Incidence, Outcomes and Risk Factors of Recurrent Ventilator Associated Pneumonia in COVID-19 Patients: A Retrospective Multicenter Study

A consensus of European experts on the definition of ventilator-associated pneumonia recurrences obtained by the Delphi method: the RECUVAP study

BACKGROUND

There are recognized diagnostic criteria for a first ventilator-associated pneumonia (VAP) episode, but not for recurrences. Many randomized clinical trials (RCTs) have used the recurrence of VAP as a criterion for efficacy evaluation. Still, the different definitions used in RCTs make it difficult to compare studies. We aimed to develop a consensual definition of VAP recurrences and of the various types of VAP recurrences.

METHODS

Thirty-six European experts constituting a multidisciplinary group of physicians (critical care, infectious diseases, microbiology) with special interest in the management of VAP were polled using the Delphi methodology.

RESULTS

After the completion of four iterations of the DELPHI method, 94% of experts agreed that the diagnostic criteria for a first VAP episode could also be used for recurrences, except for the radiological criterion, which not all the experts considered to be mandatory. Consensus was also reached regarding the definition of four distinct entities: relapse, persistent VAP, superinfection, and new-pathogen VAP. For relapse and persistent VAP, bacteriological findings were identical for different VAP episodes, whereas they differed for superinfection and new-pathogen VAP. The distinction between relapse and persistent VAP, and between superinfection and new-pathogen VAP depended on the timing of antibiotic treatment (before or after 48-72 h after the end of antibiotic therapy) and the clinical course. Microbiological criteria were proposed to facilitate the diagnosis of persistent VAP.

CONCLUSION

This consensus by European experts proposes four different VAP recurrence entities which should facilitate the harmonization of recurrence criteria for clinical practice and future studies.

A new model of endotracheal tube biofilm identifies combinations of matrix-degrading enzymes and antimicrobials able to eradicate biofilms of pathogens that cause ventilator-associated pneumonia

Ventilator-associated pneumonia is defined as pneumonia that develops in a patient who has been on mechanical ventilation for more than 48 hours through an endotracheal tube. It is caused by biofilm formation on the indwelling tube, which introduces pathogenic microbes such as Pseudomonas aeruginosa, Klebsiella pneumoniae and Candida albicans into the patient's lower airways. Currently, there is a lack of accurate in vitro models of ventilator-associated pneumonia development. This greatly limits our understanding of how the in-host environment alters pathogen physiology and the efficacy of ventilator-associated pneumonia prevention or treatment strategies. Here, we showcase a reproducible model that simulates the biofilm formation of these pathogens in a host-mimicking environment and demonstrate that the biofilm matrix produced differs from that observed in standard laboratory growth medium. In our model, pathogens are grown on endotracheal tube segments in the presence of a novel synthetic ventilated airway mucus medium that simulates the in-host environment. Matrix-degrading enzymes and cryo-scanning electron microscopy were employed to characterize the system in terms of biofilm matrix composition and structure, as compared to standard laboratory growth medium. As seen in patients, the biofilms of ventilator-associated pneumonia pathogens in our model either required very high concentrations of antimicrobials for eradication or could not be eradicated. However, combining matrix-degrading enzymes with antimicrobials greatly improved the biofilm eradication of all pathogens. Our in vitro endotracheal tube model informs on fundamental microbiology in the ventilator-associated pneumonia context and has broad applicability as a screening platform for antibiofilm measures including the use of matrix-degrading enzymes as antimicrobial adjuvants.

The Evolving Challenge of Appropriate Antibiotics Use in Hospitalized COVID-19 Patients: A Systematic Literature Review

The issue of bacterial infections in COVID-19 patients has received increasing attention. Scant data are available on the impact of bacterial superinfection and antibiotic administration on the outcome of hospitalized COVID-19 patients. We conducted a literature review from 1 January 2022 to 31 March 2024 to assess the current burden of bacterial infection and the evidence for antibiotic use in hospitalized COVID-19 patients. Published articles providing data on antibiotic use in COVID-19 patients were identified through computerized literature searches with the search terms [(antibiotic) AND (COVID-19)] or [(antibiotic treatment) AND (COVID-19)]. PubMed and SCOPUS databases were searched from 1 January 2022 to 31 March 2024. No attempt was made to obtain information about unpublished studies. English language restriction was applied. The quality of the included studies was evaluated by the tool recommended by the Joanna Briggs Institute. Both quantitative and qualitative information were summarized by means of textual descriptions. Five hundred fifty-one studies were identified, and twenty-nine studies were included in this systematic review. Of the 29 included studies, 18 studies were on the prevalence of bacterial infection and antibiotic use in hospitalized COVID-19 patients; 4 studies reported on the efficacy of early antibiotic use in COVID-19; 4 studies were on the use of sepsis biomarkers to improve antibiotic use; 3 studies were on the efficacy of antimicrobial stewardship programs and predictive models among COVID-19-hospitalized patients. The quality of included studies was high in 35% and medium in 62%. High rates of hospital-acquired infections were reported among COVID-19 patients, ranging between 7.5 and 37.7%. A high antibiotic resistance rate was reported among COVID-19 patients developing hospital-acquired infections, with a high in-hospital mortality rate. The studies evaluating multi-faceted antimicrobial stewardship interventions reported efficacy in decreasing antibiotic consumption and lower in-hospital mortality.

Recurrent ventilator-associated pneumonia in severe Covid-19 ARDS patients requiring ECMO support

OBJECTIVE

To describe ventilator-associated pneumonia (VAP) recurrence in COVID-19 patients requiring extracorporeal membrane oxygenation (ECMO) support, and to evaluate the impact of antimicrobial treatment duration of the first VAP episode on VAP recurrence.

METHODS

Adult patients with COVID-19 severe pneumonia on ECMO admitted between March 2020 and January 2022 were retrospectively included. Primary outcome was incidence of VAP recurrence, and secondary outcome was the impact of duration of antimicrobial treatment on VAP recurrence.

RESULTS

Among the 252 included patients, 226 (90%) developed a first VAP. Sixteen had lung abscess and were excluded, leaving 210 patients. VAP recurrence occurred in 172 patients (82%), with a median (IQR) time from first VAP to recurrence of 10 (7-13) days. Pseudomonas aeruginosa and Enterobacteriaceae were respectively responsible for 28% and 52% of first VAP, and 51% and 62% of first recurrence episodes. Among the 210 patients with a first VAP, 158 (75%) received a short course of antibiotics [< 8 days, median (IQR) duration 6 (5-7) days] and 52 (25%) received a prolonged course of antibiotics [≥ 8 days, median (IQR) duration 9 (8-10) days]. Estimated cumulative incidence of VAP recurrence, taking into account death and extubation as competing risks, was not different in patients with short- and prolonged-antimicrobial treatment.

CONCLUSIONS

In patients with severe Covid-19-ARDS requiring ECMO support, VAP recurrence occurs frequently, with Enterobacteriaceae and Pseudomonas aeruginosa as predominant causative microorganisms. An antimicrobial treatment of ≥ 8 days for the treatment of first VAP episode did not reduce the risk of VAP recurrence, as compared to shorter duration.

How Does Airway Surface Liquid Composition Vary in Different Pulmonary Diseases, and How Can We Use This Knowledge to Model Microbial Infections?

Growth environment greatly alters many facets of pathogen physiology, including pathogenesis and antimicrobial tolerance. The importance of host-mimicking environments for attaining an accurate picture of pathogen behaviour is widely recognised. Whilst this recognition has translated into the extensive development of artificial cystic fibrosis (CF) sputum medium, attempts to mimic the growth environment in other respiratory disease states have been completely neglected. The composition of the airway surface liquid (ASL) in different pulmonary diseases is far less well characterised than CF sputum, making it very difficult for researchers to model these infection environments. In this review, we discuss the components of human ASL, how different lung pathologies affect ASL composition, and how different pathogens interact with these components. This will provide researchers interested in mimicking different respiratory environments with the information necessary to design a host-mimicking medium, allowing for better understanding of how to treat pathogens causing infection in these environments.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Lung abscess following ventilator-associated pneumonia during COVID-19: a retrospective multicenter cohort study

BACKGROUND

Patients undergoing mechanical ventilation (MV) for COVID-19 exhibit an increased risk of ventilator-associated pneumonia (VAP). The occurrence of lung abscesses following VAP in these patients has been poorly studied. We aimed to describe the incidence, characteristics, risk factors and prognosis of lung abscesses complicating VAP after COVID-19.

METHODS

We conducted an observational, retrospective study in three French intensive care units. Patients admitted for acute respiratory failure with a confirmed SARS-CoV-2 PCR and requiring MV for more than 48 h were included.

RESULTS

Among the 507 patients included, 326 (64%) had a documented VAP. Of these, 23 (7%) developed a lung abscess. Enterobacterales (15/23, 65%) were the main documentation, followed by non-fermenting Gram-negative bacilli (10/23, 43%) and Gram-positive cocci (8/23, 35%). Lung abscesses were mainly plurimicrobial (15/23, 65%). In multivariate analysis, a plurimicrobial 1st VAP episode (OR (95% CI) 2.93 (1.16-7.51); p = 0.02) and the use of hydrocortisone (OR (95% CI) 4.86 (1.95-12.1); p = 0.001) were associated with lung abscess development. Intensive care unit (ICU) mortality of patients with lung abscesses reached 52%, but was not significantly higher than for patients with VAP but no lung abscess. Patients with lung abscesses had reduced ventilator-free days at day 60, a longer duration of MV and ICU stay than patients with VAP but no lung abscess (respectively, 0 (0-3) vs. 16 (0-42) days; p < 0.001, 49 (32-73) vs. 25 (11-41) days; p < 0.001, 52 (36-77) vs. 28 (16-47) days; p < 0.001).

CONCLUSIONS

Lung abscessing pneumonia is not uncommon among COVID-19 patients developing VAP. A plurimicrobial first VAP episode and the use of hydrocortisone are independently associated with this complication. In COVID-19 patients with persistent VAP, a chest CT scan investigating the evolution toward lung abscess should be considered.

A Predominant Cause of Recurrence of Ventilator-Associated Pneumonia in Patients with COVID-19 Are Relapses

The diagnosis of ventilator-associated pneumonia (VAP) recurrence in patients with coronavirus disease 2019 (COVID-19) pneumonia is challenging, and the incidence of recurrence is high. This study aimed to investigate the incidence and recurrence of VAP. Furthermore, we investigated the causative microorganisms of VAP and recurrent VAPs in patients with COVID-19. This retrospective, single-centre case series study was conducted during the COVID-19 pandemic from October 2020 to June 2021 at VieCuri MC Venlo. VAP and recurrent VAP were defined based on three criteria (clinical, radiological, and microbiological). During the study period, 128 mechanically ventilated patients with COVID-19 were included. The incidence ranged from 9.2 to 14 VAP/1000 ventilator days, which was higher than that in the non-COVID-19 controls. The most commonly cultured microorganisms in VAP were Pseudomonas (9/28; 32%), Klebsiella (8/28; 29%), Escherichia coli (5/28; 18%), and Staphylococcus aureus (5/28; 18%). VAP recurred often (5/19, 26%). The overall VAP rate confirmed previous findings of an increased incidence of VAP in critically ill patients with severe COVID-19 requiring mechanical ventilation. VAP recurrences occur often and are mainly relapses. A duration of antibiotic therapy longer than 7 days and therapeutic drug monitoring should be considered for VAP caused by Gram-negative microorganisms.