Pulmonary complications of influenza infection: a targeted narrative review

COVID-19 vs. non-COVID-19 related nosocomial pneumonias: any differences in etiology, prevalence, and mortality?

PURPOSE OF REVIEW

This review explores the similarities and differences between coronavirus disease 2019 (COVID-19)-related and non-COVID-related nosocomial pneumonia, particularly hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP). It critically assesses the etiology, prevalence, and mortality among hospitalized patients, emphasizing the burden of these infections during the period before and after the severe acute respiratory syndrome coronavirus 2 pandemic.

RECENT FINDINGS

Recent studies highlight an increase in nosocomial infections during the COVID-19 pandemic, with a significant rise in cases involving severe bacterial and fungal superinfections among mechanically ventilated patients. These infections include a higher incidence of multidrug-resistant organisms (MDROs), complicating treatment and recovery. Notably, COVID-19 patients have shown a higher prevalence of VAP than those with influenza or other respiratory viruses, influenced by extended mechanical ventilation and immunosuppressive treatments like corticosteroids.

SUMMARY

The findings suggest that COVID-19 has exacerbated the frequency and severity of nosocomial infections, particularly VAP. These complications not only extend hospital stays and increase healthcare costs but also lead to higher morbidity and mortality rates. Understanding these patterns is crucial for developing targeted preventive and therapeutic strategies to manage and mitigate nosocomial infections during regular or pandemic care.

Severe Bacterial Superinfection of Influenza Pneumonia in Immunocompetent Young Patients: Case Reports

Influenza can lead to or coexist with severe bacterial pneumonia, with the potential to permanently damage lung tissue, refractory to conservative treatment in the post-COVID-19 period. It can lead to serious complications; therefore, annual vaccinations are recommended. This case series with a literature review pertains to two young female patients with an insignificant past medical history, who required emergency lobectomy due to bacterial complications after influenza infection. Urgent lobectomy proves to be a feasible therapeutic option for selected patients with pleural complications.

The Hospital Burden of Flu in Italy: a retrospective study on administrative data from season 2014-2015 to 2018-2019

BACKGROUND

Every year in Italy, influenza affects about 4 million people. Almost 5% of them are hospitalised. During peak illness, enormous pressure is placed on healthcare and economic systems. This study aims to quantify the clinical and economic burden of severe influenza during 5 epidemic seasons (2014-2019) from administrative claims data.

METHODS

Patients hospitalized with a diagnosis of influenza between October 2014, and April 2019, were analyzed. Clinical characteristics and administrative information were retrieved from health-related Administrative Databases (ADs) of 4 Italian Local Health Units (LHUs). The date of first admission was set as the Index Date (ID). A follow-up period of six months after ID was considered to account for complications and re-hospitalizations, while a lookback period (2 years before ID) was set to assess the prevalence of underlying comorbidities.

RESULTS

Out of 2,333 patients with severe influenza, 44.1% were adults ≥ 65, and 25.6% young individuals aged 0-17. 46.8% had comorbidities (i.e., were at risk), mainly cardiovascular and metabolic diseases (45.3%), and chronic conditions (24.7%). The highest hospitalization rates were among the elderly (≥ 75) and the young individuals (0-17), and were 37.6 and 19.5/100,000 inhabitants/year, respectively. The average hospital stay was 8 days (IQR: 14 - 4). It was higher for older individuals (≥ 65 years, 11 days, [17 - 6]) and for those with comorbidities (9 days, [16 - 6]), p-value < 0.001. Similarly, mortality was higher in elderly and those at risk (p-value < 0.001). Respiratory complications occurred in 12.7% of patients, and cardiovascular disorders in 5.9%. Total influenza-related costs were €9.7 million with hospitalization accounting for 95% of them. 47.3% of hospitalization costs were associated with individuals ≥ 65 and 52.9% with patients at risk. The average hospitalisation cost per patient was € 4,007.

CONCLUSIONS

This retrospective study showed that during the 2014-2019 influenza seasons in Italy, individuals of extreme ages and those with pre-existing medical conditions, were more likely to be hospitalized with severe influenza. Together with complications and ageing, they worsen patient's outcome and may lead to a prolonged hospitalization, thus increasing healthcare utilization and costs. Our data generate real-world evidence on the burden of influenza, useful to inform public health decision-making.

Qin-Qiao-Xiao-Du formula alleviate influenza virus infectious pneumonia through regulation gut microbiota and metabolomics

Qin-Qiao-Xiao-Du (QQXD), a traditional Chinese medicine (TCM) formula, has been used in the clinical treatment of influenza virus pneumonia. However, the effects and mechanisms of QQXD on influenza virus pneumonia remain unknown. Therefore, this study explores the mechanisms of QQXD in the treatment of influenza virus pneumonia from the point of view of intestinal flora and metabolism. The results showed that QQXD was able to reduce mortality, weight loss, lung viral load, lung index, and lung injury in influenza virus mice. A cytokine array found that the QQXD attenuated the expression of serum IL-1α, IL-4, IL-12(P70), and TNF-α. Subsequently, 16s rRNA gene sequencing showed that QQXD could increase the relative abundances of Gemmiger, Anaerofustis, Adlercreutzia, and Streptococcus and decrease those of Dehalobacteriu, Burkholderia, Prevotella, Butyrimimonas, Delftia, and others. Meanwhile, targeted metabolic profiling analysis showed that QQXD could regulate nitrogen metabolism, phenylalanine metabolism, valine, leucine, and isoleucine biosynthesis. Correlation analysis demonstrated that the regulatory effect of QQXD on the cyanoamino acid metabolism pathway was associated with changes in the abundance of Parabacteroides, Pediococcus, and Clostridium in influenza mice. In conclusion, our study revealed that QQXD can inhibit influenza virus replication, suppress cytokine storms, and protect mice from influenza virus infection pneumonia. The mechanisms are likely to be related to improved gut microbiota dysbiosis, increased intestinal carbohydrate metabolism, and up-regulated cyanoamino acid metabolism pathways.

Evaluating a Cluster and the Overall Trend of Invasive Haemophilus influenzae Serotype b in Alaska 2005-2019

BACKGROUND

In 2019, 5 cases of invasive Haemophilus influenzae serotype b (Hib) occurred in the Anchorage region of Alaska over a period of 16 days. No cases had occurred in Alaska in the preceding 26 months.

METHODS

Alaska Hib isolates from 2005 through 2019 were analyzed using whole-genome sequencing (WGS). Rates were compared with the CDC's Active Bacterial Core surveillance (ABCs) data.

RESULTS

A total of 33 cases of invasive Hib occurred in Alaska from 2005 through 2019. Of the 5 cases associated with the cluster, 2 (40%) occurred in adults and all occurred in the Anchorage region. In contrast, only 14% (4/28) of the noncluster cases occurred in this region (P < 0.01). Two cluster cases were linked epidemiologically and the bacteria were nearly identical. The other 3 cluster cases were caused by 3 genetically distinct bacteria. When the full period was evaluated, the unadjusted rate of invasive Hib disease in Alaska was 15.5 times higher in Alaska Native (AN) people than non-AN people [1.3/100,000 vs. 0.07/100,000, 95% confidence intervals (CI): 10.2-22.5). The age-adjusted rate of invasive Hib disease in Alaska was 9.4 times higher than the ABCs rate (95% CI: 6.3-14.1).

CONCLUSIONS

While clustered in time and space, the 5 cases in 2019 were not due to a single bacterial strain. AN people continue to have elevated rates of invasive Hib infection compared with both non-AN people in Alaska and the ABCs population.

[Clinical characteristics of influenza pneumonia in the elderly and relationship between D-dimer and disease severity]

OBJECTIVE

To clarify the clinical characteristics of influenza pneumonia in the elderly patients and the relationship between D-dimer and the severity of influenza pneumonia.

METHODS

In the study, 52 hospitalized patients older than 65 years with confirmed influenza pneumonia diagnosed in Peking University People's Hospital on 5 consecutive influenza seasons from 2014 were retrospectively analyzed. General information, clinical symptoms, laboratory data, treatment methods and prognosis of the patients were collected. The relationship between D-dimer and pneumonia severity was analyzed, and receiver operating characteristic (ROC) curve was used to evaluate the predictive value of D-dimer.

RESULTS

Among the 52 patients, 31 were male (31/52, 59.6%), the average age was (77.1±7.4) years, and 19 of them (36.5%) were diagnosed with severe pneumonia. About 70% patients presenting with fever. In the severe group, the patients were more likely to complain of dyspnea than in the non-severe group (14/19, 73.7% vs. 10/33, 30.3%, P=0.004), severe pneumonia group had higher level of CURB-65 (confusion, urea, respiratory rate, blood pressure, and age>65), pneumonia severity index (PSI), C-reactive protein, urea nitrogen, lactate dehydrogenase, fasting glucose, and D-dimer (P value was 0.004, < 0.001, < 0.001, 0.003, 0.038, 0.018, and < 0.001, respectively), albumin was lower than that in the non-severe group [(35.8±5.6) g/L vs. (38.9±3.5) g/L, t=-2.348, P=0.018]. There was a significant positive correlation between the D-dimer at the first admission and PSI score (r=0.540, 95%CI: 0.302 to 0.714, P < 0.001), while a significant negative correlation with PaO₂/FiO₂ (r=-0.559, 95%CI: -0.726 to -0.330, P < 0.001). Area under the curve of D-dimer was 0.765 (95%CI: 0.627 to 0.872). Area under the curve of PSI was 0.843 (95%CI: 0.716 to 0.929). There was no statistically significant difference in test efficacy between the two (Z=2.360, P=0.174). D-dimer level over 1 225 μg/L had a positive predict value for influenza pneumonia in hospital death with a sensitivity of 76.92% and a specificity of 74.36%.

CONCLUSION

Influenza pneumonia in the elderly always has atypical symptoms, dyspnea is a prominent feature in severe cases, D-dimer level is associated with the severity of influenza pneumonia, and greater than 1 200 μg/L has a good predictive value for in-hospital death in the elderly.

Real-life antimicrobial therapy in hospitalized patients with COVID-19 (preliminary results and recommendations)

Objective. Development of local clinical protocols for antibacterial therapy of COVID-19-associated bacterial pneumonia in the therapeutic department of the city clinical hospital based on an analysis of the treatment process in patients with COVID-19-associated pneumonia. Materials and Methods. A retrospective analysis of 1382 cases of hospitalization in the therapeutic department of patients with COVID-19-associated pneumonia for the period from 2020 to 2021 was carried out. The structure of etiotropic therapy, the frequency and timing of microbiological studies of the biomaterial, the manifestations of the main markers of bacterial infection during dynamic monitoring of clinical and laboratory parameters in patients prescribed antibiotic therapy, as well as statistics of the stay of patients in the therapeutic department of the hospital were assessed. Based on the results obtained in the course of microbiological studies, an assessment was made of the microbial landscape of the lower respiratory tract of patients with an analysis of the sensitivity of strains of the leading microflora to a wide range of antibiotics. Results. The study found that the dominant flora in COVID-19-associated pneumonia in hospitalized patients was gram-negative bacteria – K. pneumoniae, P. aeruginosa and A. baumannii – their proportion was more than 50%. Among K. pneumoniae strains, 89.4% were ESBL producers, 63.5% of the strains were resistant to carbapenems, which with a high probability allows them to be considered carbapenemaseproducing strains. Among the strains of P. aeruginosa, the proportion of strains resistant to carbapenems and with a high degree of probability being strains – producers of carbapenemase was 41.1%. Among strains of Acinetobacter spp. these were 76.4%, and associated resistance to fluoroquinolones and aminoglycosides was also demonstrated. Gram-positive microorganisms were found in 34.3% of cases and were mainly represented by strains of S. aureus (74.9%), only 26.4% of strains of this pathogen were methicillin-resistant. Conclusions. Microbiological monitoring conducted in 2020–2021 revealed the presence, among the pathogens of viral-bacterial pneumonia, at an early stage of hospitalization, a significant proportion of gram-negative bacteria with resistance of the MDR and XDR types. Based on the obtained microbiological data, starting empirical schemes for antibacterial therapy of secondary viral and bacterial pneumonia, which complicated the course of a new coronavirus infection COVID-19 caused by the SARS-CoV-2 virus, were developed and proposed.

Effects of Antiviral Therapy and Glucocorticoid Therapy on Fever Duration in Pediatric Patients with Influenza

Background and Objectives: Considering developing resistance against neuraminidase inhibitors (NAIs) and their adverse reactions, restricted use of NAIs and use of alternative drugs should be considered for treating influenza. Although glucocorticoids (GCs) have been used for severe influenza, their effects on non-severe influenza have rarely been evaluated. This study aimed to evaluate the clinical responses to NAI therapy and GC therapy in pediatric patients with non-severe influenza. Materials and Methods: A total of 601 pediatric patients (<19 years of age) diagnosed with non-severe influenza were retrospectively recruited to evaluate the effects of NAI therapy and GC therapy. Post-admission fever duration and hospitalization duration were compared among four patient groups divided by the administered treatment: No therapy (n = 52), NAI therapy (n = 154), GC therapy (n = 123), and Both therapies (n = 272). Results: In a multivariate analysis with adjustment for confounding variables, the post-admission fever duration was not significantly different among the four patient groups. The post-admission fever duration tended to shorten with increasing age, longer pre-admission fever duration, and incidence of influenza A virus infection and lower respiratory tract infection. The type of administered treatment showed no significant effects on the post-admission fever duration in any subgroups according to patient age, pre-admission fever duration, influenza virus subtype, and clinical diagnosis. Conclusions: Symptomatic treatment rather than antiviral or GC therapy seems to be sufficient for patients with non-severe influenza, although the effects of NAI therapy and GC therapy according to their administered time and dose should be further evaluated.

COVID-19 versus influenza A/B supeRInfectionS in the IntenSive care unit (CRISIS): Protocol for a Danish nationwide cohort study

BACKGROUND

Superinfection following viral infection is a known complication, which may lead to longer hospitalisation and worse outcome. Empirical antibiotic therapy may prevent bacterial superinfections, but may also lead to overuse, adverse effects and development of resistant pathogens. Knowledge about the incidence of superinfections in intensive care unit (ICU) patients with severe Coronavirus Disease 2019 (COVID-19) is limited.

METHODS

We will conduct a nationwide cohort study comparing the incidence of superinfections in patients with severe COVID-19 admitted to the ICU compared with ICU patients with influenza A/B in Denmark. We will include approximately 1000 patients in each group from the time period of 1 October 2014 to 30 April 2019 and from 10 March 2020 to 1 March 2021 for patients with influenza and COVID-19, respectively. The primary outcome is any superinfection within 90 days of admission to the ICU. We will use logistic regression analysis comparing COVID-19 with influenza A/B after adjustment for relevant predefined confounders. Secondarily, we will use unadjusted and adjusted logistic regression analyses to assess six potential risk factors (sex, age, cancer [including haematological], immunosuppression and use of life support on day 1 in the ICU) for superinfections and compare outcomes in patients with COVID-19 with/without superinfections, and present descriptive data regarding the superinfections.

CONCLUSION

This study will provide important knowledge about superinfections in ICU patients with severe COVID-19.

Influenza A virus infects pulmonary microvascular endothelial cells leading to microvascular leakage and release of pro-inflammatory cytokines

Objective

To investigate the replication of influenza A virus A/Puerto Rico/8/34 (H1N1) in pulmonary microvascular endothelial cells and its effect on endothelial barrier function.

Methods

Human pulmonary microvascular endothelial cells were infected with influenza A/Puerto Rico/8/34 (H1N1) virus. Plaque reduction assay, real-time quantitative PCR, immunofluorescence staining, and western blot were used to elucidate the replication process of virus-infected endothelial cells. In addition, real-time quantitative PCR was used to detect the relative expression levels of mRNA of some inflammatory factors. The endothelial resistance assay was used to determine the permeability of the endothelial monolayer. Excavation and analysis of data from open databases, such as the GeneCards database, DAVID Bioinformatics Resources, STRING search tool, and DGIdb database determined the genes, proteins, and signal pathways related to microvascular leakage caused by the H1N1 virus, and predicted the drugs that could be effective for treatment.

Results

In vitro experiments showed that the influenza virus can infect endothelial cells, leading to a significant increase in the permeability of pulmonary microvascular endothelial cells and the release of pro-inflammatory cytokines, but does not efficiently replicate in endothelial cells. A total of 107 disease-related target genes were obtained from the Gene-cards database. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that these genes mainly affected the pathways related to "Inflammatory bowel disease" (IBD), "Chagas disease" (American trypanosomiasis), "Influenza A", and also played a key role in anti-inflammation and regulation of immunity. After enrichment analysis, 46 hub genes were screened. A total of 42 FDA-approved drugs corresponding to the hub genes were screened from the DGIdb database, and these could be formulated for topical application. In addition, these drugs can be used to treat other diseases, including cancer, inflammatory diseases, immune system disorders, and cardiovascular diseases.

Conclusion

H1N1 influenza virus affects the barrier function of endothelial cells indirectly. Combined with bioinformatics tools, we can better understand the possible mechanism of action of influenza A (H1N1) virus causing pulmonary microvascular leakage and provide new clues for the treatment of pulmonary microvascular leakage.

SARS-CoV-2 Infectivity and Severity of COVID-19 According to SARS-CoV-2 Variants: Current Evidence

BACKGROUND

We conducted this review to summarize the relation between viral mutation and infectivity of SARS-CoV-2 and also the severity of COVID-19 in vivo and in vitro.

METHOD

Articles were identified through a literature search until 31 May 2021, in PubMed, Web of Science and Google Scholar.

RESULTS

Sixty-three studies were included. To date, most studies showed that the viral mutations, especially the D614G variant, correlate with a higher infectivity than the wild-type virus. However, the evidence of the association between viral mutation and severity of the disease is scant. A SARS-CoV-2 variant with a 382-nucleotide deletion was associated with less severe infection in patients. The 11,083G > U mutation was significantly associated with asymptomatic patients. By contrast, ORF1ab 4715L and S protein 614G variants were significantly more frequent in patients from countries where high fatality rates were also reported. The current evidence showed that variants of concern have led to increased infectivity and deteriorating epidemiological situations. However, the relation between this variant and severity of COVID-19 infection was contradictory.

CONCLUSION

The COVID-19 pandemic continues to spread worldwide. It is necessary to anticipate large clinical cohorts to evaluate the virulence and transmissibility of SARS-CoV-2 mutants.

Autopsy findings after long-term treatment of COVID-19 patients with microbiological correlation

Between April and June 2020, i.e., during the first wave of pandemic coronavirus disease 2019 (COVID-19), 55 patients underwent long-term treatment in the intensive care unit at the University Hospital of Regensburg. Most of them were transferred from smaller hospitals, often due to the need for an extracorporeal membrane oxygenation system. Autopsy was performed in 8/17 COVID-19-proven patients after long-term treatment (mean: 33.6 days). Autopsy revealed that the typical pathological changes occurring during the early stages of the disease (e.g., thrombosis, endothelitis, capillaritis) are less prevalent at this stage, while severe diffuse alveolar damage and especially coinfection with different fungal species were the most conspicuous finding. In addition, signs of macrophage activation syndrome was detected in 7 of 8 patients. Thus, fungal infections were a leading cause of death in our cohort of severely ill patients and may alter clinical management of patients, particularly in long-term periods of treatment.

Adrenal crisis precipitated by influenza A led to the diagnosis of Sheehan's syndrome 18 years after postpartum hemorrhage

Physicians must recognize and treat adrenal crisis that may occur with acute viral illnesses such as influenza in women with Sheehan's syndrome that has been undiagnosed and hence untreated, sometimes for many years, after postpartum hemorrhage.

Influenza-Associated Aspergillosis: Nationwide Trends, Predictors and Outcomes From 2005 to 2014

BACKGROUND

Influenza-associated aspergillosis (IAA) has been increasingly reported in the literature in recent years, but contemporary large-scale data on the morbidity and mortality burden of IAA are lacking.

RESEARCH QUESTION

The goal of this study was to estimate the predictors, associations, and outcomes of IAA in the United States.

STUDY DESIGN AND METHODS

This retrospective cohort study was performed by using the National (Nationwide) Inpatient Sample database from 2005 to 2014 to identify influenza and IAA hospitalizations. Baseline variables and outcomes were compared between influenza hospitalizations without IAA and those with IAA. These variables were then used to perform an adjusted analysis for obtaining predictors and associations of the diagnosis and in-hospital mortality of IAA.

RESULTS

Of the 477,556 hospitalizations identified with the principal diagnosis of influenza, IAA was identified in 823 (0.17%) hospitalizations. The IAA cohort consisted more commonly of 45- to 65-year-olds in urban teaching hospitals with substance abuse. Yearly trends revealed that both influenza and IAA hospitalizations have increased over time, with a peak observed in 2009, the year of the influenza A(H1N1) pandemic. Mortality was higher (20.58% vs 1.36%), average length of stay was longer (17.94 vs 4.05 days), and mean cost per hospitalization was higher ($194,932 vs $24,286) in the IAA cohort compared with the influenza cohort without IAA (P < .005). Solid-organ transplantation, hematologic malignancies, and use of invasive mechanical ventilation were associated with higher odds of IAA, among other factors. Use of invasive mechanical ventilation (adjusted OR, 13.43; P < .005), longer length of stay (adjusted OR, 5.47; P < .005), utilization of extracorporeal membrane oxygenation (adjusted OR, 4.99; P = .014), and the group aged 45 to 64 years (adjusted OR, 3.03; P = .012) were associated with higher in-hospital mortality in the IAA cohort.

INTERPRETATION

Although IAA is a rare complication of influenza hospitalizations, it is associated with increased all-cause mortality, more extended hospital stays, and higher hospital charges compared with influenza without IAA.

Epidemic and pandemic viral infections: impact on tuberculosis and the lung: A consensus by the World Association for Infectious Diseases and Immunological Disorders (WAidid), Global Tuberculosis Network (GTN), and members of the European Society of Clinical Microbiology and Infectious Diseases Study Group for Mycobacterial Infections (ESGMYC)

Major epidemics, including some that qualify as pandemics, such as severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), HIV, influenza A (H1N1)pdm/09 and most recently COVID-19, affect the lung. Tuberculosis (TB) remains the top infectious disease killer, but apart from syndemic TB/HIV little is known regarding the interaction of viral epidemics and pandemics with TB. The aim of this consensus-based document is to describe the effects of viral infections resulting in epidemics and pandemics that affect the lung (MERS, SARS, HIV, influenza A (H1N1)pdm/09 and COVID-19) and their interactions with TB. A search of the scientific literature was performed. A writing committee of international experts including the European Centre for Disease Prevention and Control Public Health Emergency (ECDC PHE) team, the World Association for Infectious Diseases and Immunological Disorders (WAidid), the Global Tuberculosis Network (GTN), and members of the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Study Group for Mycobacterial Infections (ESGMYC) was established. Consensus was achieved after multiple rounds of revisions between the writing committee and a larger expert group. A Delphi process involving the core group of authors (excluding the ECDC PHE team) identified the areas requiring review/consensus, followed by a second round to refine the definitive consensus elements. The epidemiology and immunology of these viral infections and their interactions with TB are discussed with implications for diagnosis, treatment and prevention of airborne infections (infection control, viral containment and workplace safety). This consensus document represents a rapid and comprehensive summary on what is known on the topic.

How does one choose the appropriate pharmacotherapy for children with lower respiratory tract infections?

INTRODUCTION

The definition of acute lower respiratory tract infection (LRTI) includes any infection involving the respiratory tract below the level of the larynx. In children, the most common acute LRTIs, and those with the greatest clinical relevance, are community-acquired pneumonia (CAP), bronchiolitis, bronchitis and tuberculosis (TB). The clinical relevance of LRTIs implies that they must be addressed with the most effective therapy. Antibiotics and antivirals play an essential role in this regard.

AREAS COVERED

In this paper, the most recent advances in the drug treatment of LRTIs in children are discussed.

EXPERT OPINION

Although LRTIs are extremely common and one of the most important causes of hospitalization and death in children, anti-infective therapy for these diseases remains unsatisfactory. For CAP and BR, the most important problem is the overuse and misuse of antibiotics; for BCL, the lack of drugs with demonstrated efficacy, safety and tolerability; for TB, the poor knowledge on the true efficacy and safety of the new drugs specifically planned to overcome the problem of MDR M. tuberculosis strains. There is still a long way to go for the therapy of pediatric LRTIs to be considered satisfactory.

Therapeutic potential of resveratrol against emerging respiratory viral infections

Resveratrol has been widely studied for its therapeutic potential due to its antioxidant, anti-inflammatory and anti-microbial properties. In particular, resveratrol has shown promising antiviral activity against numerous viruses responsible for severe respiratory infections. Amongst these, influenza virus, respiratory syncytial virus and the emerging SARS-cov-2 are known to cause pneumonia, acute respiratory distress syndrome or multi-organ failure, especially, in vulnerable individuals like immunocompromised patients or the elderly, leading to a considerable economic burden worldwide. In this context, resveratrol may have potential value for its anti-inflammatory activity, since most of the severe virus-associated complications are related to the overactivation of the host-immune response, leading to lung damage. Herein, we present an overview of the antiviral activity and potential mechanisms of resveratrol against the respiratory tract viruses considered as a public threat for their rapid transmission and high morbidity and mortality in the general population.

The burden of laboratory-confirmed influenza infection in Lebanon between 2008 and 2016: a single tertiary care center experience

BACKGROUND

Influenza is a major cause of morbidity and mortality worldwide. Following the 2009 pandemic, there was widened interest in studying influenza burden in all regions. However, since data from the World Health Organization (WHO) Middle East and North Africa (MENA) region remain limited, we aimed to contribute to the understanding of influenza burden in Lebanon.

METHODS

A retrospective chart review extending over a period of 8 seasons from Jan 1st, 2008 till June 30th, 2016 at a tertiary care center in Beirut was performed. All cases confirmed to have influenza based on rapid antigen detection or/and polymerase chain reaction on a respiratory sample were included for analysis. Data on epidemiology, clinical presentation, complications, antiviral use and mortality were collected for analysis.

RESULTS

A total of 1829 cases of laboratory-confirmed influenza were identified. Average annual positivity rate was 14% (positive tests over total requested). Both influenza A and B co-circulated in each season with predominance of influenza A. Influenza virus started circulating in December and peaked in January and February. The age group of 19-50 years accounted for the largest proportion of cases (22.5%) followed by the age group of 5-19 years (18%). Pneumonia was the most common complication reported in 33% of cases. Mortality reached 3.8%. The two extremes of age (< 2 years and ≥ 65 years) were associated with a more severe course of disease, hospitalization, intensive care unit (ICU) admission, complications, and mortality rate. Of all the identified cases, 26% were hospitalized. Moderate-to-severe disease was more likely in influenza B cases but no difference in mortality was reported between the two types. Antivirals were prescribed in 68.8% and antibiotics in 41% of cases. There seemed to be an increasing trend in the number of diagnosed and hospitalized cases over the years of the study.

CONCLUSION

Patients with laboratory-confirmed influenza at our center had a high rate of hospitalization and mortality. A population based prospective surveillance study is needed to better estimate the burden of Influenza in Lebanon that would help formulate a policy on influenza control.

Clinical Characteristics and Predictors of Mortality in Critically Ill Influenza Adult Patients

Severe influenza is associated with high morbidity and mortality. The aim of this study was to investigate the factors affecting the clinical outcomes of critically ill influenza patients. In this retrospective study, we enrolled critically ill adult patients with influenza at the Kaohsiung Chang Gung Memorial Hospital in Taiwan. We evaluated the demographic, clinical, and laboratory findings and examined whether any of these measurements correlated with mortality. We then created an event-based algorithm as a simple predictive tool using two variables with statistically significant associations with mortality. Between 2015 and 2018, 102 critically ill influenza patients (median age, 62 years) were assessed; among them, 41 (40.1%) patients died. Of the 94 patients who received oseltamivir therapy, 68 (72.3%) began taking oseltamivir 48 h after the onset of illness. Of the 102 patients, the major influenza-associated complications were respiratory failure (97%), pneumonia (94.1%), acute kidney injury (65.7%), adult respiratory distress syndrome (ARDS) (51%), gastrointestinal bleeding (35.3%), and bacteremia (16.7%). In the multivariate regression model, high lactate levels, ARDS, acute kidney injury, and gastrointestinal bleeding were independent predictors of mortality in critically ill influenza patients. The optimal lactate level cutoff for predicting mortality was 3.7 mmol/L with an area under curve of 0.728. We constructed an event-associated algorithm that included lactate and ARDS. Fifteen (75%) of 20 patients with lactate levels 3.7 mmol/L and ARDS died, compared with only 1 (7.7%) of 13 patients with normal lactate levels and without ARDS. We identified clinical and laboratory predictors of mortality that could aid in the care of critically ill influenza patients. Identification of these prognostic markers could be improved to prioritize key examinations that might be useful in determining patient outcomes.

Interleukin-37 Ameliorates Influenza Pneumonia by Attenuating Macrophage Cytokine Production in a MAPK-Dependent Manner

Viral pneumonitis caused by influenza A (H1N1) virus leads to high levels of morbidity and mortality. Given the limited treatment options for severe influenza pneumonia, it is necessary to explore effective amelioration approaches. Interleukin-37 (IL-37) has been reported to inhibit excessive immune responses and protect against a variety of inflammatory diseases. In this study, by using BALB/c mice intranasally infected with A/California/07/2009 (H1N1), we found that IL-37 treatment increases the survival rate and body weight, and reduces the pulmonary index, impaired the lung injury and decreased production of pro-inflammatory cytokines in the BALF and lung tissue. Moreover, IL-37 administration enhanced not only the percentage of macrophages, but also the percentage of IL-18Rα⁺ macrophages, suggesting that enhancing the macrophages function may improve outcomes in a murine model of H1N1 infection. Indeed, macrophages depletion reduced the protective effect of IL-37 during H1N1 infection. Furthermore, IL-37 administration inhibited MAPK signaling in RAW264.7 cells infected with H1N1. This study demonstrates that IL-37 treatment can ameliorate influenza pneumonia by attenuating cytokine production, especially by macrophages. Thus, IL-37 might serve as a promising new target for the treatment of influenza A-induced pneumonia.