cause but unrelated to condition causing death/no contribution, based on the World Health Organization's death certificate; QUANT: Likert scale: 0 (no contribution) to 10 (definitely cause of death). Inter-rater reliability was assessed with weighted kappa (wk) and intra-cluster correlation coefficient (ICC). Reviewers rated the fit of the measures.ResultsFrom 2017 to 2018, 24 hospitals (11 countries) recorded 291 cases: 87 BSI, 113 pneumonia , 71 CDI and 20 SSI. The inter-rater reliability was: 3CAT wk 0.68 (95% confidence interval (CI): 0.61-0.75); WHOCAT wk 0.65 (95% CI: 0.58-0.73); QUANT ICC 0.76 (95% CI: 0.71-0.81). Inter-rater reliability ranged from 0.72 for pneumonia to 0.52 for CDI. All three measures fitted 'reasonably' or 'well' in > 88%.ConclusionFeasibility, validity and reproducibility of these MR measures was acceptable for use in HAI surveillance.

Mortality due to hospital-acquired infection after cardiac surgery

PURPOSE

Hospital-acquired infections have been associated with significant morbidity and mortality in critically ill surgical patients. However, little is known about mortality due to hospital-acquired infections in cardiac surgery.

METHODS

We conducted a retrospective analysis of prospectively collected data from the cardiac surgery unit of a university hospital. All patients who underwent cardiac surgery over a 7-year period were included. Patients with hospital-acquired infections were matched 1:1 with patients with nonhospital-acquired infections based on risk factors for hospital-acquired infections and death after cardiac surgery using propensity score matching. We performed a competitive risk analysis to study the mortality fraction due to hospital-acquired infections.

RESULTS

Of 8853 patients who underwent cardiac surgery, 370 (4.2%) developed 500 postoperative infections (incidence density rate 4.2 hospital-acquired infections per 1000 patient-days). Crude hospital mortality was significantly higher in patients with hospital-acquired infections than in matched patients who did not develop hospital-acquired infections, 15.4% and 5.7%, respectively (P < .001). The in-hospital mortality fraction due to hospital-acquired infections in our cohort was 17.1% (12.3%-22.8%). Pseudomonas aeruginosa infection (hazard ratio, 2.09; 95% confidence interval, 1.23-3.49; P = .005), bloodstream infection (hazard ratio, 2.08; 95% confidence interval, 1.19-3.63; P = .010), and pneumonia (hazard ratio, 1.68; 95% confidence interval, 1.02-2.77; P = .04) were each independently associated with increased hospital mortality.

CONCLUSIONS

Although hospital-acquired infections are relatively uncommon after cardiac surgery (4.2%), these infections have a major impact on postoperative mortality (attributable mortality fraction, 17.1%).

A Comparison of the Mortality Risk Associated With Ventilator-Acquired Bacterial Pneumonia and Nonventilator ICU-Acquired Bacterial Pneumonia

OBJECTIVES

To investigate the respective impact of ventilator-associated pneumonia and ICU-hospital-acquired pneumonia on the 30-day mortality of ICU patients.

DESIGN

Longitudinal prospective studies.

SETTING

French ICUs.

PATIENTS

Patients at risk of ventilator-associated pneumonia and ICU-hospital-acquired pneumonia.

INTERVENTIONS

The first three episodes of ventilator-associated pneumonia or ICU-hospital-acquired pneumonia were handled as time-dependent covariates in Cox models. We adjusted using the case-mix, illness severity, Simplified Acute Physiology Score II score at admission, and procedures and therapeutics used during the first 48 hours before the risk period. Baseline characteristics of patients with regard to the adequacy of antibiotic treatment were analyzed, as well as the Sequential Organ Failure Assessment score variation in the 2 days before the occurrence of ventilator-associated pneumonia or ICU-hospital-acquired pneumonia. Mortality was also analyzed for Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species(ESKAPE) and P. aeruginosa pathogens.

MEASUREMENTS AND MAIN RESULTS

Of 14,212 patients who were admitted to the ICUs and who stayed for more than 48 hours, 7,735 were at risk of ventilator-associated pneumonia and 9,747 were at risk of ICU-hospital-acquired pneumonia. Ventilator-associated pneumonia and ICU-hospital-acquired pneumonia occurred in 1,161 at-risk patients (15%) and 176 at-risk patients (2%), respectively. When adjusted on prognostic variables, ventilator-associated pneumonia (hazard ratio, 1.38 (1.24-1.52); p < 0.0001) and even more ICU-hospital-acquired pneumonia (hazard ratio, 1.82 [1.35-2.45]; p < 0.0001) were associated with increased 30-day mortality. The early antibiotic therapy adequacy was not associated with an improved prognosis, particularly for ICU-hospital-acquired pneumonia. The impact was similar for ventilator-associated pneumonia and ICU-hospital-acquired pneumonia mortality due to P. aeruginosa and the ESKAPE group.

CONCLUSIONS

In a large cohort of patients, we found that both ICU-hospital-acquired pneumonia and ventilator-associated pneumonia were associated with an 82% and a 38% increase in the risk of 30-day mortality, respectively. This study emphasized the importance of preventing ICU-hospital-acquired pneumonia in nonventilated patients.

Using flexible methods to determine risk factors for ventilator-associated pneumonia in the Netherlands

Seven hospitals participated in the Dutch national surveillance for ventilator-associated pneumonia (VAP) and its risk factors. We analysed time-independent and time-dependent risk factors for VAP using the standard Cox regression and the flexible Weighted Cumulative Effects method (WCE) that evaluates both current and past exposures. The prospective surveillance of intensive care patients aged ≥16 years and ventilated ≥48 hours resulted in the inclusion of 940 primary ventilation periods, comprising 7872 ventilation days. The average VAP incidence density was 10.3/1000 ventilation days. Independent risk factors were age (16–40 years at increased risk: HR 2.42 95% confidence interval 1.07–5.50), COPD (HR 0.19 [0.04–0.78]), current sedation score (higher scores at increased risk), current selective oropharyngeal decontamination (HR 0.19 [0.04–0.91]), jet nebulizer (WCE, decreased risk), intravenous antibiotics for selective decontamination of the digestive tract (ivSDD, WCE, decreased risk), and intravenous antibiotics not for SDD (WCE, decreased risk). The protective effect of ivSDD was afforded for 24 days with a delay of 3 days. For some time-dependent variables, the WCE model was preferable over standard Cox proportional hazard regression. The WCE method can furthermore increase insight into the active time frame and possible delay herein of a time-dependent risk factor.

Identification of respiratory microbiota markers in ventilator-associated pneumonia

PURPOSE

To compare bacteria recovered by standard cultures and metataxonomics, particularly with regard to ventilator-associated pneumonia (VAP) pathogens, and to determine if the presence of particular bacteria or microbiota in tracheal and oropharyngeal secretions during the course of intubation was associated with the development of VAP.

METHODS

In this case-control study, oropharyngeal secretions and endotracheal aspirate were collected daily in mechanically ventilated patients. Culture and metataxonomics (16S rRNA gene-based taxonomic profiling of bacterial communities) were performed on serial upper respiratory samples from patients with late-onset definite VAP and their respective controls.

RESULTS

Metataxonomic analyses showed that a low relative abundance of Bacilli at the time of intubation in the oropharyngeal secretions was strongly associated with the subsequent development of VAP. On the day of VAP, the quantity of human and bacterial DNA in both tracheal and oropharyngeal secretions was significantly higher in patients with VAP than in matched controls with similar ventilation times. Molecular techniques identified the pathogen(s) of VAP found by culture, but also many more bacteria, classically difficult to culture, such as Mycoplasma spp. and anaerobes.

CONCLUSIONS

Molecular analyses of respiratory specimens identified markers associated with the development of VAP, as well as important differences in the taxa abundance between VAP and controls. Further prospective trials are needed to test the predictive value of these markers, as well as the relevance of uncultured bacteria in the pathogenesis of VAP.

Comparative efficacy of doripenem versus meropenem for hospital-acquired and ventilator-associated pneumonia

BACKGROUND

Doripenem shows good in vitro activity against common nosocomial pathogens, such as extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae, Pseudomonas aeruginosa, and Acinetobacter baumannii. However, the use of doripenem for hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) remains controversial. The aim of this study was to compare the efficacy and safety between doripenem and meropenem for patients with HAP or VAP.

METHODS

Adult patients diagnosed with HAP and VAP at National Taiwan University Hospital, who received doripenem or meropenem for more than 48 h between January 2015 and November 2017, were retrospectively reviewed. All-cause mortality on the 30th day was used as the primary outcome measurements.

RESULTS

Fifty-seven patients with doripenem and 252 patients with meropenem were analyzed. Compared to the meropenem group, the doripenem group was younger and had a higher Sequential Organ Failure Assessment (SOFA) score. Multivariable Cox regression analysis revealed that presence of solid organ malignancies (adjusted hazard ratio [AHR], 1.82; 95% CI, 1.04-3.19, p = 0.003) and SOFA score (AHR, 1.10; 95% CI, 1.03-1.17, p = 0.003) were independent factors associated with mortality. There was no survival difference of 30-day mortality between patients receiving doripenem and meropenem for HAP or VAP (log-rank p = 0.113). However, a poorer outcome was observed among patients with hematological disease in the doripenem group (log-rank p = 0.012).

CONCLUSION

Our results demonstrate that doripenem has similar efficacy as meropenem in HAP or VAP patients. With an aim to enhance antibiotic diversity, doripenem could be an alternative choice for patients with HAP or VAP, except for those with hematological malignancies.

Randomized Trial of Ceftazidime-Avibactam vs Meropenem for Treatment of Hospital-Acquired and Ventilator-Associated Bacterial Pneumonia (REPROVE): Analyses per US FDA-Specified End Points

Background

Hospital-acquired and ventilator-associated pneumonia (HAP/VAP; nosocomial pneumonia) due to Gram-negative pathogens are associated with significant morbidity and mortality; treatment options for multidrug-resistant infections are limited. The pivotal phase III REPROVE trial evaluated the efficacy of ceftazidime-avibactam (CAZ-AVI) vs meropenem in the treatment of patients with HAP/VAP. Study results for prespecified analyses per US Food and Drug Administration–recommended trial end points are reported here.

Methods

Hospitalized adults with HAP/VAP proven or suspected to be caused by a Gram-negative pathogen were randomized 1:1 to receive CAZ-AVI or meropenem for 7 to 14 days. The primary outcome was 28-day all-cause mortality in the intent-to-treat (ITT) population. Secondary outcomes included clinical cure at test of cure (TOC) in the ITT and microbiological ITT (micro-ITT) populations, and safety and tolerability throughout the study.

Results

hundred seventy randomized patients received treatment and were included in the ITT population (CAZ-AVI, n = 436; meropenem, n = 434). CAZ-AVI was noninferior to meropenem for the primary end point (28-day all-cause mortality; ITT) based on the prespecified 10% noninferiority margin (CAZ-AVI, 9.6%; meropenem, 8.3%; difference, 1.5%; 95% confidence interval [CI], –2.4% to 5.3%) and for the clinical cure end point in the ITT population based on a prespecified –10% noninferiority margin (CAZ-AVI, 67.2%; meropenem, 69.1%; difference, −1.9%; 95% CI, –8.1% to 4.3%). Clinical cure rates at TOC for patients infected with CAZ-nonsusceptible pathogens were similar (CAZ-AVI, 75.5%; meropenem, 71.2%; micro-ITT). Safety data were consistent with established safety profiles for both agents.

Conclusions

CAZ-AVI provides an important new treatment option for HAP/VAP due to Gram-negative pathogens, including CAZ-nonsusceptible strains.

Risk factors for outcomes of acute respiratory distress syndrome patients: a retrospective study

Background

The determination of risk factors for acute respiratory distress syndrome (ARDS) patients remains a challenge. Our study aims to explore the epidemiology and risk factors affecting outcomes of ARDS patients and provide a theoretical basis for patients' prognosis.

Methods

This retrospective study included 207 ARDS patients admitted to the general intensive care unit (ICU) in the Second Affiliated Hospital of Harbin Medical University from Jan 1st, 2016 to Jan 1st, 2017. The criteria were defined according to the Berlin Definition, and clinical data were collected from the medical record system. The mortality rate and duration of mechanical ventilation were compared in ARDS patients. Furthermore, logistic regression analysis was applied to screen clinically accessible risk factors for survival and duration of mechanical ventilation.

Results

The total mortality in ARDS patients was 39.13% (81/207) compared to 13.57% (151/1,113) in the whole ICU population. The period prevalence of mild, moderate and severe ARDS was 39.61% (82/207), 37.20% (77/207) and 23.19% (48/207), respectively. Logistic regression analysis showed that acute physiology and chronic health evaluation II (APACHE II) score (OR 3.4316; 95% CI: 1.3130-8.9686; P=0.0119), number of organ failure (OR 3.4928; 95% CI: 1.9775-6.1693; P<0.0001), mean arterial pressure (MAP) (OR 5.1049; 95% CI: 1.8317-14.2274; P=0.0018), driving pressure (OR 6.0017; 95% CI: 2.1746-16.5641; P=0.0005) and lactate level (OR 4.0754; 95% CI: 1.6114-10.3068; P=0.0030) were influence factors for survival; severity of ARDS (OR 1.6715; 95% CI: 1.0307-2.7108; P=0.0373), ventilator-associated pneumonia (VAP) (OR 7.3746; 95% CI: 2.9799-18.2505; P<0.0001) and transfusion history (OR 2.2822; 95% CI: 1.0462-4.9783; P=0.0381) were influence factors for duration of mechanical ventilation.

Conclusions

Higher APACHE II score, more organ failures, lower MAP, higher driving pressure and higher lactate level are risk factors for survival. Higher severity of ARDS, VAP and transfusion history are risk factors for prolonged duration of mechanical ventilation. Application of these parameters would enable intensivists to treat their patients more precisely and comprehensively.

Pediatric Ventilator-Associated Events: Analysis of the Pediatric Ventilator-Associated Infection Data

OBJECTIVES

To compare the prevalence of infection applying the proposed pediatric ventilator-associated events criteria versus clinician-diagnosed ventilator-associated infection to subjects in the pediatric ventilator-associated infection study.

DESIGN

Analysis of prospectively collected data from the pediatric ventilator-associated infection study.

SETTING

PICUs of 47 hospitals in the United States, Canada, and Australia.

PATIENTS

Two-hundred twenty-nine children ventilated for greater than 48 hours who had respiratory secretion cultures performed to evaluate for suspected ventilator-associated infection.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Applying the proposed pediatric ventilator-associated event criteria, 15 of 229 subjects in the ventilator-associated infection study qualified as "ventilator-associated condition" and five of 229 (2%) met criteria for "infection-related ventilator-associated complication." This was compared with 89 of 229 (39%) diagnosed as clinical ventilator-associated infection (Kappa = 0.068). Ten of 15 subjects identified as ventilator-associated condition did not meet criteria for infection-related ventilator-associated complication primarily because they did not receive 4 days of antibiotics. Ventilator-associated condition subjects were similar demographically to nonventilator-associated condition subjects and had similar mortality (13% vs 10%), PICU-free days (6.9 ± 7.7; interquartile range, 0-14 vs 9.8 ± 9.6; interquartile range, 0-19; p = 0.25), but fewer ventilator-free days (6.6 ± 9.3; interquartile range, 1-15 vs 12.4 ± 10.7; interquartile range, 0-22; p = 0.04). The clinical ventilator-associated infection diagnosis in the ventilator-associated infection study was associated with fewer PICU-free days but no difference in mortality or ventilator-free days.

CONCLUSIONS

The ventilator-associated event criteria appear to be insensitive to the clinical diagnosis of ventilator-associated infection. Differentiation between ventilator-associated condition and infection-related ventilator-associated complication was primarily determined by the clinician decision to treat with antibiotics rather than clinical signs and symptoms. The utility of the proposed pediatric ventilator-associated event criteria as a surrogate for ventilator-associated infection criteria is unclear.

Ventilator-Associated Pneumonia and Events in Pediatric Intensive Care: A Single Center Study

OBJECTIVES

Ventilator-associated pneumonia is the second most common nosocomial infection in pediatric intensive care. The Centers for Disease Control and Prevention recently issued diagnosis criteria for pediatric ventilator-associated pneumonia and for ventilator-associated events in adults. The objectives of this pediatric study were to determine the prevalence of ventilator-associated pneumonia using these new Centers for Disease Control and Prevention criteria, to describe the risk factors and management of ventilator-associated pneumonia, and to assess a simpler method to detect ventilator-associated pneumonia with ventilator-associated event in critically ill children.

DESIGN

Retrospective, observational, single-center.

SETTING

PICU in a tertiary-care university hospital.

PATIENTS

Consecutive critically ill children mechanically ventilated for greater than or equal to 48 hours between November 2013 and November 2015.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of 304 patients mechanically ventilated for greater than or equal to 48 hours, 284 were included. Among them, 30 (10.6%) met clinical and radiologic Centers for Disease Control and Prevention criteria for ventilator-associated pneumonia, yielding an prevalence of 7/1,000 mechanical ventilation days. Median time from mechanical ventilation onset to ventilator-associated pneumonia diagnosis was 4 days. Semiquantitative culture of tracheal aspirates was the most common microbiological technique. Gram-negative bacteria were found in 60% of patients, with a predominance of Haemophilus influenzae and Pseudomonas aeruginosa. Antibiotic therapy complied with adult guidelines. Compared with patients without ventilator-associated pneumonia, those with ventilator-associated pneumonia had significantly longer median durations of mechanical ventilation (15 vs 6 d; p < 0.001) and PICU stay (19 vs 9 d; p < 0.001). By univariate analysis, risk factors for ventilator-associated pneumonia were younger age, reintubation, acute respiratory distress syndrome, and continuous enteral feeding. Among the 30 patients with ventilator-associated pneumonia, 17 met adult ventilator-associated event's criteria (sensitivity, 56%).

CONCLUSIONS

Ventilator-associated pneumonia is associated with longer times on mechanical ventilation and in the PICU. Using the ventilator-associated event criteria is of interest to rapidly screen for ventilator-associated pneumonia in children. However, sensitivity must be improved by adapting these criteria to children.

Diagnostic efficacy of serum procalcitonin, C-reactive protein concentration and clinical pulmonary infection score in Ventilator-Associated Pneumonia

OBJECTIVE

The aim of this study was to evaluate the diagnostic efficacy of serum procalcitonin (PCT), c-reactive protein (CRP) concentration and clinical pulmonary infection score(CPIS) in ventilator-associated pneumonia(VAP).

METHODS

Forty-nine patients who were admitted to the intensive care unit (ICU) of Zhejiang Hospital with suspected VAP were recruited in this study. The serum level of PCT and CRP of all patients were measured and CPIS was calculated at the time of VAP suspected diagnosis. Of the included 49 patients, 24 were finally confirmed of VAP by microbiology assay. And the other 25 patients were considered as clinical suspected VAP without microbiology confirmation. The diagnostic sensitivity, specificity and area under the receiver operating characteristic (ROC) curve (AUC) were calculated using the serum PCT, CRP concentration and CPIS. The correlation among serum PCT, CRP concentration and CPIS were also evaluated by Spearson correlation test.

RESULTS

A total of 100 bronchoscopic aspiration sputum specimen were examined in bacterial culture. 30 samples were found with suspected pathogenic bacteria. Six samples were found with 2 types of suspected pathogenic bacteria. PCT serum concentration and CPIS score were significantly different (P<0.05) between the patient group [1.4 (0.68 ∼ 2.24), 6.0 (4.25 ∼ 8.00)] and the control group [0.4 (0.17 ∼ 1.39), 3.0 (1.00 ∼ 5.00)] ; However, the serum CRP [102.8(66.75 ∼ 130.90) vs 86.1(66.95 ∼ 110.10)] was not statistically different between the two groups (P>0.05). A significant correlation was found between serum PCT and CRP concentrations (r=0.55, P<0.01), but not between PCT vs CPIS and CRP vs CPIS (p>0.05). The diagnostic sensitivity, specificity and AUC were 72.0%, 75.0%, 0.81 (0.69 ∼ 0.93) for CPIS; 60.0%, 87.5%, 0.76 (0.62 ∼ 0.90) for PCT and 68.0%, 58.3%, 0.59 (0.43 ∼ 0.76) for CRP.

CONCLUSION

PCT serum level and CPIS score are elevated in VAP patients and could therefore represent potential biomarkers for VAP early diagnosis.

Thrombospondin-1 protects against pathogen-induced lung injury by limiting extracellular matrix proteolysis

Acute lung injury is characterized by excessive extracellular matrix proteolysis and neutrophilic inflammation. A major risk factor for lung injury is bacterial pneumonia. However, host factors that protect against pathogen-induced and host-sustained proteolytic injury following infection are poorly understood. Pseudomonas aeruginosa (PA) is a major cause of nosocomial pneumonia and secretes proteases to amplify tissue injury. We show that thrombospondin-1 (TSP-1), a matricellular glycoprotein released during inflammation, dose-dependently inhibits PA metalloendoprotease LasB, a virulence factor. TSP-1-deficient (Thbs1-/-) mice show reduced survival, impaired host defense, and increased lung permeability with exaggerated neutrophil activation following acute intrapulmonary PA infection. Administration of TSP-1 from platelets corrects the impaired host defense and aberrant injury in Thbs1-/- mice. Although TSP-1 is cleaved into 2 fragments by PA, TSP-1 substantially inhibits Pseudomonas elastolytic activity. Administration of LasB inhibitor, genetic disabling of the PA type II secretion system, or functional deletion of LasB improves host defense and neutrophilic inflammation in mice. Moreover, TSP-1 provides an additional line of defense by directly subduing host-derived proteolysis, with dose-dependent inhibition of neutrophil elastase from airway neutrophils of mechanically ventilated critically ill patients. Thus, a host matricellular protein provides dual levels of protection against pathogen-initiated and host-sustained proteolytic injury following microbial trigger.

Update on ventilator-associated pneumonia

Ventilator-associated pneumonia (VAP) is the most frequent life-threatening nosocomial infection in intensive care units. The diagnostic is difficult because radiological and clinical signs are inaccurate and could be associated with various respiratory diseases. The concept of infection-related ventilator-associated complication has been proposed as a surrogate of VAP to be used as a benchmark indicator of quality of care. Indeed, bundles of prevention measures are effective in decreasing the VAP rate. In case of VAP suspicion, respiratory secretions must be collected for bacteriological secretions before any new antimicrobials. Quantitative distal bacteriological exams may be preferable for a more reliable diagnosis and therefore a more appropriate use antimicrobials. To improve the prognosis, the treatment should be adequate as soon as possible but should avoid unnecessary broad-spectrum antimicrobials to limit antibiotic selection pressure. For empiric treatments, the selection of antimicrobials should consider the local prevalence of microorganisms along with their associated susceptibility profiles. Critically ill patients require high dosages of antimicrobials and more specifically continuous or prolonged infusions for beta-lactams. After patient stabilization, antimicrobials should be maintained for 7-8 days. The evaluation of VAP treatment based on 28-day mortality is being challenged by regulatory agencies, which are working on alternative surrogate endpoints and on trial design optimization.

Protective effect of early low-dose hydrocortisone on ventilator-associated pneumonia in the cancer patients: a propensity score analysis

Background

Ventilator-associated pneumonia (VAP) is a care-related event that could be promoted by immune suppression caused by critical diseases, malignancies and cancer treatments. Low dose of hydrocortisone was proposed for modulation of immune response in the critically ill population.

Methods

In this monocentric observational study, all cancer patients mechanically ventilated for more than 48 h were included. Effect of low-dose hydrocortisone administered during the first 48 h of mechanical ventilation was evaluated applying inverse probability weighting analysis after propensity score assessment. VAP impact on 1-year mortality, ICU length of stay and mechanical ventilation duration was secondarily determined.

Results

Within this cohort, 190 cancer patients were followed. VAP was confirmed in 22.1% of cases in the early hydrocortisone group and confirmed in 42.6% of cases in the no or late hydrocortisone group. Early hydrocortisone exhibited a protective effect on the risk of VAP (OR 0.23; 95% CI 0.12–0.44; P < 0.0001). VAP was associated with 1-year mortality (HR 1.60; 95% CI 1.10–2.34; P = 0.017) and increased ICU length of stay (mean extra length of stay: 4.2 days; 95% CI 0.6–7.8).

Conclusions

Immune modulation with low-dose hydrocortisone administered in the first days of mechanical ventilation could protect from VAP occurrence in cancer patients.

Budesonide Nebulization in the Treatment of Neonatal Ventilator Associated Pneumonia

Objective:

To investigate the clinical effect of budesonide nebulization in the treatment of ventilator associated pneumonia of newborns and its safety.

Methods:

Forty-five newborns who had ventilator associated pneumonia and were admitted into the Binzhou People’s Hospital between May 2014 and May 2015 were selected and included as an observation group. Moreover, another forty-five newborns who had ventilator associated pneumonia but did not undergo budesonide treatment in 2014 were randomly selected and included as a control group. Patients in the observation group were given budesonide suspension nebulization in addition to the conventional treatment. The evaluation indicators for therapeutic effect were compared between the two groups. The changes of head circumference, height and weight and death rate were observed by follow up after treatment.

Results:

The mechanical ventilation time, time for recovering from chest X-ray scan and hospitalization time of patients in the observation group were shorter than that of the control group, and the difference had statistical significance (P<0.05). The oxygen index of the patients in the observation group was significantly improved compared to that of the control group, and the difference had statistical significance (P<0.05). Patients in the two groups were followed up for six months after discharge. The head circumference, height and weight of the patients in the observation group in the 3^rd and 6^th month were compared to those of the control group, suggesting no significant differences (P>0.05). The cumulative death rate of the observation group in the 6^th month after treatment was significantly lower than that of the control group, and the difference had statistical significance (P<0.05).

Conclusion:

Treating ventilator associated pneumonia of newborns with budesonide nebulization can effectively shorten mechanical ventilation time, time for recovering from chest X-ray scan and hospitalization time, improve pulmonary diffusion function and reduce the death rate, without affecting the growth and development of patients in the future.

Appropriate endpoints for evaluation of new antibiotic therapies for severe infections: a perspective from COMBACTE's STAT-Net

PURPOSE

In this era of rising antimicrobial resistance, slowly refilling antibiotic development pipelines, and an aging population, we need to ensure that randomized clinical trials (RCTs) determine the added benefit of new antibiotic agents effectively and in a valid way, especially for severely ill patients. Unfortunately, universally accepted endpoints for the evaluation of new drugs in severe infections are lacking.

METHODS

We review and discuss the current practices and challenges regarding endpoints in RCTs in this field and propose novel approaches.

RESULTS

Usual endpoints actually recommended for drug development suffer from important flaws. Mortality requires large sample size and only partly related to the infectious process. Clinical cure rate is highly subjective in critically ill patients where symptoms may be related to other intercurrent events. Currently, composite endpoints, hierarchical nested designs, and competing risks analysis seem to be the most promising new tools for designing and analyzing clinical trials in this area, although they require further validation.

CONCLUSION

Regulatory authorities, pharmaceutical companies, and clinicians need to agree on the most appropriate clinical endpoints for severe infections to ensure efficient approval of new, effective antibiotic agents.

Biofilms in ventilator-associated pneumonia

Biofilms develop rapidly following endotracheal intubation and represent a persistent source of unnecessary pathogens in the critically ill patient. Overall, the imbalance in the lung microbiome caused by an endotracheal tube and its role in biofilm formation and in ventilator-associated pneumonia is still unclear. Although endotracheal tube–biofilm preventive measures are being tested, no outcome impact has ever been demonstrated, and therefore no approach has been clinically recommended. Nonetheless, an accurate description of the actual biofilm morphology in vivo could be useful to implement effective preventive measures. The combined use of in vitro biofilm models, in vivo animal models and clinical research is vitally important to the attainment of a comprehensive understanding of biofilms in ventilator-associated pneumonia in the near future.

Breath analysis for noninvasively differentiating Acinetobacter baumannii ventilator-associated pneumonia from its respiratory tract colonization of ventilated patients

A number of multiresistant pathogens including Acinetobacter baumannii (A. baumannii) place a heavy burden on ventilator-associated pneumonia (VAP) patients in intensive care units (ICU). It is critically important to differentiate between bacterial infection and colonization to avoid prescribing unnecessary antibiotics. Quantitative culture of lower respiratory tract (LRT) specimens, however, requires invasive procedures. Nowadays, volatile organic compounds (VOCs) have been studied in vitro and in vivo to identify pathogen-derived biomarkers. Therefore, an exploratory pilot study was conceived for a proof of concept that the appearance and level of A. baumannii-derived metabolites might be correlated with the presence of the pathogen and its ecological niche (i.e. the infection and colonization states) in ICU ventilated patients. Twenty patients with A. baumannii VAP (infection group), 20 ventilated patients with LRT A. baumannii colonization (colonization group) and 20 ventilated patients with neurological disorders, but without pneumonia or A. baumannii colonization (control group) were enrolled in the in vivo pilot study. A clinical isolate of A. baumannii strains was used for the in vitro culture experiment. The adsorptive preconcentration (solid-phase microextraction fiber and Tenax(®) TA) and analysis technique of gas chromatography-mass spectrometry were applied in the studies. Breath profiles could be visually differentiated between A. baumannii cultivation in vitro and culture medium, and among in vivo groups. In the in vitro experiment, nine compounds of interest (2,5-dimethyl-pyrazine, 1-undecene, isopentyl 3-methylbutanoate, decanal, 1,3-naphthalenediol, longifolene, tetradecane, iminodibenzyl and 3-methyl-indene) in the headspace were found to be possible A. baumannii derivations. While there were eight target VOCs (1-undecene, nonanal, decanal, 2,6,10-trimethyl-dodecane, 5-methyl-5-propyl-nonane, longifolene, tetradecane and 2-butyl-1-octanol) exhibiting characteristics of A. baumannii VAP derivations. The selected VOC profile in vivo could be adopted to efficiently differentiate the presence of LRT A. baumannii from its absence, and LRT A. baumannii infection from its colonization (AUC  =  0.89 and 0.88, respectively). It is not feasible to simply transfer the metabolic biomarkers from the in vitro condition to in vivo. The direct detection of exhaled A. baumannii-derived VOCs may be adopted for an early alert of the LRT bacterial presence in ventilated ICU patients, and even in different parasitic states of A. baumannii (i.e. infection and colonization). However, further refinement and validation are required before its clinical use.

Can we improve clinical outcomes in patients with pneumonia treated with antibiotics in the intensive care unit?

INTRODUCTION

Pneumonia in the intensive care unit (ICU) is associated with high morbidity, mortality and healthcare costs. However, treatment outcomes with conventional intravenous (IV) antibiotics remain suboptimal, and there is an urgent need for improved therapy options.

AREAS COVERED

We review how clinical outcomes in patients with pneumonia treated in the ICU could be improved; we discuss the importance of choosing appropriate outcome measures in clinical trials, highlight the current suboptimal outcomes in patients with pneumonia, and outline potential solutions. We have included key studies and papers based on our clinical expertise, therefore a systematic literature review was not conducted. Expert commentary: Reasons for poor outcomes in patients with nosocomial pneumonia in the ICU include inappropriate initial therapy, increasing bacterial resistance and the complexities of IV dosing in critically ill patients. Robust clinical trial endpoints are needed to enable an accurate assessment of the success of new treatment approaches, but progress in this field has been slow. In addition, only very few new antimicrobials are currently in development for nosocomial pneumonia; two potential alternative solutions to improve outcomes could therefore include the optimization of pharmacokinetic/pharmacodynamics (PK/PD) and dosing of existing therapies, and the refinement of antimicrobial delivery by inhalation.

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.

The use of extracorporeal carbon dioxide removal to avoid intubation in patients failing non-invasive ventilation--a cost analysis

Background

To evaluate the economic implications of the pre-emptive use of extracorporeal carbon dioxide removal (ECCO₂R) to avoid invasive mechanical ventilation (IMV) in patients with hypercapnic ventilatory insufficiency failing non-invasive ventilation (NIV).

Methods

Retrospective ancillary cost analysis of data extracted from a recently published multicentre case–control-study (n = 42) on the use of arterio-venous ECCO₂R to avoid IMV in patients with acute on chronic ventilatory failure. Cost calculations were based on average daily treatment costs for intensive care unit (ICU) and normal medical wards as well as on the specific costs of the ECCO₂R system.

Results

In the group treated with ECCO₂R IMV was avoided in 90 % of cases and mean hospital length of stay (LOS) was shorter than in the matched control group treated with IMV (23.0 vs. 42.0 days). The overall average hospital treatment costs did not differ between the two groups (41.134 vs. 39.366 €, p = 0.8). A subgroup analysis of patients with chronic obstructive pulmonary disease (COPD) revealed significantly lower median ICU length of stay (11.0 vs. 35.0 days), hospital length of stay (17.5 vs. 51.5 days) and treatment costs for the ECCO₂R group (19.610 vs. 46.552 €, p = 0.01).

Conclusions

Additional costs for the use of arterio-venous ECCO₂R to avoid IMV in patients with acute-on-chronic ventilatory insufficiency failing NIV may be offset by a cost reducing effect of a shorter length of ICU and hospital stay.

Genetic Manipulation of Stenotrophomonas maltophilia

Stenotrophomonas maltophilia is a Gram-negative, aerobic, motile, environmental bacterium that is emerging as an important nosocomial pathogen with high rates of attributable mortality in severely ill patients. S. maltophilia is of particular concern to patients suffering from cystic fibrosis (CF) as it has been shown to colonize airway epithelial and establish a chronic infection. Here we describe several molecular techniques for the genetic manipulation of this bacterium, including DNA extraction, RNA extraction, conjugation of plasmids from Escherichia coli and allelic exchange.

Prevention of ventilator-associated pneumonia and ventilator-associated conditions: a randomized controlled trial with subglottic secretion suctioning

OBJECTIVES

Ventilator-associated pneumonia diagnosis remains a debatable topic. New definitions of ventilator-associated conditions involving worsening oxygenation have been recently proposed to make surveillance of events possibly linked to ventilator-associated pneumonia as objective as possible. The objective of the study was to confirm the effect of subglottic secretion suctioning on ventilator-associated pneumonia prevalence and to assess its concomitant impact on ventilator-associated conditions and antibiotic use.

DESIGN

Randomized controlled clinical trial conducted in five ICUs of the same hospital.

PATIENTS

Three hundred fifty-two adult patients intubated with a tracheal tube allowing subglottic secretion suctioning were randomly assigned to undergo suctioning (n = 170, group 1) or not (n = 182, group 2).

MAIN RESULTS

During ventilation, microbiologically confirmed ventilator-associated pneumonia occurred in 15 patients (8.8%) of group 1 and 32 patients (17.6%) of group 2 (p = 0.018). In terms of ventilatory days, ventilator-associated pneumonia rates were 9.6 of 1,000 ventilatory days and 19.8 of 1,000 ventilatory days, respectively (p = 0.0076). Ventilator-associated condition prevalence was 21.8% in group 1 and 22.5% in group 2 (p = 0.84). Among the 47 patients with ventilator-associated pneumonia, 25 (58.2%) experienced a ventilator-associated condition. Neither length of ICU stay nor mortality differed between groups; only ventilator-associated condition was associated with increased mortality. The total number of antibiotic days was 1,696 in group 1, representing 61.6% of the 2,754 ICU days, and 1,965 in group 2, representing 68.5% of the 2,868 ICU days (p < 0.0001).

CONCLUSIONS

Subglottic secretion suctioning resulted in a significant reduction of ventilator-associated pneumonia prevalence associated with a significant decrease in antibiotic use. By contrast, ventilator-associated condition occurrence did not differ between groups and appeared more related to other medical features than ventilator-associated pneumonia.

How to avoid microaspiration? A key element for the prevention of ventilator-associated pneumonia in intubated ICU patients

Microaspiration of subglottic secretions through channels formed by folds in high volume-low pressure poly-vinyl chloride cuffs of endotracheal tubes is considered a significant pathogenic mechanism of ventilator-associated pneumonia (VAP). Therefore a series of prevention measures target the avoidance of microaspiration. However, although some of these can minimize microaspiration, benefits in terms of VAP prevention are not always obvious. Polyurethane-cuffed endotracheal tubes successfully reduce microaspiration but high quality data demonstrating VAP rate reduction are lacking. An analogous conclusion can be made regarding taper-shaped cuffs compared with classic barrel-shaped cuffs. More clinical data regarding these endotracheal tube designs are needed to demonstrate clinical value in addition to in vitro-based evidence. The clinical usefulness of endotracheal tubes developed for subglottic secretions drainage is established in multiple studies and confirmed by meta-analysis. Any change in cuff design will fail to prevent microaspiration if the cuff is insufficiently inflated. At least one well-designed trial demonstrated that continuous cuff pressure monitoring and control decrease the risk of VAP. Gel lubrication of the cuff prior to intubation temporarily hampers microaspiration through sludging the channels formed by folds in high volume-low pressure cuffs. As the beneficial effect of gel lubrication is temporarily, its potential to reduce VAP risk is probably nonsignificant. A minimum positive end-expiratory pressure of at least 5 cmH₂O can be recommended as it reduces the risk of microaspiration in vitro and in vivo. One randomized controlled study demonstrated a reduced risk of VAP in patients ventilated with PEEP (5–8 cmH₂O). Regarding head-of-bed elevation, it can be recommended to avoid supine positioning. Whether a 45° head-of-bed elevation is to be preferred above 25-30° head-of-bed elevation remains unproven. Finally, the routine monitoring of gastric residual volumes in mechanically ventilated patients receiving enteral nutrition cannot be recommended.

European perspective and update on the management of nosocomial pneumonia due to methicillin-resistant Staphylococcus aureus after more than 10 years of experience with linezolid

Methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of antimicrobial-resistant hospital-acquired infections worldwide and remains a public health priority in Europe. Nosocomial pneumonia (NP) involving MRSA often affects patients in intensive care units with substantial morbidity, mortality and associated costs. A guideline-based approach to empirical treatment with an antibacterial agent active against MRSA can improve the outcome of patients with MRSA NP, including those with ventilator-associated pneumonia. New methods may allow more rapid or sensitive diagnosis of NP or microbiological confirmation in patients with MRSA NP, allowing early de-escalation of treatment once the pathogen is known. In Europe, available antibacterial agents for the treatment of MRSA NP include the glycopeptides (vancomycin and teicoplanin) and linezolid (available as an intravenous or oral treatment). Vancomycin has remained a standard of care in many European hospitals; however, there is evidence that it may be a suboptimal therapeutic option in critically ill patients with NP because of concerns about its limited intrapulmonary penetration, increased nephrotoxicity with higher doses, as well as the emergence of resistant strains that may result in increased clinical failure. Linezolid has demonstrated high penetration into the epithelial lining fluid of patients with ventilator-associated pneumonia and shown statistically superior clinical efficacy versus vancomycin in the treatment of MRSA NP in a phase IV, randomized, controlled study. This review focuses on the disease burden and clinical management of MRSA NP, and the use of linezolid after more than 10 years of clinical experience.

Higher clinical success in patients with ventilator-associated pneumonia due to methicillin-resistant Staphylococcus aureus treated with linezolid compared with vancomycin: results from the IMPACT-HAP study

Introduction

Controversy exists regarding optimal treatment for ventilator-associated pneumonia (VAP) due to methicillin-resistant Staphylococcus aureus (MRSA). The primary objective of this study was to compare clinical success of linezolid versus vancomycin for the treatment of patients with MRSA VAP.

Methods

This was a multicenter, retrospective, observational study of patients with VAP (defined according to Centers for Disease Control and Prevention criteria) due to MRSA who were treated with linezolid or vancomycin. MRSA VAP was considered when MRSA was isolated from a tracheal aspirate or bronchoalveolar lavage. Clinical success was evaluated by assessing improvement or resolution of signs and symptoms of VAP by day 14. After matching on confounding factors, logistic regression models were used to determine if an association existed between treatment arm and clinical success.

Results

A total of 188 patients were evaluated (101 treated with linezolid and 87 with vancomycin). The mean ± standard deviation Acute Physiology and Chronic Health Evaluation (APACHE) II score was 21 ± 11 for linezolid- and 19 ± 9 for vancomycin-treated patients (P = 0.041). Clinical success occurred in 85% of linezolid-treated patients compared with 69% of vancomycin-treated patients (P = 0.009). After adjusting for confounding factors, linezolid-treated patients were 24% more likely to experience clinical success than vancomycin-treated patients (P = 0.018).

Conclusions

This study adds to the evidence indicating that patients with MRSA VAP who are treated with linezolid are more likely to respond favorably compared with patients treated with vancomycin.

The lack of specificity of tracheal aspirates in the diagnosis of pulmonary infection in intubated children

OBJECTIVES

Ventilator-associated pneumonia is the first or second most commonly diagnosed nosocomial infection in the PICU. Centers for Disease Control diagnostic criteria include clinical signs or symptoms in conjunction with a "positive" tracheal aspirate, defined as more than 10 colony-forming units/mL of bacteria on quantitative culture and/or more than 25 polymorphonuclear neutrophils per low-power field on Gram stain. We hypothesized that tracheal aspirate cultures and Gram stains would not correlate with clinical signs and symptoms and would therefore not distinguish between colonization and infection.

DESIGN

Prospective observational study.

SETTING

PICU in an academic tertiary care center.

PATIENTS

Children intubated more than 48 hours.

INTERVENTIONS

Sequential tracheal aspirate quantitative cultures and Gram stains in conjunction with daily collection of concordant clinical signs and symptoms.

MEASUREMENTS AND MAIN RESULTS

Time since intubation correlated strongly (p < 0.001) with the proportion of positive (> 10 colony-forming units/mL) tracheal aspirate quantitative cultures, but Centers for Disease Control-defined clinical signs or symptoms of ventilator-associated pneumonia, either singly or in combination, did not. Use of in-line suction catheters versus new, sterile catheters to obtain tracheal aspirates was associated with significantly greater proportion of positive tracheal aspirate bacterial cultures (p < 0.001). Most subjects had more than 25 polymorphonuclear neutrophils per low-power field on Gram stain; polymorphonuclear neutrophils on Gram stain correlated with positive bacterial culture (p = 0.04). Seventy-seven percent of the bacterial isolates detected in positive quantitative cultures were "pathogens." Antibiotic use at the time tracheal aspirates were obtained was associated with a lower frequency of positive quantitative cultures only with antibiotic regimens that included cefepime.

CONCLUSIONS

Positive bacterial cultures of tracheal aspirates increase rapidly after intubation and usually include bacteria considered to be pathogens. Tracheal aspirate cultures and Gram stains do not appear to distinguish between infection and colonization. Antibiotic regimens that include cefepime decrease the frequency of positive cultures, but the significance of this is unclear.

Prevalence, risk factors, and mortality for ventilator-associated pneumonia in middle-aged, old, and very old critically ill patients*

OBJECTIVE

We investigated the epidemiology of ventilator-associated pneumonia in elderly ICU patients. More precisely, we assessed prevalence, risk factors, signs and symptoms, causative bacterial pathogens, and associated outcomes.

DESIGN

Secondary analysis of a multicenter prospective cohort (EU-VAP project).

SETTING

Twenty-seven European ICUs.

PATIENTS

Patients who were mechanically ventilated for greater than or equal to 48 hours. We compared middle-aged (45-64 yr; n = 670), old (65-74 yr; n = 549), and very old patients (≥ 75 yr; n= 516).

MEASUREMENTS AND MAIN RESULTS

Ventilator-associated pneumonia occurred in 103 middle-aged (14.6%), 104 old (17.0%), and 73 very old patients (12.8%). The prevalence (n ventilator-associated pneumonia/1,000 ventilation days) was 13.7 in middle-aged patients, 16.6 in old patients, and 13.0 in very old patients. Logistic regression analysis could not demonstrate older age as a risk factor for ventilator-associated pneumonia. Ventilator-associated pneumonia in elderly patients was more frequently caused by Enterobacteriaceae (24% in middle-aged, 32% in old, and 43% in very old patients; p = 0.042). Regarding clinical signs and symptoms at ventilator-associated pneumonia onset, new temperature rise was less frequent among very old patients (59% vs 76% and 74% for middle-aged and old patients, respectively; p = 0.035). Mortality among patients with ventilator-associated pneumonia was higher among elderly patients: 35% in middle-aged patients versus 51% in old and very old patients (p = 0.036). Logistic regression analysis confirmed the importance of older age in the risk of death (adjusted odds ratio for old age, 2.1; 95% CI, 1.2-3.9 and adjusted odds ratio for very old age, 2.3; 95% CI, 1.2-4.4). Other risk factors for mortality in ventilator-associated pneumonia were diabetes mellitus, septic shock, and a high-risk pathogen as causative agent.

CONCLUSIONS

In this multicenter cohort study, ventilator-associated pneumonia did not occur more frequently among elderly, but the associated mortality in these patients was higher. New temperature rise was less common in elderly patients with ventilator-associated pneumonia, whereas more episodes among elderly patients were caused by Enterobacteriaceae.

Effect of aerosolized colistin as adjunctive treatment on the outcomes of microbiologically documented ventilator-associated pneumonia caused by colistin-only susceptible gram-negative bacteria

BACKGROUND

The increasing frequency of ventilator-associated pneumonia (VAP) caused by colistin-only susceptible (COS) gram-negative bacteria (GNB) is of great concern. Adjunctive aerosolized (AS) colistin can reportedly increase alveolar levels of the drug without increasing systemic toxicity. Good clinical results have been obtained in patients with cystic fibrosis, but conflicting data have been reported in patients with VAP.

METHODS

We conducted a retrospective, 1:1 matched case-control study to evaluate the efficacy and safety of AS plus IV colistin vs IV colistin alone in 208 patients in the ICU with VAP caused by COS Acinetobacter baumannii, Pseudomonas aeruginosa, or Klebsiella pneumoniae.

RESULTS

Compared with the IV colistin cohort, the AS-IV colistin cohort had a higher clinical cure rate (69.2% vs 54.8%, P = .03) and required fewer days of mechanical ventilation after VAP onset (8 days vs 12 days, P = .001). In the 166 patients with posttreatment cultures, eradication of the causative organism was also more common in the AS-IV colistin group (63.4% vs 50%, P = .08). No between-cohort differences were observed in all-cause ICU mortality, length of ICU stay after VAP onset, or rates of acute kidney injury (AKI) during colistin therapy. Independent predictors of clinical cure were trauma-related ICU admission (P = .01) and combined AS-IV colistin therapy (P = .009). Higher mean Simplified Acute Physiology Score II (P = .002) and Sequential Organ Failure Assessment (P = .05) scores, septic shock (P &lt; .001), and AKI onset during colistin treatment (P = .04) were independently associated with clinical failure.

CONCLUSIONS

Our results suggest that AS colistin might be a beneficial adjunct to IV colistin in the management of VAP caused by COS GNB.

Long-Term Mortality After Pneumonia in Cardiac Surgery Patients

Background:

The role that intensive care unit (ICU)-acquired pneumonia plays in the long-term outcomes of cardiac surgery patients is not well known. This study examined the association of pneumonia with in-hospital mortality and long-term mortality after adult cardiac surgery.

Methods:

A total of 2750 patients admitted to our ICU after cardiac surgery from January 2003 to December 2009 are the basis for this observational study. Patients who developed ICU-acquired pneumonia were matched with patients without it in a 1:2 ratio. The matching criteria were age, urgent or scheduled surgery, surgical procedure, and the propensity score for pneumonia. Multiple regression analysis was used to find predictors of hospital mortality. The relationship between pneumonia and long-term survival was analyzed with Kaplan-Meier survival estimates and a risk-adjusted Cox proportional regression model for patients discharged alive from hospital.

Results:

Pneumonia was diagnosed in 32 (1.2%) patients and there were 19 cases per 1000 days of mechanical ventilation. Patients with pneumonia had a significantly higher hospital mortality rate (28% vs 6.2%, P = .003) and a higher mortality at the end of follow-up (53% vs 19%, P < .0001) than those without it. Regression analysis showed that pneumonia was a strong predictor of hospital mortality. Five-year survival was as follows: pneumonia, 62%; control, 81%; and cohort patients, 91%. The Cox model showed that, after adjusting for confounding factors, patients with pneumonia (hazard ratio = 3.96, 95% confidence interval [CI]: 1.41-11.14) had poorer long-term survival.

Conclusion:

Pneumonia remains a serious complication in patients operated for cardiac surgery and is associated with increased hospital mortality and reduced long-term survival.