The incidence of Chlamydia psittaci antibodies in patients with respiratory tract diseases

Abstract

The incidence of Chlamydia psittaci infections in Hamburg has been studied using the complement fixation test on 655 human sera collected from patients with respiratory tract diseases. Of the 653 sera investigated, 78 (11.9%) showed antibody titers between 1:8 and 1:128. Of the positive sera, 21 (16.9%) presented values of greater than or equal to 1:32. This infection is encountered more often in individuals over 21 years of age (15.9% to 23.4%) than in persons under 20 (0.8% to 6.0%). General practitioners' attention must be drawn to Chlamydia psittaci infections, since they seem to be of greater importance in human pathology than is generally assumed.

ELISPOT assay for chlamydia-specific, antibody-producing cells correlated with conventional complement fixation and microimmunofluorescence

“…There is evidence that the seroprevalence rate for TWAR increases with age and that seroreactors to chlamydia may approach 60% (20) in some clinics where higher prevalences exist. The high incidence of Chlamydia etiology in pulmonary diseases has also been previously referenced (2). Diagnosis of chlamydial cases as having confirmed TWAR or psittaci etiology always has been problematic because serology by conventional CF or MIF does not clearly delineate species specificity of the cross-reacting chlamydia antibody (1,14,21).…”

“…Serologic tests for C. psittaci serology can be positive in 16-23% of individuals (depending on age group) with respiratory tract infections (2). C. trachomatis has been shown to induce proliferation and differentiation of human peripheral B lymphocytes.…”

“…Further ELISPOT applications have been successful in species differentiation (11,12). Previously, differentiating C. pneumoniae (TWAR) from C. psittaci infections by conventional complement fixation (CF) (13) and microimmunofluorescence (MIF) has met with limited success (2,14). More refined methods of ELISPOT have been developed (15,16) that might be applied for earlier detection of chlamydial antibody production at the molecular level for the single cell.…”

“…Positive specimens had median levels of ASC above 8 per 10 6 cells (range 15-23 ASC/10 6 cells). Evidence that the ELISPOT is reliable, sensitive, and specific includes the following: (1) immunized animal and clinical human specimens in control experiments were selectively reactive in the presence of antigen, but negative without antigen, (2) serologically characterized reference sera demonstrated homologous rather than heterologous reactions with the antigens, (3) conventional complement fixation and microimmunofluorescence on serum fractions of clinical specimens correlated well (P<0.02) with ELISPOT results that were both TWAR-and psittaci-positive, and (4) the array of specimens (from healthy donors, community hospitalized, and pulmonary service patients) selected for their increasing likelihood in that order for being positive due to illness was then confirmed and supported by their respectively increasing positivity rates (6,15, and 25%) for TWAR/psittaci combined. The incidence of positive specimens for either TWAR or psittaci was greatest (23/54, 43%) in specimens from the hospitalized patients and least (8/33, 24%) in specimens from healthy individuals.…”