[Streptococcus pyogenes and Mycoplasma pneumoniae: pulmonary coinfection or serologic artefact?]

How should Mycoplasma pneumoniae seroconversion be interpreted in a patient with community-acquired Streptococcus pyogenes pneumonia?A 21-year-old man with cerebral palsy was hospitalized with acute pneumonia and fever. The bronchoalveolar lavage fluid contained Streptococcus pyogenes, and serological testing for Mycoplasma pneumoniae was positive. At 4 weeks, measurements of anti-M. pneumoniae and antistreptolysin O antibodies were positive.Two hypotheses should be considered: the patient has either a coinfection of S. pyogenes and M. pneumoniae or a nonspecific antibody response during a severe S. pyogenes infection.