Importance de la PCR dans la gestion d’une épidémie à Mycoplasma pneumoniae au centre hospitalier de Béthune (Pas-de-Calais)

SUBJECT: Molecular amplification (PCR) provides adequate rapid and specific diagnosis of Mycoplasma pneumoniae infection (first agent responsible for community-wide bacterial pneumonia in children above 5 years of age). METHOD: Positive (Chlamylège(®), Argène) PCR in nasopharyngeal aspirate, respiratory samples and nasopharyngeal swab and/or positive serological test (ELISA). RESULTS: Diagnosis of M. pneumoniae infection in 39 cases: 31 between September and December 2008 (30 children and one adult) and eight since June 2009 (three adults and five children). Children (mean age: 3.6 years) were hospitalized in 88.6% of cases, mean hospitalization duration was 2.9 days for respiratory tract infections, mainly due to lack of response to β-lactamines therapy (65.7%). Four adults (mean age: 29.5 years) presented a pneumonia, with hospitalization for three of them with one in intensive care unit. Twenty-eight PCR have proved positive (87%): without associated serology (13), eight negative serologies, IgG and IgM positive (five), and IgG alone (two). Seven patients had only serological test for diagnosis: IgM ± IgG. For two children, IgM positive only in isolation, with a PCR probably false negative. CONCLUSION: The sensitivity of the serology in the diagnosis of mycoplasma infection is limited: IgM, which appear traditionally 1 week after clinical signs are mostly inexistent for adults and IgG rise at a later stage. Early diagnosis of child pneumoniae by PCR helped rapidly characterize this epidemic phenomenon and adapt the treatment.