Identification of priority pathogens for aetiological diagnosis in adults with community-acquired pneumonia in China: a multicentre prospective study

Fei-yan-qing-hua decoction exerts an anti-inflammatory role during influenza by inhibiting the infiltration of macrophages and neutrophils through NF-κB and p38 MAPK pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Fei-Yan-Qing-Hua decoction (FYQHD) is an empirical formula that has shown clinical success in treating community-acquired pneumonia (CAP) for two decades. Influenza viral infection is a significant trigger for severe pneumonia, yet the role of FYQHD in treating influenza remains unclear.

AIM OF THE STUDY

This study aimed to assess the potential efficacy of FYQHD in treating influenza viral infection and to elucidate its underlying mechanisms.

MATERIALS AND METHODS

The protective effects of FYQHD against influenza were evaluated through survival assessments and pathological analyses. Transcriptomic analysis was performed to identify the genes and pathways influenced by FYQHD in influenza. The anti-inflammatory effects and molecular mechanisms of FYQHD were studied in macrophages stimulated by Toll-like receptor (TLR) 7 ligation in vitro. The key constituents of FYQHD absorbed in mouse sera were identified using untargeted metabolomics, and the anti-inflammatory activity of some of these compounds in macrophages was evaluated using ELISA.

RESULTS

Our findings demonstrate that FYQHD enhances survival and reduces lung damage in PR8-infected mice, primarily through its anti-inflammatory properties. Lung indexes and organ damage were significantly lower in the PR8 + OSV + FYQHD group compared to the PR8 + OSV group, indicating a potential complementary therapeutic effect of FYQHD and OSV in treating influenza. FYQHD effectively reduced chemokine expression, thereby decreasing the chemotaxis and infiltration of inflammatory monocytes/macrophages and neutrophils in the lungs. The anti-inflammatory effects of FYQHD in macrophages were achieved through the inhibition of NF-κB activation and p38 phosphorylation. The key constituents of FYQHD absorbed in mouse sera were identified, with some, such as wogonin, luteolin, kaempferol, and isorhamnetin, showing anti-inflammatory effects in primary macrophages.

CONCLUSION

FYQHD demonstrates protective efficacy against influenza and shows promise as an adjuvant therapeutic agent, particularly when used in combination with antiviral drugs like OSV. The potent anti-inflammatory components within FYQHD provide a basis for further exploration in drug research and development aimed at combating influenza.

A new pathogen pattern of acute respiratory tract infections in primary care after COVID-19 pandemic: a multi-center study in southern China

BACKGROUND

After the coronavirus disease 2019 (COVID-19) pandemic, no studies on bacterial and atypical pathogens were conducted in primary care. We aimed to describe the etiological composition of acute respiratory tract infections (ARTIs) presenting to primary care with limited resources after the pandemic.

METHODS

1958 adult patients with ARTIs from 17 primary care clinics were recruited prospectively from January 2024 to March 2024. 17 and 62 pathogens in throat swab samples were tested using polymerase chain reaction (PCR) and targeted next-generation sequencing (tNGS), respectively. We analyzed the pathogen spectrum and co-infectious pattern of viral, bacterial or atypical pathogens. Then, the associations between clinical characteristics and pathogens were investigated.

RESULTS

In PCR test, the positive rate of any pathogens was 80.3%, consisting of 60.2% for viruses, 41.8% for bacteria and 21.7% for viral-bacterial co-infection. In tNGS test, the positive rate was 89.1%, consisting of 64.7% for viruses, 55.2% for bacteria and 30.9% for viral-bacterial co-infection. Influenza virus B (18.2%), influenza virus A (16.8%) and severe acute respiratory syndrome coronavirus 2 (14.1%) were the three leading viral pathogens, and H. influenzae (36.1%), S. anginosus (15.7%) and S. pneumoniae (8.4%) were the three leading bacterial pathogens. Few M. pneumoniae (1.6%) were detected. The mixed bacterial or mixed viral-bacterial co-infections were the most common co-infectious patterns. The mixed bacterial or mixed viral-bacterial co-infections were the most common co-infectious patterns. Overall, patients with viral infection or viral-bacterial co-infection had more clinical symptoms, and patients with bacterial infection had higher inflammatory indicators.

CONCLUSIONS

After the COVID-19 pandemic, the main viral pathogens of ARTIs were unevenly distributed, and less bacterial and atypical pathogens were detected in primary care. The microbiological evidences can optimize the precision diagnosis and treatment of ARTIs in primary care with limited resources.

Clinical and prognostic relevance of Mycoplasma felis PCR detection in feline lower respiratory tract disease

OBJECTIVES

The aim of this retrospective cohort study was to compare two groups of cats with lower respiratory tract disease, one with Mycoplasma felis detected by PCR in the bronchoalveolar lavage fluid (BALF) (M+) and the other without (M-), with regard to signalment, clinical signs, diagnostic results, treatment response and survival.

METHODS

All cats for which M felis was investigated by PCR in BALF between 2016 and 2023 were included. Cats with evidence of oropharyngeal contamination, or for which PCR results were under the quantification level, or without follow-up information were excluded. Cats that had received antibiotics effective against M felis before BALF collection were excluded if PCR results were negative. Follow-up information was retrieved from the medical records and by contacting referring veterinarians and owners.

RESULTS

A total of 55 cats were included (19 in the M+ group and 36 in the M- group). Significant differences were detected between the two groups in the prevalence of systemic signs (M+: 0%, M-: 28%; P = 0.01), bronchial collapse on bronchoscopy (M+: 28%, M-: 6%; P = 0.03), radiographic alveolar lesions (M+: 57%, M-: 24%; P = 0.04), and percentage of neutrophils (M+: 65%, M-: 35%; P = 0.002) and eosinophils (M+: 9%, M-: 25%; P = 0.03) in the BALF. Antibiotics were used more frequently in M+ cats (M+: 90%, M-: 42%; P = 0.001) than in M- cats. No significant difference was found in treatment response (short term: P = 0.94, long term: P = 0.28) and risk of death (P = 0.42) between the two groups.

CONCLUSIONS AND RELEVANCE

The presence of radiographic alveolar lesions and neutrophilia in BALF was significantly associated with the detection of M felis in BALF. This association might be causal, consequential or contextual (ie, sharing the same cause). The detection of M felis in BALF did not negatively impact prognosis but the necessity to treat M felis using targeted antibiotics remains to be determined.

The Clinical Application Value of a Novel Chip in the Detection of Pathogens in Adult Pneumonia: A Multi-Centre Prospective Study in China

Purpose

The detection of pathogenic microorganisms plays a significant role in the diagnosis and management of pneumonia that are responsible for a substantial number of deaths worldwide. However, conventional microbiological tests (CMT) have low accuracy and are time-consuming. In this study, we aim to evaluate the clinical value of Chips for Complicated Infection Detection (CCID) in detecting pneumonia pathogens.

Patients and Methods

This study was conducted at nine hospitals in China from January 2021 to September 2022. Respiratory samples from adult pneumonia patients were collected from each patient. CMT and CCID were performed in parallel to identify the pathogens.

Results

A total of 245 patients were included, with 73% being elderly. CCID identified pathogenic microbes in 78.0% of patients and conventional microbiological tests (CMT) in 57.1% of the patients (p<0.001). The overall positive and negative percent agreements between CCID and CMT for pathogen detection were 90.07% and 38.46%, respectively. 38.8% of patients were diagnosed with mixed infections with at least two pathogens by CCID. Bacterial infections identified by CCID accounted for 60.0% of 245 patients, with the top 3 being Pseudomonas aeruginosa, Klebsiella pneumoniae, and Enterococcus faecium, respectively. K. pneumoniae was the most common pathogen in elderly patients, with a significantly higher prevalence compared to non-elderly patients (p = 0.0011). Among the 197 patients who had used antibiotics before sample collection, the positive rate of CCID was significantly higher than that of CMT (p < 0.001).

Conclusion

This study indicates that compared to CMT, this novel chip has significant advantages in detecting pathogens in pneumonia patients, especially in the elderly.

An Overview on Disease Burden and Management of Respiratory Syncytial Virus Infections in Older Adults in the Asia-Pacific Region

Respiratory syncytial virus (RSV) represents a significant burden on older adults (aged ≥ 50 years) globally and can lead to acute respiratory tract infections with substantial morbidity and mortality. However, there is a significant gap in knowledge regarding RSV infection in older adults, particularly in the Asia-Pacific region. This knowledge gap underscores the need for targeted and comprehensive studies to fully understand the nuanced epidemiology of RSV in ageing populations. This review synthesises data from various countries, emphasising the impact of RSV on older populations in the Asia-Pacific region. The overall proportions of RSV-related ARIs among older patients ranged from 0.2% to 5.6%. Among older adult patients with CAP, RSV accounted for 1.1%-10.3% of cases. However, it is crucial to note that the diversity in reported percentages highlights the influence of factors such as geographic location, health care settings and diagnostic practices. The most common symptoms observed in older adults with RSV infection were cough, sputum production and fever, followed by dyspnoea, sore throat and rhinorrhoea. Most of the old adults with RSV infection had underlying diseases, and RSV can cause significant morbidity and mortality in old adults. Treatment of RSV infections predominantly involve supportive care, with aerosolised ribavirin reserved for severe cases, especially immunocompromised patients. Emerging antiviral agents, including fusion and nucleoprotein inhibitors, offer promising avenues for future therapeutics. The recent approval of the bivalent RSV prefusion F protein-based vaccine for individuals aged 60 and older represents a milestone in preventive strategies. In conclusion, RSV infection remains a significant threat to older adults in the Asia-Pacific region, necessitating ongoing research and surveillance efforts. The recent vaccine approval marks a positive milestone, but further studies are crucial for refining prevention and treatment approaches.

Prognostic value of echocardiography parameters, peripheral blood T lymphocyte subpopulations, NF-κB, and CD64 levels in neonatal sepsis

BACKGROUND

To evaluate the prognostic value of echocardiography parameters, T lymphocyte subpopulations, NF-κB, and CD64 levels in neonatal sepsis.

METHODS

A retrospective analysis was conducted on 78 neonates treated for sepsis between January 2018 and December 2022, comprising 64 with poor prognosis and 14 with good prognosis. Among them, 51 were critically ill and 27 were non-critically ill. Echocardiographic parameters, T-lymphocyte subpopulations, NF-κB, and CD64 levels were compared across different prognosis and severity groups. Factors influencing prognosis were identified through multivariate logistic regression analysis.

RESULTS

The left ventricular ejection fraction (LVEF), left ventricular fractional shortening (LVFS), CD3+, and CD4+ T lymphocyte levels in critically ill neonates were (61.15±8.22)%, (32.26±6.61)%, (45.56±7.12)%, and (26.61±6.80)%, respectively, significantly lower than those of non-critically ill neonates (all P < 0.05). The levels of NF-κB and CD64 in critically ill neonates were (18.11±2.61) mg/L and (7.42±1.15)%, respectively, significantly higher than those of non-critically ill neonates (all P < 0.05). Logistic regression analysis showed that LVEF, LVFS, CD4+, CD64, and disease severity were the factors influencing prognosis in neonatal sepsis (all P < 0.05). The area under the ROC curve for the logistic regression equation in predicting prognosis in neonatal sepsis was 0.878, with sensitivity and specificity of 85.30% and 84.10%, respectively.

CONCLUSION

Echocardiography parameters, T lymphocyte subpopulations, NF-κB, and CD64 levels are associated with neonatal sepsis severity. LVEF, LVFS, CD4+ T lymphocytes, CD64, and disease severity are linked to prognosis, suggesting their potential as prognostic indicators for neonatal sepsis.

Effectiveness of influenza vaccines in preventing acute cardiovascular events within 1 year in Beijing, China

Controversies persist about the protective effects of vaccines against acute cardiovascular events. Using electronic medical records from hospitals and influenza vaccine administration data in Beijing, China, we studied individuals vaccinated between January 1, 2016, and December 31, 2018, who experienced at least one acute cardiovascular event within two years. A self-controlled case series design calculated the relative incidence (RI) and 95% confidence interval (CI) of acute cardiovascular events within one year after vaccination. Among 1647 participants (median age: 65 years, 38.43% female), the risk of events 29-365 days post-vaccination was 0.76 times the baseline level (RI: 0.76; 95% CI: 0.68-0.84). The protective effect was more pronounced in younger participants (P = 0.043) and those without cardiovascular history (P < 0.001), while acute respiratory infection (P = 0.986) and vaccination frequency (P = 0.272) had no impact. Influenza vaccines offer protection against acute cardiovascular events for at least one year, suggesting potential for cardiovascular disease prevention.

Research of recombinant influenza A virus as a vector for Mycoplasma pneumoniae P1a and P30a

BACKGROUND

Mycoplasma pneumoniae (MP) is a common respiratory pathogen affecting the longevity of the elderly and the health of children. However, the human vaccine against MP has not been successfully developed till now due to the poor immunogenicity and side effects of MP inactivated or attenuated vaccine. Therefore, it is necessary to develop a MP genetic engineering vaccine with influenza virus strain as vector.

METHODS

In this study, the major antigen genes P1a of MP adhesion factor P1(3862-4554 bases) and P30a of P30(49-822 bases) were inserted into the nonstructural protein (NS) gene of Influenza A virus strain A/Puerto Rio/8/34(H1N1), PR8 for short, to construct the recombinant vectors NS-P1a or NS-P30a. The recombinant pHW2000 plasmids containing NS-P1a or NS-P30a were cotransfected with the rest 7 fragments of PR8 into HEK293T cells. After inoculating chicken embryos, the recombinant influenza viruses rFLU-P1a and rFLU-P30a were rescued. RT-PCR and sequencing were used to identify the recombinant viruses. The hemagglutination titers of rFLU-P1a and rFLU-P30a were determined after five successive generations in chicken embryos so as to indicate the genetic stability of the recombinant viruses. The morphology of recombinant influenza viruses was observed under electron microscopy.

RESULTS

P1a or P30a was designed to be inserted into the modified NS gene sequence separately and synthesized successfully. RT-PCR identification of the recombinant viruses rFLU-P1a and rFLU-P30a showed that P1a (693 bp), P30a (774 bp), NS-P1a (1992bp) and NS-P30a (2073 bp) bands were found, and the sequencing results were correct. After five successive generations, each virus generation has a certain hemagglutination titer (from 1:32 to 1:64), and the band of P1a or P30a can be seen in the corresponding positions. The virus particles under the electron microscope appeared as spheres or long strips connected by several particles, revealing a complete viral membrane structure composed of virus lipid bilayer, hemagglutinin, neuraminidase, and matrix proteins.

CONCLUSION

The recombinant viruses rFLU-P1a and rFLU-P30a which carried the advantaged immune regions of the P1 and P30 genes in MP were successfully constructed and identified. And the genetic stability of rFLU-P1a or rFLU-P30a was relatively high. The typical and complete morphology of influenza virus was observed under the electron microscope. Our research provided a foundation for the further development of MP vaccines for human.

The efficacy of nebulized budesonide and ambroxol hydrochloride in treating pediatric community-acquired pneumonia and their impact on clinical characteristics and inflammatory markers

PURPOSE

To evaluate the therapeutic efficacy of intravenous amoxicillin clavulanate potassium combined with nebulized budesonide and ambroxol hydrochloride in pediatric community-acquired pneumonia (CAP) and its impact across various microbial strains and clinical symptoms. The primary objective of this study is to evaluate the efficacy of intravenous amoxicillin-clavulanate combined with nebulized budesonide and ambroxol hydrochloride in the treatment of pediatric community-acquired pneumonia (CAP), and to analyze their impact on different microbial strains and clinical symptoms. Secondary objectives include assessing the treatment's effect on the improvement of clinical symptoms, hospital stay duration, and the levels of inflammatory markers.

DESIGN

Prospective, single-center study.

METHODS

Fifty-six children with CAP, aged under 6 years, from Affiliated Maternity and Child Health Care Hospital of Nantong University were included. Patients were treated with conventional therapy and the study medication. Clinical characteristics, microbiological data, symptom improvement, and hospitalization times were analyzed.

FINDINGS

Young children, particularly under 1 year, exhibited a higher incidence of multiple microbial infections and severe clinical manifestations. Treatment with budesonide and ambroxol hydrochloride led to significant clinical improvement across all age groups, with notable efficacy against various pathogens.

CONCLUSIONS

Nebulized budesonide and ambroxol hydrochloride are effective in treating pediatric CAP, offering a promising therapeutic option, particularly for young children with severe presentations.

Disease burden and macrolide resistance of Mycoplasma pneumoniae infection in adults in the Asia-Pacific region

OBJECTIVES

In the Asia-Pacific region, Mycoplasma pneumoniae (MP) could be a notable pathogen responsible for adult community-acquired pneumonia (CAP), with varying prevalence rates. This comprehensive review aimed to explore the epidemiology, clinical manifestations, macrolide resistance, and molecular characteristics of MP in adults across several countries in Asia.

METHODS

PubMed, Embase, and Google Scholar were searched for relevant articles from 2010-2023 based on the following keywords: adult and Mycoplasma pneumoniae.

RESULTS

The prevalence of MP in CAP patients in these countries ranged from 2.1% in Korea to 25.5% in Japan. Macrolide resistance was prominent, particularly in China, with rates ranging 26.9-100%. Clinical manifestations of MP infection included protean extrapulmonary manifestations, and complications such as rhabdomyolysis and thrombocytopenia. Molecular characteristics, especially the multiple locus variable-number tandem-repeat analysis type 4/5/7/2, remained predominant across various countries, emphasising the importance of ongoing surveillance.

CONCLUSIONS

This review highlights the urgent need for continued monitoring of MP infections, macrolide resistance, and molecular characteristics to inform effective prevention and treatment strategies in the Asia-Pacific region.

The impact of the COVID-19 pandemic on Staphylococcus aureus infections in pediatric patients admitted with community acquired pneumonia

The COVID-19 pandemic has significantly transformed the infection spectrum of various pathogens. This study aimed to evaluate the impact of the COVID-19 pandemic on Staphylococcus aureus (S. aureus) infections among pediatric patients with community acquired pneumonia (CAP). We retrospectively reviewed pediatric CAP admissions before (from 2018 to 2019) and during (from 2020 to 2022) the COVID-19 pandemic. The epidemiology and antimicrobial resistance (AMR) profiles of S. aureus isolates were examined to assess the pandemic's effect. As a result, a total of 399 pediatric CAP patients with S. aureus infections were included. The positivity rate, gender, and age distribution of patients were similar across both periods. There was a marked reduction in respiratory co-infections with Haemophilus influenzae (H. influenzae) during the COVID-19 pandemic, compared to 2019. Additionally, there were significant changes in the resistance profiles of S. aureus isolates to various antibiotics. Resistance to oxacillin and tetracycline increased, whereas resistance to penicillin, gentamicin, and quinolones decreased. Notably, resistance to erythromycin significantly decreased in methicillin-resistant S. aureus (MRSA) strains. The number of S. aureus isolates, the proportion of viral co-infections, and the number of resistant strains typically peaked seasonally, primarily in the first or fourth quarters of 2018, 2019, and 2021. However, shifts in these patterns were noted in the first quarter of 2020 and the fourth quarter of 2022. These findings reveal that the COVID-19 pandemic has significantly altered the infection dynamics of S. aureus among pediatric CAP patients, as evidenced by changes in respiratory co-infections, AMR patterns, and seasonal trends.

Clinical Profiles, Laboratory Biomarkers, and Mortality in Cancer Patients with Lower Respiratory Tract Infections: A Prospective Cohort Study

Respiratory tract infections (RTIs) pose a substantial health burden worldwide, especially among immunocompromised groups like cancer patients. The aim of this prospective cohort study was to explore lower respiratory tract infections in cancer patients. We followed 107 cases with clinically or radiologically suspected lower respiratory tract infections until discharge or death, comprising 65 males and 42 females across diverse age groups. Clinical evaluations, including patient history, examination, and malignancy diagnosis, were conducted. Nasopharyngeal swabs (NPSs), sputum samples, and blood samples were collected within 24 h of symptom onset. Multiplex Real-Time PCR allowed for the simultaneous detection of viral, bacterial, and fungal infections, while conventional microbiological culture methods were used for bacterial and fungal analysis. SARS-CoV-2 infection was excluded in all of the enrolled patients using real-time RT-PCR. Hematological and biochemical analyses included hemoglobin, lymphocyte, neutrophil, and platelet counts, along with ALT, AST, creatinine, and CRP levels. Significant differences were noted in clinical presentations, management outcomes, and prognostic markers among patients with different hematological malignancies. Distinct clinical profiles were identified for leukemia, lymphoma, and solid tumors, with variations in age distribution and symptom prevalence. ICU admission rates varied significantly, with solid tumor patients exhibiting higher rates. The hematological and biochemical biomarkers differed across malignancies, with notable associations between lymphopenia, thrombocytopenia, and mortality following respiratory episodes. This study highlights the critical role of rapid pathogen detection and infection control measures in safeguarding vulnerable cancer patients from nosocomial transmission.

Comparison of the clinical characteristics in parents and their children in a series of family clustered Mycoplasma pneumoniae infections

BACKGROUND

Mycoplasma pneumoniae infections have increased in China recently, causing some evidence of familial clustering. The purpose of this study was to compare the clinical features of parents and children in cases of familial clustering of Mycoplasma pneumoniae infection.

METHODS

A retrospective analysis was performed on the cases of familial clustering of Mycoplasma pneumoniae infection, and the clinical characteristics of parents and children were compared.

RESULTS

We identified 63 families, of these, 57 (65.5%) adults and 65 (94.2%) children required hospitalization. Fifty-seven adults (mean age 35.1 ± 4.6 years, 80.7% female) and 55 children (mean age 6.3 ± 3.9 years, 54.5% female) were included in the analysis. The incidence of mycoplasma infection in adults had increased gradually over the past year, while the rate in children had spiked sharply since June 2023. The clinical symptoms were similar in the two groups, mainly fever and cough. The peak temperature of children was higher than that of adults (39.1 ± 0.7℃ vs 38.6 ± 0.7℃, p = 0.004). Elevated lactate dehydrogenase was more common in children than in adults (77.8% vs 11.3%, p < 0.001). Bronchial pneumonia and bilateral involvement were more common in children, while adults usually had unilateral involvement. Three (60%) adults and 21 (52.5%) children were macrolide-resistant Mycoplasma pneumoniae infected. Children were more likely to be co-infected (65.5% vs 22.8%, p < .001). Macrolides were used in most children and quinolones were used in most adults. Ten (18.2%) children were diagnosed with severe Mycoplasma pneumoniae pneumonia, whereas all adults had mild disease. Children had a significantly longer fever duration than adults ((5.6 ± 2.2) days vs (4.1 ± 2.2) days, p = 0.002). No patient required mechanical ventilation or died.

CONCLUSIONS

Mycoplasma pneumoniae infection shows a familial clustering epidemic trend at the turn of summer and autumn, with different clinical characteristics between parents and children.

Impact of viral detection in patients with community-acquired pneumonia: An observational cohort study

PURPOSE

The presence of a respiratory virus in patients with community-acquired pneumonia (CAP) may have an impact on the bacterial etiology and clinical presentation. In this study we aimed to assess the role of viral infection in the bacterial etiology and outcomes of patients with CAP.

METHODS

We performed a retrospective study of all adults hospitalized with CAP between November 2017 and October 2018. Patients were classified according to the presence of viral infection. An unvaried and a multivaried analysis were performed to identify variables associated with viral infection and clinical outcomes.

RESULTS

Overall 590 patients were included. A microorganism was documented in 375 cases (63.5%). A viral infection was demonstrated in 118 (20%). The main pathogens were Streptococcus pneumoniae (35.8%), Staphylococcus aureus (2.9%) and influenza virus (10.8%). A trend to a higher rate of S. aureus (p=0.06) in patients with viral infection was observed. Patients with viral infection had more often bilateral consolidation patterns (17.8% vs 10.8%, p=0.04), respiratory failure (59.3% vs 42.8%, p=0.001), ICU admission (17.8% vs 7%, p=0.001) and invasive mechanical ventilation (9.3% vs 2.8%, p=0.003). Risk factors for respiratory failure were chronic lung disease, age >65 years, positive blood cultures and viral infection. Influenza, virus but no other respiratory viruses, was associated with respiratory failure (OR, 3.72; 95% CI, 2.06-6.73).

CONCLUSIONS

Our study reinforces the idea that co-viral infection has an impact in the clinical presentation of CAP causing a more severe clinical picture. This impact seems to be mainly due to influenza virus infection.

A cooperativity between virus and bacteria during respiratory infections

Respiratory tract infections remain the leading cause of morbidity and mortality worldwide. The burden is further increased by polymicrobial infection or viral and bacterial co-infection, often exacerbating the existing condition. Way back in 1918, high morbidity due to secondary pneumonia caused by bacterial infection was known, and a similar phenomenon was observed during the recent COVID-19 pandemic in which secondary bacterial infection worsens the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) condition. It has been observed that viruses paved the way for subsequent bacterial infection; similarly, bacteria have also been found to aid in viral infection. Viruses elevate bacterial infection by impairing the host's immune response, disrupting epithelial barrier integrity, expression of surface receptors and adhesion proteins, direct binding of virus to bacteria, altering nutritional immunity, and effecting the bacterial biofilm. Similarly, the bacteria enhance viral infection by altering the host's immune response, up-regulation of adhesion proteins, and activation of viral proteins. During co-infection, respiratory bacterial and viral pathogens were found to adapt and co-exist in the airways of their survival and to benefit from each other, i.e., there is a cooperative existence between the two. This review comprehensively reviews the mechanisms involved in the synergistic/cooperativity relationship between viruses and bacteria and their interaction in clinically relevant respiratory infections.

Statistical Analysis of Common Respiratory Viruses Reveals the Binary of Virus-Virus Interaction

Respiratory viruses may interfere with each other and affect the epidemic trend of the virus. However, the understanding of the interactions between respiratory viruses at the population level is still very limited. We here conducted a prospective laboratory-based etiological study by enrolling 14,426 patients suffered from acute respiratory infection (ARI) in Beijing, China during 2005 to 2015. All 18 respiratory viruses were simultaneously tested for each nasal and throat swabs collected from enrolled patients using molecular tests. The virus correlations were quantitatively evaluated, and the respiratory viruses could be divided into two panels according to the positive and negative correlations. One included influenza viruses (IFVs) A, B, and respiratory syncytial virus (RSV), while the other included human parainfluenza viruses (HPIVs) 1/3, 2/4, adenovirus (Adv), human metapneumovirus (hMPV), and enterovirus (including rhinovirus, named picoRNA), α and β human coronaviruses (HCoVs). The viruses were positive-correlated in each panel, while negative-correlated between panels. After adjusting the confounding factors by vector autoregressive model, positive interaction between IFV-A and RSV and negative interaction between IFV-A and picoRNA are still be observed. The asynchronous interference of IFV-A significantly delayed the peak of β human coronaviruses epidemic. The binary property of the respiratory virus interactions provides new insights into the viral epidemic dynamics in human population, facilitating the development of infectious disease control and prevention strategies. IMPORTANCE Systematic quantitative assessment of the interactions between different respiratory viruses is pivotal for the prevention of infectious diseases and the development of vaccine strategies. Our data showed stable interactions among respiratory viruses at human population level, which are season irrelevant. Respiratory viruses could be divided into two panels according to their positive and negative correlations. One included influenza virus and respiratory syncytial virus, while the other included other common respiratory viruses. It showed negative correlations between the two panels. The asynchronous interference between influenza virus and β human coronaviruses significantly delayed the peak of β human coronaviruses epidemic. The binary property of the viruses indicated transient immunity induced by one kind of virus would play role on subsequent infection, which provides important data for the development of epidemic surveillance strategies.