The pulmonary characteristics of Staphylococcus aureus (S. aureus) co-infection with respiratory viruses, such as SARS-CoV-2 and influenza virus, are still unclear. Case series: Two patients with methicillin-susceptible S. aureus (MSSA) infection in the lungs co-infected with either SARS-CoV-2 or influenza virus are reported. Case 1 was a 66-year-old woman who was admitted with SARS-CoV-2 infection. Her chest X-ray and computed tomography (CT) showed multiple cavity formations with infiltration shadows, and MSSA was detected from her sputum and blood, suggesting COVID-19-related bacterial pneumonia and pulmonary embolism. No catheters had been used, but she had skin eruptions and a history of SARS-CoV-2 vaccination. Ampicillin/sulbactam (ABPC/SBT) was administered, and she finally improved. Case 2 was an 87-year-old man with a history of atopic dermatitis who was admitted with moderate pneumonia, and influenza virus co-infection was found. He showed multiple cavitary shadows, and MSSA was isolated from both his sputum and blood. He was diagnosed with influenza-related bacterial pulmonary embolism. No catheters had been used, but he had a history of influenza vaccination. He was also treated by ABPC/SBT and finally improved. Conclusions: These cases suggest that MSSA showed affinity to the lungs when co-infected with either SARS-CoV-2 or influenza virus, and it presented as septic emboli without catheter use. We should consider MSSA infection when patients have SARS-CoV-2 or influenza virus co-infection, and multiple cavity formation and skin disorders are seen, even though they were vaccinated and no catheters were used.

Central line-associated bloodstream infections (CLABSIs) are important hospital-acquired infections that are related to increased mortality in cardiac intensive care units (CICUs). To determine the risk factors for CLABSIs, a case-control study was conducted in the CICU of our hospital. Emergency surgery (odds ratio: 9.6, 95% confidence interval: 1.633-56.926) was the strongest risk factor comparing the case group (n=11) to the control group (n=22). In addition, the indwelling period was significantly longer in the case group than in the control group (median 9 days versus 7 days, p=0.004). An intervention for the insertion of central lines was then started, with 1) thorough use of chlorhexidine-impregnated dressings (also known as chlorhexidine patches, CHG patches) in the insertion of central lines before emergency surgery, and 2) exchange of the central line 7 days after emergency surgery. After the intervention, the CLABSI incidence rate decreased from 6.8 to 0.8/1,000 device-days. These data suggest the usefulness of CHG patches and the importance of the early exchange of central lines in the CICU in patients following emergency surgery.