title: Early Serologic Diagnosis of Mycoplasma pneumoniae Pneumonia: An Observational Study on Changes in Titers of Specific-IgM Antibodies and Cold Agglutinins.
abstract: There have been some limitations on early diagnosis of Mycoplasma pneumoniae (MP) infection because of no immunoglobulin M (IgM) responses and variable detection rates of polymerase chain reaction in the early stage of the disease. We wanted to discuss regarding early diagnostic method using short-term paired titration of MP-specific IgM and cold agglutinins (CAs) in the early stage of MP pneumonia.The participants of this study were 418 children with MP pneumonia during 2 recent epidemics (2006-2007 and 2011), and they were diagnosed by an anti-MP IgM antibody test (Serodia Myco II) examined twice during hospitalization at presentation and around discharge (mean of 3.4 ± 1.3 days apart). CA titers were simultaneously examined twice during study period. Anti-MP IgM antibody titer ≥1:40 and CA titer ≥1:4 were considered positive, respectively. The relationships between 2 IgM antibodies in the early stage were evaluated.Regarding MP-specific antibody titers, 148 patients showed a seroconversion, 245 patients exhibited increased titers, and 25 patients had unchanged higher titers (≥1:640) during hospitalization. The median MP-specific antibody titers at each examination time were 1:80 and 1:640, respectively; those of CAs were 1:8 and 1:32, respectively. Illness duration prior to admission showed a trend of association with both titers, and patients with shorter illness duration had a higher rate of negative titers or lower titers at each examination time. CAs and MP-specific antibody titers were correlated in the total patients at presentation and at 2nd examination (P < 0.001, respectively), and the diagnostic corresponding rates of CAs to IgM antibody test were 81% to 96% in patient subgroups.Short-term paired MP specific-IgM determinations in the acute stage may be used as a definitive diagnostic method for MP pneumonia. Paired CA titers showed a correlation with MP-specific antibody titers, suggesting they can be used as an adjuvant diagnostic method.
authors.affiliation: From the Department of Pediatrics, College of Medicine (S-CL, Y-SY, J-WR, J-HK, K-YL), The Catholic University of Korea, Seoul; and Department of Pediatrics (Y-SY, J-WR, K-YL), The Catholic University of Korea Daejeon St. Mary's Hospital, Daejeon, Republic of Korea.
authors.forename: Sung-Churl
authors.initials: SC
authors.lastname: Lee
authors.forename: You-Sook
authors.initials: YS
authors.lastname: Youn
authors.forename: Jung-Woo
authors.initials: JW
authors.lastname: Rhim
authors.forename: Jin-Han
authors.initials: JH
authors.lastname: Kang
authors.forename: Kyung-Yil
authors.initials: KY
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D000907:Antibodies, Bacterial / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D015941:Complement Hemolytic Activity Assay / Q000379:methods; D003450:Cryoglobulins / Q000032:analysis; D042241:Early Diagnosis; D005260:Female; D006760:Hospitalization; D006801:Humans; D007075:Immunoglobulin M / Q000097:blood* / Q000276:immunology; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009177:Mycoplasma pneumoniae / Q000276:immunology*; D011019:Pneumonia, Mycoplasma / Q000097:blood / Q000175:diagnosis* / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D003450:Cryoglobulins; D007075:Immunoglobulin M; C029443:cold agglutinins