title: [Detection of serum Chlamydia pneumoniae antibodies and analysis of epidemiologic data in 5 years].
abstract: OBJECTIVE
  To detect serum Chlamydia pneumoniae (C.pneumonia) antibodies and analyze the epidemiologic data.
  
  
  METHODS
  Micro-immunofluorescence (MIF) was used to detect IgG and IgM antibodies against C.pneumoniae in 7 802 serum specimens from May 2008 to September 2013. C.pneumoniae past or recent infections were determined based on specific IgG and IgM antibodies and their titers. The analysis of relationship between age, gender and other clinical factors associated with antibody titers was performed.
  
  
  RESULTS
  The positive rate of C.pneumonia IgG antibodies ( ≥ 1: 16 and <1: 512) was 87.5% (6 827/7 802). And the lowest rate of 50.6% (78/154) was shown in patients of 2-4 years age group while the highest rate of 98.7% (1 277/1 294) in those above 70 years old. The average geometric mean titer (GMT) of C.pneumonia IgG antibodies was 43.9. GMT in males was significantly higher than that in females (45.8 vs 41.9, P = 0.000 1). And 282 (3.6%) patients were diagnosed with recent C.pneumoniae infection (IgG ≥ 1: 512 or IgM ≥ 1: 16 or acute and convalescent serum antibody titers turned to positive or four times and more elevated). The lowest rate of 0.5% (2/417) was detected in < 2-year-old patients while the highest rate of 6.7% (24/357) in 10-14-year-old group patients. The miss ratio was as high as 68.1% (192/282) if C.pneumoniae IgM antibody was used as an only criteria for C. pneumoniae recent infection. The recent infection rates in patients with autoimmune diseases (7.1% (24/336) ) and those with pneumonia/chest radiological shadow findings (4.7% (69/1 467)) were statistically higher than the average rate (3.6%) of total population (P = 0.000 4, 0.014 0).
  
  
  CONCLUSIONS
  The positive rate of C.pneumonia IgG antibody is quite high in the population. And the GMT of C.pneumoniae IgG antibody in males is significantly high than that in females. Recent C.pneumonia infection is to be missed if IgM antibody is used as a sole criterion.
authors.affiliation: Department of Clinical Laboratories, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, China.
authors.forename: Jingtao
authors.initials: J
authors.lastname: Cui
authors.affiliation: Department of Clinical Laboratories, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, China.
authors.forename: Wenjuan
authors.initials: W
authors.lastname: Yan
authors.affiliation: Department of Clinical Laboratories, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, China. Email: niap@pumch.cn.
authors.forename: Anping
authors.initials: A
authors.lastname: Ni
authors.affiliation: Department of Clinical Laboratories, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, China.
authors.forename: Lingjun
authors.initials: L
authors.lastname: Kong
authors.affiliation: Department of Clinical Laboratories, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, China.
authors.forename: Lanlan
authors.initials: L
authors.lastname: Chen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000907:Antibodies, Bacterial / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D002690:Chlamydia Infections / Q000097:blood* / Q000453:epidemiology* / Q000276:immunology; D016993:Chlamydophila pneumoniae / Q000276:immunology; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D016036:Seroepidemiologic Studies; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial; D007074:Immunoglobulin G; D007075:Immunoglobulin M