Diagnostic Value of Fluorescent Quantitative Polymerase Chain Reaction for Mycoplasma Pneumoniae Pneumoniae in Children with Mycoplasma Pneumoniae Pneumonia

Objective To evaluate the diagnostic value of fluorescent quantitative polymerase chain reaction(PCR) for Mycoplasma pneumoniae (MP) in children with MP pneumonia(MPP).Methods From Jun.2008 to Jan.2009,153 cases hospitalized with pneumonia were enrolled,and 30 cases without respiratory infection were enrolled as control group.Their respiratory secretion (including nasopharyngeal secretion,sputum,bronchialalveolar lavage fluid or pharyngeal swab) samples were collected for fluorescent quantitative PCR for MP.And their single or paired serums were collected for specific MP antibody detection.Results There were 123 cases confirmed with MPP by serology,among whom 114 cases were MP PCR positive.The quantitation of MP DNA was among 1.20×106-3.66×1010 gene copys/L. There were 30 cases with pneumonia negative with MP by the paired serum serology,among whom 2 cases were MP PCR positive,and the quantitation of MP DNA was (1.08-3.02)×107gene copys/L.All cases of control group were MP PCR negative.During the first and second weeks of the MPP onset,the sensitivity of MP-IgM from the first single blood samples were 66.7% and 83.9%,respectively.While the sensitivity and specificity of MP PCR were 92.7% and 93.3%,respectively.From the third week of the disease onset,the sensitivity of MP-IgM from the first single blood samples increased to 90.9%-100%.The clinical manifestations of MPP were nonspecific.Conclusions PCR is superior to serology for early diagnosis on MP infection.Combination of the 2 methods may be helpful to early and accurate diagnosis on MP infection.