<i>Mycoplasma pneumoniae</i> Carriage With De Novo Macrolide-Resistance and Breakthrough Pneumonia.

Abstract

<i>Mycoplasma</i> <i>pneumoniae</i> pneumonia is prevalent in children and can be followed by upper airway carriage for months. Treatment of <i>M pneumoniae</i> pneumonia with macrolides is widespread and can lead to the development of macrolide resistance. The clinical consequences of chronic <i>M pneumoniae</i> carriage are unknown. In this article, we describe a child with acute lymphoblastic leukemia who developed macrolide-susceptible <i>M pneumoniae</i> pneumonia confirmed by nasopharyngeal secretions polymerase chain reaction and culture with good response to azithromycin. Five months later, the patient developed another <i>M pneumoniae</i> pneumonia that was diagnosed with positive macrolide-resistant <i>M pneumoniae</i> polymerase chain reaction and culture from the bronchoalveolar lavage. The child responded well to fluoroquinolones and eventually was discharged from the hospital. The <i>M pneumoniae</i> recovered from the second pneumonia is a novel strain and is genetically identical to the <i>M pneumoniae</i> that caused the first pneumonia, apart from the macrolide-resistance 23S ribosomal RNA gene. Both isolates are identical in both P1 (subtype 2 with a novel variant, 2bv) and multiple-locus variable number tandem repeat analysis type (53662). This is indicative of chronic <i>M pneumoniae</i> carriage with de novo macrolide-resistance mutation and subsequent breakthrough pneumonia that is reported for the first time here. Children with immunosuppression may be at increased risk of life-threatening macrolide-resistant pneumonia after <i>M pneumoniae</i> carriage. Further studies are required to evaluate the impact of this phenomenon. This will then guide strategies to limit the associated morbidity, such as testing for macrolide resistance, treatment of <i>M pneumoniae</i> pneumonia in high-risk children with bactericidal antibiotics (such as fluoroquinolones), and possibly eradication protocols of <i>M pneumoniae</i> carriage to prevent subsequent life-threatening infections.