Pediatric clinical features of Mycoplasma pneumoniae infection are associated with bacterial P1 genotype

The present study evaluated the association between different Mycoplasma pneumoniae (M. pneumonia) genotypes and clinical features of pediatric patients. Subjects were children diagnosed with community-acquired pneumonia at the Children's Hospital of Soochow University (Suzhou, China) from January 2012 to December 2013. Clinical and laboratory tests were conducted and clinical samples positive for M. pneumoniae were genotyped by nested-multiplex polymerase chain reaction. Three type I strains and three type II strains were also randomly selected for sequencing. A total of 335 clinical samples positive for M. pneumoniae were obtained. The average age of M. pneumonia-infected pediatric patients was 4.8±3.3 (years). Genotyping results identified 304 positive samples as group I strains and 30 samples as group II strains, in which 1 sample was type II variant 2a. It was also observed that point mutations were more likely to occur in type I strains compared with type II strains. Although clinical pulmonary infection scores between patients with type I and type II strains did not significantly differ, patients with type I strains had a higher risk of developing severe M. pneumoniae pneumonia (SMPP) and extrapulmonary complications, and had significantly higher percentages of peripheral blood neutrophils than patients with type II strains (P<0.05). Collectively, these data indicate that the predominant strains of M. pneumoniae in Suzhou between 2012 and 2013 were type I, and that pediatric pneumonia patients with type I strains of M. pneumoniae were more likely to progress to SMPP.