Bacterial colonization patterns in mechanically ventilated patients with traumatic and medical head injury. Incidence, risk factors, and association with ventilator-associated pneumonia

Ceftriaxone to prevent early ventilator-associated pneumonia in patients with acute brain injury: a multicentre, randomised, double-blind, placebo-controlled, assessor-masked superiority trial

BACKGROUND

Patients with acute brain injury are at high risk of ventilator-associated pneumonia (VAP). The benefit of short-term antibiotic prophylaxis remains debated. We aimed to establish the effect of an early, single dose of the antibiotic ceftriaxone on the incidence of early VAP in patients with severe brain injury who required mechanical ventilation.

METHODS

PROPHY-VAP was a multicentre, randomised, double-blind, placebo-controlled, assessor-masked, superiority trial conducted in nine intensive care units in eight French university hospitals. We randomly assigned comatose (Glasgow Coma Scale score [GCS] ≤12) adult patients (age ≥18 years) who required mechanical ventilation for at least 48 h after acute brain injury to receive intravenous ceftriaxone 2 g or placebo once within the 12 h following tracheal intubation. Participants did not receive selective oropharyngeal and digestive tract decontamination. The primary outcome was the proportion of patients developing early VAP from the 2nd to the 7th day of mechanical ventilation, confirmed by masked assessors. The analysis was reported in the modified intention-to-treat population, which comprised all randomly assigned patients except those who withdrew or did not give consent to continue and those who did not receive the allocated treatment because they met a criterion for non-eligibility. The trial is registered with ClinicalTrials.gov, NCT02265406.

FINDINGS

From Oct 14, 2015, to May 27, 2020, 345 patients were randomly assigned (1:1) to receive ceftriaxone (n=171) or placebo (n=174); 330 received the allocated intervention and 319 were included in the analysis (162 in the ceftriaxone group and 157 in the placebo group). 166 (52%) participants in the analysis were men and 153 (48%) were women. 15 patients did not receive the allocated intervention after randomisation and 11 withdrew their consent. Adjudication confirmed 93 cases of VAP, including 74 early infections. The incidence of early VAP was lower in the ceftriaxone group than in the placebo group (23 [14%] vs 51 [32%]; hazard ratio 0·60 [95% CI 0·38-0·95], p=0·030), with no microbiological impact and no adverse effects attributable to ceftriaxone.

INTERPRETATION

In patients with acute brain injury, a single ceftriaxone dose decreased the risk of early VAP. On the basis of our findings, we recommend that an early, single dose of ceftriaxone be included in all bundles for the prevention of VAP in patients with brain injury who require mechanical ventilation.

FUNDING

French Ministry of Social Affairs and Health.

Rebound Inverts the Staphylococcus aureus Bacteremia Prevention Effect of Antibiotic Based Decontamination Interventions in ICU Cohorts with Prolonged Length of Stay

Could rebound explain the paradoxical lack of prevention effect against Staphylococcus aureus blood stream infections (BSIs) with antibiotic-based decontamination intervention (BDI) methods among studies of ICU patients within the literature? Two meta-regression models were applied, each versus the group mean length of stay (LOS). Firstly, the prevention effects against S. aureus BSI [and S. aureus VAP] among 136 studies of antibiotic-BDI versus other interventions were analyzed. Secondly, the S. aureus BSI [and S. aureus VAP] incidence in 268 control and intervention cohorts from studies of antibiotic-BDI versus that among 165 observational cohorts as a benchmark was modelled. In model one, the meta-regression line versus group mean LOS crossed the null, with the antibiotic-BDI prevention effect against S. aureus BSI at mean LOS day 7 (OR 0.45; 0.30 to 0.68) inverted at mean LOS day 20 (OR 1.7; 1.1 to 2.6). In model two, the meta-regression line versus group mean LOS crossed the benchmark line, and the predicted S. aureus BSI incidence for antibiotic-BDI groups was 0.47; 0.09-0.84 percentage points below versus 3.0; 0.12-5.9 above the benchmark in studies with 7 versus 20 days mean LOS, respectively. Rebound within the intervention groups attenuated and inverted the prevention effect of antibiotic-BDI against S. aureus VAP and BSI, respectively. This explains the paradoxical findings.

Management of Ventilator-Associated Pneumonia: Guidelines

Two recent major guidelines on diagnosis and treatment of ventilator-associated pneumonia (VAP) recommend consideration of local antibiotic resistance patterns and individual patient risks for resistant pathogens when formulating an initial empiric antibiotic regimen. One recommends against invasive diagnostic techniques with quantitative cultures to determine the cause of VAP; the other recommends either invasive or noninvasive techniques. Both guidelines recommend short-course therapy be used for most patients with VAP. Although neither guideline recommends use of procalcitonin as an adjunct to clinical judgment when diagnosing VAP, they differ with respect to use of serial procalcitonin to shorten the length of antibiotic treatment.

Selective digestive tract decontamination in critically ill adults with acute brain injuries: a post hoc analysis of a randomized clinical trial

PURPOSE

The aim of this study was to determine whether selective decontamination of the digestive tract (SDD) reduces in-hospital mortality in mechanically ventilated critically ill adults admitted to the intensive care unit (ICU) with acute brain injuries or conditions.

METHODS

We carried out a post hoc analysis from a crossover, cluster randomized clinical trial. ICUs were randomly assigned to adopt or not to adopt a SDD strategy for two alternating 12-month periods, separated by a 3-month inter-period gap. Patients in the SDD group (n = 2791; 968 admitted to the ICU with an acute brain injury) received a 6-hourly application of an oral paste and administration of a gastric suspension containing colistin, tobramycin, and nystatin for the duration of mechanical ventilation, plus a 4-day course of an intravenous antibiotic with a suitable antimicrobial spectrum. Patients in the control group (n = 3191; 1093 admitted to the ICU with an acute brain injury) received standard care. The primary outcome was in-hospital mortality within 90 days. There were four secondary clinical outcomes: death in ICU, ventilator-, ICU- and hospital-free days to day 90.

RESULTS

Of 2061 patients with acute brain injuries (mean age, 55.8 years; 36.4% women), all completed the trial. In patients with acute brain injuries, there were 313/968 (32.3%) and 415/1093 (38%) in-hospital deaths in the SDD and standard care groups (unadjusted odds ratio [OR], 0.76, 95% confidence interval [CI] 0.63-0.92; p = 0.004). The use of SDD was associated with statistically significant improvements in the four clinical secondary outcomes compared to standard care. There was no significant heterogeneity of treatment effect between patients with and without acute brain injuries (interaction p = 0.22).

CONCLUSIONS

In this post hoc analysis of a randomized clinical trial in critically ill patients with acute brain injuries receiving mechanical ventilation, the use of SDD significantly reduced in-hospital mortality in patients compared to standard care without SDD. These findings require confirmation.

Differentiating infection, colonisation, and sterile inflammation in critical illness: the emerging role of host-response profiling

Infection results when a pathogen produces host tissue damage and elicits an immune response. Critically ill patients experience immune activation secondary to both sterile and infectious insults, with overlapping clinical phenotypes and underlying immunological mechanisms. Patients also undergo a shift in microbiota with the emergence of pathogen-dominant microbiomes. Whilst the combination of inflammation and microbial shift has long challenged intensivists in the identification of true infection, the advent of highly sensitive molecular diagnostics has further confounded the diagnostic dilemma as the number of microbial detections increases. Given the key role of the host immune response in the development and definition of infection, profiling the host response offers the potential to help unravel the conundrum of distinguishing colonisation and sterile inflammation from true infection. This narrative review provides an overview of current approaches to distinguishing colonisation from infection using routinely available techniques and proposes matrices to support decision-making in this setting. In searching for new tools to better discriminate these states, the review turns to the understanding of the underlying pathobiology of the host response to infection. It then reviews the techniques available to assess this response in a clinically applicable context. It will cover techniques including profiling of transcriptome, protein expression, and immune functional assays, detailing the current state of knowledge in diagnostics along with the challenges and opportunities. The ultimate infection diagnostic tool will likely combine an assessment of both host immune response and sensitive pathogen detection to improve patient management and facilitate antimicrobial stewardship.

In critically ill patients, anti-anaerobic antibiotics increase risk of adverse clinical outcomes

BACKGROUND

Critically ill patients routinely receive antibiotics with activity against anaerobic gut bacteria. However, in other disease states and animal models, gut anaerobes are protective against pneumonia, organ failure and mortality. We therefore designed a translational series of analyses and experiments to determine the effects of anti-anaerobic antibiotics on the risk of adverse clinical outcomes among critically ill patients.

METHODS

We conducted a retrospective single-centre cohort study of 3032 critically ill patients, comparing patients who did and did not receive early anti-anaerobic antibiotics. We compared intensive care unit outcomes (ventilator-associated pneumonia (VAP)-free survival, infection-free survival and overall survival) in all patients and changes in gut microbiota in a subcohort of 116 patients. In murine models, we studied the effects of anaerobe depletion in infectious (Klebsiella pneumoniae and Staphylococcus aureus pneumonia) and noninfectious (hyperoxia) injury models.

RESULTS

Early administration of anti-anaerobic antibiotics was associated with decreased VAP-free survival (hazard ratio (HR) 1.24, 95% CI 1.06-1.45), infection-free survival (HR 1.22, 95% CI 1.09-1.38) and overall survival (HR 1.14, 95% CI 1.02-1.28). Patients who received anti-anaerobic antibiotics had decreased initial gut bacterial density (p=0.00038), increased microbiome expansion during hospitalisation (p=0.011) and domination by Enterobacteriaceae spp. (p=0.045). Enterobacteriaceae were also enriched among respiratory pathogens in anti-anaerobic-treated patients (p<2.2×10^-16). In murine models, treatment with anti-anaerobic antibiotics increased susceptibility to Enterobacteriaceae pneumonia (p<0.05) and increased the lethality of hyperoxia (p=0.0002).

CONCLUSIONS

In critically ill patients, early treatment with anti-anaerobic antibiotics is associated with increased mortality. Mechanisms may include enrichment of the gut with respiratory pathogens, but increased mortality is incompletely explained by infections alone. Given consistent clinical and experimental evidence of harm, the widespread use of anti-anaerobic antibiotics should be reconsidered.

Development and implementation of a customised rapid syndromic diagnostic test for severe pneumonia

Background: The diagnosis of pneumonia has been hampered by a reliance on bacterial cultures which take several days to return a result, and are frequently negative. In critically ill patients this leads to the use of empiric, broad-spectrum antimicrobials and compromises good antimicrobial stewardship. The objective of this study was to establish the performance of a syndromic molecular diagnostic approach, using a custom TaqMan array card (TAC) covering 52 respiratory pathogens, and assess its impact on antimicrobial prescribing. Methods: The TAC was validated against a retrospective multi-centre cohort of broncho-alveolar lavage samples. The TAC was assessed prospectively in patients undergoing investigation for suspected pneumonia, with a comparator cohort formed of patients investigated when the TAC laboratory team were unavailable. Co-primary outcomes were sensitivity compared to conventional microbiology and, for the prospective study, time to result. Metagenomic sequencing was performed to validate findings in prospective samples. Antibiotic free days (AFD) were compared between the study cohort and comparator group. Results: 128 stored samples were tested, with sensitivity of 97% (95% confidence interval (CI) 88-100%). Prospectively, 95 patients were tested by TAC, with 71 forming the comparator group. TAC returned results 51 hours (interquartile range 41-69 hours) faster than culture and with sensitivity of 92% (95% CI 83-98%) compared to conventional microbiology. 94% of organisms identified by sequencing were detected by TAC. There was a significant difference in the distribution of AFDs with more AFDs in the TAC group (p=0.02). TAC group were more likely to experience antimicrobial de-escalation (odds ratio 2.9 (95%1.5-5.5)). Conclusions: Implementation of a syndromic molecular diagnostic approach to pneumonia led to faster results, with high sensitivity and impact on antibiotic prescribing.

Development and implementation of a customised rapid syndromic diagnostic test for severe pneumonia

Background: The diagnosis of pneumonia has been hampered by a reliance on bacterial cultures which take several days to return a result, and are frequently negative. In critically ill patients this leads to the use of empiric, broad-spectrum antimicrobials and compromises good antimicrobial stewardship. The objective of this study was to establish the performance of a syndromic molecular diagnostic approach, using a custom TaqMan array card (TAC) covering 52 respiratory pathogens, and assess its impact on antimicrobial prescribing. Methods: The TAC was validated against a retrospective multi-centre cohort of broncho-alveolar lavage samples. The TAC was assessed prospectively in patients undergoing investigation for suspected pneumonia, with a comparator cohort formed of patients investigated when the TAC laboratory team were unavailable. Co-primary outcomes were sensitivity compared to conventional microbiology and, for the prospective study, time to result. Metagenomic sequencing was performed to validate findings in prospective samples. Antibiotic free days (AFD) were compared between the study cohort and comparator group. Results: 128 stored samples were tested, with sensitivity of 97% (95% confidence interval (CI) 88-100%). Prospectively, 95 patients were tested by TAC, with 71 forming the comparator group. TAC returned results 51 hours (interquartile range 41-69 hours) faster than culture and with sensitivity of 92% (95% CI 83-98%) compared to conventional microbiology. 94% of organisms identified by sequencing were detected by TAC. There was a significant difference in the distribution of AFDs with more AFDs in the TAC group (p=0.02). TAC group were more likely to experience antimicrobial de-escalation (odds ratio 2.9 (95%1.5-5.5)). Conclusions: Implementation of a syndromic molecular diagnostic approach to pneumonia led to faster results, with high sensitivity and impact on antibiotic prescribing.

Prefer early tracheostomy

Tracheotomies are commonly performed for the patients with low GCS who needs a respiratory support. Still over the period there existed a controversy when to do tracheotomy ?  Early or late. Our study aimed at reassessing the complications of delayed tracheotomy versus the advantages of the early tracheostomy. This was a prospective comparative, observational study comprising of 140 patients in 2 different hospitals admitted to the neurosurgery ICU with poor GCS. Group A: Early tracheostomy (2-5 days) and Group B: Late tracheostomy (7-14 days). Both groups were followed ,Early tracheostomy required a mechanical ventilator support for average  5-8 days with early weaning  whereas late tracheostomy required 12-20 days of mechanical

Invasive Pulmonary Aspergillosis in Hospital and Ventilator-Associated Pneumonias

Pneumonia is the commonest nosocomial infection complicating hospital stay, with both non-ventilated hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) occurring frequently amongst patients in intensive care. Aspergillus is an increasingly recognized pathogen amongst patients with HAP and VAP, and is associated with significantly increased mortality if left untreated.Invasive pulmonary aspergillosis (IPA) was originally identified in patients who had been profoundly immunosuppressed, however, this disease can also occur in patients with relative immunosuppression such as critically ill patients in intensive care unit (ICU). Patients in ICU commonly have several risk factors for IPA, with the inflamed pulmonary environment providing a niche for aspergillus growth.An understanding of the true prevalence of this condition amongst ICU patients, and its specific rate in patients with HAP or VAP is hampered by difficulties in diagnosis. Establishing a definitive diagnosis requires tissue biopsy, which is seldom practical in critically ill patients, so imperfect proxy measures are required. Clinical and radiological findings in ventilated patients are frequently non-specific. The best-established test is galactomannan antigen level in bronchoalveolar lavage fluid, although this must be interpreted in the clinical context as false positive results can occur. Acknowledging these limitations, the best estimates of the prevalence of IPA range from 0.3 to 5% amongst all ICU patients, 12% amongst patients with VAP and 7 to 28% amongst ventilated patients with influenza.Antifungal triazoles including voriconazole are the first-line therapy choice in most cases. Amphotericin has excellent antimold coverage, but a less advantageous side effect profile. Echinocandins are less effective against IPA, but may play a role in rescue therapy, or as an adjuvant to triazole therapy.A high index of suspicion for IPA should be maintained when investigating patients with HAP or VAP, especially when they have specific risk factors or are not responding to appropriate empiric antibacterial therapy.

Antibiotics for hospital-acquired pneumonia in neonates and children

BACKGROUND

Hospital-acquired pneumonia is one of the most common hospital-acquired infections in children worldwide. Most of our understanding of hospital-acquired pneumonia in children is derived from adult studies. To our knowledge, no systematic review with meta-analysis has assessed the benefits and harms of different antibiotic regimens in neonates and children with hospital-acquired pneumonia.

OBJECTIVES

To assess the beneficial and harmful effects of different antibiotic regimens for hospital-acquired pneumonia in neonates and children.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, three other databases, and two trial registers to February 2021, together with reference checking, citation searching, and contact with study authors to identify additional studies.

SELECTION CRITERIA

We included randomised clinical trials comparing one antibiotic regimen with any other antibiotic regimen for hospital-acquired pneumonia in neonates and children.

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed studies for inclusion, extracted data, and assessed risk of bias. We assessed the certainty of the evidence using the GRADE approach. Our primary outcomes were all-cause mortality and serious adverse events; our secondary outcomes were health-related quality of life, pneumonia-related mortality, non-serious adverse events, and treatment failure. Our primary time point of interest was at maximum follow-up.

MAIN RESULTS

We included four randomised clinical trials (84 participants). We assessed all trials as having high risk of bias. We did not conduct any meta-analyses, as the included trials did not compare similar antibiotic regimens. Each of the four trials assessed a different comparison, as follows: cefepime versus ceftazidime; linezolid versus vancomycin; meropenem versus cefotaxime; and ceftobiprole versus cephalosporin. Only one trial reported our primary outcomes of all-cause mortality and serious adverse events. Three trials reported our secondary outcome of treatment failure. Two trials primarily included community-acquired pneumonia and hospitalised children with bacterial infections, hence the children with hospital-acquired pneumonia constituted subgroups of the total sample sizes. Where outcomes were reported, the certainty of the evidence was very low for each of the comparisons. We are unable to draw meaningful conclusions from the numerical results. None of the included trials assessed health-related quality of life, pneumonia-related mortality, or non-serious adverse events.

AUTHORS' CONCLUSIONS

The relative beneficial and harmful effects of different antibiotic regimens remain unclear due to the very low certainty of the available evidence. The current evidence is insufficient to support any antibiotic regimen being superior to another. Randomised clinical trials assessing different antibiotic regimens for hospital-acquired pneumonia in children and neonates are warranted.

Development and implementation of a customised rapid syndromic diagnostic test for severe pneumonia

Background: The diagnosis of pneumonia has been hampered by a reliance on bacterial cultures which take several days to return a result, and are frequently negative. In critically ill patients this leads to the use of empiric, broad-spectrum antimicrobials and compromises good antimicrobial stewardship. The objective of this study was to establish the performance of a syndromic molecular diagnostic approach, using a custom TaqMan array card (TAC) covering 52 respiratory pathogens, and assess its impact on antimicrobial prescribing. Methods: The TAC was validated against a retrospective multi-centre cohort of broncho-alveolar lavage samples. The TAC was assessed prospectively in patients undergoing investigation for suspected pneumonia, with a comparator cohort formed of patients investigated when the TAC laboratory team were unavailable. Co-primary outcomes were sensitivity compared to conventional microbiology and, for the prospective study, time to result. Metagenomic sequencing was performed to validate findings in prospective samples. Antibiotic free days (AFD) were compared between the study cohort and comparator group. Results: 128 stored samples were tested, with sensitivity of 97% (95% confidence interval (CI) 88-100%). Prospectively, 95 patients were tested by TAC, with 71 forming the comparator group. TAC returned results 51 hours (interquartile range 41-69 hours) faster than culture and with sensitivity of 92% (95% CI 83-98%) compared to conventional microbiology. 94% of organisms identified by sequencing were detected by TAC. There was a significant difference in the distribution of AFDs with more AFDs in the TAC group (p=0.02). TAC group were more likely to experience antimicrobial de-escalation (odds ratio 2.9 (95%1.5-5.5)). Conclusions: Implementation of a syndromic molecular diagnostic approach to pneumonia led to faster results, with high sensitivity and impact on antibiotic prescribing.

Burden of pneumococcal disease among adults in Southern Europe (Spain, Portugal, Italy, and Greece): a systematic review and meta-analysis

The aim was to summarize pneumococcal disease burden data among adults in Southern Europe and the potential impact of vaccines on epidemiology. Of 4779 identified studies, 272 were selected. Invasive pneumococcal disease (IPD) incidence was 15.08 (95% CI 11.01-20.65) in Spain versus 2.56 (95% CI 1.54-4.24) per 100,000 population in Italy. Pneumococcal pneumonia incidence was 19.59 (95% CI 10.74-35.74) in Spain versus 2.19 (95% CI 1.36-3.54) per 100,000 population in Italy. Analysis of IPD incidence in Spain comparing pre-and post- PCV7 and PCV13 periods unveiled a declining trend in vaccine-type IPD incidence (larger and statistically significant for the elderly), suggesting indirect effects of childhood vaccination programme. Data from Portugal, Greece and, to a lesser extent, Italy were sparse, thus improved surveillance is needed. Pneumococcal vaccination uptake, particularly among the elderly and adults with chronic and immunosuppressing conditions, should be improved, including shift to a higher-valency pneumococcal conjugate vaccine when available.

Compliance With an Antibiotic Guideline for Suspected Ventilator-Associated Infection: The Ventilator-Associated INfection (VAIN2) Study

OBJECTIVES

To evaluate a guideline for antibiotic decisions in children with suspected ventilator-associated infection.

DESIGN

Prospective, observational cohort study conducted in 22 PICUs in the United States and Canada.

SETTING

PICUs in 22 hospitals from April 2017 to January 2019.

SUBJECTS

Children less than 3 years old on mechanical ventilation greater than 48 hours who had respiratory secretions cultured and antibiotics initiated for suspected ventilator-associated infection.

INTERVENTIONS

After baseline data collection in children with suspected ventilator-associated infection (Phase 1), a consensus guideline was developed for advising antibiotic continuation or stopping at 48-72 hours (Phase 2) and implemented (Phase 3). Guideline-based antibiotic recommendations were provided to the treating clinicians once clinical and microbiologic data were available. Demographic and outcome data were collected, and guideline compliance and antibiotic utilization evaluated for Phase 1 and Phase 3.

MEASUREMENTS AND MAIN RESULTS

Despite education and implementation efforts, guideline-concordant antibiotic management occurred in 158 of 227 (70%) Phase 3 subjects compared with 213 of 281 (76%) in Phase 1. Illness severity and positive respiratory cultures were the primary determinants of antibiotic continuation. For subjects with a positive respiratory culture but a score for which antibiotic discontinuation was recommended (score ≤ 2), only 27% of Phase 3 subjects had antibiotics discontinued. Antibiotic continuation was not associated with improved outcomes in these subjects and was associated with significantly longer duration of ventilation (median 5.5 d longer) and PICU stay (5 d longer) in the overall study population. Positive respiratory cultures were not associated with outcomes irrespective of antibiotic treatment.

CONCLUSIONS

Antibiotic guideline efficacy and safety remain uncertain due to clinician failure to follow the guideline, instead primarily relying on respiratory culture results. Strategies to overcome clinician perceptions of respiratory cultures and other barriers will be vital for improving guideline adherence and antibiotic use in suspected ventilator-associated infection in future studies.

Effectiveness of a web-based learning module on oral health promotion for nursing and allied health professionals

Background Nursing and allied health professionals are helping hands for healthcare and are important in the training cascade. We aimed to develop and validate the effectiveness of a web-based learning module on oral health promotion among nursing and allied health professionals. Methods We developed and validated an oral health module focused on prevention and promotion for a web-based intervention among nurses and allied health professionals. Pre- and post-test assessment was conducted to evaluate the effectiveness of the programme. Results Of a total of 347 participants, 170 (48.9%) had a good knowledge score in the pre-test, and after attending the oral health module their number increased to 267 (76.9%). The mean difference between the pre-test and post-test scores was statistically significant (p<0.005). Conclusions Training of nurses and allied health professionals on oral health through a web-based module showed improvement in oral health literacy.

M-CSF, IL-6, and TGF-β promote generation of a new subset of tissue repair macrophage for traumatic brain injury recovery

Traumatic brain injury (TBI) leads to high mortality rate. We aimed to identify the key cytokines favoring TBI repair and found that patients with TBI with a better outcome robustly increased concentrations of macrophage colony-stimulating factor, interleukin-6, and transforming growth factor-β (termed M6T) in cerebrospinal fluid or plasma. Using TBI mice, we identified that M2-like macrophage, microglia, and endothelial cell were major sources to produce M6T. Together with the in vivo tracking of mCherry+ macrophages in zebrafish models, we confirmed that M6T treatment accelerated blood-borne macrophage infiltration and polarization toward a subset of tissue repair macrophages that expressed similar genes as microglia for neuroprotection, angiogenesis and cell migration. M6T therapy in TBI mice and zebrafish improved neurological function while blocking M6T-exacerbated brain injury. Considering low concentrations of M6T in some patients with poor prognostic, M6T treatment might repair TBI via generating a previously unidentified subset of tissue repair macrophages.

Airway Pseudomonas aeruginosa density in mechanically ventilated patients: clinical impact and relation to therapeutic efficacy of antibiotics

Background

The bacterial density of Pseudomonas aeruginosa is closely related to its pathogenicity. We evaluated the effect of airway P. aeruginosa density on the clinical course of mechanically ventilated patients and the therapeutic efficacy of antibiotics.

Methods

We retrospectively analyzed data of mechanically ventilated ICU patients with P. aeruginosa isolated from endotracheal aspirates. Patients were divided into three groups according to the peak P. aeruginosa density during ICU stay: low (≤ 10⁴ cfu/mL), moderate (10⁵‒10⁶ cfu/mL), and high (≥ 10⁷ cfu/mL) peak density groups. The relationship between peak P. aeruginosa density and weaning from mechanical ventilation, risk factors for isolation of high peak density of P. aeruginosa, and antibiotic efficacy were investigated using multivariate and propensity score-matched analyses.

Results

Four-hundred-and-sixty-one patients were enrolled. Patients with high peak density of P. aeruginosa had higher inflammation and developed more severe respiratory infections. High peak density of P. aeruginosa was independently associated with few ventilator-free days on day 28 (P < 0.01) and increased ICU mortality (P = 0.047). Risk factors for high peak density of P. aeruginosa were prolonged mechanical ventilation (odd ratio [OR] 3.07 95% confidence interval [CI] 1.35‒6.97), non-antipseudomonal cephalosporins (OR 2.17, 95% CI 1.35‒3.49), hyperglycemia (OR 2.01, 95% CI 1.26‒3.22) during ICU stay, and respiratory diseases (OR 1.9, 95% CI 1.12‒3.23). Isolation of commensal colonizer was associated with lower risks of high peak density of P. aeruginosa (OR 0.43, 95% CI 0.26‒0.73). Propensity score-matched analysis revealed that antibiotic therapy for patients with ventilator-associated tracheobronchitis improved weaning from mechanical ventilation only in the high peak P. aeruginosa group.

Conclusions

Patients with high peak density of P. aeruginosa had worse ventilator outcome and ICU mortality. In patients with ventilator-associated tracheobronchitis, antibiotic therapy was associated with favorable ventilator weaning only in the high peak P. aeruginosa density group, and bacterial density could be a good therapeutic indicator for ventilator-associated tracheobronchitis due to P. aeruginosa.

Microbiological profiles of tracheostomy patients: a single-center experience

Background

This study compared the prevalence of common microorganisms in obstructed and non-obstructed cases across the four quarters on the first post-tracheostomy year.

Methods

A retrospective chart review of the microbiological profiles of all adult patients who underwent a tracheostomy was conducted between June 2015 and September 2019 at our hospital. Based on the tracheostomy indications, patients were allocated to obstructed or non-obstructed group. Any patient with at least one positive sample was followed up quarterly for a year. The first culture result obtained was recorded at least one month following the last antibiotic dose in each quarter.

Results

Out of the 65 tracheal aspirate results obtained from 58 patients (mean age, 57.5±16.48 years), the most common procedure and indications were surgical tracheostomy (72.4%) and non-obstructed causes (74.1%), respectively. Moreover, 47.7% of the culture results indicated Pseudomonas aeruginosa, which showed significantly different proportions across the quarters (p=0.006). Among obstructed patients, P. aeruginosa was the most common (35%), followed by methicillin-resistant Staphylococcus aureus (MRSA; 23.5%).

Conclusions

The most common post-tracheostomy microorganism was P. aeruginosa. MRSA showed a strong association with tracheostomy for obstructive indications.

The microbiota in pneumonia: From protection to predisposition

Mucosal surfaces of the upper respiratory tract and gut are physiologically colonized with their own collection of microbes, the microbiota. The normal upper respiratory tract and gut microbiota protects against pneumonia by impeding colonization by potentially pathogenic bacteria and by regulating immune responses. However, antimicrobial therapy and critical care procedures perturb the microbiota, thus compromising its function and predisposing to lung infections (pneumonia). Interindividual variations and age-related alterations in the microbiota also affect vulnerability to pneumonia. We discuss how the healthy microbiota protects against pneumonia and how host factors and medical interventions alter the microbiota, thus influencing susceptibility to pneumonia.

Thermosensitive in situ liposomal gels loaded with antimicrobial agent for oral care in critically ill patients

Aim: A novel thermosensitive in situ gel loaded with meropenem (MP) liposomes was designed to improve retention in the oral cavity as a prophylactic measure to prevent ventilator-acquired pneumonia in critically ill patients. Methodology & results: Meropenem liposomes were incorporated into poloxamer 407 gels and gamma irradiated. Mean size of liposome was 247 nm, polydispersity index < 0.3 and zeta potential >-25 mV; properties remained unaltered even post sterilization. Permeation study revealed that 75.26% and 34% of MPs were released from MP in situ gel and MP in situ liposomal gel, respectively. The relation between viscosity (cp) and shear rate (1/s) indicate that in situ gels exhibited non-Newtonian behavior at 37°C. The study using Pseudomonas aeruginosa confirmed the antimicrobial activity of meropenem. Conclusion: Prolonged in situ residence, because of rapid gelation process enables an easy administration of meropenem as liposomal suspension in critically ill patients.

Delphi-Konsens der Deutschen Gesellschaft für Thoraxchirurgie über das perioperative Management bei onkologischen anatomischen Lungenresektionen

Einleitung Die anatomische Lungenresektion zur kurativen Behandlung einer malignen Grunderkrankung ist die am häufigsten durchgeführte elektive Operation in der onkologischen Thoraxchirurgie. Ziel dieses Projektes war die Erarbeitung eines Konsenses bez. der am häufigsten gestellten Fragen zum Thema perioperatives Management für elektive onkologische Lungenresektionen.

Methodik Die Arbeitsgruppe erarbeitete 2 elektronische Delphi-Fragerunden. Als Konsens wurde eine Übereinstimmung in ≥ 75% definiert. Nach der statistischen Auswertung der Ergebnisse der elektronischen Fragerunde erfolgte eine Expertenkonferenz, die in einer finalen Delphi-Abstimmung versucht hat, weiteren Konsens über strittige Themen zu erreichen.

Ergebnisse 14 Fragen bez. des perioperativen Managements für elektive onkologische Lungenresektionen konnten formuliert und abgestimmt werden. Konsens konnte für folgende Themen erreicht werden: präoperatives infektiologisches Screening, erweiterte lungenfunktionelle Diagnostik bei eingeschränkter Lungenfunktion, Verwendung eines validierten Cardiac-Risk-Assessment-Algorithmus, Überwachung des Patienten postoperativ, Thromboembolieprophylaxe, Kontrollbronchoskopie nach Bronchusmanschettenresektionen oder nach Pneumonektomie sowie Blutgasanalyse vor Entlassung. Für folgende Themen konnte kein Konsens erreicht werden: präoperative endobronchiale mikrobiologische Diagnostik, Spülung der Thoraxhöhle, standardisierte laborchemische Untersuchungen postoperativ.

Fazit Die vorliegende Arbeit fasste die Ergebnisse eines Delphi-Prozesses zusammen, der 2018/2019 mit Experten aus zertifizierten Kliniken oder hochvolumigen thoraxchirurgischen Einheiten geführt wurde. Insgesamt zeigte sich eine sehr hohe Konsensrate bez. des perioperativen Managements bei onkologischen anatomischen selektiven Lungenresektionen. Die präoperative mikrobiologische endobronchiale Diagnostik war der Hauptpunkt, wo ein Konsens nicht erreicht werden konnte.

Antimicrobial-associated harm in critical care: a narrative review

The belief that, for the individual patient, the benefit of prompt and continued use of antimicrobials outweighs any potential harm is a significant barrier to improved stewardship of these vital agents. Antimicrobial stewardship may be perceived as utilitarian rationing, seeking to preserve the availability of effective antimicrobials by limiting the development of resistance in a manner which could conflict with the immediate treatment of the patient in need. This view does not account for the growing evidence of antimicrobial-associated harm to individual patients. This review sets out the evidence for antimicrobial-associated harm and how this should be balanced with the need for prompt and appropriate therapy in infection. It describes the mechanisms by which antimicrobials may harm patients including: mitochondrial toxicity; immune cell toxicity; adverse drug reactions; selection of resistant organisms within a given patient; and disruption of the microbiome. Finally, the article indicates how the harms of antimicrobials may be mitigated and identifies areas for research and development in this field.

Influence of Single-Dose Antibiotic Prophylaxis for Early-Onset Pneumonia in High-Risk Intubated Patients

BACKGROUND

Early-onset pneumonia (EOP) after endotracheal intubation is common among critically ill patients with a neurologic injury and is associated with worse clinical outcomes.

METHODS

This retrospective cohort study observed outcomes pre- and post-implementation of an EOP prophylaxis protocol which involved the administration of a single dose of ceftriaxone 2 g around the time of intubation. The study included patients ≥ 18 years who were admitted to the University of North Carolina Medical Center (UNCMC) neuroscience intensive care unit (NSICU) between April 1, 2014, and October 26, 2016, and intubated for ≥ 72 h.

RESULTS

Among the 172 patients included, use of an EOP prophylaxis protocol resulted in a significant reduction in the rate of microbiologically confirmed EOP compared to those without prophylaxis (7.4 vs 19.8%, p = 0.026). However, EOP prophylaxis did not decrease the combined incidence of microbiologically confirmed or clinically suspected EOP (32.2 vs 37.4%, p = 0.523). No difference in the rate of late-onset pneumonia (34.6 vs 26.4%, p = 0.25) or virulent organism growth (19.8 vs 14.3%, p = 0.416) was observed. No difference was observed in the duration of intubation, duration of intensive care unit (ICU) stay, duration of hospitalization, or ICU antibiotic days within 30 days of intubation. In hospital mortality was found to be higher in those who received EOP prophylaxis compared to those who did not receive prophylaxis (45.7 vs 29.7%, p = 0.04).

CONCLUSIONS

The administration of a single antibiotic dose following intubation may reduce the incidence of microbiologically confirmed EOP in patients with neurologic injury who are intubated ≥ 72 h. A prophylaxis strategy does not appear to increase the rate of virulent organism growth or the rate of late-onset pneumonia. However, this practice is not associated with a decrease in days of antibiotic use in the ICU or any clinical outcomes benefit.

Management of Ventilator-Associated Pneumonia: Guidelines

Two recent major guidelines on diagnosis and treatment of ventilator-associated pneumonia (VAP) recommend consideration of local antibiotic resistance patterns and individual patient risks for resistant pathogens when formulating an initial empiric antibiotic regimen. One recommends against invasive diagnostic techniques with quantitative cultures to determine the cause of VAP; the other recommends either invasive or noninvasive techniques. Both guidelines recommend short-course therapy be used for most patients with VAP. Although neither guideline recommends use of procalcitonin as an adjunct to clinical judgment when diagnosing VAP, they differ with respect to use of serial procalcitonin to shorten the length of antibiotic treatment.

STRESS ULCER PROPHYLAXIS AS A RISK FACTOR FOR TRACHEAL COLONIZATION AND HOSPITAL-ACQUIRED PNEUMONIA IN INTENSIVE CARE PATIENTS: IMPACT ON LATENCY TIME FOR PNEUMONIA

Stress ulcer prophylaxis is associated with bacterial colonization of respiratory tract. The aims of our study were to determine risk factors for trachea colonization (TC), colonization of pharynx (CP) or stomach (CD) and hospital-acquired pneumonia (HAP), and divide the factors into those with high risk and low risk. The study population (ventilated intensive care unit (ICU) patients eligible to receive stress ulcer prophylaxis) was randomized to receive one of three different treatment protocols: ranitidine, sucralfate, and no stress ulcer prophylaxis (control group). Clinical data relative to pre-specified risk factors for TC or HAP were recorded, as follows: APACHE II score (second risk factor), duration of intubation or tracheotomy (third risk factor), duration of mechanical ventilation (fourth risk factor) and duration of hospitalization in the ICU (fifth risk factor). Gastric pH was recorded and microbiological data regarding stomach, pharynx and trachea were collected on the 1^st, 2^nd, 3^rd and 5^th day. Fifty-eight out of 81 patients developed HAP (including ventilator-associated pneumonia), which occurred later in patients with gastric content pH <4 or those that were tracheotomized. Stress ulcer prophylaxis was not associated with HAP; however, it was proved as a risk factor for TC. TC was detected in tracheotomized patients and was caused by gram-negative pathogens. CP was associated with TC, since the majority of patients had CP before TC. A combination of risk factors (APACHE II >18, age >65, mechanical ventilation and sedation) caused a higher incidence of HAP and lower incidence of TC. HAP was more frequent in patients staying in the ICU for >10 days and those with cardiovascular disease as the underlying disorder. Sedation and previous antibiotic therapy correlated with longer latent period (LAT), while higher values of gastric content pH were related to shorter LAT. The longest LAT was found in patients colonized with Acinetobacter spp. Risk factors that accelerated the occurrence of HAP were found to have caused previous colonization. A combination of risk factors increased the likelihood of TC and HAP, and shortened LAT between TC and HAP.

Invasive and non-invasive diagnostic approaches for microbiological diagnosis of hospital-acquired pneumonia

Background

Data on the methods used for microbiological diagnosis of hospital-acquired pneumonia (HAP) are mainly extrapolated from ventilator-associated pneumonia. HAP poses additional challenges for respiratory sampling, and the utility of sputum or distal sampling in HAP has not been comprehensively evaluated, particularly in HAP admitted to the ICU.

Methods

We analyzed 200 patients with HAP from six ICUs in a teaching hospital in Barcelona, Spain. The respiratory sampling methods used were divided into non-invasive [sputum and endotracheal aspirate (EAT)] and invasive [fiberoptic-bronchoscopy aspirate (FBAS), and bronchoalveolar lavage (BAL)].

Results

A median of three diagnostic methods were applied [range 2–4]. At least one respiratory sampling method was applied in 93% of patients, and two or more were applied in 40%. Microbiological diagnosis was achieved in 99 (50%) patients, 69 (70%) by only one method (42% FBAS, 23% EAT, 15% sputum, 9% BAL, 7% blood culture, and 4% urinary antigen). Seventy-eight (39%) patients underwent a fiberoptic-bronchoscopy when not receiving mechanical ventilation. Higher rates of microbiological diagnosis were observed in the invasive group (56 vs. 39%, p = 0.018). Patients with microbiological diagnosis more frequently presented changes in their empirical antibiotic scheme, mainly de-escalation.

Conclusions

A comprehensive approach might be undertaken for microbiological diagnosis in critically ill nonventilated HAP. Sputum sampling determined one third of microbiological diagnosis in HAP patients who were not subsequently intubated. Invasive methods were associated with higher rates of microbiological diagnosis.

Electronic supplementary material

The online version of this article (10.1186/s13054-019-2348-2) contains supplementary material, which is available to authorized users.

Ventilator-associated pneumonia: The central role of transcolonization

Ventilator-associated pneumonia remain frequent and serious diseases since they are associated with considerable crude mortality. Pathophysiology is centered on modifications of regional bacterial flora, especially tracheobronchial tree and oropharyngeal sphere. Bacterial migration from an anatomical area to another seems to be the main explanation of these alterations which are called "transcolonization". The association of transcolonization and lack of tightness of the endotracheal tube cuff provides a direct pathway for bacteria from the upper to the subglottic airways, eventually leading to ventilator-associated pneumonia. Although modification of bacterial flora has been largely studied, the mechanism which underlays the ability of the implantation, growing and interactions with the local microbiome that leads to the observed transcolonization remains to be more clearly deciphered. The aim of our review is to emphasize the cornerstone importance of the "transcolonization" as a nosological entity playing a central role in ventilator-associated pneumonia.

Are tracheal surveillance cultures useful in the intensive care unit?

Endotracheal aspirate (ETA) surveillance cultures have been used to predict the microorganisms responsible for ventilator associated pneumonia (VAP) in intensive care unit (ICU) patients for 3 decades. However, although more than a dozen studies have been performed, the usefulness and the safety of this strategy are still debated. Tracheobronchial bacterial colonization often precedes the occurrence of VAP, and it has been postulated that the microbes present in the tracheal secretions a few days before VAP might be the same as those retrieved in the lower respiratory tract. A large number of studies, with heterogeneous designs and variable results, have questioned the possibility of predicting, by regular ETA cultures after the 48^th hour of mechanical ventilation (MV), the microbiology of VAP and therefore of determining the adequate antibiotic therapy to limit the over-prescription of broad spectrum molecules when following guidelines. Although it has shown some promising results, the strategy has not achieved unanimity because of some discordant data. The aim of this review is to provide an updated overview of the literature available in the field and to attempt to determine the strengths and weaknesses of antibiotic stewardship based on ETA surveillance cultures in VAP, particularly in the global context of drug resistant microorganism emergence and the crucial necessity of broad spectrum molecule preservation.

Oropharyngeal colonization: epidemiology, treatment and ventilator-associated pneumonia prevention

Oropharyngeal (OP) colonization and ventilator-associated pneumonia (VAP) mechanisms are tightly linked. A significant within-population variation in OP colonization has been described, with its composition being dependent from patients' severity. For instance, healthy subjects have a very low rate in Gram-negative bacteria (GNB) colonization, while its rate rises in comorbid patients, reaching high proportions in ICU patients. Various factors can be put forward to explain the modifications of hospital acquired OP. ICU patients might suffer from underlying diseases; the gastric reflux induced by the presence of nasogastric tubes and the patients' position influences OP colonization; salivary composition might influence OP content, as it modulates bacterial adhesion and induces reversible bacterial changes enhancing bacterial binding. The transition from OP colonization to VAP has been shown in numerous studies, with the digestive tract acting as a filter, or as a reservoir. Some therapies have been investigated to modulate OP colonization, in order to reduce the risk for VAP. Among those, mammalian antimicrobial peptides have been shown effective in reducing GNB colonization in healthy subjects, but failed in preventing VAP in ICU patients. The widely used chlorhexidine was tested in numerous trials. Data on its efficacy are conflicting, and meta-analyses yield discordant results. Above all, several drawbacks have aroused: a poor tolerance of concentrated solutions; an increased risk of death in the less severe patients; and a reduced susceptibility towards chlorhexidine of number of VAP pathogens. Proanthocyanidins, used to prevent Escherichia coli adhesion to the urothelium, have been tested in mice model of pneumonia with interesting results. Some complementary data are needed before moving to clinical research. Future research paths should include a reappraisal of OP colonization; finding better formulations for chlorhexidine; define the best populations to target oral decontamination and developing other strategies to prevent and treat OP colonization.

Bacterial DNA patterns identified using paired-end Illumina sequencing of 16S rRNA genes from whole blood samples of septic patients in the emergency room and intensive care unit

BACKGROUND

Sepsis refers to clinical presentations ranging from mild body dysfunction to multiple organ failure. These clinical symptoms result from a systemic inflammatory response to pathogenic or potentially pathogenic microorganisms present systemically in the bloodstream. Current clinical diagnostics rely on culture enrichment techniques to identify bloodstream infections. However, a positive result is obtained in a minority of cases thereby limiting our knowledge of sepsis microbiology. Previously, a method of saponin treatment of human whole blood combined with a comprehensive bacterial DNA extraction protocol was developed. The results indicated that viable bacteria could be recovered down to 10 CFU/ml using this method. Paired-end Illumina sequencing of the 16S rRNA gene also indicated that the bacterial DNA extraction method enabled recovery of bacterial DNA from spiked blood. This manuscript outlines the application of this method to whole blood samples collected from patients with the clinical presentation of sepsis.

RESULTS

Blood samples from clinically septic patients were obtained with informed consent. Application of the paired-end Illumina 16S rRNA sequencing to saponin treated blood from intensive care unit (ICU) and emergency department (ED) patients indicated that bacterial DNA was present in whole blood. There were three clusters of bacterial DNA profiles which were distinguished based on the distribution of Streptococcus, Staphylococcus, and Gram-negative DNA. The profiles were examined alongside the patient's clinical data and indicated molecular profiling patterns from blood samples had good concordance with the primary source of infection.

CONCLUSIONS

Overall this study identified common bacterial DNA profiles in the blood of septic patients which were often associated with the patients' primary source of infection. These results indicated molecular bacterial DNA profiling could be further developed as a tool for clinical diagnostics for bloodstream infections.

The influence of immunological stressors on traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide, and typically involves a robust immune response. Although a great deal of preclinical research has been conducted to identify an effective treatment, all phase III clinical trials have been unsuccessful to date. These translational shortcomings are in part due to a failure to recognize and account for the heterogeneity of TBI, including how extracranial factors can influence the aftermath of TBI. For example, most preclinical studies have utilized isolated TBI models in young adult males, while clinical trials typically involve highly heterogeneous patient populations (e.g., different mechanisms of injury, a range of ages, presence of polytrauma or infection). This paper will review the current, albeit limited literature related to how TBI is affected by common concomitant immunological stressors. In particular, discussion will focus on whether extracranial trauma (i.e., polytrauma), infection, and age/immunosenescence can influence TBI pathophysiology, and thereby may result in a different brain injury than what would have occurred in an isolated TBI. It is concluded that these immunological stressors are all likely to be TBI modifiers that should be further studied and could impact translational treatment strategies.

World-Wide Variation in Incidence of Staphylococcus aureus Associated Ventilator-Associated Pneumonia: A Meta-Regression

Staphylococcus aureus (S. aureus) is a common Ventilator-Associated Pneumonia (VAP) isolate. The objective here is to define the extent and possible reasons for geographic variation in the incidences of S. aureus-associated VAP, MRSA-VAP and overall VAP. A meta-regression model of S. aureus-associated VAP incidence per 1000 Mechanical Ventilation Days (MVD) was undertaken using random effects methods among publications obtained from a search of the English language literature. This model incorporated group level factors such as admission to a trauma ICU, year of publication and use of bronchoscopic sampling towards VAP diagnosis. The search identified 133 publications from seven worldwide regions published over three decades. The summary S. aureus-associated VAP incidence was 4.5 (3.9–5.3) per 1000 MVD. The highest S. aureus-associated VAP incidence is amongst reports from the Mediterranean (mean; 95% confidence interval; 6.1; 4.1–8.5) versus that from Asian ICUs (2.1; 1.5–3.0). The incidence of S. aureus-associated VAP varies by up to three-fold (for the lowest versus highest incidence) among seven geographic regions worldwide, whereas the incidence of VAP varies by less than two-fold. Admission to a trauma unit is the most important group level correlate for S. aureus-associated VAP.

Unusually High Incidences of Staphylococcus aureus Infection within Studies of Ventilator Associated Pneumonia Prevention Using Topical Antibiotics: Benchmarking the Evidence Base

Selective digestive decontamination (SDD, topical antibiotic regimens applied to the respiratory tract) appears effective for preventing ventilator associated pneumonia (VAP) in intensive care unit (ICU) patients. However, potential contextual effects of SDD on Staphylococcus aureus infections in the ICU remain unclear. The S. aureus ventilator associated pneumonia (S. aureus VAP), VAP overall and S. aureus bacteremia incidences within component (control and intervention) groups within 27 SDD studies were benchmarked against 115 observational groups. Component groups from 66 studies of various interventions other than SDD provided additional points of reference. In 27 SDD study control groups, the mean S. aureus VAP incidence is 9.6% (95% CI; 6.9–13.2) versus a benchmark derived from 115 observational groups being 4.8% (95% CI; 4.2–5.6). In nine SDD study control groups the mean S. aureus bacteremia incidence is 3.8% (95% CI; 2.1–5.7) versus a benchmark derived from 10 observational groups being 2.1% (95% CI; 1.1–4.1). The incidences of S. aureus VAP and S. aureus bacteremia within the control groups of SDD studies are each higher than literature derived benchmarks. Paradoxically, within the SDD intervention groups, the incidences of both S. aureus VAP and VAP overall are more similar to the benchmarks.

Airway microbiome research: a modern perspective on surveillance cultures?

The incidence of ventilator-associated pneumonia (VAP) is estimated to be around 10% in a high-risk population. Over the last decade, major improvements have been made in the prevention of VAP, with great cost-effectiveness. However, we still do not understand the exact pathogenesis of VAP. A better understanding might explain why some patients develop ventilator-associated tracheobronchitis, while others develop VAP even though they are infected with the same types of pathogens. Microbiome research has been a hot topic in translational medicine over the past decade. Slowly, microbiome research has also been introduced to the intensive care setting. One of the areas where it may influence our pathophysiological considerations is in VAP. The adapted island has been proposed for the colonization and infection of the respiratory tract. In this model, not only the immigration of bacteria into the lung is important, but elimination and regional growth factors are of equal significance. The importance of these factors can be supported by epidemiological studies. Several small observational studies on the development of the pulmonary microbiome during mechanical ventilation also support this theory. We speculate on the consequences of the newest insights in microbiome research on the prevention and targeted treatment of VAP. We conclude that there is still a strong need for more in-depth analyses of the changes in the microbial composition of the pulmonary microbiome during mechanical ventilation and with the development of VAP.

Survey of Extent of Translation of Oral Healthcare Guidelines for ICU Patients into Clinical Practice by Nursing Staff

Nosocomial infections in critically ill/ventilated patients result from bacterial load in oropharyngeal regions. Oral decontamination serves as the easiest effective means of controlling infections. Knowledge, attitude, and practices followed by healthcare personnel in intensive care settings need to be assessed to implement concrete measures in health-care. Survey questionnaire was constructed and implemented following its validation on seventy nursing and paramedical staff working in government and private intensive care units throughout Lucknow city. 21-item questionnaire consisted of three parts of seven questions each. 78% of respondents had knowledge regarding oral care and its importance in critical settings but 44% of respondents considered it to be unpleasant task. 36% of respondents claimed to have provided oral care to all patients in ICU. Uniform guidelines for translation of oral healthcare in ICU settings are not being implemented. Previous studies in literature from various geographic diverse regions also point out to similar lacunae. Based on present survey, most respondents were aware of importance of oral care with protocols covered in academic curriculum. Attitude towards oral care is positive but respondents feel a need for specialised training. Practice for oral care is not sufficient and needs improvement and proper implementation.

Controversies and advances in the management of ventilator associated pneumonia

INTRODUCTION

Although national surveillance data suggests that the incidence of ventilator associated pneumonia (VAP) is down-trending, it remains one of the most commonly encountered hospital acquired infections in the United States and worldwide. Its association with increased healthcare costs and worsened patient outcomes warrants continued effort to improve the care of patients with VAP. Areas covered: The increasing prevalence of multi-drug resistant bacteria further drives the need to explore advances in diagnostic and treatment options. In this review, controversies pertaining to the definition and diagnosis of VAP as well as empiric treatment strategies will be discussed along with several developments related to rapid microbiologic testing methods and the use of non-traditional antimicrobial agents. Expert commentary: The application of rapid diagnostic techniques to identify microbial pathogens is perhaps one of the most impactful advancements in the treatment of serious nosocomial infections. This technology has the potential to reduce inappropriate initial antimicrobial therapy, unnecessary antimicrobial exposure, and mortality in patients with VAP. In addition, the anticipated approval of new antimicrobial agents within the next several years will provide a much-needed expansion of available treatment options in an era of growing antimicrobial resistance.

Critical Care Nutrition Support Best Practices: Key Differences Between Canadian and American Guidelines

Since 2015, Society of Critical Care Medicine/American Society for Parenteral and Enteral Nutrition and Canadian critical care nutrition support guidelines have both been updated. Despite a similar evidentiary basis, there remain key differences between guideline recommendations. These differences in recommendations may pose confusion for the clinician and may encumber widespread applicability. The aim of this review was to enhance practitioner confidence in applying critical care nutrition support guidelines to patient care in their settings by outlining the similarities and differences between the American and Canadian methods for guideline development and describing the key differences and reasons behind the differences.

Complications following hospital admission for traumatic brain injury: A multicenter cohort study

PURPOSE

To evaluate the incidence, determinants and impact on outcome of in-hospital complications in adults with traumatic brain injury (TBI).

MATERIALS AND METHODS

We conducted a multicenter cohort study of TBI patients admitted between 2007 and 2012 in an inclusive Canadian trauma system. Risk ratios of complications, odds ratios of mortality and geometric mean ratios of length of stay (LOS) were calculated using generalized linear models with adjustment for prognostic indicators and hospital cluster effects.

RESULTS

Of 12,887 patients, 3.2% had at least one neurological complication and 22.6% a non-neurological complication. Mechanical ventilation, head injury severity, blood transfusion and neurosurgical intervention had the strongest correlation with neurological complications. Mechanical ventilation, the Glasgow Coma Scale, blood transfusion and concomitant injuries had the strongest correlation with non-neurological complications. Neurological and non-neurological complications were associated with a 85% and 53% increase in the odds of mortality, and a 60% and two-fold increases in LOS, respectively.

CONCLUSIONS

More than 20% of patients with TBI developed a complication. Many of these complications were associated with increased mortality and LOS. Results highlight the importance of prevention strategies adapted to treatment decisions and underline the need to improve knowledge on the underuse and overuse of clinical interventions.

Aspiration and the Risk of Ventilator-Associated Pneumonia

Ventilator-associated pneumonia (VAP) is a major concern in the intensive care unit. It is estimated that the risk of developing VAP may be as high as 1% per ventilated day, and the attributable mortality approaches 50% in some series. A growing body of evidence implicates the role of microaspiration of contaminated oropharyngeal and perhaps gastroesophageal secretions into the airways as an integral step in the pathogenesis of VAP. In patients who have been intubated and mechanically ventilated for >72 hours, the majority of VAP is caused by enteric gram-negative organisms, presumably of gastrointestinal origin. As a result, strategies designed to minimize the risk of these contaminated secretions into the normally sterile airways are of paramount importance in terms of VAP prevention. This review highlights the important etiological role of the gut in the development of VAP and also discusses the evidence behind interventions that may modulate the risk of both aspiration and subsequent VAP.

Microbial Etiology of Pneumonia: Epidemiology, Diagnosis and Resistance Patterns

Globally, pneumonia is a serious public health concern and a major cause of mortality and morbidity. Despite advances in antimicrobial therapies, microbiological diagnostic tests and prevention measures, pneumonia remains the main cause of death from infectious disease in the world. An important reason for the increased global mortality is the impact of pneumonia on chronic diseases, along with the increasing age of the population and the virulence factors of the causative microorganism. The increasing number of multidrug-resistant bacteria, difficult-to-treat microorganisms, and the emergence of new pathogens are a major problem for clinicians when deciding antimicrobial therapy. A key factor for managing and effectively guiding appropriate antimicrobial therapy is an understanding of the role of the different causative microorganisms in the etiology of pneumonia, since it has been shown that the adequacy of initial antimicrobial therapy is a key factor for prognosis in pneumonia. Furthermore, broad-spectrum antibiotic therapies are sometimes given until microbiological results are available and de-escalation cannot be performed quickly. This review provides an overview of microbial etiology, resistance patterns, epidemiology and microbial diagnosis of pneumonia.

Risk factors for ventilator-associated pneumonia: among trauma patients with and without brain injury

Ventilator-associated pneumonia (VAP) rates remain highest among trauma and brain injured patients; yet, no research compares VAP risk factors between the 2 groups. This retrospective, case-controlled study identified risk factors for VAP among critically ill trauma patients with and without brain injury. Data were abstracted on trauma patients with (cases) and without (controls) brain injury. Data gathered on n = 157 subjects. Trauma patients with brain injury had more emergent and field intubations. Age was strongest predictor of VAP in cases, and ventilator days predicted VAP in controls. Trauma patients with brain injury may be at higher risk for VAP.

World-wide variation in incidence of Acinetobacter associated ventilator associated pneumonia: a meta-regression

Background

Acinetobacter species such as Acinetobacter baumanii are of increasing concern in association with ventilator associated pneumonia (VAP). In the ICU, Acinetobacter infections are known to be subject to seasonal variation but the extent of geographic variation is unclear. The objective here is to define the extent and possible reasons for geographic variation for Acinetobacter associated VAP whether or not these isolates are reported as Acinetobacter baumanii.

Methods

A meta-regression model of VAP associated Acinetobacter incidence within the published literature was undertaken using random effects methods. This model incorporated group level factors such as proportion of trauma admissions, year of publication and reporting practices for Acinetobacter infection.

Results

The search identified 117 studies from seven worldwide regions over 29 years. There is significant variation in Acinetobacter species associated VAP incidence among seven world-wide regions. The highest incidence is amongst reports from the Middle East (mean; 95 % confidence interval; 8.8; 6 · 2–12 · 7 per 1000 mechanical ventilation days) versus that from North American ICU’s (1 · 2; 0 · 8–2 · 1). There is a similar geographic related disparity in incidence among studies reporting specifically as Acinetobacter baumanii. The incidence in ICU’s with a majority of admission being for trauma is >2.5 times that of other ICU’s.

Conclusion

There is greater than fivefold variation in Acinetobacter associated VAP among reports from various geographic regions worldwide. This variation is not explainable by variations in rates of VAP overall, admissions for trauma, publication year or Acinetobacter reporting practices as group level variables.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1921-4) 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.

Ventilator-Associated Pneumonia: A Review

Ventilator-associated pneumonia is the most frequent intensive care unit (ICU)-related infection in patients requiring mechanical ventilation. In contrast to other ICU-related infections, which have a low mortality rate, the mortality rate for ventilator-associated pneumonia ranges from 20% to 50%. These clinically significant infections prolong duration of mechanical ventilation and ICU length of stay, underscoring the financial burden these infections impose on the health care system. The causes of ventilator-associated pneumonia are varied and differ across different patient populations and different types of ICUs. This varied presentation underscores the need for the intensivist treating the patient with ventilator-associated pneumonia to have a clear knowledge of the ambient microbiologic flora in their ICU. Prevention of this disease process is of paramount importance and requires a multifaceted approach. Once a diagnosis of ventilator-associated pneumonia is suspected, early broad-spectrum antibiotic administration decreases morbidity and mortality and should be based on knowledge of the sensitivities of common infecting organisms in the ICU. De-escalation of therapy, once final culture results are available, is necessary to minimize development of resistant pathogens. Duration of therapy should be based on the patient’s clinical response, and every effort should be made to minimize duration of therapy, thus further minimizing the risk of resistance.

Inapparent Outbreaks of Ventilator-Associated Pneumonia An Ecologic Analysis of Prevention and Cohort Studies

Objective:

To compare ventilator-associated pneumonia (VAP) rates and patterns of isolates across studies of antibiotic and non-antibiotic methods for preventing VAP.

Design:

With the use of 42 cohort study groups as the reference standard, the prevalence of VAP was modeled in two linear regressions: one with the control groups and the other with the intervention groups of 96 VAP prevention studies. The proportion of patients admitted with trauma and the VAP diagnostic criteria were used as ecologic correlates. Also, the patterns of pathogenic isolates were available for 117 groups.

Results:

In the first regression model, the VAP rates for the control groups of antibiotic-based prevention studies were at least 18 (CI95, 12 to 24) per 100 patients higher than those in the cohort study groups (P< .001). By contrast, comparisons of cohort study groups with all other control and intervention groups in the first and second regression models yielded differences that were less than 6 per 100 and not significant (P> .05). For control groups with VAP rates greater than 35%, the patterns of VAP isolates, such as the proportion ofStaphylococcus aureus,more closely resembled those in the corresponding intervention groups than in the cohort groups.

Conclusions:

The rates of VAP in the control groups of the antibiotic prevention studies were significantly higher than expected and the patterns of pathogenic isolates were unusual. These observations suggest that inapparent outbreaks of VAP occurred in these studies. The possibility remains that antibiotic-based VAP prevention presents a major cross-infection hazard.