Invasive disease due to Streptococcus pyogenes in a patient with A H1N1 influenza infection. Report of one caseBacterial superinfection is a known complication among patients affected by viral respiratory tract infections.Streptococcus pyogenes, a major bacterial agent involved in acute tonsillopharyngitis, skin and soft tissue infections, was reported as a co-infecting microorganism during the 2009 A H1N1 influenza pandemic.We report a 65-year-old male patient who evolved with multifocal pneumonia and multiple organ failure with a fatal outcome.Influenza A H1N1 was detected by a polymerase chain reaction-based technique from a tracheal aspirate sample.S. pyogenes was identified by a rapid test from a nasopharyngeal sample and isolated afterwards from a positive blood culture.(