Respiratory viruses such as influenza virus and novel coronavirus seriously threaten human health. Secondary bacterial infection is the main complication of respiratory virus infection and the main cause of severe cases or deaths of the patients. Among the bacterial infection after the respiratory virus infection, the commonest should be Gram-positive bacteria-streptococcus pneumoniae. The elderly and patients with low immunity or chronic lung disease are vulnerable to the secondary infection of Gram-negative bacteria (such as pseudomonas aeruginosa), which are more difficult to treat and have worse prognosis. Therefore, the mechanism of secondary Gram-negative bacterial infection after the respiratory virus infection and its intervention strategies were revealed and explored to provide reference for the clinical treatment of such cases.

Recently, the team led by Chen Ling with the SKLRD achieved some headway in this field, with relevant research findings published on the international academic journals of Microbiology Spectrum and Journal of Thoracic Disease respectively with the titles of “Influenza Virus Infection Increases Host Susceptibility To Secondary Infection with Pseudomonas aeruginosa, and This Is Attributed To Neutrophil Dysfunction through Reduced Myeloperoxidase Activity” and “Active immunization with Pseudomonas aeruginosa vaccine protects mice from secondary Pseudomonas aeruginosa challenge post-influenza virus infection”.

In order to simulate the patients of secondary bacterial infection after respiratory virus infection, the researchers established a model of mice killed by the secondary pseudomonas aeruginosa infection after influenza virus infection and discovered that after such secondary infection occurred, the influenza infection symptoms of the mice worsened, the mortality increased significantly, accompanied by severe lung damage and inflammatory cellular infiltration. It was further discovered that the influenza virus infection had impaired the activity of MPO in lung neutrophils and weakened the phagocytosis and digestion functions of Pseudomonas aeruginosa. Meanwhile, the research has explored its intervention strategy and discovered that before the said secondary infection, the use of BCG-PSN, anti-influenza virus immunoserum therapy, or the immune inactivated Pseudomonas aeruginosa vaccine can improve the symptoms and mortality of the mice after the said secondary infection. This research suggests that during the secondary bacterial infection after respiratory virus infection, it is vital to the improvement of symptoms by improving the functions of neutrophils, receiving antiviral treatment as early as possible and immune bacteria vaccines . The research is of guidance for the prevention and treatment of the secondary bacteria infection after the current rampant Covid-19 infection.

Original paper：

1、https://journals.asm.org/doi/10.1128/spectrum.03655-22?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed

2、https://dx.doi.org/10.21037/jtd-22-1012