Ventilator-associated pneumonia: a review

Microbiome and Mycobiome Analyses of Continuous Positive Airway Pressure Devices

OBJECTIVES

Microorganisms are likely present in continuous positive airway pressure (CPAP) devices in daily use. Given the potential risk of infection among CPAP users, we aimed to compare the microbiomes of CPAP devices with those of nasal mucosa samples obtained from patients using these devices.

METHODS

We conducted a prospective cohort study at multiple tertiary medical institutions. Samples were collected from the tubes and filters of CPAP devices and the nasal mucosa of device users. Microbiomes and mycobiomes were analyzed using 16S ribosomal RNA and internal transcribed spacer region sequencing. The results were compared according to sampling site and usage duration for each patient.

RESULTS

Overall, 27 paired samples of human nasal mucosa and CPAP components were analyzed. Bacteria were detected in 7 of the 27 tubes (25.9%) and in 22 of the 27 filters (81.5%). Fungi were found in 2 tubes (7.4%) and 16 filters (59.3%). The most prevalent bacterial phyla across all samples were Actinobacteria and Firmicutes. Fungi were not detected in any nasal mucosa samples. However, fungi were identified in the CPAP filters and tubes, with the Basidiomycota and Ascomycota phyla predominating. No significant associations were identified according to sampling site or duration of CPAP use.

CONCLUSION

Some bacteria or fungi are detectable in CPAP samples, even after a short period of CPAP usage. However, the association between respiratory infections and these microbiomes or mycobiomes was not investigated. Further research is required to clarify the risk posed by CPAP devices as a microbial contamination source.

Bacteriology of endotracheal tube biofilms and antibiotic resistance: a systematic review

Bacteria commonly adhere to surfaces and produce polymeric material to encase the attached cells to form communities called biofilms. Within these biofilms, bacteria can appear to be many times more resistant to antibiotics or disinfectants. This systematic review explores the prevalence and microbial profile associated with biofilm production of bacteria isolated from endotracheal tubes and its associations with antimicrobial resistance. A comprehensive search was performed on databases PubMed, Embase, and Google Scholar for relevant articles published between 1st January 2000 and 31st December 2022. The relevant articles were exported to Mendeley Desktop 1.19.8 and screened by title and abstract, followed by full text screening based on the eligibility criteria of the study. Quality assessment of the studies was performed using the Newcastle-Ottawa Scale (NOS) customized for cross-sectional studies. Furthermore, the prevalence of antimicrobial resistance in biofilm-producers isolated from endotracheal tube specimens was investigated. Twenty studies encompassing 981 endotracheal tubes met the eligibility criteria. Pseudomonas spp. and Acinetobacter spp. were predominant isolates among the biofilm producers. These biofilms provided strong resistance against commonly used antibiotics. The highest resistance rate observed in Pseudomonas spp. was against fluoroquinolones whereas the least resistance was seen against piperacillin-tazobactam. A similar trend of susceptibility was observed in Acinetobacter spp. with a very high resistance rate against fluoroquinolones, third-generation cephalosporins and carbapenems. In conclusion, endotracheal tubes were associated with colonization by biofilm forming bacteria with varying levels of antimicrobial resistance. Biofilms may promote the occurrence of recalcitrant infections in endotracheal tubes which need to be managed with appropriate protocols and antimicrobial stewardship. Research focus should shift towards meticulous exploration of biofilm-associated infections to improve detection and management.

Antimicrobial Stewardship for Ventilator Associated Pneumonia in Intensive Care (the ASPIC trial): study protocol for a randomised controlled trial

INTRODUCTION

Ventilator-associated pneumonia (VAP) remains the leading cause of infections treated in the intensive care units (ICU). In a personalised care approach, we hypothesise that the duration of treatment of VAP can be reduced in function of the response to treatment.

METHODS AND ANALYSIS

The Antimicrobial Stewardship for Ventilator-Associated Pneumonia in Intensive Care (ASPIC) trial is a pragmatic national multicentre, phase III, non-inferiority, comparative randomised (1:1) single-blinded clinical trial. Five hundred and ninety adult patients hospitalised in 24 French ICU with a microbiologically confirmed first episode of VAP that received appropriate empirical antibiotic therapy will be included. They will be randomly allocated to standard management with duration of appropriate antibiotic fixed for 7 days according to international guidelines or antimicrobial stewardship based on daily clinical assessment of clinical cure. The assessment of clinical cure will be repeated daily until at least three criteria of clinical cure are met, allowing the discontinuation of antibiotic therapy in experimental group. The primary endpoint is a composite endpoint combining of all-cause mortality measured at day 28, treatment failure or new episode of microbiologically confirmed VAP until day 28.The aim of the study is to demonstrate that a strategy to reduce the duration of antibiotic therapy for VAP based on clinical assessment is safe could lead to changes in practice as part of a personalised therapeutic approach, by reducing exposure to antibiotics and their side effects.

ETHICS AND DISSEMINATION

The ASPIC trial has been approved by the French regulatory agency (Agence Nationale de Sécurité du Médicament et des Produits de Santé, ANSM; EUDRACT number 2021-002197-78, 19 August 2021) and an independent ethics committee the Comité de Protection des Personnes Ile-de-France III (CNRIPH : 21.03.25.60729, 10 October 2021) for the study protocol (version ASPIC-1.3; 03 September 2021) for all study centres. Participant recruitment is scheduled to begin in 2022. Results will be published in international peer-reviewed medical journals.

TRIAL REGISTRATION NUMBER

NCT05124977.

What are the effects of care bundles on the incidence of ventilator-associated pneumonia in paediatric and neonatal intensive care units? A systematic review

PURPOSE

The purpose of this review was to ascertain the impact of ventilator bundles on the incidence of ventilator-associated pneumonia in mechanically ventilated neonates and children in intensive care units.

METHODS

A systematic review was conducted. Key computerised databases (CINAHL, Medline, Embase and Cochrane) as well as additional sources, with no publication date limitations, were extensively searched in January 2018. Inclusion criteria focused on ventilator bundles used in mechanically ventilated neonates and children aged from 0 to 18 years. After identification and inclusion, all studies were critically appraised for quality. Data were analysed and narratively synthesised.

RESULTS

Eight studies of observational and nonrandomised interventional methods design were included in the review. However, the validity of five of the eight studies which were reviewed was considered substandard. In addition, there were variations in the care bundles elements studied. Nevertheless, all these studies demonstrated that the incidences of VAP in mechanically ventilated neonates and children were found to be significantly reduced by the use of ventilator bundles.

PRACTICE IMPLICATIONS

This systematic review determines that ventilator bundles impact positively on the incidence of VAP in critically ill neonates and children in the neonatal intensive care unit and paediatric intensive care unit. However, the variations in the bundle elements and insufficient valid evidence necessitates further research in the area to validate the findings and to ensure standardisation of clinical practice. Prevention of VAP is aimed at avoiding the risk of aspiration in the lungs, colonisation of respiratory tract with pathogenic microorganisms and contamination of respiratory equipment. Moreover, the implementation of evidence-based interventions grouped together is fundamental to improve patient outcomes. It is recommended that a further bona fide research is required to standardise the components of paediatric ventilator bundles.

Improving the quality of the intensive care follow-up of ventilated patients during a national registration program

OBJECTIVES

The Belgian Public Health Organization is concerned with rates of hospital-acquired infections like ventilator-associated pneumonia (VAP). Implementing best practice guidelines for these nosocomial infections has variable success in the literature. This retrospective study was undertaken to see whether implementation of the evidence-based practices as a bundle was feasible, would influence compliance, and could reduce the rates of VAP.

STUDY DESIGN

We utilized easily collectable data about regular care to rapidly assess whether interventions already in place were effectively successfully applied. This avoided cumbersome data collection and review.

METHODS

Retrospective compliance rates and VAP ratios were compared using z tests with P-values < 0.05 considered statistically significant. This data review attempted to examine the impact of education campaigns, staff meetings, in-services, physician checklist, nurse checklist, charge nurse checklist implementation, systematic VAP bundle application, and systematic protocols for oral care and sedation protocols. Additionally, VAP ratio could be registered by the participating centers.

RESULTS

A total of 10,211 intensive care unit (ICU) patients were included in the study which represents 66,817 ICU days under artificial ventilation with an endotracheal tube. The general compliance for VAP bundle raised from VAP was 61% in February 2012 and 74.16% in December 2012 (P < 0.001). The incidence rate of VAP went from 8.34 occurrences/1000 vent days in 2009 to 4.78 occurrences/1000 vent days in 2012 (P < 0.001-Pearson test).

CONCLUSIONS

Efforts to improve physician and staff education, and checklist implementation resulted in an increase in compliance for VAP bundle and a decrease in VAP ratio. This study confirms the applicability of best practice guidelines about regular care but results on VAP incidence have to be confirmed.

Use of Gentamicin as Empiric Coverage for Ventilator-Associated Pneumonia: The "Con" Perspective

BACKGROUND

Gentamicin is used commonly as an empiric antibiotic prior to culture evidence in the treatment of ventilator-associated pneumonia (VAP) in surgical patients.

METHODS

The published literature on the use of gentamicin for empiric therapy in VAP was reviewed and in combination with the author's personal experience, an evaluation has been made about the indications for the use of this antibiotic in VAP.

RESULTS

Empiric gentamicin use appears to benefit less than 1% of patients in the treatment of presumptive VAP. The problematic pharmacokinetics of gentamicin use in this patient population combined with potential toxicity from the drug can be observed to yield greater risks than benefits in this clinical situation when published evidence is reviewed.

CONCLUSION

There is no definitive evidence to support empiric use of gentamicin in the treatment of VAP when evaluated on a cost-effective basis.

Metataxonomic and Metagenomic Approaches vs. Culture-Based Techniques for Clinical Pathology

Diagnoses that are both timely and accurate are critically important for patients with life-threatening or drug resistant infections. Technological improvements in High-Throughput Sequencing (HTS) have led to its use in pathogen detection and its application in clinical diagnoses of infectious diseases. The present study compares two HTS methods, 16S rRNA marker gene sequencing (metataxonomics) and whole metagenomic shotgun sequencing (metagenomics), in their respective abilities to match the same diagnosis as traditional culture methods (culture inference) for patients with ventilator associated pneumonia (VAP). The metagenomic analysis was able to produce the same diagnosis as culture methods at the species-level for five of the six samples, while the metataxonomic analysis was only able to produce results with the same species-level identification as culture for two of the six samples. These results indicate that metagenomic analyses have the accuracy needed for a clinical diagnostic tool, but full integration in diagnostic protocols is contingent on technological improvements to decrease turnaround time and lower costs.

Impact of a bundle on prevention and control of healthcare associated infections in intensive care unit

Inpatients in the intensive care unit (ICU) are at high risk for healthcare-associated infections (HAIs). In the current study, a bundle of interventions and measures for preventing and controlling HAIs were developed and implemented in the ICU by trained personnel, and the impact of the bundle was evaluated. The incidence of HAIs, the adjusted daily incidence of HAIs and the incidence of three types of catheter-related infections before and after the bundle implementation were compared. The execution rate of the bundle for preventing and controlling ventilator-associated pneumonia (VAP) was increased from 82.06% in 2012 to 96.88% in 2013. The execution rate was increased from 83.03% in 2012 to 91.33% in 2013 for central line-associated bloodstream infection (CLABSI), from 87.00% to 94.40% for catheter-associated urinary tract infection (CAUTI), and from 82.05% to 98.55% for multidrug-resistant organisms (MDROs), respectively. In total, 136 cases (10.37%) in 2012 and 113 cases (7.72%) in 2013 involved HAIs, respectively. Patients suffered from infection of the lower respiratory tract, the most common site of HAIs, in 134 cases (79.29%) in 2012 and 107 cases (74.30%) in 2013 respectively. The incidence of VAP was 32.72‰ and 24.60‰, the number of strains of pathogens isolated was 198 and 173, and the number of MDROs detected in the ICU was 91 and 74 in 2012 and 2013, respectively. The percentage of MDROs among the pathogens causing HAIs was decreased in each quarter of 2013 as compared with the corresponding percentage in 2012. In 2013, the execution rate of the bundle for preventing and controlling HAIs was increased, whereas the incidence of HAIs and VAP decreased as compared with that in 2012.

Single-molecule long-read 16S sequencing to characterize the lung microbiome from mechanically ventilated patients with suspected pneumonia

In critically ill patients, the development of pneumonia results in significant morbidity and mortality and additional health care costs. The accurate and rapid identification of the microbial pathogens in patients with pulmonary infections might lead to targeted antimicrobial therapy with potentially fewer adverse effects and lower costs. Major advances in next-generation sequencing (NGS) allow culture-independent identification of pathogens. The present study used NGS of essentially full-length PCR-amplified 16S ribosomal DNA from the bronchial aspirates of intubated patients with suspected pneumonia. The results from 61 patients demonstrated that sufficient DNA was obtained from 72% of samples, 44% of which (27 samples) yielded PCR amplimers suitable for NGS. Out of the 27 sequenced samples, only 20 had bacterial culture growth, while the microbiological and NGS identification of bacteria coincided in 17 (85%) of these samples. Despite the lack of bacterial growth in 7 samples that yielded amplimers and were sequenced, the NGS identified a number of bacterial species in these samples. Overall, a significant diversity of bacterial species was identified from the same genus as the predominant cultured pathogens. The numbers of NGS-identifiable bacterial genera were consistently higher than identified by standard microbiological methods. As technical advances reduce the processing and sequencing times, NGS-based methods will ultimately be able to provide clinicians with rapid, precise, culture-independent identification of bacterial, fungal, and viral pathogens and their antimicrobial sensitivity profiles.

There's no place like home: boarding surgical ICU patients in other ICUs and the effect of distances from the home unit

BACKGROUND

Intensive care units (ICUs) function frequently at capacity, requiring incoming critically ill patients to be placed in alternate geographically distinct ICUs. In some medical ICU populations, "boarding" in an overflow ICU has been associated with increased mortality. We hypothesized that surgical ICU patients experience more complications when boarding in an overflow ICU and that the frequency of these complications are greatest in boarders farthest from the home unit (HU).

METHODS

A 5-year (June 2005 to June 2010) retrospective review of a prospectively maintained ICU database was performed, and demographics, severity of illness, length of stay, and incidence of ICU complications were extracted. Distances between boarding patients' rooms and the HU were measured. Complications occurring in patients located in the same floor (BUSF) and different floor (BUDF) boarding units were compared and stratified by distance from HU to the patient room. Logistic regression was used to develop control for known confounders.

RESULTS

A total of 7,793 patients were admitted to the HU and 833 to a boarding unit (BUSF, n = 712; BUDF, n = 121). Boarders were younger, had a lower length of stay, and Acute Physiology and Chronic Health Evaluation II and were more often trauma/emergency surgery patients. Compared with in-HU patients, the incidence of aspiration pneumonia (2.2% vs. 3.6%, p < 0.01) was greater in BUSF patients and highest in those farthest from the HU (odds ratio [OR], 2.39; p = 0.01). Delirium occurred less often in HU than in BUDF patients (3.3% vs. 8.3 %, p < 0.01), and both delirium (OR, 6.09, p < 0.01) and ventilator-associated pneumonia (OR, 4.49, p < 0.05) were more frequent in patients farther from the HU.

CONCLUSION

Certain ICU complications occur more frequently in boarding patients particularly if they are located on a different floor or far from the HU. When surgical ICU bed availability forces overflow admissions to non-home ICUs, greater interdisciplinary awareness, education, and training may be needed to ensure equivalent care and outcomes.

LEVEL OF EVIDENCE

Epidemiologic study, level III. Therapeutic study, level IV.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Leakage of fluid around endotracheal tube cuffs: a cadaver study

Background

The aim of the study was to evaluate the leakage of liquid past the cuffs of tracheal tubes in fresh frozen human heads.

Methods

Six truncated fresh frozen heads were used and intubated with 8.0 mm endotracheal tubes. The intracuff pressures tested were 30 and 100 cmH₂O. Subsequently, 20 ml of each of two oral antiseptic rinses (0.2% chlorhexidine and octenidine [octenidol®, Schülke & Mayr GmbH, Norderstedt, Germany]) was applied for thirty seconds in the mouth. During the trial, leakage of the cuffs was examined.

Results

The sealing between the tracheal cuff and tracheal wall was leakage-proof for all tested intracuff pressures and all tested antiseptic rinses. However, approximately 5.6 ml and 1.8 ml leaked into the esophagus and remained as a cuff-puddle, respectively.

Conclusions

The sealing between an endotracheal tube cuff with an intracuff pressure of 30 cmH₂O and the tracheal wall is leakage-proof during oral care with antiseptic rinsing. An increase of intracuff pressure to 100 cmH₂O does not appear to be required.

Pre-emptive broad-spectrum treatment for ventilator-associated pneumonia in high-risk patients

PURPOSE

Patients requiring mechanical ventilation (MV) for >48 h after major heart surgery (MHS) are at a high risk of acquiring ventilator-associated pneumonia (VAP) and tracheobronchitis (VAT). Most non-pharmacological interventions to prevent VAP in such patients are usually already implemented. The objective of this study was to evaluate the efficacy in preventing lower respiratory infections of antibiotics active against multidrug-resistant pathogens in this very high-risk population.

METHODS

We performed a prospective randomized open-label study of MHS patients requiring MV for >48 h. Patients were randomly allocated to one of two groups: the intervention group, which received a 3-day course of linezolid and meropenem, and the control group, which received the standard of care. The main outcome was the development of VAP or VAT.

RESULTS

Overall, of the 78 patients included in the study, 40 were in the intervention group and 38 in the control group. Both groups were comparable. Data for the intervention and control groups respectively were as follows: VAP + VAT/1,000 days was 31.79 vs 64.78 (p = 0.03), median length of MV before the first episode of VAP or VAT 9 vs 4.5 days (p = 0.02). No significant differences were observed in median length of stay in the intensive care unit, median length of hospital stay, antibiotic use, Clostridium difficile infection, and overall mortality rate. We detected linezolid-resistant coagulase-negative and coagulase-positive staphylococci in the MHS intensive care unit after the study period.

CONCLUSIONS

A pre-emptive approach with broad-spectrum antibiotics may be effective in reducing the incidence and delaying the onset of VAP + VAT after MHS. The ecological consequences have to be carefully evaluated in future trials.

Stress ulcer prophylaxis in the intensive care unit: is it indicated? A topical systematic review

Stress ulcer prophylaxis (SUP) is regarded as standard of care in the intensive care unit (ICU). However, recent randomized, clinical trials (RCTs) and meta-analyses have questioned the rationale and level of evidence for this recommendation. The aim of the present systematic review was to evaluate if SUP in the critically ill patients is indicated.

DATA SOURCES

 MEDLINE including MeSH, EMBASE, and the Cochrane Library.

PARTICIPANTS

patients in the ICU.

INTERVENTIONS

pharmacological and non-pharmacological SUP.

STUDY APPRAISAL AND SYNTHESIS METHODS

Risk of bias was assessed according to Grading of Recommendations Assessment, Development, and Evaluation, and risk of random errors in cumulative meta-analyses was assessed with trial sequential analysis. A total of 57 studies were included in the review. The literature on SUP in the ICU includes limited trial data and methodological weak studies. The reported incidence of gastrointestinal (GI) bleeding varies considerably. Data on the incidence and severity of GI bleeding in general ICUs in the developed world as of today are lacking. The best intervention for SUP is yet to be settled by balancing efficacy and harm. In essence, it is unresolved if intensive care patients benefit overall from SUP. The following clinically research questions are unanswered: (1) What is the incidence of GI bleeding, and which interventions are used for SUP in general ICUs today?; (2) Which criteria are used to prescribe SUP?; (3) What is the best SUP intervention?; (4) Do intensive care patients benefit from SUP with proton pump inhibitors as compared with other SUP interventions? Systematic reviews of possible interventions and well-powered observational studies and RCTs are needed.

Management and prevention of ventilator-associated pneumonia caused by multidrug-resistant pathogens

Ventilator-associated pneumonia (VAP) due to multidrug-resistant (MDR) pathogens is a leading healthcare-associated infection in mechanically ventilated patients. The incidence of VAP due to MDR pathogens has increased significantly in the last decade. Risk factors for VAP due to MDR organisms include advanced age, immunosuppression, broad-spectrum antibiotic exposure, increased severity of illness, previous hospitalization or residence in a chronic care facility and prolonged duration of invasive mechanical ventilation. Methicillin-resistant Staphylococcus aureus and several different species of Gram-negative bacteria can cause MDR VAP. Especially difficult Gram-negative bacteria include Pseudomonas aeruginosa, Acinetobacter baumannii, carbapenemase-producing Enterobacteraciae and extended-spectrum β-lactamase producing bacteria. Proper management includes selecting appropriate antibiotics, optimizing dosing and using timely de-escalation based on antiimicrobial sensitivity data. Evidence-based strategies to prevent VAP that incorporate multidisciplinary staff education and collaboration are essential to reduce the burden of this disease and associated healthcare costs.

Achieving and sustaining ventilator-associated pneumonia-free time among intensive care units (ICUs): evidence from the Keystone ICU Quality Improvement Collaborative

Our retrospective analysis of the Michigan Keystone intensive care unit (ICU) collaborative demonstrated that adult ICUs could achieve and sustain a zero rate of ventilator-associated pneumonia (VAP) for a considerable number of ventilator and calendar months. Moreover, the results highlight the importance of adjustment for ventilator-days before comparing VAP-free time among ICUs.

Procedural and educational interventions to reduce ventilator-associated pneumonia rate and central line-associated blood stream infection rate

BACKGROUND

Implementing best practice guidelines for ventilator-associated pneumonia (VAP) and central line-associated blood stream infection (CLA-BSI) has variable success. Our institution was concerned with high rates of VAP and CLA-BSI. This retrospective study was undertaken to see whether implementation of the below practices would reduce the rates of VAP and CLA-BSI without resorting to more expensive interventions such as subglottic endotracheal (ET) tube suctioning or silver-impregnated ET tubes. We utilized easily collectable data (standardized infection ratios [SIRs]) to rapidly assess whether interventions already in place were successful. This avoided cumbersome data collection and review.

METHODS

Retrospective data review calculated SIRs using National Healthcare Safety Network benchmarks. Rates and SIRs were compared using z tests with P values <.05 considered statistically significant. This data review attempted to examine the impact of education campaigns, staff meetings, in-services, physician checklist, nurse checklist, charge nurse checklist implementation, and chlorhexidine gluconate oral care addition to the VAP bundle. Additionally, central line insertion required nursing supervision, a checklist, and physician signature.

RESULTS

The incidence rate of VAP went from 9.88 occurrences/1000 vent days in 2009 to 0 occurrences/1000 vent days in 2010 (P < .001). The CLA-BSI occurrences/1000 line days were 2.86 in 2009 and 0.97 in 2010 (P = .0187). The SIR for VAP was 4.12 in 2009 and 0 in 2010 (P < .001). For CLA-BSI, the SIR was 1.1 in 2009 and 0.37 in 2010 (P = .04).

CONCLUSIONS

Efforts to improve physician, patient, and staff education, and checklist implementation resulted in a decrease in VAP and CLA-BSI. This study confirms the applicability of best practice guidelines and suggests a benefit to the use of checklists. We utilize a practical approach for examining the success of these changes.