Risk factors for developing ventilator-associated lower respiratory tract infection in patients with severe COVID-19: a multinational, multicentre study, prospective, observational study

Early bacterial co-infections and ventilator-associated lower respiratory tract infections among intubated patients during the first and second COVID-19 waves: a European comparative cohort study

BACKGROUND

The management of severe SARS-CoV-2 pneumonia, alongside logistical constraints, evolved between the first and subsequent COVID-19 waves. This study aimed to compare the prevalence of early bacterial pulmonary co-infections and the incidence of ventilator-associated lower respiratory tract infections (VA-LRTI) across the first and second waves of the pandemic, and to characterize their microbiology.

METHODS

Latter part of a multicenter retrospective European cohort analysis conducted in 35 ICUs. Adult patients admitted for SARS-CoV-2 pneumonia and requiring invasive mechanical ventilation ≥ 48 h were consecutively included from both waves (February-May 2020 for period 1, October 2020-April 2021 for period 2). Co-infections were defined by bacterial isolation in respiratory secretions or blood cultures, or a positive pneumococcal urinary antigen test, within 48 h after intubation. VA-LRTI, including ventilator-associated tracheobronchitis (VAT) and ventilator-associated pneumonia (VAP), were diagnosed using clinical, radiological and quantitative microbiological criteria. The 28-day cumulative incidence of first VA-LRTI episodes was estimated using the Kalbfleisch and Prentice method, with co-infection prevalence and VA-LRTI incidence compared using multivariable logistic regression and Fine-and-Gray models, respectively.

RESULTS

The study included 1,154 patients (558 in period 1 and 596 in period 2). Co-infection prevalence significantly rose from 9.7% in period 1 to 14.9% in period 2 (adjusted odds ratio (95% confidence interval) 1.52 (1.04-2.22), p = 0.03). Gram-positive cocci dropped from 59 to 48% of co-infections between periods 1 and 2. The overall incidence of VA-LRTI was similar across periods (50.4% and 53.9%, adjusted sub distribution hazard ratio (sHR) 1.14 (0.96-1.35), p = 0.11), with a significant increase in VAP incidence in period 2 (36% to 44.8%, adjusted sHR 1.37 (1.12-1.66), p = 0.001), predominantly occurring within the initial 14 days after intubation, and a concurrent significant decrease in VAT incidence (14.3% to 9.1%, adjusted sHR 0.61 (0.42-0.88), p = 0.007). Gram-negative bacilli, led by Pseudomonas aeruginosa, Enterobacter spp., and Klebsiella spp., were responsible for 89% and 84% of VA-LRTI in periods 1 and 2, respectively.

CONCLUSIONS

Between the first and second COVID-19 waves, the prevalence of early bacterial pulmonary co-infections significantly increased among intubated patients. Although the overall incidence of VA-LRTI remained stable, there was a significant shift from VAT to VAP episodes.

Etiological Profile of Hospitalized Severe Acute Respiratory Infection (SARI) Patients During the COVID-19 Pandemic: A Cross-Sectional Study

Background Lower respiratory infections remain one of the top global causes of death. The application of molecular diagnostic methods (e.g., reverse transcription-polymerase chain reaction {RT-PCR} panels) for the diagnosis of lower respiratory tract infections (LRTIs) improves the understanding of respiratory pathogen epidemiology of these diseases and helps in the early detection of causative agents and formulating infection control measures and management. Methods In this study, consecutive nasopharyngeal/oropharyngeal swab, sputum, tracheal aspirate, and bronchoalveolar lavage (BAL) samples collected from patients having respiratory symptoms were tested using RT-PCR. Results Out of 372 samples, respiratory pathogens were detected in 245 (65.86%) cases. The total number of viral isolates detected in this study was 235, including the viral co-infections and viral and bacterial mixed infections, out of which SARS-CoV-2 was most common (115, 48.94%), followed by influenza A(H1N1)pdm09 (82, 34.89%), rhinovirus (17, 7.23%), adenovirus (nine, 3.83%), influenza A (eight, 3.40%), and influenza B (four, 1.70%). Conclusion The rapid detection of respiratory pathogens through molecular methods can help with targeted antiviral treatment, limit the use of antibiotics, and help in knowing the burden of the disease.

Ventilator-associated pneumonia risk factors in patients with severe COVID-19 in southern Brazil: A retrospective observational study

BACKGOUND

During the SARS-CoV-2 pandemic, a significant number of critical patients required ventilatory assistance in health institutions. In this context, Ventilator-Associated Pneumonia (VAP) was the most prevalent nosocomial infection among critically ill patients. We aimed to analyze the occurrence of VAP in critically ill patients with SARS-CoV-2 and the risk factors associated with the outcome.

METHOD

This is a multicenter, retrospective cohort study which included patients ≥18 years old, diagnosed with COVID-19, admitted to intensive care units (ICU) and who received invasive mechanical ventilation (MV) for >2 consecutive days. The associations between the variables were initially tested, and those that showed potential associations (p<0.05) were included in the multivariate logistic regression model.

RESULTS

One third of patients had an episode of VAP, with an incidence density of 34.97 cases per 1000 MV days. In addition, 42.37% (50) of the microorganisms causing VAP were multidrug-resistant, predominantly gram-negative bacteria (61.32%). More than 50% of participants developed healthcare-associated infections and 243 (73.64%) died. The factors associated with greater chances of VAP were: prone position (OR= 3.77), BMI 25-29.9 kg/m2 (OR= 4.76), pressure injury (OR= 4.41), length of stay in the ICU (OR= 1.06), positive tracheal aspirate before VAP (OR= 5.41) and dyspnea (OR= 3.80).

CONCLUSIONS

Patients with COVID-19 are at high risk of VAP, which leads to an increased risk of death (OR = 2.18). Multiple factors increase the chances of VAP in this population, namely: work overload in health institutions, prone position, prolonged ICU time, infusion of multiple drugs, invasive devices, and in particular, immobility in bed.

Epigenetic attenuation of interferon signaling drives aging-related improvements in systemic lupus

In the general human population, aging is associated with a rise in systemic inflammation, primarily involving innate immune pathways related to interferon (IFN), toll-like receptor, and cytokine signaling. In systemic lupus erythematosus (SLE), a prototypical systemic autoimmune disease, aging is distinctly associated with improvements in disease activity, suggesting a unique relationship between aging and inflammation in this disease. Using a multi-omic approach incorporating transcriptional profiling, single cell RNA sequencing, proteomics and methylation analysis, we studied age-related changes in the immune profiles of 287 SLE patients between 20 and 83 years old, and compared the results against 928 healthy controls aged between 21 and 89 years old. In contrast to the increase in inflammatory gene expression that occurs with aging in most healthy adults, SLE patients exhibited the opposite. Most notable was a decrease in type I IFN signaling that was evident across multiple cell types, with CD56-dim natural killer (NK) cells, CD4 + effector memory T cells, and naïve B cells exhibiting the most significant differences. We found that aging in SLE patients was also associated with decreased IFN-α2 and IFN-λ1 levels, and differential methylation of the genome. Notably, of the genes both downregulated and hypermethylated with older age, IFN-related genes were disproportionately represented, suggesting that age-related decreases in IFN signaling were driven in part by epigenetic silencing. Both SLE patients and healthy controls demonstrated age-related declines in naïve T cells and lymphoid progenitor cells, but only SLE patients demonstrated age-related increases in CD56-dim NK cells. Taken together, our work provides new insight into the phenomenon of inflammaging and the unique clinical improvement in disease activity that occurs in SLE patients as they age.

Tracheal tube infections in critical care: A narrative review of influencing factors, microbial agents, and mitigation strategies in intensive care unit settings

Tracheal tube infections pose significant challenges in the management of mechanically ventilated patients in intensive care units. These infections contribute to prolonged intensive care unit stays, increased healthcare costs, the spread of antibiotic resistance, and poor patient outcomes. This study aims to elucidate the complex relationship between environmental factors, hospital practices, and the incidence of tracheal tube infections. Our comprehensive review explores the impact of factors such as air quality, water sources, equipment contamination, ventilation strategies, infection control protocols, and microbial reservoirs within hospital settings on tracheal tube infection rates. Additionally, it investigates global variations in tracheal tube infection prevalence, which are influenced by differences in healthcare infrastructure, infection control adherence, antibiotic resistance profiles, and patient demographics. Our findings highlight the importance of targeted interventions and collaborative approaches to reduce the burden of tracheal tube infections and improve patient care in intensive care units. By fully understanding the interplay between environmental conditions and hospital practices, effective prevention and management strategies can be developed to reduce the impact of tracheal tube infections on patient outcomes and healthcare resources, ultimately enhancing the quality of care in critical care settings.

Microbial dynamics and pulmonary immune responses in COVID-19 secondary bacterial pneumonia

Secondary bacterial pneumonia (2°BP) is associated with significant morbidity following respiratory viral infection, yet remains incompletely understood. In a prospective cohort of 112 critically ill adults intubated for COVID-19, we comparatively assess longitudinal airway microbiome dynamics and the pulmonary transcriptome of patients who developed 2°BP versus controls who did not. We find that 2°BP is significantly associated with both mortality and corticosteroid treatment. The pulmonary microbiome in 2°BP is characterized by increased bacterial RNA mass and dominance of culture-confirmed pathogens, detectable days prior to 2°BP clinical diagnosis, and frequently also present in nasal swabs. Assessment of the pulmonary transcriptome reveals suppressed TNFα signaling in patients with 2°BP, and sensitivity analyses suggest this finding is mediated by corticosteroid treatment. Further, we find that increased bacterial RNA mass correlates with reduced expression of innate and adaptive immunity genes in both 2°BP patients and controls. Taken together, our findings provide fresh insights into the microbial dynamics and host immune features of COVID-19-associated 2°BP, and suggest that suppressed immune signaling, potentially mediated by corticosteroid treatment, permits expansion of opportunistic bacterial pathogens.

SARS-CoV-2 viremia but not respiratory viral load is associated with respiratory complications in patients with severe COVID-19

BACKGROUND

Severe COVID-19 carries a high morbidity and mortality. Previous studies have shown an association between COVID-19 severity and SARS-CoV-2 viral load (VL). We sought to measure VL in multiple compartments (urine, plasma, lower respiratory tract) in patients admitted to the intensive care unit (ICU) with severe COVID-19 pneumonia and correlate with clinical outcomes.

METHODS

Plasma, urine, and endotracheal aspirate (ETA) samples were obtained on days 1, 3, 7, 14, and 21 from subjects admitted to the ICU with severe COVID-19. VL was measured via reverse transcriptase polymerase chain reaction. Clinical data was collected from the electronic health record. Grouped comparisons were performed using Student's t-test or 1-way ANOVA. Linear regression was used to correlate VL from different compartments collected at the same time. Logistic regression was performed to model ventilator-freedom at 28 days as a function of peak plasma VL.

RESULTS

We enrolled 57 subjects with severe COVID-19 and measured VL in plasma (n = 57), urine (n = 25), and ETA (n = 34). Ventilator-associated pneumonia developed in 63% of subjects. 49% of subjects were viremic on study day 1. VL in plasma and ETA both significantly decreased by day 14 (P < 0.05), and the two were weakly correlated on study day 1 (P = 0.0037, r2 = 0.2343) and on all study days (P < 0.001, r2 = 0.2211). VL were not detected in urine. While no associations were observed with peak ETA VL, subjects with higher peak plasma VL experienced a greater number of respiratory complications, including ventilator-associated pneumonia and fewer ventilator-free and hospital-free days. There was no association between VL in either plasma or ETA and mortality. In viremic patients, plasma VL was significantly lower in subjects that were ICU-free and ventilator-free (P < 0.05), with trends noted for hospital-freedom, ventilator-associated pneumonia, and survival to discharge (P < 0.1). By logistic regression, plasma VL was inversely associated with ventilator-freedom at 28 days (odds ratio 0.14, 95% confidence interval 0.02-0.50).

CONCLUSIONS

Elevated SARS-CoV-2 VL in the plasma but not in the lower respiratory tract is a novel biomarker in severe COVID-19 for respiratory complications.

Intensive care unit-acquired infections more common in patients with COVID-19 than with influenza

Intensive care unit-acquired infections are complicating events in critically ill patients. In this study we analyzed the incidence, microbiological patterns, and outcome in patients with COVID-19 versus influenza in the intensive care unit (ICU). We included all adult patients treated with invasive mechanical ventilation due to (1) COVID-19 between January 2020 and March 2022, and (2) influenza between January 2015 and May 2023 at Sahlgrenska University Hospital, Sweden. Of the 480 participants included in the final analysis, 436 had COVID-19. The incidence rates of ICU-acquired infections were 31.6/1000 and 9.9/1000 ICU-days in the COVID-19 and influenza cohorts, respectively. Ventilator-associated lower respiratory tract infections were most common in both groups. In patients with COVID-19, corticosteroid treatment was associated with an increased risk of ICU-acquired infections and with higher 90-day mortality in case of infection. Furthermore, ICU-acquired infection was associated with a prolonged time in the ICU, with more difficult-to-treat gram-negative infections in late versus early ventilator-associated lower respiratory tract infections. Further research is needed to understand how the association between corticosteroid treatment and incidence and outcome of ICU-acquired infections varies across different patient categories.

Ventilator-Associated Pneumonia, Ventilator-Associated Events, and Nosocomial Respiratory Viral Infections on the Leeside of the Pandemic

The COVID-19 pandemic has had an unprecedented impact on population health and hospital operations. Over 7 million patients have been hospitalized for COVID-19 thus far in the United States alone. Mortality rates for hospitalized patients during the first wave of the pandemic were > 30%, but as we enter the fifth year of the pandemic hospitalizations have fallen and mortality rates for hospitalized patients with COVID-19 have plummeted to 5% or less. These gains reflect lessons learned about how to optimize respiratory support for different kinds of patients, targeted use of therapeutics for patients with different manifestations of COVID-19 including immunosuppressants and antivirals as appropriate, and high levels of population immunity acquired through vaccines and natural infections. At the same time, the pandemic has helped highlight some longstanding sources of harm for hospitalized patients including hospital-acquired pneumonia, ventilator-associated events (VAEs), and hospital-acquired respiratory viral infections. We are, thankfully, on the leeside of the pandemic at present; but the large increases in ventilator-associated pneumonia (VAP), VAEs, bacterial superinfections, and nosocomial respiratory viral infections associated with the pandemic beg the question of how best to prevent these complications moving forward. This paper reviews the burden of hospitalization for COVID-19, the intersection between COVID-19 and both VAP and VAEs, the frequency and impact of hospital-acquired respiratory viral infections, new recommendations on how best to prevent VAP and VAEs, and current insights into effective strategies to prevent nosocomial spread of respiratory viruses.

Clinical characteristics, bacterial coinfections and outcomes in COVID-19-associated pulmonary aspergillosis in a third-level Mexican hospital during the COVID-19 pre-vaccination era

BACKGROUND

Damage due to respiratory viruses increases the risk of bacterial and fungal coinfections and superinfections. High rates of invasive aspergillosis are seen in severe influenza and COVID-19. This report describes CAPA cases diagnosed during the first wave in the biggest reference centre for severe COVID-19 in Mexico.

OBJECTIVES

To describe the clinical, microbiological and radiological characteristics of patients with invasive pulmonary aspergillosis associated with critical COVID-19, as well as to describe the variables associated with mortality.

METHODS

This retrospective study identified CAPA cases among individuals with COVID-19 and ARDS, hospitalised from 1 March 2020 to 31 March 2021. CAPA was defined according to ECMM/ISHAM consensus criteria. Prevalence was estimated. Clinical and microbiological characteristics including bacterial superinfections, antifungal susceptibility testing and outcomes were documented.

RESULTS

Possible CAPA was diagnosed in 86 patients among 2080 individuals with severe COVID-19, representing 4.13% prevalence. All CAPA cases had a positive respiratory culture for Aspergillus species. Aspergillus fumigatus was the most frequent isolate (64%, n = 55/86). Seven isolates (9%, n = 7/80) were resistant to amphotericin B (A. fumigatus n = 5/55, 9%; A. niger, n = 2/7, 28%), two A. fumigatus isolates were resistant to itraconazole (3.6%, n = 2/55). Tracheal galactomannan values ranged between 1.2 and 4.05, while serum galactomannan was positive only in 11% (n = 3/26). Bacterial coinfection were documented in 46% (n = 40/86). Gram negatives were the most frequent cause (77%, n = 31/40 isolates), from which 13% (n = 4/31) were reported as multidrug-resistant bacteria. Mortality rate was 60% and worse prognosis was seen in older persons, high tracheal galactomannan index and high HbA1c level.

CONCLUSIONS

One in 10 individuals with CAPA carry a resistant Aspergillus isolate and/or will be affected by a MDR bacteria. High mortality rates are seen in this population.

Clinical and Microbiological Impact of Implementing a Decision Support Algorithm through Microbiologic Rapid Diagnosis in Critically Ill Patients: An Epidemiological Retrospective Pre-/Post-Intervention Study

BACKGROUND

Data on the benefits of rapid microbiological testing on antimicrobial consumption (AC) and antimicrobial resistance patterns (ARPs) are scarce. We evaluated the impact of a protocol based on rapid techniques on AC and ARP in intensive care (ICU) patients.

METHODS

A retrospective pre- (2018) and post-intervention (2019-2021) study was conducted in ICU patients. A rapid diagnostic algorithm was applied starting in 2019 in patients with a lower respiratory tract infection. The incidence of nosocomial infections, ARPs, and AC as DDDs (defined daily doses) were monitored.

RESULTS

A total of 3635 patients were included: 987 in the pre-intervention group and 2648 in the post-intervention group. The median age was 60 years, the sample was 64% male, and the average APACHE II and SOFA scores were 19 points and 3 points. The overall ICU mortality was 17.2% without any differences between the groups. An increase in the number of infections was observed in the post-intervention group (44.5% vs. 17.9%, p < 0.01), especially due to an increase in the incidence of ventilator-associated pneumonia (44.6% vs. 25%, p < 0.001). AC decreased from 128.7 DDD in 2018 to 66.0 DDD in 2021 (rate ratio = 0.51). An increase in Pseudomonas aeruginosa susceptibility of 23% for Piperacillin/tazobactam and 31% for Meropenem was observed.

CONCLUSION

The implementation of an algorithm based on rapid microbiological diagnostic techniques allowed for a significant reduction in AC and ARPs without affecting the prognosis of critically ill patients.

Incidence, microbiological and immunological characteristics of ventilator-associated pneumonia assessed by bronchoalveolar lavage and endotracheal aspirate in a prospective cohort of COVID-19 patients: CoV-AP study

BACKGROUND

No univocal recommendation exists for microbiological diagnosis of ventilator-associated pneumonia (VAP). Sampling of either proximal or distal respiratory tract likely impacts on the broad range of VAP incidence between cohorts. Immune biomarkers to rule-in/rule-out VAP diagnosis, although promising, have not yet been validated. COVID-19-induced ARDS made VAP recognition even more challenging, often leading to overdiagnosis and overtreatment. We evaluated the impact of different respiratory samples and laboratory techniques on VAP incidence and microbiological findings in COVID-19 patients.

METHODS

Prospective single-centre cohort study conducted among COVID-19 mechanically ventilated patients in Policlinico Hospital (Milan, Italy) from January 2021 to May 2022. Microbiological confirmation of suspected VAP (sVAP) was based on concomitant endotracheal aspirates (ETA) and bronchoalveolar lavage (BAL). Conventional and fast microbiology (FILMARRAY® Pneumonia Panel plus, BALFAPPP) as well as immunological markers (immune cells and inflammatory cytokines) was analysed.

RESULTS

Seventy-nine patients were included. Exposure to antibiotics and steroid therapy before ICU admission occurred in 51/79 (64.6%) and 60/79 (65.9%) patients, respectively. Median duration of MV at VAP suspicion was 6 (5-9) days. Incidence rate of microbiologically confirmed VAP was 33.1 (95% CI 22.1-44.0) and 20.1 (95% CI 12.5-27.7) according to ETA and BAL, respectively. Concordance between ETA and BAL was observed in 35/49 (71.4%) cases, concordance between BALFAPPP and BAL in 39/49 (79.6%) cases. With BAL as reference standard, ETA showed 88.9% (95% CI 70.8-97.7) sensitivity and 50.0% (95% CI 28.2-71.8) specificity (Cohen's Kappa 0.40, 95% CI 0.16-0.65). BALFAPPP showed 95.0% (95% CI 75.1-99.9) sensitivity and 69% (95% CI 49.2-84.7) specificity (Cohen's Kappa 0.60, 95% CI 0.39-0.81). BAL IL-1β differed significantly between VAP (135 (IQR 11-450) pg/ml) and no-VAP (10 (IQR 2.9-105) pg/ml) patients (P = 0.03).

CONCLUSIONS

In COVID-19 ICU patients, differences in microbial sampling at VAP suspicion could lead to high variability in VAP incidence and microbiological findings. Concordance between ETA and BAL was mainly limited by over 20% of ETA positive and BAL negative samples, while BALFAPPP showed high sensitivity but limited specificity when evaluating in-panel targets only. These factors should be considered when comparing results of cohorts with different sampling. BAL IL-1β showed potential in discriminating microbiologically confirmed VAP.

CLINICAL TRIAL REGISTRATION

NCT04766983, registered on February 23, 2021.