Bacterial pulmonary superinfections are associated with longer duration of ventilation in critically ill COVID-19 patients

Type I interferon autoantibody footprints reveal neutralizing mechanisms and allow inhibitory decoy design

Autoantibodies neutralizing type I interferons (IFN-Is; IFNα or IFNω) exacerbate severe viral disease, but specific treatments are unavailable. With footprint profiling, we delineate two dominant IFN-I faces commonly recognized by neutralizing IFN-I autoantibody-containing plasmas from aged individuals with HIV-1 and from individuals with severe COVID-19. These faces overlap with IFN-I regions independently essential for engaging the IFNAR1/IFNAR2 heterodimer, and neutralizing plasmas efficiently block the interaction of IFN-I with both receptor subunits in vitro. In contrast, non-neutralizing autoantibody-containing plasmas limit the interaction of IFN-I with only one receptor subunit and display relatively low IFN-I-binding avidities, thus likely hindering neutralizing function. Iterative engineering of signaling-inert mutant IFN-Is (simIFN-Is) retaining dominant autoantibody targets created potent decoys that prevent IFN-I neutralization by autoantibody-containing plasmas and that restore IFN-I-mediated antiviral activity. Additionally, microparticle-coupled simIFN-Is were effective at depleting IFN-I autoantibodies from plasmas, leaving antiviral antibodies unaffected. Our study reveals mechanisms of action for IFN-I autoantibodies and demonstrates a proof-of-concept strategy to alleviate pathogenic effects.

Colistin Treatment Outcomes in Gram-Negative Bacterial Infections in the Northeast of Romania: A Decade of Change Through Pandemic Challenges

Background: The rise in multidrug-resistant (MDR) Gram-negative bacteria (GNB) poses a critical threat to global health, exacerbated by the increased use of antibiotics during the SARS-CoV-2 pandemic. Colistin, often considered a last-resort antibiotic, has seen heightened usage, raising concerns about resistance and clinical outcomes. This study investigates the evolution of colistin resistance in GNB during the SARS-CoV-2 pandemic, with a focus on clinical outcomes in colistin-treated patients. Methods: Conducted in "Saint Spiridon" Hospital, Iasi, Romania, the study assesses antibiotic usage, trend in GNB resistance to colistin, and mortality rates across distinct pandemic phases (pre-pandemic, Delta, Omicron, and post-pandemic). A retrospective longitudinal analysis spanning 2011 to 2023 was performed. Statistical models were employed to analyze mortality risk and assess the pandemic's impact on antimicrobial dynamics. Results: Colistin usage increased significantly during the pandemic, with the highest doses recorded during the Omicron phase. Resistance to colistin, particularly among A. baumannii and K. pneumoniae, was associated with increased mortality rates. The statistical model demonstrated robust predictive accuracy for mortality across the pandemic phases, with an AUC of 0.866 in the post-pandemic period. The findings underscore the critical role of A. baumannii as a driver of adverse outcomes, with co-infections significantly linked to systemic infections and higher mortality. Conclusions: The study highlights the evolving trends in colistin therapy and resistance, emphasizing the pandemic's impact on antimicrobial stewardship and the persistent challenges posed by MDR pathogens. We emphasize the need for antimicrobial resistance surveillance, including the monitoring of colistin resistance, which is considered a last-resort antibiotic.

Empirical antibiotic therapy improves outcomes in mechanically ventilated patients with COVID-19: An emulated targeted trial within a prospective, multicentre cohort study

BACKGROUND

Bacterial pulmonary superinfections develop in a substantial proportion of mechanically ventilated COVID-19 patients and are associated with prolonged mechanical ventilation requirements and increased mortality. Albeit recommended, evidence supporting the use of empirical antibiotics at intubation is weak and of low quality. The aim of this study was to elucidate the effect of empirical antibiotics, administered within 24 h of endotracheal intubation, on superinfections, duration of mechanical ventilation, and mortality in mechanically ventilated patients with COVID-19.

METHODS

Emulated targeted trial by means of a propensity score-matched analysis of a prospective multicentre cohort study of consecutive mechanically ventilated patients admitted to 62 Spanish intensive care units suffering from COVID-19 between March 2020 and February 2021.

RESULTS

Overall, 8532 critically ill COVID-19 patients were included, of which 2580 mechanically ventilated patients remained after matching. Empirical antibiotics were prescribed to 1665 (64%) at intubation. Pulmonary superinfections developed in 39% and 47% of patients treated with and without empirical antibiotics, respectively (p<0.01). Patients treated with empirical antibiotics had a shorter duration of mechanical ventilation (incidence risk ratio: 0.85 [95% confidence interval (CI), 0.78 - 0.94], p<0.01) and a reduced stay in the intensive care unit (incidence risk ratio: 0.89 [95% CI, 0.82 - 0.97] days, p<0.01). Mortality 28 days after endotracheal intubation was 28% in patients treated with empirical antibiotics as opposed to 32% in patients treated without (odds ratio: 0.76 [95% CI, 0.61 - 0.94], p<0.01).

CONCLUSION

The administration of empirical antibiotics at intubation in mechanically ventilated COVID-19 patients was associated with a reduced incidence of pulmonary superinfections, a shorter duration of mechanical ventilation and intensive care unit stay, and a lower mortality rate. Notwithstanding these benefits, the applicability of these findings to other viral pneumonias and beyond the pandemic context remains uncertain.

REGISTRATION

www.

CLINICALTRIALS

gov (NCT04457505).

Secondary Bacterial Infections in Critically Ill COVID-19 Patients Admitted in the Intensive Care Unit of a Tertiary Hospital in Romania

Background: The outbreak of the COVID-19 pandemic caught healthcare systems in many countries unprepared. Shortages of personnel, medicines, disinfectants, and intensive care unit (ICU) capacities, combined with inadvertent use of antibiotics and emergence of drug-resistant secondary infections, led to a surge in COVID-19-related mortality. Objective: We aimed to evaluate the prevalence of secondary bacterial infections and the associated antibiotic resistance in a temporary established ICU dedicated to COVID-19 patients. We also assessed the utility of clinical and routine laboratory data as predictors of secondary infections and mortality in these patients. Methods: We examined the medical records of 243 patients admitted to the COVID-19 Medical Support Unit of Târgu Mures, Romania, between 1 August 2020 and 31 January 2021. Results: Among the 243 patients admitted to the COVID-19 Medical Support Unit of Târgu Mures between 1 August 2020 and 31 January 2021, 59 (24.3%) presented secondary infections. Acinetobacter baumannii and Klebsiella pneumoniae were the most frequent isolates (31.1% and 18.9%, respectively), most of them multidrug resistant. Chronic obstructive pulmonary disease had a higher prevalence in patients who developed secondary infections (p = 0.012). Secondary infections were associated with longer stay in the ICU and with higher mortality (p = 0.006 and p = 0.038, respectively). Conclusions: Early identification of secondary infections and proper use of antibiotics are necessary to limit the spread of multidrug-resistant microorganisms in COVID-19 patients admitted in the ICU.

Calprotectin, a Promising Serological Biomarker for the Early Diagnosis of Superinfections with Multidrug-Resistant Bacteria in Patients with COVID-19

Bacterial and fungal superinfections are common in COVID-19, and early diagnosis can enable timely intervention. Serum calprotectin levels increase with bacterial, fungal, and viral infections. This study evaluated serum calprotectin as a diagnostic and prognostic tool for microbial superinfections in COVID-19. Serum samples from adult patients with moderate and severe COVID-19 were collected during hospitalization from 2020 to 2024. Calprotectin levels were measured using an enzyme-linked immunosorbent assay in 63 patients with moderate COVID-19, 60 patients with severe COVID-19, and 34 healthy individuals. Calprotectin serum levels were elevated in patients with moderate COVID-19 compared with controls, and these levels were further increased in the severe cases. Patients with severe COVID-19 and vancomycin-resistant enterococci (VRE) bacteremia had elevated calprotectin levels, but their C-reactive protein and procalcitonin levels were not increased. Fungal superinfections and herpes simplex virus reactivation did not change the calprotectin levels. A calprotectin concentration of 31.29 µg/mL can be used to diagnose VRE bloodstream infection with 60% sensitivity and 96% specificity. These data suggest that serum calprotectin may be a promising biomarker for the early detection of VRE bloodstream infections in patients with COVID-19.

John A, Tierce R, Zheng X, Zhou C, Noval MG, O'Keeffe A, Podkowik M, Gonzales S, Inglima K, Desvignes L, Hochman SE, Stapleford KA, Thorpe LE, Pironti A, Shopsin B, Cadwell K, Dittmann M, Torres VJ. SARS-CoV-2 infection predisposes patients to coinfection with Staphylococcus aureus

Severe COVID-19 has been associated with coinfections with bacterial and fungal pathogens. Notably, patients with COVID-19 who develop Staphylococcus aureus bacteremia exhibit higher rates of mortality than those infected with either pathogen alone. To understand this clinical scenario, we collected and examined S. aureus blood and respiratory isolates from a hospital in New York City during the early phase of the pandemic from both SARS-CoV-2+ and SARS-CoV-2- patients. Whole genome sequencing of these S. aureus isolates revealed broad phylogenetic diversity in both patient groups, suggesting that SARS-CoV-2 coinfection was not associated with a particular S. aureus lineage. Phenotypic characterization of the contemporary collection of S. aureus isolates from SARS-CoV-2+ and SARS-CoV-2- patients revealed no notable differences in several virulence traits examined. However, we noted a trend toward overrepresentation of S. aureus bloodstream strains with low cytotoxicity in the SARS-CoV-2+ group. We observed that patients coinfected with SARS-CoV-2 and S. aureus were more likely to die during the acute phase of infection when the coinfecting S. aureus strain exhibited high or low cytotoxicity. To further investigate the relationship between SARS-CoV-2 and S. aureus infections, we developed a murine coinfection model. These studies revealed that infection with SARS-CoV-2 renders mice susceptible to subsequent superinfection with low cytotoxicity S. aureus. Thus, SARS-CoV-2 infection sensitizes the host to coinfections, including S. aureus isolates with low intrinsic virulence.

IMPORTANCE

The COVID-19 pandemic has had an enormous impact on healthcare across the globe. Patients who were severely infected with SARS-CoV-2, the virus causing COVID-19, sometimes became infected with other pathogens, which is termed coinfection. If the coinfecting pathogen is the bacterium Staphylococcus aureus, there is an increased risk of patient death. We collected S. aureus strains that coinfected patients with SARS-CoV-2 to study the disease outcome caused by the interaction of these two important pathogens. We found that both in patients and in mice, coinfection with an S. aureus strain lacking toxicity resulted in more severe disease during the early phase of infection, compared with infection with either pathogen alone. Thus, SARS-CoV-2 infection can directly increase the severity of S. aureus infection.

COVID-19 PBMCs are doubly harmful, through LDN-mediated lung epithelial damage and monocytic impaired responsiveness to live Pseudomonas aeruginosa exposure

Introduction

Although many studies have underscored the importance of T cells, phenotypically and functionally, fewer have studied the functions of myeloid cells in COVID disease. In particular, the potential role of myeloid cells such as monocytes and low-density neutrophils (LDNs) in innate responses and particular in the defense against secondary bacterial infections has been much less documented.

Methods

Here, we compared, in a longitudinal study, healthy subjects, idiopathic fibrosis patients, COVID patients who were either hospitalized/moderate (M-) or admitted to ICU (COV-ICU) and patients in ICU hospitalized for other reasons (non-COV-ICU).

Results

We show that COVID patients have an increased proportion of low-density neutrophils (LDNs), which produce high levels of proteases (particularly, NE, MMP-8 and MMP-9) (unlike non-COV-ICU patients), which are partly responsible for causing type II alveolar cell damage in co-culture experiments. In addition, we showed that M- and ICU-COVID monocytes had reduced responsiveness towards further live Pseudomonas aeruginosa (PAO1 strain) infection, an important pathogen colonizing COVID patients in ICU, as assessed by an impaired secretion of myeloid cytokines (IL-1, TNF, IL-8,…). By contrast, lymphoid cytokines (in particular type 2/type 3) levels remained high, both basally and post PAO1 infection, as reflected by the unimpaired capacity of T cells to proliferate, when stimulated with anti-CD3/CD28 beads.

Discussion

Overall, our results demonstrate that COVID circulatory T cells have a biased type 2/3 phenotype, unconducive to proper anti-viral responses and that myeloid cells have a dual deleterious phenotype, through their LDN-mediated damaging effect on alveolar cells and their impaired responsiveness (monocyte-mediated) towards bacterial pathogens such as P. aeruginosa.

The significance of monitoring respiratory sample cultures and polymerase chain reaction tests for detecting bacterial pathogens in severely and critically ill patients with COVID-19

Background

Bacterial superinfection is one of the most common and potentially lethal complications in severely and critically ill patients with COVID-19.

Objectives

To determine the colonisation time frame and the spectrum of potential bacterial pathogens in respiratory samples from patients with severe and critical COVID-19, using routine culture and polymerase chain reaction (PCR) tests.

Methods

A prospective observational study was conducted on patients aged ≥18 years with confirmed severe and critical COVID-19 who were admitted to or transferred to the intensive care unit (ICU). Respiratory samples were collected for microbial culture and PCR testing within the first 2 days after ICU admission/transfer, between days 3 and 6, and after 7 days of ICU stay.

Results

A total of 82 patients, with a median (interquartile range) age of 74.5 (67.3 - 81.0) years and a median Charlson comorbidity index of 4 (3 - 5), were enrolled in the study. Colonisation with any pathogen was observed in 67% of patients, after a median of 4 (2 - 6) days in the ICU. On days 0 - 2 of the ICU stay, micro-organisms were detected in 18% of patients, with Klebsiella pneumoniae (without acquired antibiotic resistance) and methicillin-susceptible Staphylococcus aureus being most frequently identified. Later, A. baumannii and carbapenem-resistant K. pneumoniae became the predominant micro-organisms, identified in nearly half of the patients. In 74% of the samples, the results of microbial culture and PCR tests were identical. In 17%, PCR revealed bacterial pathogens not identified by culture.

Conclusion

Our study confirms that colonisation of the respiratory tract occurs early in the course of ICU stay. Superinfections are predominantly caused by multidrug-resistant Gram-negative bacteria.

Study synopsis

What the study adds. This real-world study provides valuable insights into the significance of microbiological monitoring of critically ill COVID-19 patients. It confirms that bacterial colonisation of the respiratory tract occurs early in the course of ICU stay, with nosocomial superinfections caused predominantly by multidrug-resistant Gram-negative pathogens. Polymerase chain reaction (PCR) testing can assist in ruling out colonisation and in early detection of potential bacterial superinfections.Implications of the findings. Bacterial superinfections present a major challenge in critically ill COVID-19 patients, owing to their high prevalence and mortality rates. Their early detection, determination of causative agents, and antibiotic susceptibility profiling are therefore of paramont importance. PCR testing of clinical specimens appears to be a valuable supplement to respiratory culture, enhancing the precision of diagnosis of lower respiratory tract infections.

Secondary Klebsiella pneumoniae infection in patients with COVID-19: A systematic review

This study aims to investigate the development of secondary bacterial infection and risk factors associated with it in critical COVID-19 patients, and to identify the most common pathogen groups in them. All the cohort studies were retrieved from Scopus, Google Scholar, Web of Science, and MEDLINE from the inception of COVID-19 to 2022 for the following keywords: 'Klebsiella" AND "COVID-19". The most common comorbidities among the patients with COVID-19 were respiratory disease (33.62%), obesity (28.99%), and heart disease or cardiovascular disease (16.31%). We report 42.91% rate of Klebsiella spp co-infection in ICU admission patients, mostly related to K. pneumonia (26.81%), K. aerogenes (9.4%), and K. oxytoca (6.7%). The overall incidence of bacterial infection in hospitalized COVID-19 patients is estimated at 15.5% and in 32.5% of cases of co-infection patients deceased. The threat of carbapenem-resistant K. pneumoniae infections in patients with COVID-19 is imminent, therefore rational antibiotic therapy based on antibiotic sensitivity test should be implemented.

Clinical features of omicron SARS-CoV-2 variants infection associated with co-infection and ICU-acquired infection in ICU patients

BACKGROUND

Although the decreasing rate of hospital admission in the omicron wave has led countries to loosen control, still the patients requires ICU admission. It is common for viral respiratory infections to be co-infected with bacteria. However, the difference between co-infection and ICU-acquired infection on their clinical characteristics and outcomes during the Omicron wave was little reported.

METHODS

Clinical and microbiological data were collected from ICU patients with omicron infection between April 1st, 2022, and May 31th, 2022 and a comprehensive comparative study of the clinical characteristics and endpoint were conducted.

RESULTS

The Omicron SARS-CoV-2 variants-infected patients requiring intensive care had high rates of co-infection (42.55%). Additionally, the ICU COVID-19 patients with co-infection showed more severe clinical features compared to those with ICU-acquired infection. Furthermore, Multivariate Cox analysis demonstrated that co-infection (hazard ratio: 4.670, p = 0.018) was a significant risk factor for poor outcomes in ICU patients with COVID-19. Besides, Kaplan-Meier survival curve analysis revealed that COVID-19 patients with co-infection had a significantly shorter 28-Day survival time compared to those with ICU-acquired infection (p < 0.001). Finally, our investigation identified a significant association between the presence of Candida app. in the broncho-alveolar lavage and an elevated risk of mortality (OR: 13.80, p = 0.002) and invasive ventilation (OR: 5.63, p = 0.01).

CONCLUSION

Co-infection is prevalent among patients requiring intensive care and is linked to unfavorable outcomes in the Omicron wave. Consequently, more attention may be needed for the empirical antibacterial treatment in ICU patients within the COVID-19 Omicron variant, especially anti-fungi.

Risk factors for prolonged mechanical ventilation in critically ill patients with influenza-related acute respiratory distress syndrome

BACKGROUND

Patients with influenza-related acute respiratory distress syndrome (ARDS) are critically ill and require mechanical ventilation (MV) support. Prolonged mechanical ventilation (PMV) is often seen in these cases and the optimal management strategy is not established. This study aimed to investigate risk factors for PMV and factors related to weaning failure in these patients.

METHODS

This retrospective cohort study was conducted by eight medical centers in Taiwan. All patients in the intensive care unit with virology-proven influenza-related ARDS requiring invasive MV from January 1 to March 31, 2016, were included. Demographic data, critical illness data and clinical outcomes were collected and analyzed. PMV is defined as mechanical ventilation use for more than 21 days.

RESULTS

There were 263 patients with influenza-related ARDS requiring invasive MV enrolled during the study period. Seventy-eight patients had PMV. The final weaning rate was 68.8% during 60 days of observation. The mortality rate in PMV group was 39.7%. Risk factors for PMV were body mass index (BMI) > 25 (kg/m2) [odds ratio (OR) 2.087; 95% confidence interval (CI) 1.006-4.329], extracorporeal membrane oxygenation (ECMO) use (OR 6.181; 95% CI 2.338-16.336), combined bacterial pneumonia (OR 4.115; 95% CI 2.002-8.456) and neuromuscular blockade use over 48 h (OR 2.8; 95% CI 1.334-5.879). In addition, risk factors for weaning failure in PMV patients were ECMO (OR 5.05; 95% CI 1.75-14.58) use and bacteremia (OR 3.91; 95% CI 1.20-12.69).

CONCLUSIONS

Patients with influenza-related ARDS and PMV have a high mortality rate. Risk factors for PMV include BMI > 25, ECMO use, combined bacterial pneumonia and neuromuscular blockade use over 48 h. In addition, ECMO use and bacteremia predict unsuccessful weaning in PMV patients.

Characteristics and risk factors of secondary bacterial infections in COVID-19 patients

Objective

To describe the characteristics and find out risk factors of COVID-19 patients infected with different categories of bacteria.

Design

Case-control.

Methods

We conducted a retrospective study including 129 COVID-19 patients admitted to a tertiary hospital between October 13, 2022 and December 31, 2022. Patients' data were collected from the hospital information system. Patients were classified as having or not having confirmed secondary bacterial infections, or gram-positive and gram-negative bacterial infections for analysis. Categories and sources of isolated bacteria, characteristics of the patients, and the risk factors for developing secondary bacterial infections were analyzed.

Results

Gram-negative bacteria accounted for the majority of secondary bacterial infections of the included patients. Critical type of COVID-19 (OR = 12.98, 95%CI 3.43∼49.18, p < 0.001), invasive therapy (OR = 9.96, 95%CI 3.01∼32.95, p < 0.001), and previous antibiotics use (OR = 17.23, 95%CI 1.38∼215.69, p = 0.027) were independent risk factors of secondary bacterial infections in COVID-19 patients. Ceftriaxone/cefotaxime use (OR = 15.45, 95%CI 2.72∼87.79, p = 0.002) was associated with gram-positive bacterial infections while age over 70 (OR = 3.30, 95%CI 1.06∼10.26, p = 0.039), invasive therapy (OR = 4.68, 95%CI 1.22∼17.93, p = 0.024), and carbapenems use (OR = 8.48, 95%CI 2.17∼33.15, p = 0.002) were associated with gram-negative bacterial infections.

Conclusions

Critical patients with invasive therapy and previous antibiotics use should be cautious with secondary bacterial infections. Third-generation cephalosporins and carbapenems should be used carefully because both are risk factors for gram-positive or gram-negative bacterial infections.

Immunologic and vascular biomarkers of mortality in critical COVID-19 in a South African cohort

Introduction

Biomarkers predicting mortality among critical Coronavirus disease 2019 (COVID-19) patients provide insight into the underlying pathophysiology of fatal disease and assist with triaging of cases in overburdened settings. However, data describing these biomarkers in Sub-Saharan African populations are sparse.

Methods

We collected serum samples and corresponding clinical data from 87 patients with critical COVID-19 on day 1 of admission to the intensive care unit (ICU) of a tertiary hospital in Cape Town, South Africa, during the second wave of the COVID-19 pandemic. A second sample from the same patients was collected on day 7 of ICU admission. Patients were followed up until in-hospital death or hospital discharge. A custom-designed 52 biomarker panel was performed on the Luminex® platform. Data were analyzed for any association between biomarkers and mortality based on pre-determined functional groups, and individual analytes.

Results

Of 87 patients, 55 (63.2%) died and 32 (36.8%) survived. We found a dysregulated cytokine response in patients who died, with elevated levels of type-1 and type-2 cytokines, chemokines, and acute phase reactants, as well as reduced levels of regulatory T cell cytokines. Interleukin (IL)-15 and IL-18 were elevated in those who died, and levels reduced over time in those who survived. Procalcitonin (PCT), C-reactive protein, Endothelin-1 and vascular cell adhesion molecule-1 were elevated in those who died.

Discussion

These results show the pattern of dysregulation in critical COVID-19 in a Sub-Saharan African cohort. They suggest that fatal COVID-19 involved excessive activation of cytotoxic cells and the NLRP3 (nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3) inflammasome. Furthermore, superinfection and endothelial dysfunction with thrombosis might have contributed to mortality. HIV infection did not affect the outcome. A clinically relevant biosignature including PCT, pH and lymphocyte percentage on differential count, had an 84.8% sensitivity for mortality, and outperformed the Luminex-derived biosignature.

Respiratory bacterial co-infections and their antibiotic resistance pattern in COVID-19 patients at a tertiary care centre in India

Introduction

Patients with coronavirus disease-2019 (COVID-19) are prone to develop respiratory bacterial infections irrespective of their need for mechanical ventilatory support.

Hypothesis/Gap Statement

Information about the incidence of concomitant respiratory bacterial infections in COVID- 19 patients from India is limited.

Aim

This study aimed to determine the incidence of concomitant respiratory bacterial pathogens and their drug resistance in these patients.

Methodology

A prospective study was performed by including patients who were admitted to our tertiary care centre from March 2021 to May 2021 to evaluate secondary bacterial respiratory co-infections in patients via real-time PCR (RT-PCR)-confirmed cases of COVID-19 disease caused by SARS CoV-2.

Results

Sixty-nine culture-positive respiratory samples from patients with COVID-19 were incorporated into this study. The most commonly isolated bacterial microorganisms were Klebsiella pneumoniae (23 samples, 33.33 %) and Acinetobacter baumannii (15, 21.73 %), followed by Pseudomonas aeruginosa (13, 18.84 %). Among the microorganisms isolated, 41 (59.4 %) were multidrug-resistant (MDR) and nine (13 %) were extensively drug-resistant (XDR). Among the Gram-negative bacteria isolated, K. pneumoniae showed high drug resistance. Fifty carbapenem-resistant microorganisms were isolated from the patients included in our study. Concerning the hospital stay of the patients enrolled, there was an increased length of intensive care unit stay, which was 22.25±15.42 days among patients needing mechanical ventilation in comparison to 5.39±9.57 days in patients on ambient air or low/high-flow oxygen.

Conclusion

COVID-19 patients need increased length of hospitalization and have a high incidence of secondary respiratory bacterial infections and high antimicrobial drug resistance.

Staphylococcus aureus bacteremia in patients with SARS-CoV-2 infection

Objectives

The aim was to compare the incidence of Staphylococcus aureus bacteremia in COVID-19 and non-COVID-19 adult patients during the pandemic period versus the previous two years. Also, we described the characteristics of both cohorts of patients in pandemic period to find differences.

Material and methods

Retrospective study in our tertiary-care centre reviewing S. aureus bacteremia episodes in COVID-19 and non-COVID-19 patients through clinical records and the Microbiology Department database.

Results

In 2018 and 2019, the incidence of S. aureus bacteremia episodes was 1.95 and 1.63 per 1000 admissions respectively. In the pandemic period, global incidence was 1.96 episodes per 1000 non-COVID-19 admissions and 10.59 episodes per 1000 COVID-19 admissions. A total of 241 bacteremia was registered during this pandemic period in 74 COVID-19 patients and in 167 non-COVID-19 patients. Methicillin resistance was detected in 32.4% and 13.8% of isolates from COVID-19 and non-COVID-19 patients respectively. In COVID-19 patients, mortality rates were significantly higher.

Conclusions

We showed a significantly high rates of S. aureus bacteremia incidence in COVID-19 patients and higher methicillin resistance and 15-day mortality rates than in non-COVID-19 patients.

Outcomes of patients with coronavirus disease versus other lung infections requiring venovenous extracorporeal membrane oxygenation

Background

Patients with Coronavirus Disease (COVID-19) often develop severe acute respiratory distress syndrome (ARDS) requiring prolonged mechanical ventilation (MV), and venovenous extracorporeal membrane oxygenation (V-V ECMO).Mortality in COVID-19 patients on V-V ECMO was exceptionally high; therefore, whether survival can be ameliorated should be investigated.

Methods

We collected data from 85 patients with severe ARDS who required ECMO support at the University Hospital Magdeburg from 2014 to 2021. The patients were divided into the COVID-19 group (52 patients) and the non-COVID-19 group (33 patients). Demographic and pre-, intra-, and post-ECMO data were retrospectively recorded. The parameters of mechanical ventilation, laboratory data before using ECMO, and during ECMO were compared.

Results

There was a significant difference between the two groups regarding survival: 38.5% of COVID-19 patients and 63.6% of non-COVID-19 patients survived 60 days (p = 0.024). COVID-19 patients required V-V ECMO after 6.5 days of MV, while non-COVID-19 patients required V-V ECMO after 2.0 days of MV (p = 0.048). The COVID-19 group had a greater proportion of patients with ischemic heart disease (21.2% vs 3%, p = 0.019). The rates of most complications were comparable in both groups, whereas the COVID-19 group showed a significantly higher rate of cerebral bleeding (23.1 vs 6.1%, p = 0.039) and lung bacterial superinfection (53.8% vs 9.1%, p = <0.001).

Conclusion

The higher 60-days mortality among patients with COVID-19 with severe ARDS was attributable to superinfection, a higher risk of intracerebral bleeding, and the pre-existing ischemic heart disease.

COVID-19 Therapeutic Potential of Natural Products

Despite the fact that coronavirus disease 2019 (COVID-19) treatment and management are now considerably regulated, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is still one of the leading causes of death in 2022. The availability of COVID-19 vaccines, FDA-approved antivirals, and monoclonal antibodies in low-income countries still poses an issue to be addressed. Natural products, particularly traditional Chinese medicines (TCMs) and medicinal plant extracts (or their active component), have challenged the dominance of drug repurposing and synthetic compound libraries in COVID-19 therapeutics. Their abundant resources and excellent antiviral performance make natural products a relatively cheap and readily available alternative for COVID-19 therapeutics. Here, we deliberately review the anti-SARS-CoV-2 mechanisms of the natural products, their potency (pharmacological profiles), and application strategies for COVID-19 intervention. In light of their advantages, this review is intended to acknowledge the potential of natural products as COVID-19 therapeutic candidates.

Fungal-Bacterial Co-Infections and Super-Infections among Hospitalized COVID-19 Patients: A Systematic Review

This study systematically reviewed fungal-bacterial co-infections and super-infections among hospitalized COVID-19 patients. A PRISMA systematic search was conducted. On September 2022, Medline, PubMed, Google Scholar, PsychINFO, Wiley Online Library, NATURE, and CINAHL databases were searched for all relevant articles published in English. All articles that exclusively reported the presence of fungal-bacterial co-infections and super-infections among hospitalized COVID-19 patients were included. Seven databases produced 6937 articles as a result of the literature search. Twenty-four articles met the inclusion criteria and were included in the final analysis. The total number of samples across the studies was 10,834, with a total of 1243 (11.5%) patients admitted to the intensive care unit (ICU). Of these patients, 535 underwent mechanical ventilation (4.9%), 2386 (22.0%) were male, and 597 (5.5%) died. Furthermore, hospitalized COVID-19 patients have a somewhat high rate (23.5%) of fungal-bacterial co-infections and super-infections. Moreover, for SARS-CoV-2 patients who have a chest X-ray that suggests a bacterial infection, who require immediate ICU admission, or who have a seriously immunocompromised condition, empiric antibiotic therapy should be taken into consideration. Additionally, the prevalence of co-infections and super-infections among hospitalized COVID-19 patients may have an impact on diagnosis and treatment. It is crucial to check for fungal and bacterial co-infections and super-infections in COVID-19 patients.

Rapid antimicrobial susceptibility testing in patients with bacteraemia due to Enterobacterales: an implementation study

AIMS OF THE STUDY

The goal of this descriptive study was to assess the performance as well as the extent of the clinical impact of rapid automated antimicrobial susceptibility testing in patients with bacteraemia due to Enterobacterales. We also aimed to analyse how rapid automated antimicrobial susceptibility testing influences clinical decision-making.

METHODS

This single-centre study conducted at the University Hospital of Zurich included data from all consecutive patients with Enterobacterales bacteraemia from November 2019 to October 2020. There was no control group. The primary outcome was the effect of rapid automated antimicrobial susceptibility testing on antibiotic therapy (no adjustment, escalation to a broader-spectrum antibiotic or de-escalation to a narrower-spectrum antibiotic). Rapid automated antimicrobial susceptibility testing results were further compared to susceptibility tests using European Committee on Antimicrobial Susceptibility Testing (EUCAST) standard methods and erroneous results were noted. Additionally, we investigated turnaround times for rapid automated antimicrobial susceptibility testing and routine diagnostic testing.

RESULTS

We analysed 106 patients with 116 episodes of bacteraemia due to Enterobacterales, with Escherichia coli and Klebsiella pneumoniae being the most frequent isolates. Almost 8% of pathogens were multidrug resistant. Rapid automated antimicrobial susceptibility testing showed category agreement in 98.4% of all interpretable cases. A significant reduction of more than 20 h in turnaround times could be achieved with rapid automated antimicrobial susceptibility testing compared to the routine diagnostic workflow. In the majority of cases, rapid automated antimicrobial susceptibility testing had no effect, given that the empirical therapy was already correct or circumstances did not allow for de-escalation. In 38.8% of cases, antimicrobial therapy was adjusted, whereas eight cases were de-escalated based on rapid automated antimicrobial susceptibility testing alone.

CONCLUSIONS

Rapid automated antimicrobial susceptibility testing may be a valuable and safe way to accelerate diagnosis. In particular, time to suitable therapy can be shortened in cases of incorrect therapy. However, physicians are reluctant to de-escalate antibiotic therapy based on rapid automated antimicrobial susceptibility testing alone, limiting its impact in everyday clinics. To further explore the potential of rapid automated antimicrobial susceptibility testing, a stringent/compulsory antibiotic stewardship programme would be a valuable next step.

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

Around one-third of patients diagnosed with COVID-19 develop a severe illness that requires admission to the Intensive Care Unit (ICU). In clinical practice, clinicians have learned that patients admitted to the ICU due to severe COVID-19 frequently develop ventilator-associated lower respiratory tract infections (VA-LRTI). This study aims to describe the clinical characteristics, the factors associated with VA-LRTI, and its impact on clinical outcomes in patients with severe COVID-19. This was a multicentre, observational cohort study conducted in ten countries in Latin America and Europe. We included patients with confirmed rtPCR for SARS-CoV-2 requiring ICU admission and endotracheal intubation. Only patients with a microbiological and clinical diagnosis of VA-LRTI were included. Multivariate Logistic regression analyses and Random Forest were conducted to determine the risk factors for VA-LRTI and its clinical impact in patients with severe COVID-19. In our study cohort of 3287 patients, VA-LRTI was diagnosed in 28.8% [948/3287]. The cumulative incidence of ventilator-associated pneumonia (VAP) was 18.6% [610/3287], followed by ventilator-associated tracheobronchitis (VAT) 10.3% [338/3287]. A total of 1252 bacteria species were isolated. The most frequently isolated pathogens were Pseudomonas aeruginosa (21.2% [266/1252]), followed by Klebsiella pneumoniae (19.1% [239/1252]) and Staphylococcus aureus (15.5% [194/1,252]). The factors independently associated with the development of VA-LRTI were prolonged stay under invasive mechanical ventilation, AKI during ICU stay, and the number of comorbidities. Regarding the clinical impact of VA-LRTI, patients with VAP had an increased risk of hospital mortality (OR [95% CI] of 1.81 [1.40-2.34]), while VAT was not associated with increased hospital mortality (OR [95% CI] of 1.34 [0.98-1.83]). VA-LRTI, often with difficult-to-treat bacteria, is frequent in patients admitted to the ICU due to severe COVID-19 and is associated with worse clinical outcomes, including higher mortality. Identifying risk factors for VA-LRTI might allow the early patient diagnosis to improve clinical outcomes.Trial registration: This is a prospective observational study; therefore, no health care interventions were applied to participants, and trial registration is not applicable.

Continuous population-level monitoring of SARS-CoV-2 seroprevalence in a large European metropolitan region

Effective public health measures against SARS-CoV-2 require granular knowledge of population-level immune responses. We developed a Tripartite Automated Blood Immunoassay (TRABI) to assess the IgG response against three SARS-CoV-2 proteins. We used TRABI for continuous seromonitoring of hospital patients and blood donors (n = 72'250) in the canton of Zurich from December 2019 to December 2020 (pre-vaccine period). We found that antibodies waned with a half-life of 75 days, whereas the cumulative incidence rose from 2.3% in June 2020 to 12.2% in mid-December 2020. A follow-up health survey indicated that about 10% of patients infected with wildtype SARS-CoV-2 sustained some symptoms at least twelve months post COVID-19. Crucially, we found no evidence of a difference in long-term complications between those whose infection was symptomatic and those with asymptomatic acute infection. The cohort of asymptomatic SARS-CoV-2-infected subjects represents a resource for the study of chronic and possibly unexpected sequelae.

Impact of Bacterial Infections on COVID-19 Patients: Is Timing Important?

BACKGROUND

Along with important factors that worsen the clinical outcome of COVID-19, it has been described that bacterial infections among patients positive for a SARS-CoV-2 infection can play a dramatic role in the disease process. Co-infections or community-acquired infections are recognized within the first 48 h after the admission of patients. Superinfections occur at least 48 h after admission and are considered to contribute to a worse prognosis. Microbiologic parameters differentiate infections that happen after the fifth day of hospitalization from those appearing earlier. Specifically, after the fifth day, the detection of resistant bacteria increases and difficult microorganisms emerge.

OBJECTIVES

The aim of the study was to evaluate the impact of bacterial infections in patients with COVID-19 on the length of the hospital stay and mortality.

METHODS

A total of 177 patients hospitalized due to COVID-19 pneumonia were consecutively sampled during the third and fourth wave of the pandemic at a University Hospital in Greece. A confirmed bacterial infection was defined as positive blood, urinary, bronchoalveolar lavage (BAL) or any other infected body fluid. Patients with confirmed infections were further divided into subgroups according to the time from admission to the positive culture result.

RESULTS

When comparing the groups of patients, those with a confirmed infection had increased odds of death (odds ratio: 3.634; CI 95%: 1.795-7.358; p < 0.001) and a longer length of hospital stay (median 13 vs. 7 days). A late onset of infection was the most common finding in our cohort and was an independent risk factor for in-hospital death. Mortality and the length of hospital stay significantly differed between the subgroups.

CONCLUSION

In this case series, microbial infections were an independent risk factor for a worse outcome among patients with COVID-19. Further, a correlation between the onset of infection and a negative outcome in terms of non-infected, community-acquired, early hospital-acquired and late hospital-acquired infections was identified. Late hospital-acquired infections increased the mortality of COVID-19 patients whilst superinfections were responsible for an extended length of hospital stay.

The under investigated facet of the COVID-19 pandemic: Molecular analysis of secondary bacterial infections at a COVID dedicated intensive care unit within a tertiary care center in Lebanon

Background

The coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread worldwide. Secondary bacterial infections are associated with unfavorable outcomes in respiratory viral infections. This study aimed at determining the prevalence of secondary bacterial infections in COVID-19 patients admitted at a tertiary medical center in Lebanon.

Methodology

From May till November, 2020, a total of 26 Gram-negative isolates were recovered from 16 patients during the course of their COVID-19 infection with Escherichia coli being the most prevalent. The isolates were assessed for their antimicrobial susceptibility by broth microdilution against 19 antimicrobial agents from different classes. Whole genome sequencing of 13 isolates allowed the mining of antimicrobial resistance (AMR) determinants as well as mobile genetic elements and sequence types (ST). Finally, broth microdilution with three different efflux pump inhibitors [theobromine, conessine and PheArg-β-naphthylamide (PAβN)] was done.

Results

Antimicrobial susceptibility testing showed that out of the 26 Gram-negative isolates, 1 (4%) was extensively drug resistant and 14 (54%) were multi-drug resistant (MDR). Whole genome sequencing results revealed a plethora of AMR determinants among the 13 sequenced isolates. Moreover, the 9 Enterobacterales and 4 Pseudomonas aeruginosa sequenced isolates belonged to 9 and 2 different ST, respectively. Using a variety of efflux pump inhibitors we demonstrated that only PAβN had a significant effect when combined with levofloxacin, and the latter regained its activity against two P. aeruginosa isolates.

Conclusion

The identification of carbapenem and colistin resistant Gram-negative bacilli causing secondary bacterial infections in critical patients diagnosed with COVID-19 should be of high concern. Additionally, it is crucial to monitor and track AMR, post-COVID pandemic, in order to better understand the effect of this disease on AMR exacerbation.

Staphylococcus aureus bacteremia in patients with SARS-CoV-2 infection

OBJECTIVES

The aim was to compare the incidence of Staphylococcus aureus bacteremia in COVID-19 and non-COVID-19 adult patients during the pandemic period versus the previous two years. Also, we described the characteristics of both cohorts of patients in pandemic period to find differences.

MATERIAL AND METHODS

Retrospective study in our tertiary-care centre reviewing S. aureus bacteremia episodes in COVID-19 and non-COVID-19 patients through clinical records and the Microbiology Department database.

RESULTS

In 2018 and 2019, the incidence of S. aureus bacteremia episodes was 1.95 and 1.63 per 1000 admissions respectively. In the pandemic period, global incidence was 1.96 episodes per 1000 non-COVID-19 admissions and 10.59 episodes per 1000 COVID-19 admissions. A total of 241 bacteremia was registered during this pandemic period in 74 COVID-19 patients and in 167 non-COVID-19 patients. Methicillin resistance was detected in 32.4% and 13.8% of isolates from COVID-19 and non-COVID-19 patients respectively. In COVID-19 patients, mortality rates were significantly higher.

CONCLUSIONS

We showed a significantly high rates of S. aureus bacteremia incidence in COVID-19 patients and higher methicillin resistance and 15-day mortality rates than in non-COVID-19 patients.

Pulmonary Surfactant Proteins Are Inhibited by Immunoglobulin A Autoantibodies in Severe COVID-19

Rationale: Coronavirus disease 2019 (COVID-19) can lead to acute respiratory distress syndrome with fatal outcomes. Evidence suggests that dysregulated immune responses, including autoimmunity, are key pathogenic factors. Objectives: To assess whether IgA autoantibodies target lung-specific proteins and contribute to disease severity. Methods: We collected 147 blood, 9 lung tissue, and 36 BAL fluid samples from three tertiary hospitals in Switzerland and one in Germany. Severe COVID-19 was defined by the need to administer oxygen. We investigated the presence of IgA autoantibodies and their effects on pulmonary surfactant in COVID-19 using the following methods: immunofluorescence on tissue samples, immunoprecipitations followed by mass spectrometry on BAL fluid samples, enzyme-linked immunosorbent assays on blood samples, and surface tension measurements with medical surfactant. Measurements and Main Results: IgA autoantibodies targeting pulmonary surfactant proteins B and C were elevated in patients with severe COVID-19 but not in patients with influenza or bacterial pneumonia. Notably, pulmonary surfactant failed to reduce surface tension after incubation with either plasma or purified IgA from patients with severe COVID-19. Conclusions: Our data suggest that patients with severe COVID-19 harbor IgA autoantibodies against pulmonary surfactant proteins B and C and that these autoantibodies block the function of lung surfactant, potentially contributing to alveolar collapse and poor oxygenation.

Bacterial and Fungal Superinfections in COVID-19 Patients Hospitalized in an Intensive Care Unit from Timișoara, Romania

PURPOSE

Critically ill patients hospitalized in the intensive care unit (ICU) have an increased infection risk. The aim of this study was to determine the bacterial and fungal superinfections rate in Coronavirus disease 2019 (COVID-19) patients stationed in the ICU, identify risk factors associated with their development and to determine whether superinfection plays a role in patients' outcome in this population.

PATIENTS AND METHODS

In this retrospective, non-interventional, single centre, cohort study, medical records of 302 consecutive patients with SARS-COV-2 pneumonia admitted into the COVID-19 ICU of the largest university hospital from Western Romania between October 2020 and May 2021, were reviewed, of whom 236 patients met the inclusion criteria.

RESULTS

One hundred and nineteen patients developed a superinfection ≥48 h after being admitted to the hospital. Superinfection rate in the ICU was 50.42%. Coagulase-negative Staphylococci (CoNS) and Enterococcus spp. were predominantly isolated from blood cultures, while Acinetobacter baumannii, Staphylococcus aureus and Candida spp. from tracheobronchial aspirates. Significant independent risk factors regarding bacterial/fungal superinfection in COVID-19 patients were obtained for the following variables: number of days of central venous catheter (HR = 1.13 [1.07-1.20], p < 0.001) and prior administration of corticosteroids (HR = 2.80 [1.33-5.93], p = 0.007). Four independent predictive risk factors were associated with unfavorable outcome: age (HR = 1.07 [95% CI 1.03-1.12], p = 0.001); Carmeli Score (HR = 6.09 [1.18-31.50], p = 0.031); body mass index (HR = 1.11 [1.02-1.21], p = 0.011) and the presence of a central venous catheter (HR = 6.49 [1.93-21.89], p = 0.003).

CONCLUSION

The superinfection rate in COVID-19 patients was high in this study group. Exogenous risk factors were associated with superinfection more than endogenous factors. Only a small percentage of uninfected COVID-19 patients were not prescribed antibiotics during their hospitalization, raising serious concerns regarding the judicious prescribing of antibiotics in viral infections.

A Cephalosporin-Tripodalamine Conjugate Inhibits Metallo-β-Lactamase with High Efficacy and Low Toxicity

The wide spread of metallo-β-lactamase (MBL)-expressing bacteria has greatly threatened human health, and there is an urgent need for inhibitors against MBLs. Herein, we present a cephalosporin-tripodalamine conjugate (DPASC) as a potent MBL inhibitor with a block-release design. The cephalosporin tag blocks the ligand binding site to reduce toxicity and is cleaved by MBLs to release active ligands to inhibit MBLs in situ. The screening of MBL-expressing pathogenic strains with 16 μg/mL DPASC showed a decrease of the minimum inhibitory concentration of meropenem (MEM) by 16 to 512-fold, and its toxicity was minimal to human HepG2 cells, with an IC₅₀ exceeding 512 μg/mL. An in vivo infection model with Galleria mellonella larvae showed an increased 3-day survival rate of 87% with the coadministration of DPASC and MEM, compared to 50% with MEM alone and no toxicity at a dose of 256 mg/kg of DPASC. Our findings with DPASC demonstrate that it is an effective MBL inhibitor and that the block-release strategy could be useful for the development of new MBL inhibitors.

Host and microbiome features of secondary infections in lethal covid-19

Secondary infections contribute significantly to covid-19 mortality but driving factors remain poorly understood. Autopsies of 20 covid-19 cases and 14 controls from the first pandemic wave complemented with microbial cultivation and RNA-seq from lung tissues enabled description of major organ pathologies and specification of secondary infections. Lethal covid-19 segregated into two main death causes with either dominant diffuse alveolar damage (DAD) or secondary pneumonias. The lung microbiome in covid-19 showed a reduced biodiversity and increased prototypical bacterial and fungal pathogens in cases of secondary pneumonias. RNA-seq distinctly mirrored death causes and stratified DAD cases into subgroups with differing cellular compositions identifying myeloid cells, macrophages and complement C1q as strong separating factors suggesting a pathophysiological link. Together with a prominent induction of inhibitory immune-checkpoints our study highlights profound alterations of the lung immunity in covid-19 wherein a reduced antimicrobial defense likely drives development of secondary infections on top of SARS-CoV-2 infection.

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Covid-19 autopsy cohort complemented with microbial cultivation and deep sequencing

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Major death causes stratify into DAD and secondary pneumonias

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Prototypical bacterial and fungal agents are found in secondary pneumonias

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Macrophages and C1q stratify DAD subgroups and indicate immune impairment in lungs

Dysregulated Neutrophil Phenotype and Function in Hospitalised Non-ICU COVID-19 Pneumonia

Rationale: Infection with the SARS-CoV2 virus is associated with elevated neutrophil counts. Evidence of neutrophil dysfunction in COVID-19 is based on transcriptomics or single functional assays. Cell functions are interwoven pathways, and understanding the effect across the spectrum of neutrophil function may identify therapeutic targets. Objectives: Examine neutrophil phenotype and function in 41 hospitalised, non-ICU COVID-19 patients versus 23 age-matched controls (AMC) and 26 community acquired pneumonia patients (CAP). Methods: Isolated neutrophils underwent ex vivo analyses for migration, bacterial phagocytosis, ROS generation, NETosis and receptor expression. Circulating DNAse 1 activity, levels of cfDNA, MPO, VEGF, IL-6 and sTNFRI were measured and correlated to clinical outcome. Serial sampling on day three to five post hospitalization were also measured. The effect of ex vivo PI3K inhibition was measured in a further cohort of 18 COVID-19 patients. Results: Compared to AMC and CAP, COVID-19 neutrophils demonstrated elevated transmigration (p = 0.0397) and NETosis (p = 0.0332), and impaired phagocytosis (p = 0.0036) associated with impaired ROS generation (p < 0.0001). The percentage of CD54+ neutrophils (p < 0.001) was significantly increased, while surface expression of CD11b (p = 0.0014) and PD-L1 (p = 0.006) were significantly decreased in COVID-19. COVID-19 and CAP patients showed increased systemic markers of NETosis including increased cfDNA (p = 0.0396) and impaired DNAse activity (p < 0.0001). The ex vivo inhibition of PI3K γ and δ reduced NET release by COVID-19 neutrophils (p = 0.0129). Conclusions: COVID-19 is associated with neutrophil dysfunction across all main effector functions, with altered phenotype, elevated migration and NETosis, and impaired antimicrobial responses. These changes highlight that targeting neutrophil function may help modulate COVID-19 severity.

Modeling the crossover behavior of the bacterial infection with the COVID-19 epidemics

To explore the crossover linkage of the bacterial infections resulting from the viral infection, within the host body, a computational framework is developed. It analyzes the additional pathogenic effect of Streptococcus pneumonia, one of the bacteria that can trigger the super-infection mechanism in the COVID-19 syndrome and the physiological effects of innate immunity for the control or eradication of this bacterial infection. The computational framework, in a novel manner, takes into account the action of pro-inflammatory and anti-inflammatory cytokines in response to the function of macrophages. A hypothetical model is created and is transformed to a system of non-dimensional mathematical equations. The dynamics of three main parameters (macrophages sensitivity κ , sensitivity to cytokines η and bacterial sensitivity ϵ ), analyzes a "threshold value" termed as the basic reproduction numberR 0 which is based on a sub-model of the inflammatory state. Piece-wise differentiation approach is used and dynamical analysis for the inflammatory response of macrophages is studied in detail. The results shows that the inflamatory response, with high probability in bacterial super-infection, is concomitant with the COVID-19 infection. The mechanism of action of the anti-inflammatory cytokines is discussed during this research and it is observed that these cytokines do not prevent inflammation chronic, but only reduce its level while increasing the activation threshold of macrophages. The results of the model quantifies the probable deficit of the biological mechanisms linked with the anti-inflammatory cytokines. The numerical results shows that for such mechanisms, a minimal action of the pathogens is strongly amplified, resulting in the "chronicity" of the inflammatory process.

Critically ill COVID-19 patients with neutralizing autoantibodies against type I interferons have increased risk of herpesvirus disease

Autoantibodies neutralizing the antiviral action of type I interferons (IFNs) have been associated with predisposition to severe Coronavirus Disease 2019 (COVID-19). Here, we screened for such autoantibodies in 103 critically ill COVID-19 patients in a tertiary intensive care unit (ICU) in Switzerland. Eleven patients (10.7%), but no healthy donors, had neutralizing anti-IFNα or anti-IFNα/anti-IFNω IgG in plasma/serum, but anti-IFN IgM or IgA was rare. One patient had non-neutralizing anti-IFNα IgG. Strikingly, all patients with plasma anti-IFNα IgG also had anti-IFNα IgG in tracheobronchial secretions, identifying these autoantibodies at anatomical sites relevant for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection. Longitudinal analyses revealed patient heterogeneity in terms of increasing, decreasing, or stable anti-IFN IgG levels throughout the length of hospitalization. Notably, presence of anti-IFN autoantibodies in this critically ill COVID-19 cohort appeared to predict herpesvirus disease (caused by herpes simplex viruses types 1 and 2 (HSV-1/-2) and/or cytomegalovirus (CMV)), which has been linked to worse clinical outcomes. Indeed, all 7 tested COVID-19 patients with anti-IFN IgG in our cohort (100%) suffered from one or more herpesviruses, and analysis revealed that these patients were more likely to experience CMV than COVID-19 patients without anti-IFN autoantibodies, even when adjusting for age, gender, and systemic steroid treatment (odds ratio (OR) 7.28, 95% confidence interval (CI) 1.14 to 46.31, p = 0.036). As the IFN system deficiency caused by neutralizing anti-IFN autoantibodies likely directly and indirectly exacerbates the likelihood of latent herpesvirus reactivations in critically ill patients, early diagnosis of anti-IFN IgG could be rapidly used to inform risk-group stratification and treatment options.

Trial Registration: ClinicalTrials.gov Identifier: NCT04410263.

Autoantibodies that neutralize the antiviral action of type I interferons are associated with predisposition to severe COVID-19. This study shows that this deficiency in the interferon system is associated with a heightened risk of herpesvirus disease in critically ill patients infected with SARS-CoV-2.

Repurposing benzbromarone as antifolate to develop novel antifungal therapy for Candida albicans

Fungal infections in humans are responsible for mild to severe infections resulting in systemic effects that cause a large amount of mortality. Invasive fungal infections are having similar symptomatic effects to those of COVID-19. The COVID-19 patients are immunocompromised in nature and have a high probability of developing severe fungal infections, resulting in the development of further complications. The existing antifungal therapy has associated problems related to the development of drug resistance, being sub-potent in nature, and the presence of undesirable toxic effects. The fungal dihydrofolate reductase is an essential enzyme involved in the absorption of dietary folic acid and its conversion into tetrahydrofolate, which is a coenzyme required for the biosynthesis of the fungal nucleotides. Thus, in the current study, an attempt has been made to identify potential folate inhibitors of Candida albicans by a computational drug repurposing approach. Based upon the molecular docking simulation-based virtual screening followed by the molecular dynamic simulation of the macromolecular complex, benzbromarone has been identified as a potential anti-folate agent for the development of a novel therapy for the treatment of candidiasis.

Impairment of neutrophil functions and homeostasis in COVID-19 patients: association with disease severity

Background

A dysregulated immune response is emerging as a key feature of critical illness in COVID-19. Neutrophils are key components of early innate immunity that, if not tightly regulated, contribute to uncontrolled systemic inflammation. We sought to decipher the role of neutrophil phenotypes, functions, and homeostasis in COVID-19 disease severity and outcome.

Methods

By using flow cytometry, this longitudinal study compares peripheral whole-blood neutrophils from 90 COVID-19 ICU patients with those of 22 SARS-CoV-2-negative patients hospitalized for severe community-acquired pneumonia (CAP) and 38 healthy controls. We also assessed correlations between these phenotypic and functional indicators and markers of endothelial damage as well as disease severity.

Results

At ICU admission, the circulating neutrophils of the COVID-19 patients showed continuous basal hyperactivation not seen in CAP patients, associated with higher circulating levels of soluble E- and P-selectin, which reflect platelet and endothelial activation. Furthermore, COVID-19 patients had expanded aged-angiogenic and reverse transmigrated neutrophil subsets—both involved in endothelial dysfunction and vascular inflammation. Simultaneously, COVID-19 patients had significantly lower levels of neutrophil oxidative burst in response to bacterial formyl peptide. Moreover patients dying of COVID-19 had significantly higher expansion of aged-angiogenic neutrophil subset and greater impairment of oxidative burst response than survivors.

Conclusions

These data suggest that neutrophil exhaustion may be involved in the pathogenesis of severe COVID-19 and identify angiogenic neutrophils as a potentially harmful subset involved in fatal outcome.

Graphic Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-04002-3.

Klebsiella pneumoniae induces host metabolic stress that promotes tolerance to pulmonary infection

K. pneumoniae sequence type 258 (Kp ST258) is a major cause of healthcare-associated pneumonia. However, it remains unclear how it causes protracted courses of infection in spite of its expression of immunostimulatory lipopolysaccharide, which should activate a brisk inflammatory response and bacterial clearance. We predicted that the metabolic stress induced by the bacteria in the host cells shapes an immune response that tolerates infection. We combined in situ metabolic imaging and transcriptional analyses to demonstrate that Kp ST258 activates host glutaminolysis and fatty acid oxidation. This response creates an oxidant-rich microenvironment conducive to the accumulation of anti-inflammatory myeloid cells. In this setting, metabolically active Kp ST258 elicits a disease-tolerant immune response. The bacteria, in turn, adapt to airway oxidants by upregulating the type VI secretion system, which is highly conserved across ST258 strains worldwide. Thus, much of the global success of Kp ST258 in hospital settings can be explained by the metabolic activity provoked in the host that promotes disease tolerance.

Superinfections caused by carbapenem-resistant Enterobacterales in hospitalized patients with COVID-19: a multicentre observational study from Italy (CREVID Study)

Objectives

To describe clinical characteristics and outcomes of COVID-19 patients who developed secondary infections due to carbapenem-resistant Enterobacterales (CRE).

Methods

Retrospective observational study including COVID-19 patients admitted to 12 Italian hospitals from March to December 2020 who developed a superinfection by CRE. Superinfection was defined as the occurrence of documented bacterial infection &gt;48 h from admission. Patients with polymicrobial infections were excluded. Demographic, clinical characteristics and outcome were collected. Isolates were classified as KPC, metallo-β-lactamase (MBL) and OXA-48-producing CRE. A Cox regression analysis was performed to identify factors independently associated with 30 day mortality.

Results

Overall, 123 patients (median age 66 years, IQR 59–75) were included. The majority of infections occurred in the ICU (81, 65.9%), while 42 (34.1%) in medical wards. The most common types of infection were bloodstream infections (BSI) (n = 64, 52%), followed by urinary-tract infections (UTI) (n = 28, 22.8%), hospital-acquired/ventilator-associated pneumonia (HAP/VAP) (n = 28, 22.8%), intra-abdominal infections (n = 2, 1.6%) and skin infections (n = 1, 0.8%). Sixty-three (51.2%) infections were caused by KPC-, 54 (43.9%) by MBL-, and 6 (4.8%) by OXA-48-producing CRE. Thirty-day mortality was 33.3% (41/123). On Cox regression analysis, HAP/VAP compared with UTI (HR 7.23, 95% CI 2.09–24.97, P = 0.004), BSI compared with UTI (HR 3.96, 95% CI, 1.33–11.77, P = 0.004), lymphopenia on admission (HR 3, 95% CI 1.44–6.26, P = 0.003) and age (HR 1.05, 95% CI 1.02–1.08, P = 0.002) were predictors of 30 day mortality.

Conclusions

Superinfections by CRE were associated with high risk of 30 day mortality in patients with COVID-19. HAP/VAP was the strongest predictor of death in these patients.

HDAC Inhibition as Potential Therapeutic Strategy to Restore the Deregulated Immune Response in Severe COVID-19

The COVID-19 pandemic has had a devastating impact worldwide and has been a great challenge for the scientific community. Vaccines against SARS-CoV-2 are now efficiently lessening COVID-19 mortality, although finding a cure for this infection is still a priority. An unbalanced immune response and the uncontrolled release of proinflammatory cytokines are features of COVID-19 pathophysiology and contribute to disease progression and worsening. Histone deacetylases (HDACs) have gained interest in immunology, as they regulate the innate and adaptative immune response at different levels. Inhibitors of these enzymes have already proven therapeutic potential in cancer and are currently being investigated for the treatment of autoimmune diseases. We thus tested the effects of different HDAC inhibitors, with a focus on a selective HDAC6 inhibitor, on immune and epithelial cells in in vitro models that mimic cells activation after viral infection. Our data indicate that HDAC inhibitors reduce cytokines release by airway epithelial cells, monocytes and macrophages. This anti-inflammatory effect occurs together with the reduction of monocytes activation and T cell exhaustion and with an increase of T cell differentiation towards a T central memory phenotype. Moreover, HDAC inhibitors hinder IFN-I expression and downstream effects in both airway epithelial cells and immune cells, thus potentially counteracting the negative effects promoted in critical COVID-19 patients by the late or persistent IFN-I pathway activation. All these data suggest that an epigenetic therapeutic approach based on HDAC inhibitors represents a promising pharmacological treatment for severe COVID-19 patients.

Animal models for studying covid-19, prevention, and therapy: Pathology and disease phenotypes

Translational models have played an important role in the rapid development of safe and effective vaccines and therapeutic agents for the ongoing coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Animal models recapitulating the clinical and underlying pathological manifestations of COVID-19 have been vital for identification and rational design of safe and effective vaccines and therapies. This manuscript provides an overview of commonly used COVID-19 animal models and the pathologic features of SARS-CoV-2 infection in these models in relation to their clinical presentation in humans. Also discussed are considerations for selecting appropriate animal models for infectious diseases such as COVID-19, the host determinants that can influence species-specific susceptibility to SARS-CoV-2, and the pathogenesis of COVID-19. Finally, the limitations of currently available COVID-19 animal models are highlighted.

Impact of COVID-19 on Antimicrobial Consumption and Spread of Multidrug-Resistance in Bacterial Infections

The spread of COVID-19 pandemic may have affected antibiotic consumption patterns and the prevalence of colonized or infected by multidrug-resistant (MDR) bacteria. We investigated the differences in the consumption of antibiotics easily prone to resistance and the prevalence of MDR bacteria during the COVID-19 pandemic (March 2020 to September 2021) compared to in the pre-pandemic period (March 2018 to September 2019). Data on usage of antibiotics and infections caused by methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), carbapenem-resistant Enterobacteriaceae (CRE), carbapenem-resistant Acinetobacter baumannii (CRAB), and carbapenem-resistant Pseudomonas aeruginosa (CRPA) were obtained from hospitalized patients in four university hospitals. The consumption of penicillin with β-lactamase inhibitors (3.4% in ward, 5.8% in intensive care unit (ICU)), and carbapenems (25.9% in ward, 12.1% in ICU) increased during the pandemic period. The prevalence of MRSA (4.7%), VRE (49.0%), CRE (22.4%), and CRPA (20.1%) isolated in clinical samples from the ward and VRE (26.7%) and CRE (36.4%) isolated in clinical samples from the ICU were significantly increased, respectively. Meanwhile, only the prevalence of CRE (38.7%) isolated in surveillance samples from the ward increased. The COVID-19 pandemic is associated with increased consumption of antibiotics and has influenced the prevalence of infections caused by MDR isolates.

Correlation between Multidrug Resistance Infection with Clinical Outcomes of Critically ill Patients with COVID-19 Admitted to an Intensive Care at RSUP Dr. M. Djamil in Indonesia

BACKGROUND: Approximately 14–50% of severe COVID-19 patients are admitted to the Intensive Care Unit (ICU) that acquires a multidrug-resistant bacterial infection (MDR) and worsens clinical outcomes of patients. AIM: We aim to determine the increased risk of MDR infection in the ICU including large-spectrum antibiotic administration, invasive procedure performance (mechanical ventilation), and clinical outcomes of patient. METHODS: We analyzed 227 patients with a primary diagnosis of COVID-19 on mechanical ventilation who were admitted to ICU COVID-19 RSUP Dr. M. Djamil from 2020 to 2021. Demographic information, sputum culture results, intubation, and clinical outcomes were all collected in the medical records for this retrospective cohort study. Patients who were hospitalized for <48 h in the ICU were excluded from the study. An independent t-test and a Chi-square test were used to analyze the data. RESULTS: In sixty patients (26.4%), bacteria were found in the sputum culture, 40 patients (66.7%) of them were MDR. The most common bacteria found was Acinetobacter baumanii (35%) followed by Klebsiella pneumonia (21.7%). There is a significant relationship between MDR (p-value 0.000) and intubation (p-value, 000) to clinical outcomes of patients (improvement or death). There is a significant relationship between intubation and MDR (p-value 0.009). CONCLUSION: MDR patient status affected the outcomes of COVID-19 patients in the ICU. Patients with MDR were more likely to have a poor clinical outcome.

Long-Term Persisting SARS-CoV-2 RNA and Pathological Findings: Lessons Learnt From a Series of 35 COVID-19 Autopsies

BACKGROUND

Long-term sequelae of coronavirus disease 2019 (COVID-19), including the interaction between persisting viral-RNA and specific tissue involvement, pose a challenging issue. In this study, we addressed the chronological correlation (after first clinical diagnosis and postmortem) between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA and organ involvement.

METHODS

The presence of postmortem SARS-CoV-2 RNA from 35 complete COVID-19 autopsies was correlated with the time interval between the first diagnosis of COVID-19 and death and with its relationship to morphologic findings.

RESULTS

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA can be evident up to 40 days after the first diagnosis and can persist to 94 hours after death. Postmortem SARS-CoV-2 RNA was mostly positive in lungs (70%) and trachea (69%), but all investigated organs were positive with variable frequency. Late-stage tissue damage was evident up to 65 days after initial diagnosis in several organs. Positivity for SARS-CoV-2 RNA in pulmonary swabs correlated with diffuse alveolar damage (p = 0.0009). No correlation between positive swabs and other morphologic findings was present. Cerebral (p = 0.0003) and systemic hemorrhages (p = 0.009), cardiac thrombi (p = 0.04), and ischemic events (p = 0.03) were more frequent in the first wave, whereas bacterial pneumonia (p = 0.03) was more prevalent in the second wave. No differences in biometric data, clinical comorbidities, and other autopsy findings were found.

CONCLUSIONS

Our data provide evidence not only of long-term postmortem persisting SARS-CoV-2 RNA but also of tissue damage several weeks after the first diagnosis of SARS-CoV-2 infection. Additional conditions, such as concomitant bacterial pulmonary superinfection, lung aspergillosis, thromboembolic phenomena, and hemorrhages can further worsen tissue damage.

Coronavirus disease 2019 (COVID-19): Secondary bacterial infections and the impact on antimicrobial resistance during the COVID-19 pandemic

Secondary bacterial infections and bacterial coinfections are an important complication of coronavirus disease 2019 (COVID-19), leading to antibiotic overuse and increased rates of antimicrobial resistance (AMR) during the COVID-19 pandemic. In this literature review, we summarize the reported rates of secondary bacterial infections and bacterial coinfections in patients with COVID-19, the impact on patient outcomes, the antibiotic treatment approaches employed, and the resistance patterns observed. The reported data suggest that although the incidence of secondary bacterial infections or bacterial coinfections is relatively low, they are associated with worse outcomes such as prolonged hospitalization, intensive care unit admission, mechanical ventilator use, and increased mortality. Interestingly, antibiotic prescription rates are typically higher than secondary bacterial and bacterial coinfection rates, and reports of AMR are common. These findings highlight the need for an improved understanding of secondary bacterial and bacterial coinfection in patients with COVID-19, as well as improved treatment options, to mitigate inappropriate antibiotic prescribing and AMR.

Hyperinflammatory environment drives dysfunctional myeloid cell effector response to bacterial challenge in COVID-19

COVID-19 displays diverse disease severities and symptoms including acute systemic inflammation and hypercytokinemia, with subsequent dysregulation of immune cells. Bacterial superinfections in COVID-19 can further complicate the disease course and are associated with increased mortality. However, there is limited understanding of how SARS-CoV-2 pathogenesis and hypercytokinemia impede the innate immune function against bacterial superinfections. We assessed the influence of COVID-19 plasma hypercytokinemia on the functional responses of myeloid immune cells upon bacterial challenges from acute-phase COVID-19 patients and their corresponding recovery-phase. We show that a severe hypercytokinemia status in COVID-19 patients correlates with the development of bacterial superinfections. Neutrophils and monocytes derived from COVID-19 patients in their acute-phase showed an impaired intracellular microbicidal capacity upon bacterial challenges. The impaired microbicidal capacity was reflected by abrogated MPO and reduced NETs production in neutrophils along with reduced ROS production in both neutrophils and monocytes. Moreover, we observed a distinct pattern of cell surface receptor expression on both neutrophils and monocytes, in line with suppressed autocrine and paracrine cytokine signaling. This phenotype was characterized by a high expression of CD66b, CXCR4 and low expression of CXCR1, CXCR2 and CD15 in neutrophils and low expression of HLA-DR, CD86 and high expression of CD163 and CD11b in monocytes. Furthermore, the impaired antibacterial effector function was mediated by synergistic effect of the cytokines TNF-α, IFN-γ and IL-4. COVID-19 patients receiving dexamethasone showed a significant reduction of overall inflammatory markers in the plasma as well as exhibited an enhanced immune response towards bacterial challenge ex vivo. Finally, broad anti-inflammatory treatment was associated with a reduction in CRP, IL-6 levels as well as length of ICU stay and ventilation-days in critically ill COVID-19 patients. Our data provides insights into the transient functional dysregulation of myeloid immune cells against subsequent bacterial infections in COVID-19 patients and describe a beneficial role for the use of dexamethasone in these patients.

COVID-19 Pulmonary Pathology: The Experience of European Pulmonary Pathologists throughout the First Two Waves of the Pandemic

Autoptic studies of patients who died from COVID-19 constitute an important step forward in improving our knowledge in the pathophysiology of SARS-CoV-2 infection. Systematic analyses of lung tissue, the organ primarily targeted by the disease, were mostly performed during the first wave of the pandemic. Analyses of pathological lesions at different times offer a good opportunity to better understand the disease and how its evolution has been influenced mostly by new SARS-CoV-2 variants or the different therapeutic approaches. In this short report we summarize responses collected from a questionnaire survey that investigated important pathological data during the first two pandemic waves (spring-summer 2020; autumn-winter 2020–2021). The survey was submitted to expert lung pathologists from nine European countries involved in autoptic procedures in both pandemic waves. The frequency of each lung lesion was quite heterogeneous among the participants. However, a higher frequency of pulmonary superinfections, both bacterial and especially fungal, was observed in the second wave compared to the first. Obtaining a deeper knowledge of the pathological lesions at the basis of this complex and severe disease, which change over time, is crucial for correct patient management and treatment. Autoptic examination is a useful tool to achieve this goal.

Microbiological monitoring of COVID-19 patients in the ICU: a prospective observational study

Objective. To study spectrum of pathogens and the time to colonization of respiratory samples in patients with severe and critical COVID-19 as well as to analyze incidence of nosocomial infections and structure of prescribed antibacterial drugs. Materials and Methods. The prospective observational study included patients aged 18 years and older with confirmed severe and critical COVID-19 from December 2021 to February 2022. During the first 48 hours and then every 2–3 days of hospitalization, a respiratory sample was collected: sputum, tracheal aspirate (if intubated), bronchoalveolar lavage (if bronchoscopy was performed) for microscopy and microbiological examination. Some patients were screened for invasive aspergillosis. Clinical and demographic data, comorbidities, pathogenetic therapy for COVID-19, antibiotic therapy, cases of probable/documented bacterial nosocomial infections, antibiotic-associated diarrhea, and hospital treatment outcomes were recorded. Results. A total of 82 patients were included in this study. Patients with lung parenchyma involvement of more than 50% by computer tomography predominated; most of them (77%) required intubation and mechanical ventilation due to progression of respiratory failure, and 76% of patients had a lethal outcome. During the first 48 hours, a respiratory sample was obtained from 47 patients; the rest of the patients presented with non-productive cough. No growth of microorganisms was detected in 31 (36.8%) cases; clinically significant pathogens were detected in 16 (19.5%) patients. A subsequent analysis included data from 63 patients with a sufficient number of samples for dynamic observation were used. During the first 3 days of ICU stay, the most common bacterial pathogens were Klebsiella pneumoniae without acquired antibiotic resistance and methicillin-susceptible Staphylococcus aureus. From 3rd day and afterwards, an increase in the proportion of Acinetobacter baumannii, other non-fermenting bacteria, and carbapenemresistant Enterobacterales was noted. Among the pathogens causing lower respiratory tract infections, A. baumannii and carbapenem-resistant K. pneumoniae were predominant pathogens and accounted for 76% of cases. Positive galactomannan test results were obtained in 4 cases. Conclusions. The study confirmed importance of bacterial nosocomial infections in patients with severe and critical COVID-19. In the case of the development of nosocomial lower respiratory tract infections, empirical antimicrobial therapy should take into account the predominance of carbapenem-resistant Enterobacteria and A. baumannii, as well as the possibility of invasive aspergillosis.

How Does COVID-19 Pandemic Impact on Incidence of Clostridioides difficile Infection and Exacerbation of Its Gastrointestinal Symptoms?

Coronavirus disease 2019 (COVID-19) has rapidly spread all over the world with a very high rate of mortality. Different symptoms developed by COVID-19 infection and its impacts on various organs of the human body have highlighted the importance of both coinfections and superinfections with other pathogens. The gastrointestinal (GI) tract is vulnerable to infection with COVID-19 and can be exploited as an alternative transmission route and target for virus entry and pathogenesis. The GI manifestations of COVID-19 disease are associated with severe disease outcomes and death in all age groups, in particular, elderly patients. Empiric antibiotic treatments for microbial infections in hospitalized patients with COVID-19 in addition to experimental antiviral and immunomodulatory drugs may increase the risk of antibiotic-associated diarrhea (AAD) and Clostridioides difficile infection (CDI). Alterations of gut microbiota are associated with depletion of beneficial commensals and enrichment of opportunistic pathogens such as C. difficile. Hence, the main purpose of this review is to explain the likely risk factors contributing to higher incidence of CDI in patients with COVID-19. In addition to lung involvement, common symptoms observed in COVID-19 and CDI such as diarrhea, highlight the significance of bacterial infections in COVID-19 patients. In particular, hospitalized elderly patients who are receiving antibiotics might be more prone to CDI. Indeed, widespread use of broad-spectrum antibiotics such as clindamycin, cephalosporins, penicillin, and fluoroquinolones can affect the composition and function of the gut microbiota of patients with COVID-19, leading to reduced colonization resistance capacity against opportunistic pathogens such as C. difficile, and subsequently develop CDI. Moreover, patients with CDI possibly may have facilitated the persistence of SARS-CoV-2 viral particles in their feces for approximately one month, even though the nasopharyngeal test turned negative. This coinfection may increase the potential transmissibility of both SARS-CoV-2 and C. difficile by fecal materials. Also, CDI can complicate the outcome of COVID-19 patients, especially in the presence of comorbidities or for those patients with prior exposure to the healthcare setting. Finally, physicians should remain vigilant for possible SARS-CoV-2 and CDI coinfection during the ongoing COVID-19 pandemic and the excessive use of antimicrobials and biocides.

Blunted sFasL signalling exacerbates TNF-driven neutrophil necroptosis in critically ill COVID-19 patients

OBJECTIVES

Critically ill coronavirus disease 2019 (COVID-19) patients are characterised by a severely dysregulated cytokine profile and elevated neutrophil counts, impacting disease severity. However, it remains unclear how neutrophils contribute to pathophysiology during COVID-19. Here, we assessed the impact of the dysregulated cytokine profile on the regulated cell death (RCD) programme of neutrophils.

METHODS

Regulated cell death phenotype of neutrophils isolated from critically ill COVID-19 patients or healthy donors and stimulated with COVID-19 or healthy plasma ex vivo was assessed by flow cytometry, time-lapse microscopy and cytokine multiplex analysis. Immunohistochemistry of COVID-19 patients and control biopsies were performed to assess the in situ neutrophil RCD phenotype. Plasma cytokine levels of COVID-19 patients and healthy donors were measured by multiplex analysis. Clinical parameters were correlated to cytokine levels of COVID-19 patients.

RESULTS

COVID-19 plasma induced a necroptosis-sensitive neutrophil phenotype, characterised by cell lysis, elevated release of damage-associated molecular patterns (DAMPs), increased receptor-interacting serine/threonine-protein kinase (RIPK) 1 levels and mixed lineage kinase domain-like pseudokinase (MLKL) involvement. The occurrence of neutrophil necroptosis MLKL axis was further confirmed in COVID-19 thrombus and lung biopsies. Necroptosis was induced by the tumor necrosis factor receptor 1 (TNFRI)/TNF-α axis. Moreover, reduction of soluble Fas ligand (sFasL) levels in COVID-19 patients and hence decreased signalling to Fas directly increased RIPK1 levels, exacerbated TNF-driven necroptosis and correlated with disease severity, which was abolished in patients treated with glucocorticoids.

CONCLUSION

Our results suggest a novel role for sFasL signalling in the TNF-α-induced RCD programme in neutrophils during COVID-19 and a potential therapeutic target to curb inflammation and thus influence disease severity and outcome.

High Rates of Bacterial Pulmonary Co-Infections and Superinfections Identified by Multiplex PCR among Critically Ill COVID-19 Patients

BACKGROUND

The role of bacterial co-infection and superinfection among critically ill COVID-19 patients remains unclear. The aim of this study was to assess the rates and characteristics of pulmonary infections, and associated outcomes of ventilated patients in our facility.

METHODS

This was a retrospective study of ventilated COVID-19 patients between March 2020 and March 2021 that underwent BioFire^®, FilmArray^® Pneumonia Panel, testing. Community-acquired pneumonia (CAP) was defined when identified during the first 72 h of hospitalization, and ventilator-associated pneumonia (VAP) when later.

RESULTS

148 FilmArray tests were obtained from 93 patients. With FilmArray, 17% of patients had CAP (16/93) and 68% had VAP (64/93). Patients with VAP were older than those with CAP or those with no infection (68.5 vs. 57-59 years), had longer length of stay and higher mortality (51% vs. 10%). The most commonly identified FilmArray target organisms were H. influenzae, S. pneumoniae, M. catarrhalis and E. cloacae for CAP and P. aeruginosa and S. aureus for VAP. FilmArray tests had high negative predictive values (99.6%) and lower positive predictive values (~60%).

CONCLUSIONS

We found high rates of both CAP and VAP among the critically ill, caused by the typical and expected organisms for both conditions. VAP diagnosis was associated with poor patient outcomes.

Atypical response to bacterial co-infection and persistent neutrophilic broncho-alveolar inflammation distinguish critical COVID-19 from influenza

Neutrophils are recognized as important circulating effector cells in the pathophysiology of severe coronavirus disease 2019 (COVID-19). However, their role within the inflamed lungs is incompletely understood. Here, we collected broncho-alveolar lavage (BAL) fluids and parallel blood samples of critically ill COVID-19 patients requiring invasive mechanical ventilation and compared BAL fluid parameters with those of mechanically ventilated influenza patients, as a non-COVID-19 viral pneumonia cohort. Compared to influenza, BAL fluids of COVID-19 patients contained increased numbers of hyperactivated degranulating neutrophils and elevated concentrations of the cytokines IL-1β, IL-1RA, IL-17A, TNF-α and G-CSF, the chemokines CCL7, CXCL1, CXCL8, CXCL11 and CXCL12α, and the protease inhibitors elafin, secretory leukocyte protease inhibitor (SLPI) and tissue inhibitor of metalloproteinases 1 (TIMP-1). In contrast, α-1 antitrypsin levels and net proteolytic activity were comparable in COVID-19 and influenza BAL fluids. During antibiotics treatment for bacterial co-infections, increased BAL fluid levels of several activating and chemotactic factors for monocytes, lymphocytes and NK cells were detected in COVID-19 patients whereas concentrations tended to decrease in influenza patients, highlighting the persistent immunological response to co-infections in COVID-19. Finally, the high proteolytic activity in COVID-19 lungs suggests considering protease inhibitors as a treatment option.

Bacterial and fungal growth in sputum cultures from 165 COVID-19 pneumonia patients requiring intubation: evidence for antimicrobial resistance development and analysis of risk factors

BACKGROUND

Coronavirus SARS-CoV-2 causes COVID-19 illness which can progress to severe pneumonia. Empiric antibacterials are often employed though frequency of bacterial coinfection superinfection is debated and concerns raised about selection of bacterial antimicrobial resistance. We evaluated sputum bacterial and fungal growth from 165 intubated COVID-19 pneumonia patients. Objectives were to determine frequency of culture positivity, risk factors for and outcomes of positive cultures, and timing of antimicrobial resistance development.

METHODS

Retrospective reviews were conducted of COVID-19 pneumonia patients requiring intubation admitted to a 1058-bed four community hospital system on the east coast United States, March 1 to May 1, 2020. Length of stay (LOS) was expressed as mean (standard deviation); 95% confidence interval (95% CI) was computed for overall mortality rate using the exact binomial method, and overall mortality was compared across each level of a potential risk factor using a Chi-Square Test of Independence. All tests were two-sided, and significance level was set to 0.05.

RESULTS

Average patient age was 68.7 years and LOS 19.9 days. Eighty-three patients (50.3% of total) originated from home, 10 from group homes (6.1% of total), and 72 from nursing facilities (43.6% of total). Mortality was 62.4%, highest for nursing home residents (80.6%). Findings from 253 sputum cultures overall did not suggest acute bacterial or fungal infection in 73 (45%) of 165 individuals sampled within 24 h of intubation. Cultures ≥ 1 week following intubation did grow potential pathogens in 72 (64.9%) of 111 cases with 70.8% consistent with late pneumonia and 29.2% suggesting colonization. Twelve (10.8% of total) of these late post-intubation cultures revealed worsened antimicrobial resistance predominantly in Pseudomonas, Enterobacter, or Staphylococcus aureus.

CONCLUSIONS

In severe COVID-19 pneumonia, a radiographic ground glass interstitial pattern and lack of purulent sputum prior to/around the time of intubation correlated with no culture growth or recovery of normal oral flora ± yeast. Discontinuation of empiric antibacterials should be considered in these patients aided by other clinical findings, history of prior antimicrobials, laboratory testing, and overall clinical course. Continuing longterm hospitalisation and antibiotics are associated with sputum cultures reflective of hospital-acquired microbes and increasing antimicrobial resistance.

TRIAL REGISTRATION

Not applicable as this was a retrospective chart review study without interventional arm.