A seroepidemiologic study of Chlamydia pneumoniae in Rhode Island. Evidence of serologic cross-reactivity.
OBJECTIVE
Although Chlamydia pneumoniae is considered a common cause of pneumonia worldwide, the evidence is mainly serologic. Therefore, we examined whether the currently used chlamydial microimmunofluorescence (MIF) antibody test is specific for C pneumoniae infection.


METHODS
Secondary analysis of data from a cohort study of sarcoidosis among the graduates of ten consecutive apprenticeship classes of firefighters and police officers.


METHODS
One hundred forty-seven young adult men.


METHODS
Immunoglobulin G and M antibodies to C pneumoniae, 15 serovars of C trachomatis, and 2 strains of C psittaci as measured by MIF.


RESULTS
Evidence of previous C pneumoniae and C trachomatis infection (IgG > or = 1:16 yet < 1:512) was present in 108 (73 percent) and 59 (40 percent) subjects, respectively. Serologic evidence of recent C pneumoniae and C trachomatis infection (IgM > or = 1:16 or IgG > or = 1:512) was present in 19 (13 percent) and 14 (10 percent) subjects, respectively. Chlamydia pneumoniae and C trachomatis IgM titers were highly correlated (r = 0.80; 95 percent CI, 0.73 to 0.85) while C pneumoniae and C trachomatis IgG titers were fairly correlated (r = 0.44; 95 percent CI, 0.30 to 0.56).


CONCLUSIONS
The C pneumoniae seroprevalence of 86 percent is the highest yet reported. The correlations between C pneumoniae and C trachomatis antibody titers suggest that chlamydial MIF may be less specific than is generally appreciated. Moreover, the observed 13 percent seroprevalence of recent C pneumoniae infection in a healthy working population challenges the serologically based belief that this agent accounts for 6 to 10 percent of community-acquired pneumonia. A more objective, more specific test is needed in the serodiagnosis of C pneumoniae infection.
Kern
D G
DG
Division of General Internal Medicine, Memorial Hospital, Providence, RI 01860.
Neill
M A
MA
Schachter
J
J
D000328:Adult; D000907:Antibodies, Bacterial / Q000032:analysis*; D002690:Chlamydia Infections / Q000453:epidemiology* / Q000276:immunology; D002692:Chlamydia trachomatis / Q000276:immunology; D016993:Chlamydophila pneumoniae / Q000276:immunology*; D002691:Chlamydophila psittaci / Q000276:immunology; D003429:Cross Reactions; D005455:Fluorescent Antibody Technique; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D008171:Lung Diseases / Q000382:microbiology; D008297:Male; D016017:Odds Ratio; D011014:Pneumonia / Q000382:microbiology; D012237:Rhode Island / Q000453:epidemiology; D012507:Sarcoidosis / Q000382:microbiology; D016036:Seroepidemiologic Studies; D012698:Serologic Tests
D000907:Antibodies, Bacterial; D007074:Immunoglobulin G