COVID-19 complicated with severe M1-lineage Streptococcus pyogenes infection in elderly patients: A report of two cases.

Case 1: A 71-year-old man was admitted to our hospital with progressive fever and dyspnea, which had developed three days after the onset of COVID-19. Initial chest computed tomography (CT) revealed a pulmonary lesion consistent with a secondary bacterial infection. Streptococcus pyogenes was isolated from cultures of primary sputum collected from the endotracheal tube, and identified as the causative microorganism.