Staphylococcus aureus pneumonia complicated with lower limb gangrene secondary to influenza A virus：a case report

<title>Abstract</title> Background Millions of people worldwide die from lower respiratory tract infections every year, and a significant portion of these deaths can be attributed to seasonal influenza virus infections, due to the continuous emergence of new variants of influenza A virus (IAV) and secondary bacterialinfection with other viruses or bacteria. This report describes a female patient with IAV who secondary bacterial infection with <italic>Staphylococcus aureus</italic> and lower limb gangrene. Case presentation The patient was a 39-year-old female who had persistent cough, sputum and tight breath for 2 days, worsening for 11+hours. She received VV-ECMO treatment for severe pneumonia. Her alveolar lavage fluid showed Staphylococcus aureus, Influenza A virus was positive for H3N2. After anti infection treatment, the patient's condition improved, and gangrene occurred in the lower limbs and amputation surgery was performed. Conclusions <italic>Subsequent aureus </italic>infections after influenza can exacerbate respiratory failure in patients, leading to multiple organ dysfunction and even endangering patient safety. Early identification, identification of pathogens, and effective anti-infection treatment can improve prognosis.